Category Archives: Hurricane

Hurricane Nate Updated

Update Thursday AM

As expected, Nate emerged as a named storm over night. The storm is now interacting withland in Central America and is therefore having trouble getting organized. And, as expected given the uncertainty this causes, the forecasts are unclear on future intensity. The most recent National Hurricane Center projection has Nate Maxing out as a much weaker storm than yesterday’s projection suggested. And, the center of the expected path of the storm has shifted west and is now centered roughly on New Orleans.

After leaving Central America, Nate is expected to pass just over the eastern Yucatan as a tropical storm. That’s thea rea of Cancune and the Maya Riviera, which has seen its share of bad storms. Nate will probably be departing that area and moving out over the Gulf, still as a tropical storm, early Saturday morning.

Between Saturday morning and Sunday Morning, Nate will have turned into an actual Hurricane, Category I, perhaps with maximum sustained winds of around 75 miles per hour. Then, during the day Sunday, the storm will come ashore with the center somewhere between a point west of New Orleans and a point west of Tallahasse. That would be the center of the storm, not the full effect.

The National Weather Service is not yet issuing information on storm surges.

When people hear about Nate they say, “Only a Category I, no big deal.” I was in a weak Category II/Category I hurricane once. I walked around in it. It seemed like a really strong Nor’easter, not much more. Meanwhile, some 60 miles away, my sister-in-law’s house, way up on a hill overlooking the ocean, was 100% covered with the sea. She had seaweed in her attic, crabs in her bathroom, and bluefish in kitchen. All I’m saying is that just because some hurricanes get called “major” does not mean that the other ones are “minor.”

Update Wed PM:

As expected, the intensification projected for this storm has been upgraded a bit but it still likely to stay in the Category 1 range, with landfall on the Gulf coast (tentatively) at around 5PM Sunday, so strong winds etc. affecting the coast starting any time over the weekend.

There are now some projected tracks that put the center of the storm right in New Orleans, others that keep it over the Florida panhandle. On one hand it is too early to say, but on the other hand, the storm is forming fairly quickly and will move fairly quickly to make a landfall in just a few days.

Original Post:

The next named storm in the Atlantic Hurricane Basin will be called Nate. There is currently a tropical depression located not far from Nicaragua that is expected to become a named storm pretty soon. It may pass over or interact with land between now and Friday, but if it does what the experts project, some time between Friday mid day and Saturday PM, it will be over very warm waters in the Gulf of Mexico, heading mostly north, and turning into a hurricane. It will likely remain a Category I hurricane until making landfall on the Gulf Coast by the end of the day Sunday. Location of landfall of the center of the storm is between some point east of New Orleans and some point north of Tampa, with the general area of Tallahassee being the current, but subject to change, bulls-eye.

This is all fairly speculative at the moment. The track seems very likely but it can change. The most important change that could happen is that the storm turns out to be stronger than currently anticipated. I say this simply because unexpected strengthening seems to be association with warm deep waters, which is a fairly new phenomenon. As far as I know, meteorological science is silent on this issue, and this is just my gut feeling. But if a storm doing what this storm is doing is projected as having 80 mph winds near landfall, I’d leave open the possibility of stronger winds closer to 100 mph. If so, the storm would be a weak Category 2. Again, this is just a guess.

As indicated in the graphic above, an experimental NWS product, tropical storm force winds could arrive in the keys by late Friday PM, and along the gulf coast near NOLA and the panhandle overnight Saturday.

Hurricane Maria

As you already know, Hurricane Maria is a Category 5 storm menacing the Leewards, and heading, likely, for Puerto Rico.

Please avoid making the mistakes that were made in talking about Irma. There will probably be no Category 5 storm hitting Puerto Rico. The storm will probably be a Category 4 before it hits. So, reporters will sloppily declare that “a category 5 storm is heading for Puerto Rico” then later Rush Limberger will say “Look there was never no such storm, see?” and so on.

But, a Category 4 storm is still nothing to sneeze into, and Puerto Rico and the other island in this storm’s path are in big trouble.

As we wait for that to develop further, let’s talk a bit about predicting hurricane seasons. A lot of people are arguing about whether or not global warming means more, or bigger, or whatever, Atlantic hurricanes. (Short answer: there are probably already more hurricanes in the Atlantic, and bigger ones, but they are hard to count because they are in fact rare events, and science says that there will likely be more in the future). One of the dumber counter arguments to science suggesting that there may be bigger storms, or more of them, is this: You can’t even predict the weather for next weekend, so what the heck, right?

The counter argument to that is this: Ok, fine, we don’t know very accurately what the weather is going to be like next weekend, but what would you say if I told you that we can do a pretty good job of telling, before the hurricane season starts, how many named storms there will be? Huh? Wouldn’t that be amazing?

Turns out we can. And the fact that we can suggests that we should be trusting the models, generally, and therefore, expecting more and bigger hurricanes.

I looked at the predictions made in several recent years by several groups that do this prediction, and found out that the total average wrongness averaging across all of them is down near one hurricane, with the range of wrongness being between -8 and 4, but with most of the predictions being within just a few one way or another.

First, a quick look at the number of named tropical storms in the Atlantic per year:

People will tell you there is no trend here, but as you can see, about 44% of the variation seen in the number of storms over time is accounted for by year, so there is a good argument that there is an increasing trend. One might argue that back in the 70s we missed some Hurricanes. That, I do not buy, but if you need to believe that, you can see there is still a trend from 1980 on. So there is an increase.

But I digress. Here’s the point I wanted to make with this graph. The number of hurricanes in a given year varies quite a bit, from 4 to 28 over this time period (and less over the most recent years). So, a method of prediction that gets within two or three in either direction is pretty good.

The number of named storms (many, usually most, of which will be hurricanes) that will happen in a give season in the Atlantic is predicted with reasonable accuracy by several groups. Here’s a chart showing several different prediction groups compared to reality.

The light blue line is the actual number, and you can see that except for 2011 and 2012, the number of storms predicted by various groups, and the number that occur, are very similar. Let’s assume 2011 and 2012 are strange years and arbitrarily ignore them (I know, this would normally be cheating but we’ll come back to that in a minute).

Looking only at those years, one prediction undershot by 4, one prediction undershot by 3, and 7 overshot by 3 or 4. The other 20 predictions were off by no more than two storms.

So, why is it OK to fudge the data like that? Well, it isn’t really, but the last two years of predictions have been off by one or fewer storms on average, and I’m assuming the predictions are getting better and better. In other words, if I were to lay odds on predicting three years in a row a few years in the future, I’d bet that the average difference between all the predictions an the actual observations would be less than one named storm, and I’d win that bet. For this reason I don’t care so much about older data.

Notice that I’m only using predictions made prior to the start of the season, not later updates which some groups do provide.

For this year, we’ve had 13 named storms so far, and all the various groups predicted 14. There is plenty of time to have a couple more storms, so likely, this year will be a bit more active than expected, but just by a couple of storms.

Back to Maria for a moment, you may be wondering if this storm will hit the coast along the lower 48. It is possible, it is too early to tell, but history and the models that exist so far both suggest that it probably will not, but stay tuned.

New Research on Assessing Climate Change Impact on Extreme Weather

Three statisticians go hunting for rabbit. They see a rabbit. The first statistician fires and misses, her bullet striking the ground below the beast. The second statistician fires and misses, their bullet striking a branch above the lagomorph. The third statistician, a lazy frequentist, says, “We got it!”

OK, that joke was not 1/5th as funny as any of XKCD’s excellent jabs at the frequentist-bayesian debate, but hopefully this will warm you up for a somewhat technical discussion on how to decide if observations about the weather are at all explainable with reference to climate change.


[source]

We are having this discussion here and now for two reasons. One is that Hurricane Harvey was (is) a very serious weather event in Texas and Louisiana that may have been made worse by the effects of anthropogenic global warming, and there may be another really nasty hurricane coming (Irma). The other is that Michael Mann, Elisabeth Lloyd and Naomi Oreskes have just published a paper that examines so-called frequentist vs so-called Bayesian statistical approaches to the question of attributing weather observations to climate change.

Mann, Michael, ElisabethLloyd, Naomi Oreskes. 2017. Assessing climate change impacts on extreme weather events; the case for an alternative (Baesian) approach. Climate Change (2017) 144:131-142.

First, I’ll give you the abstract of the paper then I’ll give you my version of how these approaches are different, and why I’m sure the authors are correct.

The conventional approach to detecting and attributing climate change impacts on
extreme weather events is generally based on frequentist statistical inference wherein a null hypothesis of no influence is assumed, and the alternative hypothesis of an influence is accepted only when the null hypothesis can be rejected at a sufficiently high (e.g., 95% or Bp = 0.05^) level of confidence. Using a simple conceptual model for the occurrence of extreme weather events, we
show that if the objective is to minimize forecast error, an alternative approach wherein likelihoods
of impact are continually updated as data become available is preferable. Using a simple proof-of-concept, we show that such an approach will, under rather general assumptions, yield more
accurate forecasts. We also argue that such an approach will better serve society, in providing a
more effective means to alert decision-makers to potential and unfolding harms and avoid
opportunity costs. In short, a Bayesian approach is preferable, both empirically and ethically.

Frequentist statistics is what you learned in your statistics class, if you are not an actual statistician. I want to know if using Magic Plant Dust on my tomatoes produces more tomatoes. So, I divide my tomato patch in half, and put a certain amount of Magic Plant Dust on one half. I then keep records of how many tomatoes, and of what mass, the plants yield. I can calculate the number of tomatoes and the mass of the tomatoes for each plant, and use the average and variation I observe for each group to get two sets of numbers. My ‘null hypothesis’ is that adding the magic dust has no effect. Therefore, the resulting tomato yield from the treated plants should be the statistically the same as from the untreated plants. I can pick any of a small number of statistical tools, all of which are doing about the same thing, to come up with a test statistic and a “p-value” that allows me to make some kind of standard statement like “the treated plants produced more tomatoes” and to claim that the result is statistically significant.

If the difference, though, is very small, I might not get a good statistical result. So, maybe I do the same thing for ten years in a row. Then, I have repeated the experiment ten times, so my statistics will be more powerful and I can be more certain of an inference. Over time, I get sufficient sample sizes. Eventually I conclude that Magic Plant Dust might have a small effect on the plants, but not every year, maybe because other factors are more important, like how much water they get or the effects of tomato moth caterpillars.

In an alternative Bayesian universe, prior to collecting any data on plant growth, I do something very non-statistical. I read the product label. The label says, “This product contains no active ingredients. Will not affect tomato plants. This product is only for use as a party favor and has no purpose.”

Now, I have what a Bayesian statistician would call a “prior.” I have information that could be used, if I am clever, to produce a statistical model of the likely outcome of the planned experiments. In this case, the likely outcome is that there won’t be a change.

Part of the Bayesian approach is to employ a statistical technique based on Bayes Theorem to incorporate a priori assumptions or belief and new observations to reach towards a conclusion.

In my view, the Bayesian approach is very useful in situations where we have well understood and hopefully multiple links between one or more systems and the system we are interested in. We may not know all the details that relate observed variation in one system and observed variation in another, but we know that there is a link, that it should be observable, and perhaps we know the directionality or magnitude of the effect.

The relationship between climate change and floods serves as an example. Anthropogenic climate change has resulted in warmer sea surface temperatures and warmer air. It would be very hard to make an argument from the physics of the atmosphere that this does not mean that more water vapor will be carried by the air. If there is more water vapor in the air, there is likely to be more rain. Taken as a Bayesian prior, the heating of the Earth’s surface means more of the conditions that would result in floods, even if the details of when, how much, and where are vague at this level.

A less certain but increasingly appreciated effect of climate change is the way trade winds and the jet stream move around the planet. Without going into details, climate change over the last decade or two has probably made it more likely that large storm systems stall. Storms that may have moved quickly through an area are now observed to slow down. If a storm will normally drop one inch of rain on the landscape over which it passes, but now slows down but rains at the same rate, perhaps 3 inches of rain will be dropped (over a shorter distance). What would have been a good watering of all the lawns is now a localized flood.

That is also potentially a Bayesian prior. Of special importance is that these two Bayesian priors imply change in the same direction. Since in this thought experiment we are thinking about floods, we can see that these two prior assumptions together suggest that a post-climate change weather would include more rain falling from the sky in specific areas.

There are other climate change related factors that suggest increased activity of storms. The atmosphere should have more energy, thus more energetic storms. In some places there should more of the kind of wind patterns that spin up certain kinds of storms. It is possible that the relationship between temperature of the air at different altitudes, up through the troposphere and into the lower stratosphere, has changed so that large storms are likely to get larger than they otherwise might.

There is very little about climate change that implies the reverse; Though there may be a few subsets of storm related weather that would be reduced with global warming, most changes are expected to result in more storminess, more storms, more severe storms, or something.

So now we have the question, has climate change caused any kind of increase in storminess?

I’d like to stipulate that there was a kind of turning point in our climate around 1979, before which we had a couple of decades of storminess being at a certain level, and after which, we have a potentially different level. This is also a turning point in measured surface heat. In, say, 1970 plus or minus a decade, it was possible to argue that global warming is likely but given the observations and data at the time, it was hard to point to much change (though we now know, looking back with better data for the previous centuries, that is was actually observable). But, in 2008, plus or minus a decade, it was possible to point to widespread if anecdotal evidence of changes in storm frequency, patterns, effects, as well as other climate change effects, not the least of which was simply heat.

I recently watched the documentary, “An Inconvenient Sequel.” This is a fairly misunderstood film. It is not really part two of Al Gore’s original “An Inconvenient Truth.” The latter was really Al Gore’s argument about climate change, essentially presented by him. “An Inconvenient Sequel” was made by independent film makers with no direct input by Gore with respect to contents and production, though it is mostly about him, him talking, him making his point, etc. But I digress. Here is the salient fact associated with these two movies.An Inconvenient Truth came out in May 2006, so it is based mainly on information available in 2005 and before. In it, there are examples of major climate change effects, including Katrina, but it seems like the total range of effects is more or less explicated almost completely. When An Inconvenient Sequell came out a few weeks ago, a solid 10+ years had passed and the list of actual climate effects noted in the movie was a sampling, not anything close to a full explication, of the things that had happened over recent years. Dozens of major flooding, storming, drying, and deadly heat events had occurred of which only a few of each were mentioned, because there was just so much stuff.

My point is that there is a reasonable hypothesis based on anecdotal observation (at least) that many aspects of weather in the current decade, or the last 20 years, or since 1979 as I prefer, are different in frequency and/or severity than before, because of climate change.

A frequentist approach does not care why I think a certain hypothesis is workable. I could say “I hypothesize that flies can spontaneously vanish with a half life of 29 minutes” and I could say “I hypothesis that if a fly lays eggs on a strawberry there will later be an average of 112 maggots.” The same statistical tests will be usable, the same philosophy of statistics will be applied.

A Bayesian approach doesn’t technically care what I think either, but what I think a priori is actually relevant to the analysis. I might for example know that the average fly lays 11 percent of her body mass in one laying of eggs, and that is enough egg mass to produce about 90-130 maggots (I am totally making this up) so that observational results that are really small (like five maggots) or really large (like 1 million maggots) are very unlikely a priori, and, results between 90 and 130 are a priori very likely.

So, technically, a Bayesian approach is different because it includes something that might be called common sense, but really, is an observationally derived statistical parameter that is taken very seriously by the statistic itself. But, philosophically, it is a little like the pitcher of beer test.

I’ve mentioned this before but I’ll refresh your memory. Consider an observation that makes total sense based on reasonable prior thinking, but the standard frequentist approach fails to reject the null hypothesis. The null hypothesis is that there are more tornadoes from, say, 1970 to the present than there were between 1950 and 1970. This graph suggests this is true…

Annual number of tornadoes for the period 1916-1995; the dashed line connecting solid circles shows the raw data, the red heavy solid line is the result of smoothing. Also shown in the green light solid line is the number of tornado days (i.e., days with one or more tornadoes) per year.

… but because the techniques of observation and measuring tornado frequency have changed over time, nobody believes the graph to be good data. But, it may not be bad data. In other words, the questions about the graph do not inform us of the hypothesis, but the graph is suggestive.

So, I take a half dozen meteorologists who are over 55 years old (so they’ve seen things, done things) out for a beer. The server is about to take our order, and I interrupt. I ask all the meteorologists to answer the question … using this graph and whatever else you know, are there more tornadoes in the later time interval or not? Write your answer down on this piece of paper, I say, and don’t share your results. But, when we tally them up, if and only if you all have the same exact answer (all “yes” or all “no”) then this pitcher of beer is on me.

Those are quasi-Bayesian conditions (given that these potential beer drinkers have priors in their heads already, and that the graph is suggestive if not conclusive), but more importantly, there is free beer at stake.

They will all say “yes” and there will be free beer.

OK, back to the paper.

Following the basic contrast between frequentist and Bayesian approaches, the authors produce competing models, one based on the former, the other on the latter. “In the conventional, frequentist approach to detection and attribution, we adopt a null hypothesis of an equal probability of active and inactive years … We reject it in favor of the alternative hypothesis of a bias toward more active years … only when we are able to achieve rejection of H0 at a high… level of confidence”

In the bayesian version, a probability distribution that assumes a positive (one directional) effect on the weather is incorporated, as noted above, using Bayes theorem.

Both methods work to show that there is a link between climate change and effect, in this modeled scenario, eventually, but the frequentist approach is very much more conservative and thus, until the process is loaded up with a lot of data, more likely to be wrong, while the bayesian approach correctly identifies the relationship and does so more efficiently.

The authors argue that the bayesian method is more likely to accurately detect the link between cause and effect, and this is almost certainly correct.

This is what this looks like: Frank Frequency, weather commenter on CNN says, “We can’t attribute Hurricane Harvey, or really, any hurricane, to climate change until we have much more data and that may take 100 years because the average number of Atlantic hurricanes to make landfall is only about two per year.”

Barbara Bayes, weather commenter on MSNBC, says, “What we know about the physics of the atmosphere tells us to expect increased rainfall, and increased energy in storms, because of global warming, so when we see a hurricane like Harvey it is really impossible to separate out this prior knowledge when we are explaining the storms heavy rainfall and rapid strengthening. The fact that everywhere we can measure possible climate change effects on storms, the storms seem to be acting as expected under climate change, makes this link very likely.”

I hasten to add that this paper is not about hurricanes, or severe weather per se, but rather, on what statistical philosophy is better for investigating claims linking climate change and weather. I asked the paper’s lead author, Michael Mann (author of The Madhouse Effect: How Climate Change Denial Is Threatening Our Planet, Destroying Our Politics, and Driving Us Crazy, The Hockey Stick and the Climate Wars: Dispatches from the Front Lines, and Dire Predictions, 2nd Edition: Understanding Climate Change), about Hurricane Harvey specifically. He told me, “As I’ve pointed out elsewhere, I’m not particularly fond of the standard detection & attribution approach for an event like Hurricane Harvey for a number of reasons. First of all, the question isn’t whether or not climate change made Harvey happen, but how it modified the impacts of Harvey. For one thing, climate change-related Sea Level Rise was an important factor here, increasing the storm surge by at least half a foot.” Mann recalls the approach taken by climate scientist Kevin Trenberth, who “talks about how warmer sea surface temperatures mean more moisture in the atmosphere (about 7% per degree C) and more rainfall. That’s basic physics and thermodynamics we can be quite certain of.”

The authors go a step farther, in that they argue that there is an ethical consideration at hand. In a sense, an observer or commenter can decide to become a frequentist, and even one with a penchant for very low p-values, with the purpose of writing off the effects of climate change. (They don’t say that but this is a clear implication, to me.) We see this all the time, and it is in fact a common theme in the nefarious politicization of the climate change crisis.

Or, an observer can chose to pay attention to the rather well developed priors, the science that provides several pathways linking climate change and severe weather or other effects, and then, using an appropriate statistical approach … the one you use when you know stuff … be more likely to make a reasonable and intelligent evaluation, and to get on to the business of finding out in more detail how, when, where, and how much each of these effects has taken hold or will take hold.

The authors state that one “… might therefore argue that scientists should err on the side of caution and take steps to ensure that we are not underestimating climate risk and/or underestimating the human component of observed changes. Yet, as several workers have shown …the opposite is the case in prevailing practice. Available evidence shows a tendency among climate scientists to underestimate key parameters of anthropogenic climate change, and thus, implicitly, to understate the risks related to that change”

While I was in contact with Dr. Mann, I asked him another question. His group at Penn State makes an annual prediction of the Atlantic Hurricane Season, and of the several different such annual stabs at this problem, the PSU group tends to do pretty well. So, I asked him how this season seemed to be going, which partly requires reference to the Pacific weather pattern ENSO (El Nino etc). He told me

We are ENSO neutral but have very warm conditions in the main development region of the Tropcs (which is a major reason that Irma is currently intensifying so rapidly). Based on those attributes, we predicted before the start of the season (in May) that there would be between 11 and 20 storms with a best estimate of 15 named storms. We are currently near the half-way point of the Atlantic hurricane season, and with Irma have reached 9 named storms, with another potentially to form in the Gulf over the next several days. So I suspect when
all is said and done, the total will be toward the upper end of our predicted range.

I should point out that Bayesian statistics are not new, just not as standard as one might expect, partly because, historically, this method has been hard to compute. So, frequency based methods have decades of a head start, and statistical methodology tends to evolve slowly.

Hurricane Irma: Important changes in intensity, changes in track

UPDATE Sept 9, AM

Note that tropical storm force winds may start hitting southern Florida around 1 or 2 PM today, Saturday, and will reach central Florida by about 8AM Sunday.

The eye of the storm should be abreast southern Florida at around sunup on Sunday. The storm may remain a major hurricane as it moves all along the west coast, reaching south of Tallahasse, still as a major hurricane, Monday morning.

Irma has interacted with Cuba more than previously expected. The storm also seems likely to move farther west than previously expected.

Moving over very warm waters over the next several hours will strengthen the storm. If it does move along the west coast of Florida the focus now shifts to different communities, such as the Cape Coral / Fort Myers area.

As a rule, storm surge risks on the west coast are greater than the east coast. The west coast has a broader shallow shelf, and since the hurricanes rotate counter clockwise, there is a greater chance of a direct hit. Correspondingly, the following storm surge map (most current version HERE), which has inundation of over 9 feet if conditions pertain in a given spot, is what we should be paying attention to:

It also seems to me that the keys are in more danger with this track than with the central track.

Here is a reasonable likely scenario, WHICH IS SUBJECT TO CHANGE based on current consensus.

Over-simply put, there are two things that determine the future location of a hurricane. One is the simple long distance movement of the major air mass that is our lower atmosphere. The hurricane is like a cork floating along in a stream. If the stream flow is steady and straight, the cork will be just down stream from where it is now, moving alongat an easily discernible rate, so the distance over a fixed time interval is easy to calculate.

The other factor is all the other stuff. The complex movement of other low pressure systems and ridges of high pressure, all that. The land and the ocean have their own things going with respect mainly to high and low pressure, so as a hurricane moves from being out at sea to being on or near land, these interactions grow increasingly complex. Over the next several hours, this second factor (everything else) takes over and this is where the prediction gets complicated. How much exactly will the storm change its angle of movement, and exactly at what hour will that occur and how long will it take?

So, the tack above looks pretty solid but it may in face be off by a hundred miles or even more before the storm is abreast of southern Florida. That difference will make all the difference in the world.

Update based on NWS advisory Sept 7, late PM

A Hurricane Warning is in effect for…
* Dominican Republic from Cabo Frances Viejo to the northern border
with Haiti
* Haiti from the northern border with the Dominican Republic to Le
Mole St. Nicholas
* Southeastern Bahamas and the Turks and Caicos Islands
* Cuban provinces of Camaguey, Ciego de Avila, Sancti Spiritus, and
Villa Clara
* Central Bahamas
* Northwestern Bahamas

Maximum sustained winds remain near 175 mph (280 km/h) with higher
gusts. Irma is a category 5 hurricane on the Saffir-Simpson
Hurricane Wind Scale. Some fluctuations in intensity are likely
during the next day or two, but Irma is forecast to remain a
powerful category 4 or 5 hurricane during the next couple of days.

Hurricane-force winds extend outward up to 70 miles (110 km) from
the center, and tropical-storm-force winds extend outward up to 185
miles (295 km).

The combination of a life-threatening storm surge and large breaking
waves will raise water levels ABOVE NORMAL TIDE LEVELS by the
following amounts within the hurricane warning area near and to the
north of the center of Irma. Near the coast, the surge will be
accompanied by large and destructive waves.

Turks and Caicos Islands…15 to 20 ft
Southeastern and central Bahamas…15 to 20 ft
Northwestern Bahamas…5 to 10 ft
Northern coast of the Dominican Republic…3 to 5 ft
Northern coast of Haiti and the Gulf of Gonave…1 to 3 ft
Northern coast of Cuba in the warning area…5 to 10 ft

RAINFALL: Irma is expected to produce the following rain
accumulations through Saturday evening:

Northeast Puerto Rico and the British and U.S. Virgin Islands…
additional 1 to 2 inches
Much of the Bahamas and Turks and Caicos…8 to 12 inches, isolated
20 inches
Andros Island and Bimini, Bahamas…12 to 16 inches, isolated 25
inches
Northern Dominican Republic and northern Haiti…4 to 10 inches,
isolated 15 inches
Southern Dominican Republic and southern Haiti…2 to 5 inches
Eastern and central Cuba…4 to 10 inches, isolated 15 inches
Southeast Florida and the upper Florida Keys…8 to 12 inches,
isolated 20 inches
Lower Florida Keys…2 to 5 inches

Update Sept 7, PM

Everything I said in the last post applies now except the chances of the storm making landfall on the Florida Peninsula, and even the chances of a fairly direct hit on Miami and surrounding areas, is much higher than it was this morning. But we are still talking about something that will happen in the middle of the weekend, and this is still Thursday.

Also, repeating, note that if this storm makes landfall at the southern tip of the Florida peninsula, it is expected to move north very quickly (about twidce as fast as it is moving now) and reach southern Georgia WHILE STILL BEING A HURRICANE. A land hurricane, if you will. Except of course huge parts of it will be handing out over the very warm Atlantic.

I heard a guy on the news today saying the only ticket he could get out of Florida was a one way flight to Memphis. The hurricane will be in the vicinity of Memphis, or at least central Tennessee/Kentucky, Tuesday. It will be a big wet storm at that time, but that is an area that floods so take it seriously.

This might be a good time to read this post if you haven’t already: Hurricane Landfall: What is it and don’t be stupid about it.
Update Sept 7, Mid Day

Storm surge watches have now been issued for South Florida. The experimental storm surge system of NWS suggests storm surges of up to 6 feet or so in a few places. But, the details of where storm surges may happen and how high they might be will probably sharpen a great day between now and Friday late PM.

Mean while, do the same with storm surge information as I asked you to do with the overall Hurricane information below. Recognize how this information is produced and what it means. There will NOT be a storm surge of the maximum amount indicate on the maps in all the areas covered by the map. The way to use the map is this: If you are in a particular spot with a possible storms surge, the map tells you your local worst case scenario, the scenario you should be prepared for even though something less is probably what is going to happen. If you assume less will happen and are washed out to sea and never seen again, don’t come complaining to me, because that is NOT what I said. If you are in a place where it says 6 foot surge, and you get a 3 foot surge, that is normal. Hopefully, though, you are no where hear the south Florida coast, right?

You can see the storm surge maps here.

Update Sept 7 AM

I want you to look at this graphic and understand its meaning:

There is about a 70% chance that the CENTER of Irma (the eye, approximately but not exactly) will remain between the two blue lines between midnight Saturday and midnight Sunday as it first interacts with Florida. In other words, between those two “m” markers. So, you have to start out by imagining the hurricane’s eye in the Gulf over by Cape Coral, and think about that for a moment. Then, you have to imagine the eye out near Freeport and think about that for a moment. With each of these scenarios, understand that the Miami and Miami Beech area is in a bad storm, windy, lots of rain, probably flooding, etc. but not Houston and not Andrew.

Now, look at the black line with the “M” markers on it. As you move from either blue line towards the black line, there is an increasing chance of the center of the storm being there. It is a bell curve, where the high point of the curve holds that black line. So there is a better chance that the center of the storm will be near Miami than Tampa or Freeport.

Now let’ consider the structure of the storm itself. Catastrophic sustained winds and gusts extend out from the center of the storm about the same width ad Florida itself, but as the storm approaches Florida it will weaken. The strongest wind and most severe storm tides are in the front right quadrant. So, if the storm comes on land in Florida along the southwest tip of the peninsula, that front right punch is going to only graze Miami but will obviously be very meaningful in the keys and everglades. If the center of the storm passes to the right of Miami about the same distance, perhaps Grand Bahama is toast, but Miami and Miami Beech is hit hard but it is a mere bad disaster.

What are the chances that the storm will essentially ride this black line all the way? Low. Maybe 10% chance. But if it does, or does something close to that, what happens?

There are three things to know, one of which I’ve already mentioned. That is that the front right is the most important part of the storm. So, if the storm is close to riding the line, but off to the right 10 miles, that is hugely different from if the storm is close to riding the line but off to the left 10 miles. The difference is in the survival of this urban area, potentially.

Second: Note that there is an M on the track south of Miami, and another one north quite a distance. The lower M corresponds to sustained winds of about 150mph, the upper M to sustained winds of 120 mph. So, as the storm moves over the area, it will weaken but it will be very strong anyway.

Third: The shape of the coastline, as discussed and depicted below, in an earlier update, means that the storm surge coming up into the Miami Beach area could be very high. The Hurricane Prediction Center has not posted storm surge estimates at this time, but depending on the exact path of the storm there could be many many feet of flooding over a very large area in and around Miami.

Or, again, the storm may be nothing more than a bad day for the Magic City. Remember that. We still do not know.

Beyond this, there is other complex bad news. Even if Irma scrapes the Atlantic coast of Florida, it may remain a hurricane all the way up to the Carolinas. If it misses Florida, it may go north and then hit the Carolinas with more force. Or it could go into the gulf, or miss everything. Still too early to tell, but Florida looks to be in some sort of trouble.

Remember, mainly, that despite what the news agencies are saying, there is currently no valid prediction of what Irma will do over the weekend. So, if it does something that you were not expecting, that’s you. You don’t get to say “but they said yada yada” because they are saying nothing more specific than the vague and rambling things I said above.

Update Sept 6, late AM

Just hours after the NWS five day put Irma dead in the middle of Florida’s south coast, the newest estimate is quite different. I point this out to underscore what I’ve been saying all along (and I hope you have not been ignoring): Five days out is too far to be accurate. Look:

Update Sept 6, AM

I keep seeing news phrases like “Irma has Puerto Rico in her sights.” Puerto Rico will have some very bad weather, but the main path of the storm has never crossed the island, and there is probably a less than 10% chance of a direct hit there, or less. The small islands of the northern Leewards have been hit directly or close to it, and more are in trouble. It seems most likely that the first larger body of land Irma might strike is Cuba, which has is almost entirely within the cone of probability, but south of the central line of expected movement. If the storm interacts a lot with Cuba, or turns into the island nation, that will be bad for Cuba, and Irma will weaken considerably. Meanwhile, the Bahamas and islands between Irma and the Bahamas are likely to get hit hard.

The more accurate three day forecast puts Irma as a Major Hurricane between Cuba and the Bahamas, or hitting Cuba or the Bahamas. The much less reliable five day forecast has Irma then curving north and striking the very tip of Florida and moving, as a major hurricane, onto the peninsula.

However, as a target, Florida is small compared to the cone of uncertainty Look:

Given this, it is distinctly possible that Irma will pass to the right (east) of Florida and head up the Atlantic. If that happens, it may then strike the mainland somewhere else, or not. Or, given this probability map, it is possible that Irma will pass to the left (west, gulf-side) of Florida, and go into the Gulf, then it will be pretty much impossible for the hurricane to not hit something.

The fact that the middle of this forecast graph is centered on Florida does not mean that it is more likely that the storm will hit Florida head on than not, given the wide margin of error and the relative narrowness of the state from this angle. I am emphasizing this because I don’t want to hear any bellyaching later if Irma skips Florida and hits Louisiana or South Carolina or something.

Either way, Irma is expected to be making whatever northerly turn it is going to make during the night time hours between Saturday and Sunday, and the current (but too far out to be certain of) projection is that Irma will be a Category 4 hurricane at that time. By Sunday night, Irma will have hit Florida, dead on, or not, and is expected to be a Category 3 hurricane on land and inland a ways, if that happens. In other words, worst case scenario includes southern Florida suffering a major hurricane for over 24 hours straight.

It has been said over and over again that the real risk of death in a hurricane is inland flooding that often happens after the hurricane has come ashore, and not so much from the coastal flooding and the winds. I’m not going to exactly dispute that but I want to complexify it a bit. If we count all the hurricane dead in the US, the most people who have died of hurricane effects were killed in the coastal storm surge of one single storm. That is not an outlier in the classic sense (i.e., a number that is so out of whack that something must be wrong with the number). It is a real number but an extreme one, however, and meaningful averages should probably ignore it.

But I bring this up now because it might be that a catastrophic hurricane will come ashore in an area where a lot of people live on low ground. There could be a storms surge that is substantial relative to the topography, and there could be winds strong enough to flatten homes and buildings and, generally, structures previously thought to be storm shelters. In other words, a worst case version of Irma would have a deadly storm surge and a deadly wind, more so than Atlantic hurricanes tend to have. Then, of course, the inland flooding as well, maybe quite substantial.

Storm surges are more extreme when there is focusing terrain, like a bay flanked by high hills leading to a town or city. In such environments, however, the storm itself is likely to suffer attrition from the nearby mountainous topography. In the case of Florida, the good news is that there are not hill flanked embayments, and the bad news is that florida is as flat as a pancake, so the storm will not be reduced from that sort of friction.

There are some potentially very uncomfortable scenarios. Look at a map of the Miami and Everglades area.

Now imagine a counter-clockwise spinning storm, centered close to the very southern tip of the state. Besides sweeping high winds along teh keys, it may also force a storm surge up the lagoonish area west of Key Largo, up into the northern part of Biscayne Bay, and right up into the waterways of Miami. I would not want to be on Dodge Island if that comes through. Also, northern Biscayne Bay could be flooded and the outlets to the south blocked, so any of several smaller low spots or outlets in Miami Beach may volunteer to be the new channel connecting the bay to the sea. That would be locally very very bad.

Miami is thought to be less vulnerable to storm surge than other cities, because the sea deepens fairly quickly off shore, which decreased the amount of surge that is possible. But, this particular hurricane, coming from the south and being large, obviates that benefit because the storm surge could be coming through the zone behind the Keys, which is very very shallow. Even if Miami itself is spared, the areas around the keys themselves, and the everglades, are pretty vulnerable.

Or, Irma may do nothing like this, and go somewhere else. We’ll soon find out.

Update Sept 5, evening

In the fairly current infrared image below, Irma is clearly bearing down on some land masses. The twin (double) blobs south of the eye just being engulfed by read is Guadeloupe, and the largish two islands south of that are Dominca and Martinique. The several tiny dots right in the path of the eye or near it are Antiqua and Barbuda, Monserrat, St Kits & Nevis, and Anguilla. You probably recognize Puerto Rico; the tiny dots in the blue specked area between Puerto Rico and Irma are the British and US Virgin Islands.

These island are on the elbow of an ark that runs from Grenada to the Greater Antilles. This mostly volcanic island arc, rimming a small continental plate, would be a large arm of much more land and much less sea during low sea level stands of the Pleistocene.

(I just thought I’d mention that because you probably want to know some things about these islands that are about to get blottoed.)

It is still too early to predict what Irma will do when it is nearing the end of its path along the Greater Antilles and Leeward Islands, i.e., when it is nearer the US mainland. To give you an idea of how uncertain all this is, the average of all the models had Irma striking Florida at the end of the peninsula, but now, hours later, there are other models that tend to be pretty reliable showing Irma not hitting Florida at all, and rather, striking land in the Carolina region.

What this means is this: If you are in Florida and preparing for a hurricane, continue to prepare. If you are in South Carolina and thought you dodged a bullet on this one, don’t assume that.

The one thing we are 70% sure of: Late PM on Friday, Irma will be somewhere between eastern Cuba and the Bahamas. Probably. But possibly not.

Update Sept 5, mid day

We have been back and forth on Irma all along, with the possibility of a landfall in the US being very uncertain.

I’m here to tell you that it is still uncertain. There are still some models that show the storm curving north and becoming one with the Atlantic.

However, most models are showing Irma hitting the continental US, and of those, Florida seems to be a favorite spot.

Several models indicate that Irma will interact with Cuba before heading north and running into Florida. It will not cross Cuba on the way north, but rather, veer into Cuba from the North and maybe not even make eyewall landfall there. It is hard to say what this will do but likely the storm will weaken before hitting Florida.

Also, generally, reports of the storm’s strength are exaggerated. It is now a very powerful storm and it could become more powerful but there is almost no way Irma will not decrease in strength, down to a Category 3 or even Category 2 before hitting the US, if it hits the US. There are reasons that Atlantic hurricanes are not as big, not as powerful, and not as persistent as many Pacific storm, and those reasons have not applied to the storm in recent days, but will start applying to the storm now and onward.

Nonetheless, it is very likely true that somewhere in the US there will be a serious hurricane, possibly a major hurricane, hitting something.

Meanwhile Irma is starting to impact land and will continue to do so for several days, mainly on islands.

So, here is a reasonably likely scenario for the next several days, in DECREASING order of certainty as you go down the list.

1) Certainly: Irma is at the moment impressing the heck out of weather watchers. It has a very clear and distinct eye with interesting features. The winds are very very high, and it is classed as a Category five hurricane. At this point, Irma is not merely a major hurricane, but rather, a catastrophic hurricane (that’s not an official word, but it is a word that will be used on the Leeward Islands … there is a good chance the name Irma will be retired).

There are hurricane warnings in effect for Antiqua, Barbuda, Anguilla, Monserrat, St. Kitts, the Virgin Islands, Puerto Rico, and other locations. Between Wednesay AM and early morning Thursday, approximately, Irma will bear down on locations between St. Johns and Puerto Rico. It will likely hit the first islands more directly with the center passing north of Puerto Rico, but it will affect everything in that area and this is going to be a disaster. A direct hit on Puerto Rico is in the range of possibilities.

2) Probably: Between perhaps Thursday AM and Friday mid day the storm will weaken slightly. It may pass north of Hispaniola and eastern Cuba, but a direct hit on DR and Cuba is well within the range of possibilities. If so, it will weaken more, if not, it will weaken less.

3) Maybe, maybe not: Between 4 and five days out, so starting in the middle of the weekend, the storm, still weaker but still possibly a major hurricane, will either be interacting with Cuba or staying north of Cuba, and poised to hit, possibly, Florida. Or not.

If you live in Florida, it would be good to assume you need to react to a major hurricane. If you live in the keys, south of Miami, or the Miami area or the southern Gulf area, and this storm hits Florida, you will need to be paying close attention.

By Thursday it should be a lot easier to say if Floridians, or some other group of people on the US Mainland are in trouble. Whatever you can do to be ready for a Hurricane that is non-committal and reasonable, do now, and you should probably have done that at the beginning of the season.

Update Sept 2, PM

Underscoring the futility of making projections of a hurricane’s path beyond five days out, the bulk of the models now show Irma hitting the East Coast or sliding around Florida and hitting the gulf. One puts it through the Louisiana-Mississippi border, one has it heading for Halifax, and then all the others are in between.

What does this mean? In terms of projecting the hurricanes ultimate path or chance of landfall, and location of any landfall, it means nothing yet. However the fact that this category 2 storm is likely to become category 3 storm over the next few days, and then will head in the general direction of land, means, well, that it gets its own blog post (this one) for now, if nothing else.

Update Sept 2 AM

The latest models, still too early to tell but there they are, mostly have Irna going off to sea. A couple have the storm hitting the east coast. None have the storm in the gulf.

Updated Aug 31 Mid Day

Two new developments in expectations about this storm, but all very provisional.

First, the storm is intensifying more quickly than expected, and it is expected to become a very powerful storm, ultimately.

Second, while earlier projections from many models allowed for a very wide range of possible paths, the models, still being worked far too out in time but also converging significantly, are starting to suggest that Irma’s most likely course will be to curve up the Atlantic. This involves the possibility of landfall anywhere from the middle sates north to Canada, or no landfall at all. It is still too early to say, but it is looking unlikely for this storm to go into the gulf, but at least one or two models do allow for that.

Updated Aug 31 AM:

Here’s a tweet that shows the current range of model projections for this storm (Note it is way to early to actually predict this far out, but this gives an idea of the range of possibilities):

The National Huricane Center originally suggested that Irma was going to remain relatively low grade for a while as it crossed the first part of Atlantic. However, it is rapidly intensifying and is already on the verge of being a major hurricane. That was not expected. So, this may be an interesting storm.

Original

I’ve been putting comments on, or links to posts on, the 2017 Atlantic Hurricane Season Here, but I wanted to start a thread on Irma, which just now became a named storm. Irma is way out in the Atlantic, and its formation is so early that the NWS doesn’t have any significant information on it as of this writing. But, it is heading roughly west.

Stay tuned.

Harvey The Hurricane Is A Significant Event UPDATED

Harvey the Hurricane will hit Texas roughly between Corpus Christi and Victoria (but stay tuned for exact details).

Harvey is passing over water that is significantly warmer than usual, owing to global warming. This storm was too disorganized to even, under normal conditions, to have a name, just a day or so. But, when this storm hits Texas late this week (maybe by the time you are reading this) it is likely to be a Category III storm.

Then, after landfall, the storm will hang around that area for a while dumping huge amounts of rain on the Texas flatness.

The target area may have 15 inches of rain or more over fairly large areas. There may be spots with more than 25 inches. This is one of those storms that requires the weather forecasters to add new colors to their usual maps.

The last “major hurricane” (Category 3 or larger) to hit the US was Wilma in 2005.

This is an area with abundant oil extraction and processing facilities which are subject to damage from large storms.

Since the ocean has risen since the last major storm surge in this area, local residents and businesses need to make an adjustment in their expectations. If you are in the area look at the National Weather Service’s science based information on storm surges. They have some new tools available. Good thing they have not been removed yet!

For more on the link between this storm and climate change, see THIS.

Added Aug 24 9:30PM

This is probably not going to happen, but …

We don’t know how strong this storm is going to be, but a lot of experts are saying they are above average worried.

UPDATE: Friday AM

Despite rumors of weakening, the storm continues to strengthen. The main change in forecast is that the center of the storm’s expected landfall is father south than expected, away from Houston, but Houston will still receive a great deal of rain, maybe most of the high rainfall amounts.

Storm surges of up to 9 feet or more are possible around Victoria and Corpus Christi.

Atlantic Hurricane Season 2017 (frequently updated)

UPDATE (Aug 30th)

Irma is a new named storm in the Eastern Atlantic. See this post for details, eventually.

UPDATE (Aug 29th)

There is a system currently raining on Cabo Verde, off the West Coast of Africa (nee Cape Verde) that is expected to develop. It is on the verge of becoming a tropical depression. The National Hurricane Center has estimated that there is a high probability of this stormy feature becoming a tropical storm in a couple of days or so. If it gets a name, it will be Irma, unless some other large rotating wet object takes that name first.

UPDATE (Aug 29th)

How is the Atlantic Season doing so far, in relation to most hurricane seasons?

Using data from NOAA, we can say that on average (using the 1966-2009 baseline) we reach the eight named storm in the Atlantic (Harvey is the eighth) on September 24th. So, we’re having more named storms than average.

This year so far we’ve had 3 hurricanes. Normally one reaches that number of hurricanes on September 9th. That’s a week and a half from now, so we can declare this year a bit above average in this measure, but not spectacularly so.

So far this year we’ve had one major hurricane (Category 3 or above). There are some years with zero major hurricanes, but on average one major hurricane occurs by September 4th. So, we’re close to average now.

UPDATE (Aug 29th)

The following posts discuss various aspects of Harvey

Harvey The Hurricane: Truly Climate Change Enhanced

Is Harvey a failure of the assumption that we’ll adapt to climate change?

Harvey’s effects on petroleum pricing and related things

UPDATE:

I’m writing up Harvey here on its own post. This is going to prove to be an important hurricane. If you are in Texas get caught up right now.

UPDATE:

Well, finally, something interesting happened in the Atlantic! Tropical Depression Harvey is heading for Texas and in a very short amount of time is going to whip up into a hurricane and hit the Lone Star State right on the coastline.

From the NWS HPC:

1. Harvey is likely to bring multiple hazards, including heavy
rainfall, storm surge, and possible hurricane conditions to portions
of the Texas coast beginning on Friday.

2. Heavy rainfall is likely to spread across portions of eastern
Texas, Louisiana, and the lower Mississippi Valley from Friday
through early next week and could cause life-threatening flooding.
Please refer to products from your local National Weather Service
office and the NOAA Weather Prediction Center for more information
on the flooding hazard.

3. A Storm Surge Watch is in effect from Port Mansfield to High
Island, Texas, indicating the possibility of life-threatening
inundation from rising water moving inland from the coast during the
next 48 hours. For a depiction of areas at risk, see the Storm
Surge Watch/Warning Graphic at hurricanes.gov.

4. The Potential Storm Surge Flooding Map is available on the NHC
website. This product depicts a reasonable worst-case scenario –
the amount of inundation that has a 10 percent chance of being
exceeded at each individual location. Because the Flooding Map is
based on inputs that extend out only to about 72 hours, it best
represents the flooding potential in those locations within the
watch area.


We still hear the yammering that climate change has not affected storms. “They said there would be more storms. There’s no more storms,” they say.

They are wrong in so many ways. For example, the total energy observed in tropical storms around the globe is up. There have been several big huge scary storms in the tropics in recent years, some of which are unprecedented in their size, strength, rapidity of forming, when they formed, where they went, and what they messed up. Other types of storms show either likely increases or, if not clearly increased yet, still show strong liklihood of increasing in the future based on models. Models that are good.

This is from Emannuel 2005, showing his “Power Dissipation Index” over time and sea surface temperatures.

Smoothed Power Dissipation Index (dotted line, a measure of hurricane intensity) versus Tropical Atlantic Sea Surface Temperature (solid black line)

This shows the long term up and down swings in total tropical storm activity, and an overall upward trend exactly as expected with effects from global warming.

This is from “Increasing destructiveness of tropical cyclones over the past 30 years” by Kerry Emanuel, Nature 436:686-688.

See also this post for more details.

Roger Pielke Jr. is one of those yammering fools (I used to try to be nice to him until he accused me of horrible things a few months back and almost none of them were true!) who will tell you this. Roger says, there have bee no more landfalling Atlantic Hurricanes in the US recently than ever before. But trying to figure out what is occurring on the Earth by only considering what the smallest of the Hurricane basins produces, and only counting the small subset of those hurricanes that hit the US (and, by thew way, ignoring some of them such as Hurricane Sandy in order to fudge the numbers) is like trying to get a handle on the frequency of major train derailments by watching the 100 mile length of track you drive along five times a year on the way up north fishing. Nobody would do that. Except Roger.

The normal number of named Atlantic storms is 12.1 of which 6.4 are hurricanes, and 2.7 major hurricanes, in a given year. The record high is 28 named storms, and the record low, is 4.

There have been various predictions for how much storm activity we expect this year. The predictions that are most recent and most reliable call for 11, 12, 11-15, 14, 11-17, and 15.3 storms. So, generally, close to average plus.

The prediction I watch most closely is from PSU’s Earth System Science Center. PSU has been making very accurate predictions for a number of years. For this year, they predict 15.3 +/- 3.9 named storms this year (i.e., about 11 to 20 with the best guess being 15). Their prediction will drop a little if there is a mild El Niño this year, but that seems increasingly unlikely. Also, PSU has a second alternative model that produces a lower estimate, of around 12.4.

So, in short, barring an El Niño, we can expect a near average but slightly above average year for Atlantic hurricanes. And no, that does not mean that global warming is not happening. It means that no derailments are expected along a particular section of recently maintained rail track.

Anyway, for the second year in a row, IIRC, we got cheated on our A storm. Below, I’ve put the official list of storm names for the Atlantic 2017 season (as headings, we’ll fill in info as the year progresses), but the first tropical storm to talk about today, 19 days into the season, is Bret (one ‘t’). Arlene happened last April.

Tropical storms don’t happen in the Atlantic in April. ‘Cept for Arlene. Generally, it seems like the boundaries are becoming enfuzzied. Expect more “extraseasonal” storms over the next few years, and expect eventually, perhaps a decade from now, for the National Hurricane Center crew to be asked to start watching year round, because a tropical storm that hits your fleet in April is still a tropical storm. Even if Roger says it doesn’t exit.

Bret

Bret formed near the very southern edge of the Atlantic Hurricane basin.

This is the earliest far south forming hurricane in the Atlantic Basin. So, our first storm of the season happened months early, the second storm hundreds of miles south, compared to normal. Roger that.

Bret will menace the northern edge of South America, then in a few days from now it will be gone. Bret is not expected to strengthen and will not be a hurricane. Nor will it hit the United States of America. Therefore, according to Roger, Bret, as novel as it is, does not exist.

Cindy

The next storm, to be named Cindy, is very likely to form from a disturbance now seen in the south-central Gulf of Mexico. This is fairly typical place to see a tropical storm or hurricane form this time of year. Cindy will likely become a north-moving tropical storm, and will likely stay just at tropical storm strength, coming ashore somewhere between Houston, Texas and Morgan City, Louisiana. The chances of Cindy wetting down NOLA is very good, but again, this will not be a hurricane. This will happen some time late Wednesday, most likely.

While possible-Cindy would transform from a tropical storm to a depression with landfall, the storm will track up the Mississippi and cause lots of rain.

Don


Emily


Franklin


Gert


Harvey


Irma


Jose


Katia


Lee


Maria


Nate


Ophelia


Philippe


Rina


Sean


Tammy


Vince


Whitney

Hurricane Otto

This is a bit late in the year for an Atlantic Hurricane. The season normally runs from June 1st through November 30th, but that includes a bit of buffer time.

Otto is a tropical storm that will turn into a hurricane on Wednesday, probably, and make landfal near the border of Nicaragua and Costa Rica. Expect coastal flooding as well as serious inland flooding. The storm will arrive in the Pacific on Friday as a tropical depression.

Then, we’ll have to see if it turns into something in the Eastern Pacific basin.

Getting #Matthew Wrong

This morning I was forced to do the “get off my lawn” thing with the kids at the bus stop. They were systematically destroying the pavement around the common mailbox area down the street from my house, throwing chunks in the street. I lined them up and read them the riot act. They are children, so they can be excused for bering a bit stupid about life, and the guy down the street telling them to get off the lawn is part of the learning process for them.

And now it’s your turn.

The right wing yahoos have already started yelling about conspiracies related to Hurricane Matthew. “They are telling us lies, that it will be a total disaster because of [some dumbass reason nobody quite understands]” This has lead, on the internet, to “don’t leave your homes, Obama and Shillary will be down here to take away your guns” (OK, I admit, that last one was me being sarcastic, but there are similar tweets out there.”

Let me explain something to you.

Matthew is a very large and dangerous hurricane that was predicted to go on a course the center line of which (where the eye would be, approximately) would parallel the coast, just off shore, for a long distance, for hundreds of miles. At any moment the eye could shift left or right, the predictions said. Also, the size of the hurricane force wind field could widen or narrow. Therefore, if the hurricane did as predicted, it could seriously affect the entire coast, knocking down power lines and trees, doing other damage.

RELATED: An Interview With Michael Mann (in which we discuss Matthew and other matters).

So far, that is exactly what has happened. No deviation. You hear “the eye moved east.” Bullshit. There was never a line on which the eye was to move.There was a center line of a prediction cone, and the storm has stayed right in the predicted area. It was alway predicted to be about where it is, plus or minus. It is well within the plus or minus.

Every here and there, the predictions indicated, the hurricane could produce a dangerous storm tide. Each section of coast has a different potential for this because of its shape. The exact timing of high tide matters. The storm’s exact configuration and distance from the coast matters. So you can’t predict in detail what will happen, but what you CAN do is produce a likely scenario in the worst case. If all the factors come together, and you live in a house in this region, you are truly fuckered. The Hurricane turns left a bit, or a certain band of winds interacts with an embayment just right at high tide, or whatever. If you live in that house, and you do not act as though this may happen to you (i.e., evacuate), then you are a dumbass.

A maximum storm tide of something around 11 feet, sometimes more, sometimes only about 6 feet or so, was (and is for the next day or two) predicted for the entire coast from some point north of Palm Beach all the way up through Georgia and beyond.

This does not mean, and it never meant, that there would be an 11 foot flood covering the entire coast. No. It. Never. Meant. That. If most of the Atlantic coast from South Florida to Bogna Riva does not flood to 11 feet killing all the people and puppies and kittehs, THAT DOES NOT MEAN THAT THE PREDICTIONS WERE WRONG.

This morning NBC actually had a snarky local yahoo meteorologist on (the commenters and Al Roker were visibly embarrassed after the fact) who went through the whole storm chaser routine …

“… Here I am in my car. Here I am getting out of my car. Her I am cutting through the bushes, telling you breathlessly: wait ’til you see this, look at what Imma show you now’ etc. etc…..”

Then he brought the camera out on the beach and there was nothing there but some waves.

“See? They said there would be a storm surge. There is no storm surge. Nothing happened here.”

They cut away from that dude, I’m afraid because he was counter sensationalizing, not because he was being all Rush Limbaugh, though the latter was clearly true. Roker and the others hinted that the storm tide in that area, had there been one, would have passed hours ago so of course it is not visible. Etc.

This is a very smart thing on the part of the right wing. They were prepared for this hurricane in this manner. Somebody figured this out, got the word around, and they are pulling off an excellent and well designed public image manipulation event for Matthew. Here is what they figured out.

1) The hurricane is going to be near something close to 500 miles of coast.

2) There will be breathless yammering about the dangers along 500 miles of coast, recruiting perhaps 40 or more storm studs, national and local, and hundreds of tweeting meteorologists, etc. etc. going on about how bad it will be.

3) Even if the storm seriously damages one place, kills people in part of Georgia or whatever, it will not be 500 miles of 11 foot flood everywhere, like promised.

4) Therefore the storm was hyped, by Hillary Clinton and Barack Obama flying overhead in their Black Helicopters, swooping in to take our guns and bibles.

5) In the end there will be 500 miles worth of things that were said would happen but never happened, and maybe five miles of real disaster in some feckless coastal town.

So that’s the real getting Matthew wrong. A public image coup for the right wing, the climate deniers. They won this storm.

Got it? Great. Now get the hell off my lawn. And get it right next time (giving stern look to the climate communicators).

Tropical Storm Nicole

The 14th named storm has just appeared in the Atlantic.

The average number of named storms in the Atlantic, based on a fairly long climatology, is about 10.1. An average of 5.9 become hurricanes.

So, this year are more than average named storms. But is it more than predicted?

On average, the expert forecasts suggested anywhere from 12 to 18 named storms. We are well past the midpoint of the 2016 season, and are just about to reach the midpoint of these forecasted ranged, and there is still plenty of time left for a few more storms. The largest number predicted, as the upper end of the range, was 18, with several forecasts suggesting 14, 15, 16, or 17. So, it looks like the forecasts are all going to come in light, and this will be a noticeably stronger than average yer.

Why am I talking about the season overall instead of Nicole? Because Nicole isn’t very interesting. Probably won’t even become a hurricane. Nicole will wander around ay out to sea for a while, and go away in a week or so, most likely.

Hurricane Matthew: The Scary Clown of Hurricanes!

LATEST UPDATE IS HERE. CLICK HERE FOR LATEST UPDATE.

Update: Wed Mid Day

Matthew weakened, strengthened, strengthening

Matthew has interacted with land masses in Hispaniola and Cuba to the extent that the storm weakened quite a bit, losing its temporary Category 5 status.

But, now Matthew is already showing signs of strengthening, and is likely to grow back to Category 3 or 4 status as it moves over the Bahamas. How bad a hurricane is when it makes contact with land depends in large part on the angle of the attack, and Matthew will likely be affecting several spots in the Bahamas at a particularly bad angle.

Bahamas are in serious danger now

This is the current warning for the Bahamas:

At 200 PM EDT (1800 UTC), the eye of Hurricane Matthew was located
near latitude 22.1 North, longitude 75.3 West. Matthew is moving
toward the northwest near 12 mph (19 km/h), and this motion is
expected to continue during the next 24 to 48 hours. On this track,
Matthew will be moving across the Bahamas today and tomorrow, and is
expected to be very near the east coast of Florida by Thursday
evening.

Maximum sustained winds are near 120 mph (195 km/h) with higher
gusts. Matthew is a category 3 hurricane on the Saffir-Simpson
Hurricane Wind Scale. Some strengthening is forecast during the
next couple of days, and Matthew is expected to remain at category 3
or stronger while it moves through the Bahamas and approaches the
east coast of Florida.

Rainfall in the Bahamas is likely to be 8-12 inches wiht up to 15 in isolated areas.

A huge risk in this area is overtopping land masses with what may be a 10 foot storm surge. There may be large areas where fresh water, and fresh water plant communities, are destroyed, and may be affected for months or years to come, depending on exactly how this plays out. Nassau, the largest settlement in the area, is facing away from the storm’s track, so it will probably be spared a serious storm surge.

Florida is most likely to be affected in the US

Matthew, as a Category 3 or Category 4 will be getting close to Florida during the day on Friday. Depending on exactly what the storm does, it may spend enough time over extra warm waters of the Gulf Stream where it may strengthen. The storm may or may not make landfall in Florida. If the storm does not technically make landfall, there is still a very high probability of serious effects on the coast, most likely near central Florida.

NOTE: This is a perfectly good storm to display stupidity about landfall. Please avoid doing that.

Matthew is the scary clown of hurricanes

Then comes the strange part. Jeff Masters of the Wunderblog writes:

Thanks to my advancing years and a low-stress lifestyle that features daily meditation, there’s not much that can move me to profanity—except the occasional low-skill driver who endangers my life on the road. But this morning while looking at the latest weather model runs, multiple very bad words escaped my lips. I’ve been a meteorologist for 35 years, and am not easily startled by a fresh set of model results: situations in 2005 and 1992 are the only ones that come to mind. However, this morning’s depiction by our top models—the GFS, European, and UKMET—of Matthew missing getting picked up by the trough to its north this weekend and looping back to potentially punish The Bahamas and Florida next week was worthy of profuse profanity. While a loop back towards Florida and The Bahamas next week is not yet a sure thing, the increasing trend of our top models in that direction is a strong indication that Matthew will be around for a very long time. Long-range forecasts of wind shear are not very reliable, but this morning’s wind shear forecast from the 00Z run of the European model does show a low to moderate shear environment over the Bahamas and waters surrounding South Florida late next week, potentially supportive of a hurricane–if Matthew survives the high wind shear of 50+ knots expected to affect the storm early next week. The bottom line is that it currently appears that Matthew will not recurve out to sea early next week, and The Bahamas and Florida may have to deal with the storm again next week.

At this partiuclar moment, the red line in this graphic is the best guess for what may happen:

euro-highprob-oct5-1

There is a version of this where Matthew crosses Florida and ends up in the Gulf.

This scenario probably involves Matthew experiencing a lot of wind shear starting around the time it is near Florida and points north, and out at sea. This may actually make the storm a Category 1 hurricane or even weaker. But, if it makes this loop, the storm will be ina position to reform as a hurricane and menace the coast again.

I wrote a piece of fiction in which a hurricane in this general area finds a loop like this, but never stops. It just keeps going and going. In that story, Florida is mostly inundated by sea level rise, so it is actually a somewhat different configuration, but the same idea. I wonder….

Final point for now: Do not take your eyes off this storm.

I’m posting Climate Signals causality widget for this storm here, hope it works for you!

Update: Tuesday AM

Hurricane Matthew May Be One Of The Worst Hurricanes Ever

Such things are typically in reference to the region. There will always be Pacific hurricanes that are bigger than Atlantic hurricanes. Etc. But Matthew may be, for many years, on the list of the top few Hurricanes in the Caribbean region, in terms of strength and damage. The storm also has a number of odd features, some of which seem to be associated with anthropogenic global warming.

Hurricane Matthew will almost certainly end up being one of the worst weather disasters of the decade. It may end up being the worst storm to affect the region around Jamaica, eastern Cuba, western Hispaniola, and the Bahamas, but especially the island of Hispaniola, where an unusual feature of this storm (see below) is causing extraordinary rainfall. Haiti is more clearly in the path of the storm, but the Dominican Republic could end up experiencing a serious disaster (see below). (See: Matthew Hits Haiti, Their Strongest Hurricane in 52 Years)

In the end, it is likely that Matthew will be a poster child for social justice and climate change, since the storm is global warming enhanced and is affecting one of the most vulnerable populations in the world, in an area that is also geographically vulnerable.

Matthew’s Mysterious Blob

Also, Matthew has a strange new feature. A “mysterious blob” formed within the storm several days ago. The blob is probably going to end up being one of those interesting weather patterns that Rush Limbaugh and Al Roker do battle over. It is a complicated and mysterious phenomenon perhaps never before recorded with modern instruments but anticipated by meteorologists in the textbooks.

Hurricane Matthew's Mysterious Blob
Hurricane Matthew’s Mysterious Blob

Marshall Shepherd, of the University of Georgia (and former president of the American Meteorological Society) provides a discussion of the blob here. I’m not going to try to recreate his discussion here because it is very preliminary, but I note that Matthew is record breaking (nearly) in how far south if formed as a large storm. Matthew shouldn’t really have ever been born. But it was. And, the factors thought to be associated with Matthew’s Mysterious Blob might be more likely to occur in a south-forming hurricane.

The blob is basically a mini storm system, a small and quasi-independent tropical storm sort of, embedded within the larger hurricane. Like that birth mark that turns out to be your twin sibling. Maybe. Regardless of which metaphor works best, the blob could end up causing regions far to the east of the center of Matthew to experience rainfall of truly Biblical proportions. There are places on Hispaniola that may have rainfall amounts of well over three feet, and some wether stations near the blob have measured rainfall of well over 5 inches an hour. And, the storm is moving very slowly, so whatever the rainfall rate turns out to be at any given spot, it will add up to a large total, over rugged mud slide prone terrain occupied by under-built dwellings.

Matthew Is Global Warming Enhanced

Matthew is large, has a very low pressure core, very strong winds, and is moving slowly over waters that are, on the surface, warmer than normal because of global warming, which has contributed to the storm’s strength. The Atlantic is expected (and observed) to have more vertical wind shear as an effect of global warming, which should attenuate the formation or strengthening of most hurricanes in the region, but Matthew formed and grew large anyway, somewhat baffling meteorologists. Perhaps, in the end, extremely warm water will trump wind shear in the formation of disastrous storms.

Bob Henson wrote about this a few days ago:

Vertical wind shear of up to 20 knots has plagued Matthew for most of the last two days, yet the storm has not only maintained its structure but grown at a ferocious rate. Dissertations may be written on how this happened! Working in Matthew’s favor has been a steadily moistening atmosphere along its westward path, which means that the shearing winds didn’t push too much dry air into Matthew. Once it developed a central core, Matthew was able to fend off the wind shear much more effectively.

But wait, there’s more.

The waters in this region are also warmer at depth (100-200 meters or so?) because of global waring.

Again, Bob Henson:

…water temperatures are unusually warm throughout the Caribbean (and the entire western North Atlantic), with an area of high oceanic heat content directly beneath Matthew’s path. Such deep oceanic heat allows a storm to strengthen without churning up cooler waters from below that could blunt the intensification.

The degree to which the ocean is heated not just on the surface, is reflected in this graphic from NOAA:

The ocean below Matthew is not just warm on the surface, but warm at depth, and very warm at that.
The ocean below Matthew is not just warm on the surface, but warm at depth, and very warm at that.

A hurricane can maintain strength by moving fast over warm water. The storm itself cools the surface of the water by using that energy in its own formation, and by roiling the surface waters, causing mixing from cooler water below. So, underneath a typical hurricane may be regions where the water is not really warm enough to form or sustain a hurricane. So, running fast avoids that. One might expect a slow moving hurricane to damage itself by using up some of this heat and dispersing it to depth.

But, sometimes the water is at “hurricane warmth” (about 80 degrees F) for many tens of meters of depth. This allows the surface waters to contribute to the hurricane’s maintenance, enhancing the overall strength of the storm. Katrina did this in the Gulf of Mexico (though that story is a bit complex so be careful what you infer here) and Haiyan did it in the Pacific.

And now, Matthew is doing it in the Caribbean/Atlantic.

My strong impression is that this warming at depth is an effect of excessive sea surface temperatures, and is an effect of anthropogenic global warming. It will take the meteorological research community a few years to catch up to this idea, but your dollars and my donuts are on the table on this one, and I’ll be taking your money. This, if confirmed, could be thought of as a qualitative change in the nature of storms caused by global warming.

Matthew may be, in a sense, a representative of a new kind of tropical storm. We’ve been seeing a lot of outlier storms lately. This includes storms that form really fast, like Patricia. Matthew did that to some extent as well. Matthew may be defying the effects of wind shear. Like Katrina and Haiyan, Matthew is feeding off of deep warm water. And, Matthew has this mysterious blob thing. Sandy was an outlier as well, a major hurricane that maintained strength way far north, then ate a Nor’Easter and became a Super Storm. Matthew is heading along a track similar to the one that took Sandy north (not uncommon, nothing odd about that). We don’t know what will happen. But, if storms had real personalities (which they don’t but this is a blog post, not a peer reviewed paper) I would expect Matthew to be on the hunt for a Nor’Easter to eat!

Please note that Climate Signals (BETA) has a page up now on Matthew, exploring the climate change connection.

Matthew may hit the US.

And, of course, Matthew may hit the US coast. This has always been a possibility, but now the chances are increased, with more models suggesting that the storm will track farther west than the previous models (on balance) suggested, with several models suggesting a US coast landfall.

Where?

Take your pick:

where_might_hurricane_matthew_hit_the_us_if_it_hits_the_us_at201614_ensmodel

That graphic is from here.

Though it is hard to see in that depiction, it seems most likely that Matthew will skip Florida, but probably still hose it down and make waves. The more likely landfall scenarios are anywhere from the Carolinas north.

This is a storm to watch very closely, and in which we shall remain in awe.

Older updates:



Update: Monday Mid Day

Matthew is a major hurricane, and is just starting to affect the area of eastern Cuba and western Haiti. Jamaica has already been affected and there are two or more dead there.

Starting about now and over the next 36 to 48 hours, both countries will likely be seriously affected by this storm. I suppose three countries, technically, given that the US has a bit of territory in the region as well. Various islands in the Bahamas are also likely to be very strongly affected.

This is a major hurricane, fairly large, very strong, and it will be spending enough time over very warm water to maintain its strength as a Category 4 hurricane, or nearly so, during this entire time.

Most but not all models put the hurricane to the east of Florida, but not too far, and later, it is possible that it will strike the US east coast. The average of all the models says no, it will stay at sea, but there is not much certainty behind that prediction.

Meanwhile, there is a another storm, which has somewhat less than better than a one in three chance of becoming Nicole, is quickly spinning up out in the Atlantic.

Matthew will be a news maker and a disaster for a lot of people. But they are brown and not Americans, so few will take notice and science deniers will continue to say that nothing has happened in the Atlantic in years. But, Matthew is something, and it is a bigger something than it otherwise would have been because of increased sea surface temperatures caused by anthropogenic global warming.

vis_lalo-animated
Update: Friday Mid Day

Matthew seems to have had, as a key characteristic, the capacity for very rapid change. What just became a hurricane about 24 hours ago is either now, or about to be, a Category 2 hurricane, and may well develop into something close to a Category 3 before hitting Cuba in a few days. The storm is expected to cross Cuba and perhaps stay as a hurricane the whole way, or to reform quickly, where it will vis_lalo-animated heading north.

Vertical wind shear has been affecting the storm, which should be weakening it, but he weakening is not observed. Further wind shear is expected to slow rapid growth over the next day, but that may or may not happen. Then the shear lets up and strengthening begins. I have the sense that the predicted transition to ca 100 knot maximum sustained winds starting in about 24 hours is a bit conservative.

Some earlier models had this hurricane possibly crossing into the Gulf of Mexico, but now it seems that all the models are in aagreement on a course that will parallel the Florida Coast (possibly getting very lose to Florida, but probably not) then heading up the atlantic. (See graphic above, from Weather Underground.) Most of the models have Matthew staying out at sea, but a number have the storm coming ashore in any of several possible locations from North Carolina Through Buzzards Bay, Mass, or perhaps even farther north.

It is very likely that Matthew will have crossed Cuba and be north of the Island nation by around mid day next Wednesday, and it is certainly true that there will be a much better idea then as to where the storm will go next.

at201614_sat_2

Update: Thursday Mid Day

The hurricane status of Matthew is so fresh that the NWS, at this moment, has a mixture of products that call it a tropical storm and products that call it a hurricane. To be a hurricane, a storm’s wind speed have to be 74 mph (64 knots) or more, and of course it has to be organized properly. The NWS Public Advisory and some of their graphical products call the storm a hurricane and the advisory indicates that maximum sustained winds are at 75 mph.

Interestingly, the “discussion” which is usually the best source of information, has the storm turning into a hurricane in several hours from now. I have gotten the impression all along that the strengthening of this storm has been a bit quicker than usual. This may be an example of that phenomenon.

The storm is expected to make landfall in a few days, as a hurricane, in Western Cuba, then head back out over the sea where it will likely strengthen owing to very warm waters.

It is hard to say what this storm will eventually do, but there is a non trivial chance that it will make landfall as a hurricane in the US, a better chance that it will stay out to sea but be close enough to the coast to be bothersome, and a very good chance that it will eventually wack into Canada or someplace as an extratropical storm. Very few models seem to suggest that Matthew will be one of those mid-Atlantic hurricanes that remains boring until it finally dissipates.

Update: Wed Evening:

Just a quick note to say that about a third of the forecast models suggest that Matthew could become a major hurricane, and a smaller number even suggest a category 5 hurricane.

Update: Wed PM:

Matthew has formed into a named storm, and continues to head westward across the Caribbean. This is a region sometimes called the “Hurricane Graveyard” because various effects tend to reduce the chance of hurricane strengthening, and increase the chance of weakening.

The storm is expected to upgrade to hurricane status by the end of the week, possibly late tomorrow. Later, it may make a right turn and head north toward Jamaica and eventually Cuba, or environs. Around the time the storm reaches Jamaica, it may be a Category 2 hurricane.

The chances of this storm, as a tropical storm or hurricane, striking or affecting the US coast is not insignificant. Keep an eye on it.

From Weather Underground, the “ensemble models” to give you an idea of what the computers are thinking:

at201614_ensmodel

Original Post:

The next named Atlantic storm will be Matthew. There is currently a well organized stormy blob in the Atlantic, heading for the Lesser Antilles, that has a very high probability of becoming a named storm, and that could happen by Wednesday or Thursday.

This seems to be a fairly fast developing storm. Also, though it is way to early to say much, its possible futures are interesting.

The storm could continue roughly westward and either encounter the Yucatan or western Cuba, then presumably on to the Gulf. But, it also seems very likely to make a hard right and squeeze between Cuba and Hispaniola, or perhaps traverse on e or the other, on the way to the Bhamas or Turkes and Caicos, then north into the Atlantic. This is not one of those storms with a near 100% probability of wandering out over the Atlantic until it dissipates. There is a reasonable chance that this could be a land falling storm in the US. Again, this is way too early to say but this is one to watch very closely.

Sea surface temperatures are plenty high in the waters over which this storm will track no matter which way it goes. Global warming enhanced anomalously hight. So, it is pretty much impossible for this storm to not be stronger than it otherwise would be owing to human caused global warming. Let us hope it doesn’t hit anything.

screen-shot-2016-09-27-at-2-07-28-pm