Dorian is a tropical storm that formed in the eastern tropical Atlantic ago. Dorian is probably going to head almost straight west-northwest and menace the vicinity north of the Greater Antilles and the Bahamas. This is going to take some time. By the end of the weekend, Dorian will be encountering islands in the northeastern Caribbean as a topical storm, most likely. The chance of Dorian remaining as a storm (as opposed to regressing to a depression) or strengthening from storm to hurricane is not at all large. But, unlike some others storms we’ve seen lately, Dorian seems to gain a little strength or add a certain degree of organization rather than the opposite. Over the next few days, Dorian will pass over warmer waters, which should strengthen it, but the storm will also encounter win shear and drier mid-level winds, which may weaken it. Here’s the thing: If Dorian gets strong enough soon enough, the storm will start to make a bit more of its own weather and survive threats from shear or dry conditions.
So what you say? This storm is days away and has little chance of being a hurricane. Well, that’s all true, but there’s more.
First, Dorian formed very far east. That is unusual this early in the year. Second, if Dorian becomes a hurricane and had formed this far east the storm will come close to (but not break) some sort of record, or at least be impressive. Third, and this is highly speculative, but there are some models rumored to project Dorian forming a very large hurricane, traveling up the Atlantic coast, menacing (just barely) New England and hitting Nova Scotia. The chance of that exact thing happening are pretty much zero. That would be close to 2 weeks from now, and we simply can not predict what a hurricane is going to do in two weeks.
But the reason this is interesting is that the hurricane tarot cards have a North Atlantic track in Dorian’s Future, and it’s current track may have Florida in its future. Therefore, we will want to watch Dorian.
If any of this works out, Dorian will be a long-lived hurricane. If warm Gulf waters strengthen Dorian, the storm will then appear younger than it is for a while. Then, at the end, things could get very ugly all of the sudden.
The first named storm of the Atlantic hurricane season has developed. Tropical Storm Andrea formed over the last several hours, and now exhibits winds of 63 knots at 5000 feet, with a surface intensity of about 50 knots, though these winds are only found in the “right hand” side of the storm, now sitting in the northeastern Gulf of Mexico. Most likely, this is all Andrea is going to manage as the storm moves north to make landfall, where it will also interact with upper level winds which will convert the storm to a big rain storm over the next day and a half. However, Andrea will be a very noticeable storm in Florida and later along the east coast. There will be some flooding along the Florida coast and lots of rain in Florida and later to the north. Isolated tornadoes may be formed as well.
A TROPICAL STORM WARNING IS IN EFFECT FOR…
* THE WEST COAST OF FLORIDA FROM BOCA GRANDE TO INDIAN PASS
* FLAGLER BEACH FLORIDA TO CAPE CHARLES LIGHT VIRGINIA
* PAMLICO AND ALBEMARLE SOUNDS
* LOWER CHESAPEAKE BAY SOUTH OF NEW POINT COMFORT
If you are in the path…the thousand mile wide path…of Hurricane Sandy, a.k.a. Frankenstorm, then you should make sure you know what the storm could do in relationship to where you are. If you are in or near an area with mountains, look for very serious flash flooding. The winds will be strong everywhere. If you are near the coast, be aware that the highest storm surges seen in years are expected in many areas. At the same time, it is important for those of us writing or talking about this storm to be realistic and careful in making predictions. This is becasue every case of dire prediction that does not materialize is a morsel of ignorance that will be served up later by climate change denialists who profit from confusing the general public about the connection between climate change and storminess. Here, I’d like to do the following: Give a brief overview of what Sandy is all about; address the question “Can you attribute Sandy or any other large storm to Global Warming?”; and tell you about some recent research related to that question. I’ll also throw in a little bit of historical background by way of discussing a nightmare scenario that actually didn’t happen.
First the nightmare scenario. Years ago, my first long distance trip anywhere not involving aircraft was a road trip from Albany, NY to the Southeast, the Southwest, California, and back. This was in the 1970s, and it took months. On the way out, I encountered a storm in Texas that stranded me there, in Big Spring, for several days. The state was covered with a layer of ice, and there was no way to handle it. Months later, on the way back, I drove through the aftermath of that storm and a very long time after the storm had passed though, there were still wrecked semis littering Routes 30 and 40.
I did not live in Boston at the time, but that was the year Boston was hit with a very severe storm, was part of the same system that iced the Lone Star State. In Boston, so much snow fell during rush hour that the cars on the major beltways that go around the urban core were trapped in situ. People died of exposure in their own cars, or en route on foot to “safety” from more remote parts of the road. Hundreds of homes and cabins along the coast were destroyed.
That was one of several storms leading to changes in zoning and regulation along the north Atlantic coast in the US which led to no more building and in some cases the aggressive removal of structures on the open coast or barrier islands. A couple of years later I did move to the coast, and spent a fair amount of time on the shores of Cape Cod, Plumb Island and elsewhere. As an archaeologist, I fully enjoyed encountering the remains of homes or small settlements. There would be nothing standing, but the remains of houses and their contents would be poking up here and there. It was always interesting to try to figure out based on the position and location of the largest bits where the home may have originally sat, and based on the degree of deterioration of the remains, which of the recent storms had destroyed the home or cabin.
One of the great historical events one learns of while working, in historic preservation and archaeology in New York and New England is the Great Storm of 38. The big storm in the 70s happened 35 years ago, and 35 years or so before that a storm came up the Atlantic, crossed Long Island, slammed into Rhode Island and Southeast Massachusetts, and generally made a mess of the interior, destroying lots of homes and killing lots of people. We now think it was a hurricane, but the people of New England at the time, including fisherfolk who’s lives and livelihood depended on the sea and on knowledge of the weather, had not even heard of a “Hurricane” before. Surely, hurricanes had come up the coast before, but with such infrequency that they were not a named phenomenon. Just another (big) storm. Years after the Storm of ’38, when I was busy climbing all the High Peaks in the Adirondack Mountains, I was often challenged by “slides” and blowdowns caused by that storm. Anyone who knows the ADK’s of the 1960s and 1970s or earlier knows of the big slides on Giant and the other steep sloped mountains, and the blowdowns on the Dix range. Those features of hiking and climbing are mostly courtesy of the big storm of ’38.
Here’s the thing. Imagine that a storm like Sandy came along in either of two years; 70 years ago or 35 years ago. Sandy is much larger and contains much more energy than the ’38 storm, or for that matter, of any known storm of the North Atlantic (we’ll get to that below). If Sandy hit the region in the 1930s, it would have been without warning, and it would have been prior to the reconstruction of seawalls and the development of flood mitigation measures inland that have happened in recent decades. Sandy, in ’38, would kill tens of thousands and destroy thousands of structures. That would be an average Sandy, a Sandy not being as bad as the most dire predictions we are considering today as the storm begins to take a grip on the eastern seaboard.
A Sandy of 35 years ago would have been predicted. The ability to see hurricanes coming was in place, but not as well developed as it is today. We would have seen Sandy coming, but her massiveness and extent, and her exact trajectory, would probably have been unknown. But at least there would be warning. Many of the seawalls and flood mitigation systems would have been in place, but the overbuilding on barrier islands and other vulnerable coastal regions would have been at or near a peak. With evacuations, Sandy would not kill 10s of thousands… probably only hundreds. But the number of buildings destroyed would be unthinkable. Most of those buildings are now gone or shored up. A Sandy in 1975 would have left some very interesting coastal archaeology for me to have observed during my trips to the shore in the 1980s. Very interesting indeed.
Do you remember the October storm of 1991, a.k.a., the Halloween Nor’easter a.k.a. The Perfect Storm? I do. I was living in Somerville, Ma. After the storm raged for hours and finally calmed down a bit I went out for a walk. Power lines and large tree fragments littered the landscape. There would be no driving for a day or two in many neighborhoods. I was able to get out the next day, and I drove right up to Cape Anne, near Gloucester (Bass Point to be exact), where the Andrea Gail had sailed from never to return. I had not heard about the Andrea Gail yet but I went down to Glouscter to see the waves.
Is Sandy Caused By Global Warming?
I remember parking the car along side the road, and climbing over a granite riprap structure to get to the shore. I stood on that high point, and from there could see a few dozen people milling around at a much lower elevation, taking pictures of the waves that were rolling in. I did a rough calculation. How far inland would a wave wash if it was double the size of those I could see now? Double and triple size waves … rogue waves … would not be unlikely after a storm like this. When I realized that my shoes would probably get wet, and all the people down at a lower elevation would probably get washed away, if that happened, I went back to the car and drove to the clam shack in Ipswich for lunch. Later that day, I hear, the authorities cleared the beaches. The waves I was watching were 10 meters if they were a centimeter. Indeed, 30 meter waves were recorded asea in Nova Scotia, and high waves killed a couple of looky-loos on Staten Island. That storm was one of several that hit New England since the big storm of the 1970s. Everybody who lives in the region knows that the storms have become more common and more severe, and probably lager, wider, in extent.
But is there any evidence to support that?
Well, yes, actually, there is. Here’s the abstract from a recent paper:
Detection and attribution of past changes in cyclone activity are hampered by biased cyclone records due to changes in observational capabilities. Here we construct an independent record of Atlantic tropical cyclone activity on the basis of storm surge statistics from tide gauges. We demonstrate that the major events in our surge index record can be attributed to landfalling tropical cyclones; these events also correspond with the most economically damaging Atlantic cyclones. We find that warm years in general were more active in all cyclone size ranges than cold years. The largest cyclones are most affected by warmer conditions and we detect a statistically significant trend in the frequency of large surge events (roughly corresponding to tropical storm size) since 1923. In particular, we estimate that Katrina-magnitude events have been twice as frequent in warm years compared with cold years (P < 0.02).
So, over the years, it gets warmer and colder and in warmer years there is more stormosity, as it were. Warm=storm. At the same time, the amount of warm (number of warm years and how warm they are) has been going up. More storms over time, just as any honest Salt can tell you. Here’s a nice graph from the same paper:
Now, here is what you’ll hear a lot of people say. People will tell you that “you can’t attribute any given storm to global warming.” There is a certain way in which that is true, but there is also a certain way in which it is wrong, and the importance of recognizing the relationship between global warming and storminess is now so important that the former has become little more than a pedantic nuisance and we’d better start focusing on the latter.
One of the reasons why this statement is true is a little unfair to those saying it, or for that matter to the phrase itself, and is extrinsic to the logic of the statement itself, yet is still a valid reason. Here’s the thing. People often say “Well, you can’t attribute a given weather event to climate change” or, more importantly, people often hear that said, and then in their brains a disconnect between climate and weather is established or verified. In other words, people use that phrase to give themselves permission to not worry about climate change vis-a-vis storminess. One might argue that it does not matter that people use this phrase incorrectly, it is still true. But it does matter a great deal because the bigger, overwhelmingly important issue is the lack of social and political will to tackle global warming as a problem. Phrases that are a) technically true but b) miss the point and c) contribute to the end of civilization do not deserve our protection. Just. Stop. Saying. It.
The other way to look at it, the way in which we might fairly and logically say that warming weather can be said to be the cause of a particular storm, is best viewed in a thought experiment first. Suppose there were no Nor’easters, like Sandy. Suppose hurricanes were never, ever known to travel north of Georgia and were not that common. Now, imagine that we warm the world up a bit and this warming causes Nor’easters to start to form, and it causes hurricanes to start heading farther north, and then, some of those Nor’easter low pressure systems combine with some of those hurricanes and cause Frankenstorms.
Those Frankenstorms were caused by global warming.
In a world in which storms generally are more severe, more common, bigger, go farther north, or do some other nasty trick (any subset of this list may pertain, it is not necessary that all are true), one might well ask the question: “Is there any way to say that a given North Atlantic Frankenstorm emerged from the sea and the atmosphere without any of the added energy of global warming contributing to the severity, size, and northerly track of that storm?” And the answer is, “No, of course not, don’t be a bonehead.”
It is often said that storms are going to happen anyway, but global warming ramps up the probability, which is akin to saying that there is always going to be variation in temperature or some other weather related factor but global warming raises the baseline. That’s true. But the corollary to that is NOT that you can’t link climate change to a given storm. All storms are weather, all weather is the immediate manifestation of climate, climate change is about climate. Before we started talking about global warming, storms were caused by … things. Climate things. Did we ever say, back in the 1950s when a hurricane hit Florida, “Oh, ya, that was some hurricane, but the thing is, you can’t really attribute a given hurricane to the Intertropical Convergence Zone’s relationship to warm Mid Atlantic currents. The former is a weather event and the latter is a climate system.” Why did we not ever say that? Because it would have been irrelevant, even dumb.
The truth is, we experience more Atlantic severe storms because of global warming, though we are still working out the details of which features of which kinds of storms are affected most. Beyond this, it may well also be possible that something I hinted at above is true: We may be experiencing kinds of storms today that were very rare in recent centuries, because of global warming.
In any event, there’s more. From the paper:
We detect a statistically significant increasing trend in the number of moderately large surge index events since 1923. We estimate that warm years have been associated with twice as many Katrina-magnitude events compared with cold years in the global average surface temperature record.
Jeff Masters, at The Wunderblog, has an excellent post on Sandy, what’s going on now, and what might happen. It is here. Keep in mind that by the time you click through to that he may have put up a newer post, so check for that. Meantime, here’s a few salient items you may want to know about:
Sandy, the storm, is of record size, larger than any storm ever seen before. It is over 1,000 miles wide, with 12 foot seas covering that entire area. There’s been a couple of storms with this or that dimension exceeding Sandy, but in some other way they fell short. Sandy wins.
You already know about the whole “landfall” problem with storms, so I won’t go into this here. The thing is, even while Sandy’s worst rains and winds are no where near the coast, she is putting up storm surges already, and roads are being washed away as we speak with days of storminess ahead of us. (This is the thing about “Nor’easters… they go on for much longer than mere hurricanes!)
Sandy will generate modest storm surges from South Carolina to Canada, with severe storm surges from Delaware to Massachusetts.
The storm surge in New York City may be higher than ever seen before, and has about a 50-50 chance of flooding the subway system in the vicinity of the Battery. That has never happened before.
Tropical force winds will batter 1000 miles of coast on Monday and Tuesday, with hurricane force winds covering a 500 mile section of coast.
Remember all the flooding associated with Irene in 2011? Sandy will also cause major inland flooding, but not as much rain overall will fall, so overall the flooding will be less. However, what “less” means is relative. If you are in a hilly region of Pennsylvania or some other part of the northeast, you may well experience worse flooding with Sandy than you did with Irene. Or not. Overall, there will be less, but it will still be bad.
And yes, there will be snow. The usual places that get snow during Nor’easters are at risk. Any place with a high elevation or that is up north has a good chance of getting a few inches, or in some cases, a couple of feet.
I found it very interesting that the Maya recently came out to ask people to stop suggesting that somehow their cyclic calendar was going to cause the end of civilization, or the world, or whatever, at the end of the present year. This is a case of a traditional people well versed in their own indigenous technology (in this case, time tracking technology) noticing that the “civilized Western world” was making a major fool of itself, as usual, and then helpfully suggesting that certain people STFU. At the same time, we are doing it wrong for real and truly putting the future at risk, and not just with climate change, but how we address climate change. We are not making it part of the conversation in national elections, we are not making it part of our budget considerations, we are not making it part of our shovel-ready-stimulus activities. We are not even letting ourselves keep track of what we are ruining. The number of satellites that will be available to track storms like this will probably fall off in the near future to the extent that we won’t be able to do it. Talk about the end of civilization! Even if we didn’t simply screw up plans for putting up more satellites, we have this other growing problem with space junk. Our technology is warming our planet and at the same time blinding us, hampering our ability to manage the problem we are creating.
Grinsted, A., Moore, J., & Jevrejeva, S. (2012). Homogeneous record of Atlantic hurricane surge threat since 1923 Proceedings of the National Academy of Sciences DOI: 10.1073/pnas.1209542109
It is time to discuss, once again, the falsehood known as “Hurricane Landfall.”
A hurricane is a whopping big thing. A hurricane can be bigger than some states. The physical region across which a hurricane is potentially deadly and damaging is very large, many tens of miles across, sometimes a couple of hundred miles across. The danger zones are often organized like this:
The central storm surge. A central region may have a strong storm surge caused by the low pressure of the storm. This may be dozens of miles wide, but the area of effect is determined as much by the shape of the coastline the hurricane is landing on as by the hurricane itself.
The Right Punch. To the right of the central storm surge area is a region where the counter-clockwise rotating storm bearing down on the coast and hinterland will have very strong winds combined with very low pressure to increase the storm surge even more.
The storm surge caused by the low pressure system and the right punch can be a very wide area, and it can affect a coastal region for a long period of time, as the “surge” itself maybe several miles “deep.” If a hurricane is moving slowly, if the winds are strong and the pressure low, and if tides are already high and coastal flooding is already underway because of hurricane caused rain that came through for several hours before the surge arrives, this flooding can be extensive.
In some cases, the initial flooding may be very bad but the secondary flow of flood waters can be worse. If a hurricane storm surge and rain-related floods fill up the lagoons behind barrier islands, and at the same time the outlets get clogged by debris pushed up by high waves, that flooding can break open the barrier beaches in new locations, which may or my not be underneath settlements, major roads, etc. (This was, by the way, the theme of the famous book “Condominium” by John D. MacDonald which had a lot of inaccurate or outdated science but still stands as a classic “Disaster” book.)
So to review so far, around the middle of the hurricane is very low pressure, and to the right of this middle are very strong winds (and low pressure) that can cause a big flood that can first run over the land and flood stuff, then run back to the ocean and do even worse damage. Well within this area is the “eye” of the storm. The area of storm surge is much, much larger than the eye.
Spin-off Tornadoes. The big giant hurricane may cause the formation of many small tornadoes which will essentially act as very intense ambassadors of the passing cyclone. The tornadoes actually form as a function off the weakening, or generally messing up, of the organized cyclonic hurricane. They tend to form in advance of “Landfall” by as much as two days, but are most common as the hurricane’s right front quadrant is over land, and occur over a very large area. (They can also occur long after the Hurricane is downgraded to a tropical storm and is mostly on land, days after “landfall.”)
Hurricane Winds. Around this area of storm surge is a region of hurricane- or near hurricane-force winds which, especially if the hurricane is moving slowly, can buffet an area for hours and hours of time. This is like one of those nasty thunderstorms with the ‘straight line winds” coming through and knocking down a couple of trees, but for several hours. The area of these winds is typically measurable in the hundreds of miles in all directions.
Flooding Rains. Usually, over a larger area than this wind zone there will be bands of rain falling. The region over which sufficient rain to cause flooding may fall is hundreds of miles in any one direction. Flooding may start long before the hurricane force winds reach the coast. After the hurricane is way inland and is no longer called a hurricane, it can still cause major flooding. If you live, say, in Virginia or Connecticut, don’t think the hurricane has missed you just because it hits the Gulf Coast. You may be in for some major flooding in a week or so.
The Landfall Fallacy. Now, there is this thing about scientists, even meteorologists. When dealing with time-based phenomena, they need to know when something starts and when it ends, so they can do things like measure when on average certain things start, how long on average they last, etc. Therefore, there has to be an agreed upon point in time when a hurricane starts to exist (this is when the winds reach a certain strength and the cyclonic storm reaches a certain degree of organization, all of which is actually kinda hard to measure but they do it anyway). There is also an agreed upon point at which the hurricane “hits land” … known as landfall. This is when the eye of the hurricane, which is usually still visible on satellite views, on radar, as well as on the ground, crosses the shoreline. That is the arbitrarily decided on moment when scientists say the hurricane is at a certain point in its life cycle.
This does not. Repeat, not. NOT. mean that a hurricane “hits land” or “arrives” or “becomes a problem” or “starts to do damage” on “landfall.” No. The hurricane arrived hours before landfall! The outer bands that brought the beginnings of flooding rain came way before. The occasional tornado spun off by a hurricane may have already done in a neighborhood hours before. The highly damaging winds arrived long ago. The storm surge may have even started to chew up cities, towns, and industrial areas along the coast before the eye wall crosses landward, depending on all sorts of different factors. Hell, it is actually possible for a hurricane to totally mess up a coastal region then move back out to sea with the eye never crossing the coast. No landfall, but big problems. Landfall is not arrival.
The reason I mention this is that the “landfall fallacy” was one of the two Great Stupidosities that happened in relation to Hurricane Katrina, the anniversary of which is coming soon, and I fear that this fallacy remains in place (or has made a comeback) as we approach the visitation of Hurricane Isaac, now entering the Gulf of Mexico. (The other fallacy is that Katrina did not breach the dikes in NOLA, that they were breached by a flood. Which must have happened at the same time as the hurricane. But really was the hurricane… yes, you can imagine that these two Stupidosities, both perpetuated by a combination of ill intentioned politicians and not very well trained weather reporters and other journalists, are related.)
In a way, Hurricane Isaac is already affecting the Gulf coast because people are reacting to it! But really, it may be hours before “landfall” when we see our first serious flooding, wind damage, tornadoes, and all that, wherever Isaac ends up going. The area across which it will affect things will be much, much broader than the spot it makes landfall. When Katrina hit, Mississippi really took it in the neck. Huge areas of coastal Mississippi were wiped out. But, since “landfall” was in New Orleans, it didn’t make a lot of sense to report much of that in the early days of that disaster.
The hurricane hits where it hits, and it is a Big Giant Thing. Isaac may very well hit BOTH Mississippi and New Orleans, and a bit of Florida, just like Katrina did.
A “pre-existing condition” in the North Indian Ocean stoked the sudden intensification of last year’s Tropical Cyclone Nargis just before its devastating landfall in Burma, according to a new NASA/university study. The cyclone became Burma’s worst natural disaster ever and one of the deadliest cyclones of all time.