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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no it doesn't.
current 12z run curves it just east of FL.
THats what i am worried about with the spin by the keys.
Can you give me an idea of what the steering,high, or what ever will be next week.
Thanks
Brandy
is that a recent (like today) pic?
yep they may have good circulation but they are lacking in the convection department xD
The funny part is that Ana is forecasted to make landfall in extreme eastern PR and Td 3 is forcasted to pass close to our northeast,
I do hope they continue like this and dissipate xD
Ike, does it bring it in as a mere rain maker or something more??
Yup...I posted yesterdays GFS by mistake.
The new GFS takes it over far eastern Bahamas and out to sea.
What happened to the post claiming an east Florida hit?
Link
And for Ana:
Link
One system is struggling, TD3's doing alright according to Dr. Masters. Convection dying over the COC somewhat but its increasing in the bands, that will feed it more moister.
i'm not convinced it will dig that deep but i guess we'll see.
Mainly a rainmaker...but the GFS is bad on intensity...maybe it could be a TD...weak TS....
http://www.elnuevodia.com/tormentatropicalanallegaraellunesapuertorico-604008.html
Use a translator for English =P. It basically says we are getting hit on Monday and probably Thursday.
Lowest pressure I could find in the area is 1016mb....
Quoting floridafisherman:
52. AussieStorm 4:30 PM GMT on August 15, 2009 Proof plz
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dont quote the trolls. just poof them and let them essentially talk to themselves. quoting them only emboldens them to make more outragous statements. and yes, hurricanelover is a troll. hes only posting to get reactions from ppl like you who actually know the science behind tropical development.
That's Hurricanelover not CaneLover....I'm not a troll, just an observer with questions! :)
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reread my post. i never mentioned your name. i only mentioned hurricanelover. and as i posted before, im surprised dr masters made no mention of the AOI in the gulf. although it wont have very long to develop (if it should in fact do so), i still think it should be watched or at least mentioned since conditions in the gulf are actually pretty favorable right now
Key West, Base Reflectivity 1.45 Degree Elevation Range 124 NMI
Ridge is expected to set up over the west Atlantic, allowing Ana to follow a relatively westward track.
Yup...GFS is back on with a strong trough....
So your saying bill goes north out to sea! and this from how many days out?
Ok..thanks! Does it state about when?? Just curious. I can look at a list of the models but can't make head or tails from them unless their nicely animated. :)
Quoting mikatnight:
Good idea! Thanks Aussie!
Good Afternoon Everyone, been lurking and wanted to say hello to all the bloggers.
This is an excellent idea that many have posted again and again in the past which becames just as bad as the Thanks Doc comments. You aren't going to stop the comments by posting this and may actually be adding to it which certainly is not your intension.
It looks like things are starting to heat up for the Carribean and Florida, we are all going to start biting our nails and watching closely this next week. I tend to agree with the models that these three weather events may not be more than Tropical Storms or maybe barely a minimum hurricane based on the current conditions. This may all change as conditions warrent. As alpha992000 stated above, now is a good time to get your vienna sausage if that's what you are into.
LOL I never claimed a east Florida hit
are you talking about WS?
I posted yesterday's run by mistake.
I dont read the date, just the time. LOL
The runs were initialized correctly.
dr. masters says the model for td3 may be wrong because the center of the storm formed way south from where the models had the center.
i would think that could factor in a little bit.
i think we will get better runs later today and tomorrow after it becomes a tropical storm.
I agree...though it seems later 4-5 days..agree?
Not yet.
South of me....
as I said from yesterday both are going to be caribbean storms
yep that will sure create a little chaos at the supermarket xD
I was just showing what the GFS shows. As some of the others are suggesting, there is a chance that the trough may erode, and thus will less susceptible to recurvature.
I did that yesterday on another model.
It's okay.
this is not what dr. masters is saying.
NEXRAD Radar
Key West, 1 Hour Running Surface Rainfall Accumulation Range 124 NMI
Viewing: 101 - 151
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