Tag Archives: Severe weather

Global Warming Changing Weather in the US Northeast

February 23, 2015UncategorizedClimate Change, Climate Change, Global Warming, Global Warming, Precipitation, Severe weather, Uncategorized, weather whiplashGreg Laden

A newly published study has identified changes in precipitation patterns in the US Northeast, which are likely caused by human pollution of the atmosphere with greenhouse gasses, which has resulted in global warming. According to the study, there has been an increase in extreme precipitation events, and an increase in the clumping across time of precipitation, with longer or more intense rainy periods, and longer dry periods.

Generally, climate and weather watchers have noticed that arid regions are drier, wetter regions are wetter, and many feel this is a consequence of global warming. Increased temperatures may increase the intensity of precipitation; this is a matter of physics. As air temperature increase, the air is able to hold more water, and this increase is not linear; a little more heat means a lot more moisture.

Also, the overall pattern of movement of air currents seems to be affecting the distribution of precipitation. For example, the main jet stream that influences weather in the Northern Hemisphere seems to be more often wavy and slower moving. This causes low pressure systems that bring precipitation to move more slowly, so a given area may have both more intense rainfall and rainfall over a longer period of time. Nonetheless, while an increasing number of climatologists are thinking that global warming is changing the weather, it has only been happening for a few years, and it is a system with a high level of natural variability. This means the basic observational data may be difficult to bring to bear on understanding what is going on. The physics predict these changes. Modeling of climate has demonstrated a high likelihood of these changes. Direct observations are beginning to show these changes.

In a recent paper, “Quasi-resonant circulation regimes and hemispheric synchronization of extreme weather in boreal summer,” Dim Coumou, Vladimir Petoukhov, Stefan Rahmstorf, Stefan Petri, and Hans Joachim Schellnhuber noted the emergence of more frequent “Rossby Waves” in the jet stream, indicating that these waves have become more common and more persistent. They said, “We show that high-amplitude quasi- stationary Rossby waves, associated with resonance circulation regimes, lead to persistent surface weather conditions and therefore to midlatitude synchronization of extreme heat and rainfall events. Since the onset of rapid Arctic amplification around 2000, a cluster of resonance circulation regimes is observed involving wave numbers 7 and 8. This has resulted in a statistically significant increase in the frequency of high- amplitude quasi-stationary waves with these wave numbers. Our findings provide important new insights regarding the link between Arctic changes and midlatitude extremes.” (I elaborate on this finding here: More Research Linking Global Warming To Bad Weather Events.)

Climate Scientist Jennifer Francis, writing in Scientific American, notes,

One thing we do know is that the polar jet stream—a fast river of wind up where jets fly that circumnavigates the northern hemisphere—has been doing some odd things in recent years. Rather than circling in a relatively straight path, the jet stream has meandered more in north-south waves. In the west, it’s been bulging northward, arguably since December 2013—a pattern dubbed the “Ridiculously Resilient Ridge” by meteorologists. In the east, we’ve seen its southern-dipping counterpart, which I call the “Terribly Tenacious Trough.”

Different research teams differ somewhat in their explanation of this phenomenon, some seeking explanations in the warming Arctic, others in sea surface temperatures in the Pacific. Either way, the phenomenon seems to be real and important. I asked Justin Guilbert, lead author of the paper under consideration here, about this, and he noted, “The current very persistent atmospheric setup consists of a ridge in the west and a trough in the east. This setup is causing drought in the west and extreme cold and storminess in the east. All of which is consistent with recent studies suggesting that amplified planetary waves contribute to persistence. Such conditions tend to lead to persistent surface weather conditions because it is thought that high-amplitude waves do not move laterally as fast as lower-amplitude waves. The real weather story this year and last is the combination of persistent cold and repeated storms affecting the northeast. While we did not explore temperature persistence in the record, our analysis of the data shows that such setups may be on the rise concurrent with recent climate change.” So, the phenomenon of changes in precipitation patterns in the Northeastern US is yet another example, it seems, of warming induced changes in weather patterns. This applies as well to the cold many of us have been experiencing during our northern Winter.

So, now on to the details of the new paper just out in the American Geophysical Union addresses change in weather resulting from anthropogenic global warming. This study looks specifically at precipitation in the Northeastern United States. The paper is timely (though only by accident, the timing of peer reviewed publication and that of news cycles are entirely unconnected!) because of the recent heavy snows in New England. The study concludes that there is “… evidence of increasing persistence in daily precipitation in the Northeastern United States that suggests global circulation changes are affecting regional precipitation patterns… Precipitation in the northeastern United States is becoming more persistent; Precipitation in the northeastern United States is becoming more intense; [and these] Observed trends constitute an important hydrological impact of climate change.”

The paper is “?Characterization of increased persistence and intensity of precipitation in the Northeastern United States” by Justin Guilbert, Alan Betts, Donna Rizzo, Brian Beckage and Arne Bomblies.

The study used data from 222 weather stations in the US Northeast (defined as Connecticut, Delaware, Maine, Maryland, Massachusetts, New Hampshire, New York, Pennsylvania, Vermont, West Virginia, and the District of Columbia, but in the end excluding DC and Maryland because the data did not meet the study criteria). They used data from stations that had over 50 years of measurements and ran to past January 1, 1990, and excluded station data missing too many years of observation. The various data sets go back in time to as far as 174 years, with a mean coverage of about 84 years.

How do you count rain?

It is hard to count rain. If it rains on Friday and Saturday, you will get two records in a weather database, one for each day. But isn’t that just one storm? Maybe. Maybe not. Say it starts raining. It stops. It is still cloudy. It starts raining again, the same day. Or the next day. Is that one or two precipitation events? Is the rain from one low pressure system all one storm? Probably. So, OK, go back to 1882 and look at the rain gauge data for a particular town. It rained Monday and Tuesday. Were those the same low pressure system? Well, just check the satellite data for those days. But wait, satellites were still science fiction then! This is why most climate scientists a) don’t like the Weather Channel naming storms; you often can not define the boundaries of a given weather event unless it is something very compact like a hurricane or tornado, and even then, it can be a problem; and b) often have little hair.

The method used in this study is complicated but appropriately so. To measure precipitation extremes, they took precipitation data and subjected it to two streams of processing. First, they looked at the lower 75th percentile of daily precipitation values, and second, they looked at the upper, remaining, tail. Various appropriate distributional statistical analysis were applied. The data were then looked at using a moving 30 year window, so any given representation would have plenty of data to dampen out variation caused by low sample sizes. (Remember, the station data varies in density across time and space.) This information was then characterized as a median trend (typical rainfall) and extreme (high rainfall events). Then time trends were tested for. The research team did not find large changes in average precipitation, but they did identify increases in extreme events.

More than … two-thirds … of the 222 stations show positive trends for [extreme precipitation events] in the months of October through May and at least half of the stations display significant (p<0.01) positive trends during every month except July and September. The strongest regional trend in the 95th percentile of daily precipitation was observed in April when the average trend was +0.7 mm per day per decade. ... these trends are not spatially uniform. The entire region experienced an average trend of +0.5mm per decade in annual 95th percentile daily precipitation while Connecticut was found to have the greatest increase with a trend of +1.1mm per day per decade in annual 95th percentile daily precipitation . No trend was found for West Virginia in annual 95th percentile daily precipitation.

How dry I am

The other weather pattern the study looked at was, essentially, clumping of rain. We seem to see this a lot lately. Here in Minnesota, we experienced what Paul Douglas called a “Flash Drought” a few years ago. Not enough dry to make a full on drought, but the rain falling across the larger region seemed to be clumped in time and space such that there was very little in the Upper Midwest corn belt. Last summer, by contrast, it rained nearly every day in Minnesota from just before the start of June up through the end of June. We got totally clumped on by rain. (See: Minnesota’s Current Weather Disaster — Don’t worry we’ll be fine.)

The research team figured out a way to characterize this by looking at the relationship between two simple questions: Is it raining/not raining now? Is it raining/not raining the next day? That is an oversimplification of their methods, but I think it gets the point across. Imagine that today’s conditions with respect to precipitation is used to predict tomorrow’s, based on experience. If so, changes in the distribution across time of events would change the way that prediction would work out. The researchers found that “For daily precipitation events, the warmer months show the greatest increase in wet persistence, the colder months show larger increases in the magnitude of extremes, and dry persistence increases in early spring and decreases in early fall. … on an annual basis, it is likely that the study region will experience increasingly persistent and intense precipitation events.”

These findings confirm observations made by many people in the weather industry. They also may relate to patterns we see in things like snowfall in New England. Prior to the late 1970s, New England seemed to have the occasional large scale snow storm or blizzard (they are not exactly the same thing). Since then, the frequency of these events seems to have risen to about one every other year, at least in Southern New England. This year seems to be exceptionally snowy even by those standards. The concern here is that places like Boston have an infrastructure adapted to the occasional debilitating winter storm, but the storms may not remain occasional. One can imagine the T (that’s what they call the public transit system there) welding snow plows on to the front of the trollies.

I asked Guilbert if his team could put a time frame on these changes. Did alterations in precipitation patterns start at a certain point in time, or is there an acceleration in the rate at which these changes are happening? He told me, “Unfortunately the record is not long enough to robustly explore this question. I used a linear model to represent all the changes that were discussed so that a positive or negative symbol could be assigned to trends in persistence and intensity of precipitation. I looked back at the data on an annual level across the entire region to see if there was any evidence of non-linear behavior happening or if there appeared to be a ‘start time’ of which I found no evidence for either. However, this does not mean that there hasn’t been an acceleration in our metrics, it’s just that we haven’t been able to detect anything yet.”

A few days ago, using data from Jeff Master’s blog at Weather Underground, I plotted out the major snow storm events at four locations in the general vicinity of Boston, and got this graph:

There certainly were major storms before the cluster you see here, but early enough, or located in the wrong place, so that they don’t show up at these weather stations. So even though the study being discussed here does not directly address the question of “start time” there is an indication of this being a relatively new phenomenon with timing suggestive of a global warming related cause. We also know that weather related natural disasters in the US have been on the increase in recent decades. This graph is of events, not costs of events (that would go up just with inflation):

Note that the snow event graph above ends before the last few large events in New England. Note also that the natural disaster graph is not fully up to date. Also note that the Guilbert et al study reported here does not run up to the present. One gets the impression that the changes we are observing in weather patterns are happening quickly, a bit too quickly for longer term, carefully done studies, to keep up with. That simply means that whatever you were thinking based on the peer reviewed research, changes are, global warming’s effects are coming on faster than previously thought.

Boston Snow Climate Change Amplified

February 9, 2015UncategorizedBoston snow, Climate Change, Climate Change, Global Warming, Severe weatherGreg Laden

New England is now experiencing the fifth in a series of worse than average winter storms. So far, Winter has dumped over 60 inches of snow on Boston, and after the present storm, it will probably be possible to say that a total of 60 inches or more have fallen there in just over 2 weeks, according to Paul Douglas, meteorologist and founder of Media Logic Group. Douglas notes “I’ve never seen a SST anomaly of +11.5C, but that’s the case just east of Cape Cod. No wonder Boston is submerged…. Quite amazing, really.” As such, Boston has already broken it’s 30 day snowfall record going into the latest storm. According to Massachusetts Governor Baker, the region has had enough snow to fill Foxboro Stadium 90 times. That is, of course, a meaningless number for most people, but I can tell you (because I saw Paul McCartney there … I think a sports team also plays there), that iss a huge stadium and since it has no roof and one can pile the snow quite high, mighty impressive!

The huge amount of snow falling on the region is normal snow amplified in amount by extraordinary sea surface temperatures, supplying more moisture and creating a stronger contrast across cold fonts moving through the region, which together brings more snow. The US National Climate Assessment indicates that there has already been an increase in extreme precipitation in the region, up over 71% in the Northeast, and climate experts predict further change in that direction. And it is costly. According to Climate Nexus, it costs Boston about $300,000 for every inch of snow removal, and a large storm costs the state of Massachusetts about a quarter of a billion dollars.

Severe weather is becoming the new normal.

ADDED: There has been some denialist chatter on twitter suggesting that Paul Douglas, Michael Mann, Chris Mooney, and I got our facts wrong regarding SST temperatures. That chatter involves looking at the sea right next to Cape Cod. When we use the term “Off Cape Cod” when referring to a huge storm system and a subcontinent (northeastern US) we are using Cape Cod, which on the big map is a little hook shaped thing, to orient to that general area of the sea. So the complaints, I’m afraid, are mere yammering and of no consequence. Nonetheless, I did throw together a simple instructional graphic showing the 11C anomaly in relation to “off Cape Cod.” Here:

Featured Image Photo Credit: Aviad T via Compfight cc

What happened to the Blizzard of 2015?

January 28, 2015UncategorizedBlizzard of 1978, Blizzard of 2015, Climate and weather, Climate Change, Climate Change, severe weather, Severe weather, Uncategorized, Weather ForecastingGreg Laden

What happened to the Blizzard of 2015? Well, it happened. Despite breathless complaining about how the forecasters got it all wrong, they didn’t. As the storm was predicted, there should have been close to about two feet of snow in the New York City metropolitan area, but as it turns out, there was between 8 and 12 inches. That means that New York City experienced a typical winter month’s worth of snow in one day. Also, most snow that falls on The City falls a few inches at a time and melts more or less instantly, as few cities can match New York in its heat island effect. So, 8-12 inches of snow all at once is a meaningful, crippling snow storm. Two feet would have been much worse, but it is not like The City did not experience a memorable weather event.

More importantly, the forecast was for a huge blizzard with up to three feet of snow across a blob shaped region of the Northeast approximately 475 miles along its longest dimension (see graphic above). The blob ended up being off, on the southwest end, by about 40 or 50 miles. So the spatial extent of the storm was misestimated, days in advance, by about 10%. An object the size of a country was off by the distance a healthy adult can walk in a long day. That was, ladies and gentleman, an excellent, accurate prediction.

But, since the storm’s outcome was different than predicted in the world’s most inward looking city (you’ve seen the self-effacing maps produced now and then by the New Yorker magazine), it is assumed by many that the forecast was bad, that forecasting was bad, that weather models are bad, and so on.

As meteorologist Paul Douglass told me yesterday when I asked him if he was going to be kneeling on any carpets today over the difference between prediction and reality, “No kneeling, Greg. Just because we tap supercomputers and Doppler radar doesn’t mean we can predict snowfall down to the inch. Models are good and getting better, but they’re not perfect and never will be. People expect perfection in an imperfect world. Boston picked up 20-30” snow, Long Island saw 15-23”, so did much of Connecticut. There was an 8 foot storm surge on Cape Cod where winds gusted to 78 mph.”

Paul also told me something he shared later that day on the Ed Show. “Over 30 years I’ve worked with a series of anchormen in the Twin Cities and Chicago. When they invariably gave me a hard time for busting a forecast I reminded them that a monkey in a sport coat could report on what happened yesterday. Look at the trends and predict tomorrow’s news headlines!” He indicated that when sportscasters started to routinely predict tomorrow’s scores rather than report today’s scores, they would be on a level playing field with the meteorologists.

Here is that Ed Show piece:

The Blizzard of 2015 was in some ways comparable to the Blizzard of 1978, which was one of the first storms of the modern era of increased storminess. The snowfall totals may have been greater for 2015, but coastal winds were greater for 1978. But, in 1978 over 100 people died, and most of them died of exposure because they were caught in the snow. So, in terms of cost of human lives, the two storms are very comparable despite the differences in winds.

Why did over 100 people die in New England’s 1978 storm, but either zero or one person died (depending on attribution of a single sledding accident related death to the storm) in 2015?

Weather forecasting. It got better because the science and technology behind it got better. And, frankly, that is partly a result of storms like the ’78 storm and various hurricanes, which prompted an interest in advancing this technology, which includes on one hand satellites producing piles of data and on the other hand advanced computer and software producing powerful models.

You should buy your local meteorologist a beer.

The image comparing 1978 and 2015 is a chimera of images that come from NOAA and the Boston Globe.

The Great Blizzard of 2015: Fair to say it is AGW amplified.

January 26, 2015UncategorizedBlizzard of 2015, Climate Change, Climate Change, Global Warming, Global warming amplified storm, Sea Surface Temperature, severe weather, Severe weatherGreg Laden

About 20 million people are currently under a blizzard warning, and double that under a winter weather advisory, for a storm moving into the Northeast today and tomorrow, with snow falling though Wednesday. Thousands of flights have been cancelled. Wind will be at tropical storm force, and occasionally, hurricane force, and coastal flooding is expected to be epic. The total amounts of snowfall will be over a foot for a very large area, and well over that here and there, though this is very difficult to predict.

This is a strong low pressure system that will gather significant energy from a warm sea surface as it moves into the Atlantic.

This is a system that would normally not produce a lot of snow, but the odd configuration of the jet stream (once again) is moving the low pressure system through a pattern that will create an epic blizzard.

Storms of roughly this magnitude, in this the New York City area, have occurred in 1888, 1947, 1978, 1993, 1996, 2003, 2006, 2010. A similar pattern would emerge if the focal area was Boston. Weather Wunderground lists these snow events for New York City, indicating that half of the heavy events since the mid nineteenth century have occurred in the last 12 years:

26.9″ Feb 11-12, 2006
25.8″ Dec 26-27, 1947
21.0″ Mar 12-14, 1888
20.9″ Feb 25-26, 2010
20.2″ Jan 7-8, 1996
20.0″ Dec 26-27, 2010
19.8″ Feb 16-17, 2003
19.0″ Jan 26-27, 2011
18.1″ Jan 22-24, 1935
18.1″ Mar 7-8, 1941

Both the odd jet stream and the warm sea surface temperatures can be pegged as likely effects of anthropogenic global warming (AGW). This added to the clear pattern of more of these storms happening very recently strongly suggest that it is reasonable to characterize this storm as a “global warming amplified storm.” This is not unexpected.

I’m not sure if the sea surface temperatures in the region are at a record high, but they are very high. Over time, North Atlantic sea surface temperatures have certainly risen:

(a) Global annual mean sea-surface temperature (SST) anomalies from HadISST for the period 1870–2008 (Ref. 58)(thin black line). (b) Annual mean North Atlantic SST anomalies for the period 1870–2008 (ref. 58; thin black line). (c) The Atlantic multidecadal oscillation (AMO) index for the period 1870–2008. The modern AMO index4 is defined by subtracting the global mean SST anomalies (a) from the North Atlantic SST anomalies (b). Five-year running means are shown by heavy black lines with fill in all panels.

And here is the current sea surface temperature anomaly map for the region, showing current temperatures off New York and New England in the upper range:

There has been an increase in extreme precipitation in the Northeast, with a 71% change in the region:

This is inline with predictions the IPCC has been making for some time now. According to climate scientist Michael Mann, “The U.N. Intergovernmental Panel on Climate Change has found that Nor’easters like this one may grow stronger w/ human-caused climate change, as they are driven by the contrast between cold Arctic air masses and ever-warming ocean surface temperatures. We also know that ocean surface temperatures off the U.S. east coast right now are unusually warm, and there is no doubt that a component of that anomalous warmth is due to human-caused climate change. Those warm ocean temperatures also mean that there is more moisture in the air for this storm to feed on and to produce huge snowfalls inland. Climate change is making these sorts of storms more common, much as it is making Sandy-like Superstorms and unusually intense hurricanes more common. Asking whether these storms were caused by climate change, however, is asking the wrong question. What we can say is that they were likely made worse by climate change.”

Kevin Trenbeth, of the National Center for Atmospheric Research notes that the main reason there is a big blizzard coming to the northeast is that it is winter, but “it is warm over the oceans and the contrast between the cold continent and the warm Gulf Stream and surrounding waters is increasing. At present sea surface temperatures are more than 2F above normal over huge expanses (1000 miles) off the east coast and water vapor in the atmosphere is about 10% higher as a result. About half of this can be attributed to climate change.” I would add that the actual anomolies over large areas of the sea where this low pressure system will track are closer to 4 degrees.

There is a live blog at Weather Underground that you may want to keep an eye on, here. There, we see that current predictions for the region are:

New York City, NY: 18 – 24″
Boston, MA: 20 – 30″
Providence, RI: 20 – 30″

The National Weather Service has a page on the storm here.

And, yes, folks, this is a trend:

So, are we going to have an El Nino, or what?

January 20, 2015UncategorizedClimate Change, El Nino, ENSO, Global Warming, Severe weatherGreg Laden

Officially, 2014 closed without an official El Nino. Probably. If you went back in a time machine to the spring, and told El Nino watchers that, they would be a little surprised, but they would also say something like, “Yeah, well, you know, we keep saying this is hard to predict.”

Despite the fact that for the most part there was not an official El Nino declared, a subset of El Nino conditions have been around, off and on, for many months. To officially declare an El Nino, a number of things have to add up, and while some of those things developed, the standard was not met. A few weeks ago, the Japan Meteorological Agency did retroactively say that there had been an El Nino, but others are not really going along with that. Some agencies are saying something similar but with less certainty.

Over the last few days, a number of new statements about El Nino have come out, and it looks like we are not too likely to see a large El Nino in 2015, but maybe a weak one. Or maybe none. (But some who watch this phenomenon have quietly suggested there could be a strong one.) Here are some of those statements.

Let’s start with the Australian Bureau of Meteorology ENSO Wrap-Up:

Tropical Pacific Ocean moves from El Niño to neutral
Issued on 20 January 2015
Since late 2014, most ENSO indicators have eased back from borderline El Niño levels. As the natural seasonal cycle of ENSO is now entering the decay phase, and models indicate a low chance of an immediate return to El Niño levels, neutral conditions are considered the most likely scenario through into autumn.

Central tropical Pacific Ocean surface temperatures have fallen by around half a degree from their peak of 1.1 °C above average in late November. Likewise, the Southern Oscillation Index has weakened to values more consistent with neutral conditions, while recent cloud patterns show little El Niño signature. As all models surveyed by the Bureau favour a continuation of these neutral conditions in the coming months, the immediate threat of El Niño onset appears passed for the 2014–15 cycle. Hence the ENSO Tracker has been reset to NEUTRAL. The Tracker will remain at NEUTRAL unless observations and model outlooks indicate a heightened risk of either La Niña or El Niño developing later this year.

From NOAA’s climate prediction center, from a statement issued on January 8th, 2015:

Although the surface and sub-surface temperature anomalies were consistent with El Niño, the overall atmospheric circulation continued to show only limited coupling with the anomalously warm water. The equatorial low-level winds were largely near average during the month, while upper-level easterly anomalies continued in the central and eastern tropical Pacific. The Southern Oscillation Index (SOI) remained slightly negative, but the Equatorial SOI remained near zero. Also, rainfall remained below-average near the Date Line and was above-average over Indonesia (Fig. 5). Overall, the combined atmospheric and oceanic state remains ENSO-neutral.

Similar to last month, most models predict the SST anomalies to remain at weak El Niño levels (3-month values of the Niño-3.4 index between 0.5oC and 0.9oC) during December-February 2014-15, and lasting into the Northern Hemisphere spring 2015 (Fig. 6). If El Niño were to emerge, the forecaster consensus favors a weak event that ends in early Northern Hemisphere spring. In summary, there is an approximately 50-60% chance of El Niño conditions during the next two months, with ENSO-neutral favored thereafter (click CPC/IRI consensus forecast for the chance of each outcome).

And now a shout out from NOAA, January 15th:

CURRENT ATMOSPHERIC AND OCEANIC CONDITIONS CONTINUE TO SHOW MIXED SIGNALS
REGARDING THE ENSO STATE. SEA-SURFACE TEMPERATURES (SSTS) REMAINED NEAR TO
ABOVE AVERAGE FOR MOST OF THE EQUATORIAL PACIFIC, BUT THROUGH EARLY JANUARY,
THE ATMOSPHERIC RESPONSE IS NOT ROBUST. TAKEN AS A WHOLE, THE ENSO SYSTEM
REMAINS IN AN ENSO NEUTRAL STATE, WITH SOME ASPECTS OF A WARM EVENT. THE
CHANCES OF EL NINO DEVELOPING DURING THE NEXT 2 MONTHS ARE 50-60 PERCENT, WITH
A RETURN TO ENSO NEUTRAL CONDITIONS FAVORED THEREAFTER.

(I thought they were going to stop using all caps.)

From the International Research Institute for Climate and Society, Columbia University, IRI ENSO forecast:

During December 2014 through early January 2015 the SST exceeded thresholds for weak Niño conditions, although the anomaly level has weakened recently. Meanwhile, only some of the atmospheric variables indicate an El Niño pattern. Most of the ENSO prediction models indicate weak El Niño conditions during the January-March season in progress, continuing through most or all of northern spring 2015.

And now a few pullouts from the January 19th ENSO: Recent Evolution, Current Status and Predictions report from NOAA, a PDF file chock full of graphics and stuff put out every month.

This table (of ONI Index values) puts the current year in context of previous El Nino (red) and La Nina (blue) seasons. It is interesting to look at how long it has been since the last strong El Nino event. Most of 2012, and all of 2013 and 2014, qualify as being enough of anything by this measure to call it anything other than Neutral.

This graphic summarizes the chance of El Nino over coming months.

ENSO Alert System Status: El Niño Watch
ENSO-neutral conditions continue.
Positive equatorial sea surface temperature (SST) anomalies continue across
most of the Pacific Ocean.
There is an approximately 50-60% chance of El Niño conditions during the
next two months, with ENSO-neutral favored thereafter.

So, did we have an El Nino? Not officially, though some features that make up this phenomenon were present, off and on, over the last several months. Will we have an El Nino? Well, the indications we are having now are not too different than what we have been having, so who knows? My personal opinion is that the last year and the coming months together are going to have to be looked at carefully to determine if the way in which El Nino is measured need to be tweaked. But, that is nothing new, there is an ongoing conversation among climatologists about this.

The graphic at the head of the post is from “Fishing in pink waters: How scientists unraveled the El Niño mystery.”

Typhoon Hagupit (Ruby): Update and what you can do to help

December 5, 2014UncategorizedClimate and weather, hurricane, Hurricane, Philippines, severe weather, Severe weather, Typhoon Hagupit, UncategorizedGreg Laden

The outer reaches of Typhoon Hagupit are already affecting the target region in the Philippines. Hundreds of thousands of people have fled the areas most under the gun, but the potential for serious problems covers a very large area. The storm has gone through quite a few changes over the last couple of days, but is probably strengthening somewhat right now. No matter what happens, it is going to hit the Philippines as a very serious storm.

Jeff Masters has an update here.

This is the same area that was hit with Typhoon Haiyan last year. Haiyan was a bigger storm. But, Haiyan was also one of the biggest typhoons ever observed (I think people are still arguing over whether it was the biggest, second biggest, etc.). There is potential for very high storm surges, serious winds, very heavy rains (over two feet in some places) which could cause devastating mudslides and flooding.

When this sort of storm hits people often want to know what they can do to help. I’ve learned about a recent project that you may be interested in. This is by Direct Relief. As background, let’s look at a relatively objective source of information about Direct Relief, Wikipedia:

Direct Relief (formerly known as Direct Relief International) is a private humanitarian nonprofit organization based in Santa Barbara, California, with a mission to “improve the health and lives of people affected by poverty or emergency situations by mobilizing and providing essential medical resources needed for their care.”[1] Founded in 1948 by Estonian immigrant William D. Zimdin, the organization is headed by President and CEO Thomas Tighe and a 31-member Board of Directors.[5] Direct Relief has received a 100% fundraising efficiency rating by Forbes,[6] been ranked by the Chronicle of Philanthropy as California’s largest international relief organization,[7] and topped Charity Navigator’s 2014 list of “10 of the Best Charities Everyone’s Heard Of.[8]” Direct Relief is the first nonprofit organization in the United States to be designated by The National Association of Boards of Pharmacy (NABP) as a Verified-Accredited Wholesale Distributor licensed to distribute pharmaceutical medicines to all 50 U.S. States and Washington, D.C.[9]

So it is an experienced organization, gets the money you give it out into the field efficiently, and is secular. All things I’m sure you want to see in an organization you make a donation to.

But the Hagupit situation offers an additional opportunity because Direct Relief has a new project in the field there, which looks promising. I was planning on talking to someone at Direct Relief about it, to find out more, but I think he got stuck in a meeting at the UN or something, so we’ll probably talk later (and I’ll report on that to you). Meanwhile, check this out:

Direct Relief’s Emergency Response Team is monitoring Typhoon Hagupit (locally known as Ruby), as it approaches the Philippines. On its current trajectory, the typhoon is expected to make landfall in the Eastern Visayas in the next 72 hours and could affect 4.5 million people.

Direct Relief already has staff on the ground ready to respond in the event of a disaster and has reached out to local partners and health officials located in high-risk regions 5, 6, 7 and 8.

There are also three strategically pre-positioned typhoon modules ready to be rapidly utilized in the event of an emergency. These modules contain enough medicines and supplies supplies to treat 5,000 people for a month following a disaster.

Philippine authorities are currently in the process of evacuating vulnerable communities. Vice Mayor of Tacloban city, Jerry Yaokasin, stated that “we will now strictly enforce forced evacuation.” Yaokasin said that “we have no more excuses, we have gone through Yolanda, and to lose that many lives, it’s beyond our conscience already.”

Direct Relief’s staff on the ground will be maintaining contact with partners and monitoring the situation as it develops in the next 72 hours.

There are three things you will find at Direct Relief’s web site.

<li>First, there is <a href="http://www.directrelief.org/hpp/?extent=99.1924,-1.6963,144.8076,27.1137">a monitor of the storm's path</a>, an interactive googly mappy think which is very cool.</li>


<li>Second, there is more information about <a href="http://www.directrelief.org/2014/12/monitoring-typhoon-hagupit-approaches-philippines/">Direct Relief and the situation in the Philippines</a>; they have one of the better organized web sites for disaster relief non profits. </li>


<li>Third, and most importantly, <a href="https://secure2.convio.net/dri/site/Donation2?df_id=2105&2105.donation=form1&_ga=1.168290657.1168894472.1417733221">there is a way to donate money</a>. </li>

When donating, frankly, I’d suggest the “wherever it is needed most” or “disaster relief” options. They are already there, on the ground; they will be relieving people as it happens. I have a feeling they know best where to spend the money.

Super Typhoon Hagupit

December 4, 2014UncategorizedHurricane, Severe weather, Super Typhoon HagupitGreg Laden

Super Typhoon Hagupit is on its way to the Philippines. The image above shows the storm track for Typhoon Haiyan, which was a very damaging super Typhoon that came through the same area last year, and served as an example of climate change making things worse. The smaller map is the Japan Meteorological Agency’s prediction of Hagupit’s path. They are very very similar.

Hagupit will not likely be as strong as Haiyan (see details here) because the region does not have the extra warm deep water that supercharged Haiyan. But Hagupit is still going to be a bad storm.

How scientists unraveled the El Niño mystery

December 4, 2014UncategorizedClimate and weather, Climate Change, Climate Change, Climate Change Graphics, El Nino, Global Warming, History of science, Severe weather, WeatherGreg Laden

The Road to Paris is a web site created by the ICSU, “…a non-governmental organization representing a global membership that includes both national scientific bodies (121 National Members representing 141 countries) and International Scientific Unions (30 Members),” founded in 1931. If the ICSU had not existed when the UN was formed, the UN would have formed it. Think of the ICSU as the UN of Science. More or less.

(Follow Road to Paris on Twitter.)

Anyway, Road to Paris refers to the 2015 international meetings on climate change, and the purpose of the web site is to provide excellent information about climate change, up to date, so those engaged in that process, either as direct participants or as onlookers, will be well informed.

“Fishing in pink waters: How scientists unraveled the El Niño mystery” is an amazing piece of work written by Daniel Gross (I made minuscule contributions), looking at the history of the science of the El Nino Southern Oscillation, which is one of the most important climate or weather related things on this planet. This is timely, because we are expecting an El Niño to form over the winter. Maybe. Well, eventually we will have an El Niño. (It has been an unusually long time since the last strong one.)

Please visit this web page, read it, enjoy it (it is highly interactive), and spread it around.

The Polar Vortex Is Dead. But that does not mean it isn't cold out

November 17, 2014UncategorizedClimate and weather, Climate Change, Climate Change, Global Warming, polar vortex, Severe weather, Winter 2014 preditionGreg Laden

The term “Polar Vortex” was thrown around a lot last year, in reference to the persistent mass of very cold air that enveloped much of southern Canada and the US. As you will remember, Rush Limbaugh accused climate scientists and librul meteorologists of making up the polar vortex to scare everyone into thinking climate change is real. You may also remember Al Roker pointing out on national TV and on Twitter that the term “polar vortex” has been in meteorology textbooks for decades.

This year, with a new wave of cold air arriving unseasonably in the upper middle part of the US, the term is being used again. I was amused to see the term being used on accuweather such that it was placed on each of several graphics used to show that this year’s cold snap is not actually the polar vortex, unlike last year.

It turns out that while the polar vortex is a real thing, it really is not the correct term to apply to either last year’s cold incursion or the current cold spell. The polar vortex is a thing that gets going in a big way during the norther Winter, and swirls around all vortexy at high altitude over the pole. It can become more or less compact, more or less well defined, and it certainly has a relationship to the weather. But the proper term for a huge bundle of cold air heading south and freezing us out would not be “polar vortex” but rather, something like “cross-polar flow with low-level winds advecting frigid air southward from polar regions” (see this for a great discussion of what the polar vortex is and isn’t). At least in some cases; other descriptions may apply in other cases.

The unseasonable cold air is potentially important, especially if large scale bending of the jet streams that can cause these “troughs” of cold air to move farther south than typical are more common because of global warming (see this).

Anyway, I was wondering exactly how the term was originally introduced into the conversation last winter, so I used google to narrow down its occurrence and found these:

AP, on January 3rd 2014:

Temperature records will likely be broken during the short, yet forceful deep freeze that will begin in many places on Sunday and extend into early next week. That’s thanks to a perfect combination of the jet stream, cold surface temperatures and the polar vortex — a counterclockwise-rotating pool of cold, dense air, said Ryan Maue, of Tallahassee, Fla., a meteorologist for Weather Bell.

“All the ingredients are there for a near-record or historic cold outbreak,” he said. “If you’re under 40 (years old), you’ve not seen this stuff before.”

New York Mag, January 4th, 2014:

… there’s something happening in the country called a “polar vortex” or, as Weather Bell meteorologist Ryan Maue called it, a “frigid air blanket.”

Maue said the cold air system is caused by a “counterclockwise-rotating pool of cold, dense air, once piled up at the North Pole, and pushed down to the U.S.” It’s expected to arrive Sunday.

Huffington Post, January 3rd, 2014:

Temperature records will likely be broken during the short, yet forceful deep freeze that will begin in many places on Sunday and extend into early next week. That’s thanks to a perfect combination of the jet stream, cold surface temperatures and the polar vortex — a counterclockwise-rotating pool of cold, dense air, said Ryan Maue, of Tallahassee, Fla., a meteorologist for Weather Bell.

“All the ingredients are there for a near-record or historic cold outbreak,” he said. “If you’re under 40 (years old), you’ve not seen this stuff before.”

So, the common ingredient in the misuse of the term “polar vortex” is a meteorologist Ryan Maue, of Weather Bell. He’s the one that screwed this up originally and the press kind of took off with it.

You can’t totally blame the press. Given the choice between “polar vortex” and “advecting cross polar flow yadayada” it isn’t a hard choice. If they were both right, and they just didn’t know.

Ryan Maue, by the way, is a climate change science denier. I checked my twitter list of climate change deniers and he is on it. That means he annoyed me on twitter with his climate change science denial yammering. So a science denier came up with this bone headed misuse of a term and the press more or less blindly went along with it.

As my friend Paul Douglas notes, in speaking of the polar vortex problem vis-a-vis our current cold snap “For me the bigger question is will it last? What made last winter’s polar displacement so unusual was its persistence. The bitter blob all but stalled for the better part of 3 months.”

Long term predictions for this winter suggest an average winter, but for many parts of the US a bit warmer than average. So far the weather is not cooperating with the prediction. I predict that the prediction will be wrong because I suspect the models used to make these predictions don’t properly account for the increased frequency of formerly rare phenomena related to the jet streams. But, on the other hand, eventually there is supposed to be a shift to official El Nino conditions. (The Pacific is already El Nino warm, just not acting El Nino-ish in other ways). So, really, I’m predicting a warmer than average winter in the Northern Hemisphere but with the 5% or so of that hemisphere occupied by the largest concentration of climate science deniers, Americans, colder than average. It is like Climate Change doesn’t want to be believed in by Americans. It wears an invisibility cloak.

The Eye of the Storm, And The Storm

October 17, 2014UncategorizedEye of Hurricane, Gonzalo, Hurricane, hurricane, Severe weather, severe weatherGreg Laden

There has not been much hurricane activity in the Atlantic for a while now, so unsurprisingly the reporting is starting to slip again. This post goes out to all you reporters at CNN and Reuters and Yahoo and everywhere else. Imma give you an example of what you are doing wrong, then I’ll send you to a place to learn up on it.

A recent report noted that “hurricane force winds are now bearing down on Bermuda, and the storm is expected to arrive within hours” meaning the eye would arrive within hours (paraphrased). This is not what is happening. When there is a hurricane arriving at your location, and the “hurricane force winds” start, that’s the hurricane. Not some other thing. The eye of the storm is one part of the storm. The rest of the storm is big and when you have hurricane force winds form that big circle thingie you see in the weather reports, that is the hurricane. For that matter, the lesser winds that arrive sooner, that’s the hurricane too. It’s a big thing, that hurricane. And the whole thing is the hurricane.

What does “Hurricane Landfall” mean?

But… but…. but what about when they say that word, what is is, “landfall,” isn’t that the EYE of the hurricane, so isn’t that the hurricane?

No. Read this: Hurricane Landfall: What it is and don’t be stupid about it.

Keep an eye on Hurricane Gonzalo (Updated)

October 16, 2014UncategorizedAtlantic Hurricane Gonzalo, Bermuda, Hurricane, Severe weather, UncategorizedGreg Laden

Atlantic Hurricane Gonzalo is a Major Hurricane, Category 3 at the moment, and it is heading towards Bermuda. The storm will weaken a little bit before getting there but it will still be major. This is a significant event. It is possible that a storm surge of about 10 feet could occur there. Gonzales will be very near Bermuda in by Friday Evening, and past it by Saturday morning.

Interestingly, Gonzalo is expected to remain a hurricane strength storm (though it may be called a “post-tropical cyclone” it will still have sustained winds at hurricane level) as it passes the Canadian Maritimes. It will be interesting to see how much of its hurricane shape it maintains as this happens. Gonzalo will still be a pretty nasty storm when, in several days it arrives in the general vicinity if Ireland and Great Britain.

UPDATE:
From NWS:

Although it appears that a gradual weakening has begun, Gonzalo is
expected to be a dangerous Category 3 hurricane as it
moves near or over Bermuda later today. After that time, increasing
shear and cooler waters along the track of the hurricane should
result in a faster weakening. Gonzalo is likely to transition
into a post-tropical cyclone by 36 to 48 hours as it moves near or
south of Newfoundland, and become fully extratropical thereafter.

Significant coastal flooding on Bermuda is likely if Gonzalo
continues on the current NHC forecast track. Although specific
amounts cannot be forecast for Gonzalo, Hurricane Fabian produced an
estimated 10 feet of storm surge when it moved over Bermuda as a
major hurricane in 2003, and similar values could occur with
Gonzalo.

Bermuda radar:

Explaining Extreme Events of 2013: Limitations of the BAMS Report

October 3, 2014UncategorizedBAMS Report, Climate Change, Climate Change, Extreme Weather Events, Global Warming, Global Warming, Severe weatherGreg Laden

The American Meteorological Society, in it’s Bulletin of the American Meteorological Society (BAMS), has released a report called “Explaining Extreme Events of 2013 from a Climate Perspective.” Three studies looked at excessive heat in Australia, three at drought or dry conditions in California, and 14 looked at various other extreme events (though some of those events may overlap or be related) for a total of about 15 different phenomena.

There was a pattern in the results. The studies looking at heat all suggested a link to anthropogenic global warming (AGW). This is not surprising because AGW has involved a global increase in average temperature which is manifest across a variable climate, so even a modest increase in global temperature, bunched up in to places that are a bit cooler or warmer than average (at a given moment in time) is going to be blatantly obvious when picking out heat events. Some of the studies that looked at the California drought and drought in New Zealand attributed these conditions to climate change, others were more ambiguous or suggested that there was no link. All of the studies that looked at extreme precipitation events concluded that there was no way to make a connection, except one (in Northern India) which as ambiguous.

Michael Mann has pointed out that there is a basic problem with the BAMS study. Many of the extreme climate events of recent years have been linked by various researchers to climate change, but a) none of these researchers seem to have been invited to contribute to this collection of papers, and b) some of those specific events have been linked to climate change by some of those researchers.

It might be tempting to view this volume as an authoritative statement by the scientific community on the role climate change may or may not have had in some high profile, devastating recent extreme weather events. But that would be misguided. The BAMS special issue is not a representative, community-wide scientific assessment like those published by the National Academy of Sciences or the Intergovernmental Panel on Climate Change. The editors, instead, have solicited contributions from a relatively small number of groups, so the findings do not necessarily reflect the range of views of the broader scientific community. Some leading climate scientists who were not included in the effort have presented evidence of a greater role for climate change in several of the events dismissed or downplayed by the BAMS articles (see e.g. Kevin Trenberth of NCAR on the September 2013 Colorado floods, Stefan Rahmstorf of the University of Potsdam on the June 2013 Central European floods and Jennifer Francis of Rutgers on the 2013/2014 California Drought).

I’ve provided references and links to the studies mentioned by Mann, as well as other studies, below.

Mann points out, and I had noticed this when I first read the BAMS volume, that the studies that looked at extreme precipitation pretty much leave out the mechanism implicated by the above mentioned researchers. In fact, I would say that the basic methodology used to examine these events is flawed in two ways. Before describing that, here is summary information about the studies.

The spatial and temporal context of the studies, and attribution

In order to evaluate the studies in the BAM report, I ranked attribution from 1 to 5. 1 means no effect of climate change at all, 5 means climate change is a major contributor or THE explanation. 3 is the nickpoint; a 3 means maybe maybe not, or serious ambiguity. So 4 and 5 are yes, climate change mattered, 1 and 2 are no, climate change did not matter (but 1 is more strongly stated) and 3 means you can’t say but maybe.

The four studies that look at dryness and drought (including more than one for California so these are not all independent data in that respect) had attribution vales of 2, 3, 4, and 4. The minimum surface area of the climatic events evaluated was about 268,021 km2, and the maximum about 423,970 km2. These events are generally long term. Drought or dry periods are large and slow moving things, and the period of time over which they happen ranges from several months to years. Notably, some meteorologists such as Paul Douglas have noticed a shorter term event, which Douglas calls a “Flash Drought,” a period of little or no rain where there usually is some rain lasting for several weeks, sufficient to disrupt crop growing but not sufficient to lead to long term effects such as depletion of ground water supplies.

The 10 studies that looked at heat (all but one excessive heat, one cold) had attribution values of 1 (the cold in UK), 4, 4, 5, 5, 5, 5, 5, 5 and 5, with a surface area ranging from about 220,000 km2
to 133,453,480 km2. Heat waves usually cover large areas, but can be very short term, lasting several days to several weeks.

The 8 studies that looked at extreme precip (most rain, one snow) had attribution values of 1,1,1,1,1,2,3, and 3 … no case was attributed unambiguously to climate change, most not at all. These areas covered a region of between 27,980 km2 and 8,080,464 km2, but most clustered near the lower end of that range. Most extreme precipitation events cover small areas (though the extreme rain experienced during the summer of 2014 in North America may have been a physically very large event running form the Upper Plains to the Ohio Vally, and beyond). Extreme rain and snow storms normally occur over a matter of several days.

Spacial-temporal bias in the BAMS study

The size and lifespan of the events under consideration is the best single predictor of level of attribution given by the individuals studies. For the most part, relatively small short term events were not attributed to climate change, while large slow moving events were more often attributed to climate change. Exactly parallel to this is, of course, the nature of the event. It isn’t just the size and lifespan of the event, but the kind of event that matters, which in turn relates to the size and time frame. But, the size and lifespan of the precipitation events may be part of the explanation for why attribution is low.

This is why. The studies that looked at precipitation used a number of different approaches but for the most part they had the same characteristics. Underlying the application of the various analytical techniques is the question of probability. If a certain kind of event (a large amount of rainfall in one place over a contiguous number of days) is rare, and climate change makes is somewhat less rare, it may be impossible to detect this probabilistically unless the sampling is done right. It is difficult to measure, with statistical confidence, the difference between something that is very very rare vs. merely very rare. Since the studies essentially tried to do this (for the most part), it is not surprising the study results did not attribute those events to change over time.

It may the case that a year by year study of changes in probability of rare events will not detect a change until the change is huge.

And now for a brief thought experiment.

Imagine for a moment that all climate events are the result of the distribution and behavior of small imaginary objects that float around in the air. We’ll call them climaticulus. Climaticules have two attributes: temperature and moisture. Unspecified processes alter these attributes. If enough climaticules in a region are dry for long enough, you might get a drought. If enough are wet, you might get lots of rain or snow. If a lot are warm, you might get a heat wave.

With the climaticule thought-model, variation in two attributes can generate a spatially large long term event (like a drought) or a spatially concentrated short term event (like flooding rains). At the surface, these events look like qualitatively distinct events, but underlying them is a simple system. In this system, the smaller and shorter term events are going to present statistical distributions that are different than the statistical distributions of the larger scale events. Even if they are the same kind of distribution, they will be scaled very differently. It is quite possible that a numerical change in one category of event will remain invisible while others are latent, given similar basic approaches such as “what happened over a year’s time” or “what happened in a particular space.”

That thought experiment may or may not have been helpful, but I can put it another way: Under climate change, the climaticules are sending out a signal that results from changes in average temperature and moisture. When the signal comes as a large slow moving event, it is hard to miss. When it comes as a small ephemeral event, it is easy to miss.

Mechanistic bias in the BAMS study.

As pointed out by Mann (see above), the BAMs study fails to consider an already proposed and reasonably well supported mechanism for increased occurrence of extreme precipitation events. This is the change in the patterns of trade winds and jet streams that seems to result from regionally increased sea surface temperatures and/or relatively more warming in the Arctic.

Under normal conditions, in the northern Temperate zone, air masses move from west to east, between two jet streams. The jet streams guide the air masses and the air masses push around the jet stream … they can be thought of as two aspects of the same system that arises from a a combination of the Earth’s rotation and the movement of heat from equatorial regions north towards the pole.

Under these conditions, the air masses vary in barometric pressure and moisture, and this variation causes rainy atmosphere to move at the large scale from west to east at a fairly rapid clip. So if you are sitting there in Iowa, it might be sunny mid day, than a front comes through bringing some storms, then the sky clear again, over several hours. Or, you might get a larger, wetter, air mass coming along that brings a day of variable amounts of rain.

It is thought that recently it is more common for the jet stream to for giant curves, which relates to the temperate air masses bulging northwards or being pushed southwards. The jet stream slows down. So, air masses that might bring precipitation are either blocked from their west to east movement or move very slowly (and in a somewhat different direction) than they normally would. So, a stormy, wet, rainy air mass may take two or three times longer to move across a given region, causing much more rain to fall there. At the same time, other regions may experience long term lack of precipitation. This is all further complicated by the changes in where the air mostly comes from and goes to, allowing some air to be dryer than usual and other air to be wetter than usual. And, because of AGW, the air is on average warmer so it can hold more moisture.

So, you get a bunch of extra moist air arriving in a place where contact with colder air masses and changes in pressure cause it to be rain-producing, and it sticks around for several days in one spot, or moves very slowly, and you end up with flooding like we saw in Calgary, or Boulder, or long periods of continuous storm formation and rainfall over a large area like we had in the upper Midwest in June of 2014.

What was the jet stream doing for each of the studied extreme events?

Focusing only on temperate regions in the US and Europe, I assembled a set of wind stream maps (from here) that more or less show the behavior of the jet stream at the time of each event. These are a little hard to read but you will notice that the location of the event is in every case up against a wavy part of the jet stream at the time. For reference, I took one of the events, September 13th, and picked out several earlier wind stream maps (every five years for several decades in the past). This is not a systematic sample, but it shows that typically the jet stream, not so long ago, was flatter (probably) than it was during these extreme events. These graphics are all pasted below, and I’m sorry if it takes a while for them to load.

The examination of the relationship between climate change and extreme weather events is tricky, in in its infancy, but we are beyond the point where we should be ignoring emerging research pertaning to the link. The BAMS report ignores that research. Also, the examination of extreme precipitation events should be done in larger blocks of time than one year. Looking year by year, and event by event, almost guarantees not making the link because of the bias in spatial and temporal features of these events.

Colorado storm, September:

South Dakota Blizzard, October 4-5:

Wet southern European winter, 2013:

Heavy precipitation, May-June, Upper Danube and Elbe Basins:

Extreme snow, Western Spanish Pyrenees:

Violent Storm in Northern Germany and Denmark, 28 October:

For comparison, September 13th from several prior years:

1970:

1975:

1980:

1985:

Prior work related to climate change and extreme weather events:

Linking Weather Extremes to Global Warming
More Research Linking Global Warming To Bad Weather Events
Is Global Warming Behind the Polar Vortex?
Extreme Jet Stream Pattern Triggers Historic European Floods
Are you ready for more floods and wildfires?
Drunken Arctic Goes Head Over Heels

What will this winter be like in North America?

September 18, 2014UncategorizedClimate and weather, Climate Change, Global Warming, Severe weather, Uncategorized, Weather, Winter PredictionGreg Laden

The Polar Vortex hurt. We who lived in it, through it, with it, are like farm animals that got zapped by the electric fence a couple of times … notice all that long grass growing by the fence. Stay away. It hurt! So we are worried that this will happen again.

It is a reasonable worry, from a scientific point of view. The Polar Vortex visitation last winter was the result of changes to trade winds and jet streams that has characterized our weather for the last few years. One of the big questions on my mind is this: Are wavy jet streams and corresponding changes in the distribution of excessive rainfall and drought likely to become spatially patterned? In other words, is it likely that when the Polar Vortex wanders that it will tend to wander to the same small set of locations, like Siberia or North America? So far this seems to be at least partly true. The drought in California has not been maintained because of a lack of rainfall at that latitude, but rather, a lack of certain seasonal precipitation (winter snows) at that longitude, because of the oft-cited “ridiculously resilient ridge” which is actually one of several standing waves in the polar jet stream that shunts wet air around California, to places the Midwest. It is conceivable that the Polar Vortex, as part of the climate change induced “new normal,” will wanter off-pole and onto a landmass (either Eurasia or North America) often-ish, from now on, or until continued global warming results in some other pattern which we’ll probably call “New Normal 2.0”.

This is a question I’ve asked various scientists who are working on this problem. The answer I’ve gotten so far has been, paraphrased, “Yeah, I don’t know, maybe, we’re thinking about that. Get back to you later.”

But there is hope. I’ve put links to three places you can go for more discussion and information below. Here’s the tl;dr. The National Weather Service does a very good job of predicting what winter will be like in North America, but the accuracy of that prediction, unsurprisingly, drops off month by month. So the current prediction is probably pretty good for November/December, but as January and February come along, what is predicted now may be off. With that caveat, these are the salient predictions:

1) There will not be a Polar Vortex excursion into North America. Probably. The thing is, if this is a recent phenomenon and increasing in likelihood, the predictions may be off, but there are good reasons to believe they are not. Don’t assume the Polar Vortex will visit us, but don’t sell your wool pants at that last garage sale of the year.

2) California may actually get some rasonable precipitation this winter. It is hard to say if it will be drought-breaking rain, but it may help.

3) Although winter seems to be starting early this year (with many inches of snow having fallen or about to fall on the Front Range, the Dakotas, etc.) the overall prediction is a somewhat warmer than average winter for most of North America.

4) The Southwest, California, Texas, North-Central Mexico will have a bit more moisture than average, but other than Pacific coastal Mexico, not a lot more. That won’t translate into huge snowfalls except at high elevations. The middle of the country, from Montana to western Ohio and Michigan, south to a line running from southern Idaho across to Florida, including the Southeast, will have average precip. So, Minnesotans may see early snow if it remains cool, but this will not be an exceptionally snowy winter. Less than usual moisture is predicted for Kentucky, Ohio, western Pensylvaina, parts of New York and most of New England. But, this is only a small amount, so don’t sell your snow blower at that garage sale.

Parts of the Pacific Northwest and inland across to western Montana may be a bit dryer than usual.

Overall, temperature wise, no region is expected to be especially cold, mostly somewhat warm. The regions of Canada and Alaska along the Arctic Circle will be very warm (relatively … so many degrees below zero instead of many more degrees below zero) as we would expect with “Arctic Amplification.” Moisture levels, overall, are not going to be extreme in either direction anywhere, though the dry in the Northwest may be noticeable.

In other words, the average person’s perception of weather, which varies from reality a great deal, will include the actual realized variation, if the predictions hold up.

The NWS predictions can be found via this page.

Eric Holthaus has a discussion of the coming winter here.

Paul Douglas of Weather Nation has more here, with a lot of other info relevant to Minnesota.

Odile, Polo, and the Eastern Pacific Hurricane Season 2014

September 16, 2014UncategorizedClimate and weather, Eastern Pacific, Hurricane, hurricanes, Severe weatherGreg Laden

Odile was the strongest hurricane to strike the Baja Peninsula during the period of available data, roughly similar to Hurrican Olivia (1967). The storm reached Category 4 strength but was then weakened because of interaction with the effects of a prior hurricane in the area (Norbert). At the moment, Odile is a tropical storm and still in the Baja. There was flooding, and two fatalities, including a lightning strike and a nine year old boy taken by floodwaters. Several building in Acapulco were damaged. There has been a lot of damage and disruption in the Baja region.

Tropical Storm Polo is currently south of Mexico and is expected to stay away from the coast, and it is not clear that it will reach Hurricane strength. If so, only for a brief time.

Hurricane Iselle was the strongest tropical cyclone to hit Hawaii (the big island).

Hurricane Marie was the first Category 5 Pacific hurricane in the region in four years.

Hurricane Genevieve was the first hurricane to pass through all three defined Pacific hurricane basins since 2003.

Including Polo, there have been 17 named storms in the Eastern Pacific so far this year. Eleven have been hurricanes. The average Eastern Pacific hurricane season has 15.4 (range 7-25) storms with 8.4 hurricanes (range 3-16). Officially the season ends on November 30th. So, this is clearly an exceptional year.

Most Efficient Tornado Hunt Ever

September 9, 2014UncategorizedSevere weather, Tornado, Tornado HuntingGreg Laden

Al Franken likes to joke about having run the most efficient campaign for Senate ever, referring to when he beat incumbent Norm Coleman by just a couple of hundred votes (on the first count … the number went up during the grueling recount). Now, we have an example of the most efficient ever tornado hunt.

This is in Russia where, apparently, every single vehicle has a dash cam just in case something interesting happens. You see the guy back out of his garage, see the tornado coming down the street, and when he tries to drive back into his garage for safety … well, just have a look:

Hat tip Paul Douglas, source of video here.