Hurricane tracks, changes in hurricane clustering, and other notes from Tucson
I'm in Tucson for the American Meteorological Society's 29th Conference on Hurricanes and Tropical Meteorology. This is the premier scientific conference on hurricanes, and is held only once every two years, so pretty much all of the world's greatest hurricane experts are here. Below are some quick snapshots of four of the talks I attended yesterday; I hope to more more snapshots each day this week.
Angela Colbert of the University of Miami/RSMAS showed how different weather and climate patterns affect the Azores-Bermuda High, and thus the tracks of Atlantic hurricanes. She divided storms into straight-moving storms that move straight west-northwest through the Caribbean, recurving landfalling hurricane that hit the east coast of the U.S., and recurving ocean storms that miss land. Roughly 1/3 of all hurricanes between 1950 - 2009 fell into each of these three categories. These proportions stayed pretty constant during La Niña and neutral years, but El Niño caused a weakening of the high, resulting in far fewer hurricanes hitting the U.S. East Coast. These storms instead recurved out to sea.
Jim Kossin of the University of Wisconsin separated all Atlantic storms from 1950 - 2007 into 4 clusters, based on genesis location. Two of the clusters were more northerly-forming storms that tended to be less tropical in nature--Gulf of Mexico storms, and storms off the U.S. East Coast that tended to recurve. The other two clusters were more southerly tropical-origin systems--ones that tended to form in the Caribbean, and storms that form near the Cape Verde Island region off the coast of Africa. The more tropical Cape Verde and Caribbean storms dominated major hurricane frequency by a factor of four. In mid-1980s, there was an abrupt shift to more of these more dangerous tropical type storms--ten years prior to the active hurricane period that began in 1995. It is unknown what caused this shift. The shift is unlikely to be a result of measurement error, since we had good satellite imagery then. Independent of any trends in frequency, this shift caused an increase in intensity metrics of Atlantic hurricanes. A doubling of these tropical systems has also occurred since 1950. Interestingly, there has been no change in the number of Gulf of Mexico storms, and a slight increase in storms forming off of the U.S. East Coast. Since slight changes in track can make a big difference in what SSTs and atmospheric environment a storm sees, there is a lot of natural "noise" in the system that will make it difficult to get a clear sense of when climate change is having a substantial impact on hurricane intensity.
Bin Wang of the University of Miami studied the global number of storm days from 1965 - 2008, which should be a less sensitive quantity to data problems than the number of storms or their intensity. Storm days were defined as any day when a tropical cyclone of tropical depression strength or greater existed. However, there are still some data problems, as evidenced by a sharp drop in storm days observed in the North Indian Ocean beginning in 1978. Dr. Wang found that there was no global trend in storm days. The Atlantic was the only individual basin that showed an increase in storm days.
Greg Holland of NCAR looked at the distribution of the strongest hurricanes over time by using a mathematical description of the historical hurricane data. His analysis showed that during the period 1995 - 2008, we probably had about a 30% increase in Category 5 storms in the Atlantic, and an 18% increase in Category 4 hurricanes. Using a climate model, he predicted that by the years 2045 - 2055, we should see a 60% increase in Cat 5s, 32% increase in Cat 4s, and 16% increase in Cat 3s in the Atlantic.
Jeff Masters
Reader Comments
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NVRM
number 57
Yeah. One thing though is the MJO takes 30-40 days to circle the globe, which is why it's also known as "the 40-day wave". Since it is just now organizing in octan 4, I think the GFS may be rushing a bit too fast in putting it over the Atlantic as soon as the 17th. I think we'll see more of the main MJO burst come into our area of the world (octans 8 and 1) between May 25th and June 10th. That is the period when I think we are most likely to get our first named storm, if we're going to get one this early.
Another indication that the GFS may be rushing the MJO.
The CMC is anticipating a weak low pressure to form along the wave. I think one is already there. The cyclone phase diagram is telling me its a very weak one, with gale force winds almost non-existent and pressures near 1010 mb. Waves dont normally have an "L" attached their axis in May.
Great update storm. I look foward to all your updates.
It's been rushing over the past week, which caused it verify poorly
The forecast made on 4 May green and blue is no where the actual observations - red line. The MJO is slower than the forecast made by the GFS and GEFS.
They are both within 70-80 E & about 5-8S.. pretty nuch look the same..
Why does NAVY have 94S, 95S & 97S where is their 96S? or RAMMB's 97S?
Navy has miss numbered a few in the last few months.. May see a renumber in the coming hours.
The weak ones can be hard to see. If you look closely at visible satellite loop, you can see low-level turning off the NE coast of South America near 57W. This is a wave. If you look just west of our featured wave at 37W, you can see slight low-level turning and an inverted-V signature in the clouds at 45W. This too is a wave. The last one over South America is diving into Columbia. Tropical waves over South America are very hard to spot on satellite imagery so they take more detailed analysis. There is a 5th wave east of our featured wave along 28W but I can't find the nice Navy image that extends to Africa to show it.
97S
95S
94S
They look different to me.
Excellent job,the windward islands are going to get a good soaking soon.I'm excited,on my side of the island there has only been a few mm of rain this month so far, north western areas have got plenty.
They are not the same, they simply look alike. 97S is at near 6S 76E......95S is near 7S 98E. Quite far apart.
Noticed that.....I'm checking it out now it just vanished from my photos page lol. Sigh....I'll have to find it again and re-upload it.
Choppy loop...Can't see anything spinning.
Spinning cloud feature at 20N 30W. Loop
It looks low level, can just be seen on Infrared, and can't be seen on water vapor.
Fixed it.
Just a tiny little surface trough. It is marked on surface analysis.
would it be worth watching?
They would need to dump a million tons of toxic stuff there, do do what he says will happen. Note what he says about the amount of water involved flowing by there....maybe a million cubic yards a second or something.
What is being put into the Gulf is BAD, but it is miniscule in reality.
But it is all relative to what is being put in there already. Any increase of anything bad is a disaster. Not going to kill the corals though, I dont think.
30 C, -70 C = 187.9 mph, 883 mb
30.5C, -70 C = 191.6 mph, 878 mb
30 C, -76 C = 198.2 mph, 864 mb
30.5 C, -76 C = 202.1 mph, 857 mb
This produces a clearly non-trivial increased drag force on structures of 15.7%, and a dissipated power increase of 24.4 %.
We all know that only a few percent of storms ever reach their theoretical maximum intensity. But it does happen. With the remarkable TCHP in the Atlantic Basin so far, and the record SSTs, maybe we’ll get to see a new record holder to take the place of Wilma at 185 mph and 882 mb. Looks like El Nino ~ is fading too. It will be an exciting season no doubt.
By the way,…anyone watching the conditions in the North Indian? Wow!!! SSTs and TCHP,..sky high. I compared them to previous years,..amazing.
What. They could'nt find a dead one??
sorry, couldnot resist.
Hope it does no harm to anyone......
I dont like the way that big red arrow is pointing straight at me.
Live Video: Okla. Tornado Coverage
it's nice to see greg forbes out there with vortex 2, to hear him break down the super cell they are watching.
Trinidad. At the end of the arrow!!
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