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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i've had a look at both sites and still has 04L .Four
Exactly..when you get that feeling in the pit of your stomach you know..just as well as any experienced met-you just can feel it when you've been around long enough
I live in the Tampa Bay area. Does anyone have the latest info on TD 04? Thanks.
i don't think so.... it appears bill will be a fish storm.. it is already moving nothward..
I forget some people go to church these days. I don't know a single person who goes unless there is a wedding or funeral!
At this stage no one 'knows' where the storm is going.
The only 'virtual' certainty is that it will be a major hurricane with serious destruction on whatever comes into its path.
No - "I'll have an update Sunday. Jeff Masters "
See Saturday's update (at the end)
Conditions are good, but I think it will move over land fast before it tries to pull a Humberto.
LOL...No it wont....It would have to hit land first and right now the only land in danger is Bermuda.
Ana is (again apparently) going to dissipate.
Bill was hype and is going out to sea.
(wasn't Ike called 'hype'?)
TD4/Claudette is going to be nothing more than a thunderstorm even though SST's are some of the hottest on Earth. Never know, think of Humberto.
:)
hahaha sarcasm at its finest.
You've got it!
The reason I say 50MPH, is because it should have sufficient convection around its center to allow it to consolidate effectively. Inflow would be abundant in all channels.
your in the clear
Dont think even the islands should have issues with bill.EURO is a great model in the tropics and called this recurve days ago.As of 12z bill is already moving wnw.
Here fishy fishy fishy.
It appears so rofl.
We have absolutely no idea where Ana or Bill is going to go or the strength of all 3 systems.
I know though TD4/Claudette will make the second US landfall this year. (First amazingly went to TD Felicia on Hawaii)
I sense a hint of sarcasm in your post...
How about Ana is weakening, could regenerate or not.
Bill - Models say it is now gonna go North. Still have watch since it is a week or so more from CONUS.
TD4 - LOOKOUT... Run for the hulls. Whether it becomes a Cat1 or not, looks like alot of wind and rain regardless.
Prepare for the worst and hope for the best.
Clearer skies yep, mucked up water Yep.
great quikscat of "Bill" COC around 11.5N in my estimation.
It will still probably kill a few U.S citizens from rough waves on the east coast especially if it gets strong like its forcasted to do so. East coast to Bermuda needs to watch it as it passes north of the islands.
Interesting, wonder why.
Gosh, y'all are so confident.
A little warning, remember it is early in the season yet and such early storms tend NOT to go too far North.
There is some high level wv streaming N to meet Comet Ana...will it help...who knows.
gulf is like bath water...pretty impressive blow up on dvorak
That's what some people in here will have you think, I on the other hand don't think that.
But as I said, prepare for the worst & hope for the best!
Alberto was an UGLY storm!
Updated: 2 sec ago
79.8 °F
Clear
Humidity: 88%
Dew Point: 76 °F
Wind: 6.0 mphfrom the SE
Wind Gust: 18.0 mph
Pressure: 30.05 in (Steady)
Viewing: 4701 - 4751
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