Ana and TD 3 take aim at the Lesser Antilles
Tropical Storm Ana was born this morning, when the remnants of Tropical Depression Two made a comeback and organized into the first tropical storm of the 2009 Atlantic hurricane season. Ana is the latest first named storm of the season since Hurricane Andrew got its name on August 17, 1992. The two storms have some similarities, as Andrew formed in the same part of the ocean, and also struggled in its early days with high wind shear and dry air. Let's hope the similarities end there.
Ana is struggling this afternoon. After an modest burst of heavy thunderstorm activity prompted NHC to upgrade Ana to a tropical storm early this morning, Ana has run into strong upper-level winds from the west that are creating high wind shear. This shear was not forecast, and it is not clear how long it will last. The shear has acted to drive dry air into the core of Ana, destroying almost all of Ana's heavy thunderstorms. The low-level center of the storm is now exposed to view, something that often foreshadows the death of a storm. It is possible the shear will destroy Ana, and several models (the GFS and ECMWF) forecast this may be the case. However, the shear forecast calls for shear to drop into the low range, 5 - 10 knots, tonight through Tuesday. If the shear does drop as forecast, Ana should be able to moisten the atmosphere around it sufficiently to protest itself from the dry Saharan air that surrounds it (Figure 1). SSTs are 27°C today, and will increase to 28°C by Sunday. By the time Ana moves into the Bahamas, total ocean heat content rises steeply (Figure 2), and rapid intensification of Ana is possible, if the shear and dry air haven't disrupted the storm. The intensity forecast models, for the most part, predict a steady intensification of Ana to the threshold of hurricane strength five days from now. The HWRF model is on the strong side, predicting a Category 2 hurricane. The GFDL predicts a weak tropical storm five days from now, but that is because the model has Ana passing over the rugged terrain of Hispaniola, something the other models do not predict. In summary, the intensity forecast for Ana has higher than usual uncertainty, and I give equal chances that the storm will be a hurricane--or non-existent--four days from now.
Figure 1. Water vapor image from this morning showing the large area of dry, Saharan air surrounding Ana, and lying to the north of Tropical Depression Three. Image credit: NOAA/SSD
Tropical Depression Three forms, could be Bill later today
QuikSCAT data from this morning and satellite loops revealed that the tropical wave (90L) in the middle Atlantic has finally developed a well developed surface circulation and can be classified as Tropical Depression Three. Recent satellite imagery suggests that TD 3 may already be Tropical Storm Bill. Water vapor imagery (Figure 1) shows that TD 3's center consolidated a few hundred miles south of the dry air of the Saharan Air Layer (SAL). Thus, the storm should not be affected by dry air and dust as much as Ana has been. Ana may also act to moisten the atmosphere in front of TD 3, helping protect the storm from the SAL as it edges farther north over the the three days.
Figure 2. Heat content of the ocean, in kJ per square cm. Oceanic heat content steadily increases for Ana and TD 3 as they approach the Lesser Antilles Islands. Oceanic heat content levels of 90 kJ per square cm are frequently associated with rapid intensification of hurricanes. Image credit: University of Miami.
Wind shear is moderate, 15 knots, but is forecast to fall to 10 - 15 knots on days 2 - 5. Sea Surface Temperatures are about 27.5°C, and will remain in the 27.5 - 28°C range the next five days. The combination of low wind shear and sufficiently warm SSTs should allow TD 3 to intensify steadily, and I expect the storm will be at hurricane strength by Wednesday, when it will be near the northern Lesser Antilles Islands. Most of our reliable intensity models strengthen TD 3 into a hurricane by Wednesday. Oceanic heat content (Figure 2) increases sharply just before the islands, so TD 3 could be intensifying rapidly as it moves through or just north of the Lesser Antilles on Thursday. TD 3 consolidated farther south than expected, so the track models calling for a more northerly path were probably incorrect. In particular, the ECMWF model, which had TD 3 turning sharply northwestward and missing the Lesser Antilles Islands, was probably much too far to the north in this morning's 00Z run. TD 3 will probably pass very close to the northern Lesser Antilles islands on Wednesday and Thursday.
I'll have an update Sunday.
Jeff Masters
Reader Comments
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that was last year? i totally dont remember that... :( i have the memory of Dory, for sure
lol
Moving at 300 degrees is WNW...moving at near 16 mph...looks like it's got 36 hours +/- before landfall.
Could have Claudette in the GOM....a little wearing and tearing on GOM folks...
here
Give it a rest already.
Yes, these models will flip back and forth many more times. I always believe that until a storm passes your latitude anything can happen and you need to pay attention if it is coming in your direction.
thelmores is right. It's imbeded in an area of 1017+ mb...pressure gradient makes the wind.
Link
just keep an eye out for now.
I think this could be Claudette, too. Seems to be moving more westerly than northerly. I am wondering, though, what is steering it? Could it hit TX/LA border, or MS/AL? Either way, TX really needs the rain the most.
stormno has been talking about it for a couple of days. He said he would update tonight. Haven't seen anything from him unless I missed it....
Bastardi has been talking about it.
I bet 50 % of this site has an average age of below 20 years old. Me? I'll take the opinion of a seasoned Vet anytime to compare Ananlsis over an Intern or wannabe. so I'll just sit back and lurk watching and laughing at the video game going on keeping my analysis to myself
Link
They say that about me all the time, but my name is spelled "Ann" & I hate being called Ana! :) Sorry, couldn't resist. I've been here all day and have been soooo quiet & good - knew it couldn't last!
91L was that tropical wave we've been watching since it got a 'yellow' near by where Bill is a week or so back.
hi i'm not too sure on what stormW training is.. but here's what i see from his signing(credentials) after posting his synopsis for the tropics
T. F. "STORM" WALSH III
GMCS, USCG (ret)
METEOROLOGIST/TROPICAL FORECASTER
MEMBER WEST CENTRAL FL AMS
CERTIFIED SKYWARN OFFICIAL STORM SPOTTER
is it cause he doesn't have a phd? is that why you're saying he's not fully trained? i just have one more question.. are all mets phd holders? jw what your thoughts were..
That would be me I predicted 8 storms in a 3 week period
AL, 03, 2009081506, , BEST, 0, 118N, 320W
AL, 03, 2009081512, , BEST, 0, 115N, 333W
AL, 03, 2009081518, , BEST, 0, 113N, 345W
AL, 03, 2009081600, , BEST, 0, 112N, 359W
My take:
1) orange or red code for invest 91
2) more south on the models for Bill
3) no change for Ana
By the standards set forth by the AMS he is a met.
He had one of his "special" weather statements. Said he would have more info into his office at 2 AM. Cropduster flight?
What does this mean for the overall track?
True...forgot about TampaSpin...add him to the list....
99.9% chance this invest crosses land....
LOL!
What did his update say? Batten down the hatches?
From the American Meteorologist Society web site.
WHAT IS A METEOROLOGIST?
When we hear the word "meteorologist," we often think of the person on the television screen who tells us about tomorrow's high and low temperatures and precipitation. Many radio and television weathercasters are professional meteorologists, but others are reporters who are passing on information provided by the National Weather Service or private weather forecasters. The American Meteorological Society defines a meteorologist as a person with specialized education "who uses scientific principles to explain, understand, observe, or forecast the earth's atmospheric phenomena and/or how the atmosphere affects the earth and life on the planet." This education usually (my emphasis) includes a bachelor's or higher degree from a college or university. Many meteorologists have degrees in physics, chemistry, mathematics, and other fields. The broader term "atmospheric science" often is used to describe the combination of meteorology and other branches of physical science that are involved in studying the atmosphere.
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