Ana and TD 3 take aim at the Lesser Antilles

By: Dr. Jeff Masters , 4:17 PM GMT on August 15, 2009

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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

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Oh my I posted here about 10 mins ago and it didn't take.. I know my post did "stall" so figured the site was over loaded.

Oh well, Thanks Dr Jeff, glad to get a new blog, of course it will be full by end of day. LOL

I agree, that blob in the Keys, has rotation and clouds and rainfall with it... and it is entering the hot GOM.. not good.

Ike, didn't you say there was a model on it?

The others, Ana and TD3/Bill...will take awhile.. and those models will swing back and forth on those two storms every time they have a new model run...

be patient little grasshoppers! LOL

it is fun to watch and comment our thoughts!

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AOI
MARK
25N/81W


TS ANA


03L
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Watch TD3 explode in convection tonight, people will all be over it again rofl.
Member Since: August 10, 2009 Posts: 3 Comments: 672
Quoting WeatherStudent:
Throw out the GFS.


How 'bout...we keep the GFS...and throw you out?
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Quoting Hurricanejer95:
The storms are 900 miles apart, will they encounter fujiwara effect?


Too far apart.
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Quoting AussieStorm:

Pity you said it 1st


Thanks Aussie, but I think you're just jealous! I've never been first to post before and I wasn't even trying. I even posted "new blog!" in the old blog before I posted in the new...how exciting! I've already told my wife three times, "Honey, I'm #1!" "You're easily amused", she said, and went back to her hurricane preparation list.
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Quoting StormW:
STEERING LAYERS FORECAST MAPS


You rock!!!
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Quoting WeatherStudent:
Throw out the GFS.
Why? u r really sounding like a troll, u r on the way to not only being banned but being in my and everybody's ignore list.
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156. jpsb
Quoting LightningCharmer:


In the last blog, I included a link to a Florida Key's buoy that indicated continuous nearly 30 knots/hour west shifting winds on the southern end of circulation which although I am not an expert would indicate to me a surface low. No-one on this blog responded to my post which indicated to me that perhaps the buoy readings were not meaningful. Perhap everyone was too busy commenting on a sometimes annoying blogging who I will not name. Sorry if I offend, it is not my intention just wanted some expert analysis regarding the buoy readings I linked and posted.
I saw your post and was surprised by the lack of interest in it. I also saw another post eariler that had the low all the way down to 5k feet. I think our little blob is just not as sexy and Ana and Bill. But there are a few smart people (not me, I just live on the gulf coast so I pay attention to anything in the gulf) watching it too. thanks for the info and the interest, FYI NHC gives it a less then 30% chance of devolopment (same as Ana a few days ago). Should the wave continue west into the central Gulf I will start worring again.
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The storms are 900 miles apart, will they encounter fujiwara effect?
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Quoting stormpetrol:
Both of these systems will probably make into Caribbean from what I can tell.


That's what I am worried about, a least with TD 3. Tracking Westerly into our area.
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Quoting Drakoen:
GFS keeps going back on forth with the trough. It's too early to tell exactly what will happen.

bingo.

the best we can go on right now is that it should be a hurricane 5 days from now and be around the northern Leeward Islands and Puerto Rico.
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NOGAPS 12z takes Ana through the FL straits to become a significant hurricane in the GOM.
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NEXRAD Radar
Key West, 1 Hour Running Surface Rainfall Accumulation Range 124 NMI


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If TD3 keeps up the current trend it's center will be exposed too lol. That's Hurricane Season 2009 for you.
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This Atlantic Ocean during this Hurricane Season has not been very impressive. Too much dry air is preventing any thunderstorm formation. 'Not impressed...
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Quoting rareaire:


So your saying bill goes north out to sea! and this from how many days out?

this is not what dr. masters is saying.
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145. IKE
Quoting WPBHurricane05:


I posted yesterday's run by mistake.

I dont read the date, just the time. LOL


I did that yesterday on another model.

It's okay.
Member Since: June 9, 2005 Posts: 23 Comments: 37858
Guys if it can be just a rain maker. S Tx is in bad shape right now. So all the wishcasters can wish for a S TX landfall. I will tell yall last year i said SE Tx can take one for the team because everyone was getting beat up. Not this time...
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Quoting rareaire:


So your saying bill goes north out to sea! and this from how many days out?


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.
Member Since: July 19, 2008 Posts: 43 Comments: 4051
GFS keeps going back on forth with the trough. It's too early to tell exactly what will happen.
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140. JLPR
Quoting Relix:
PR News:

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.


yep that will sure create a little chaos at the supermarket xD
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Quoting stormpetrol:
Both of these systems will probably make into Caribbean from what I can tell.

as I said from yesterday both are going to be caribbean storms
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138. IKE
Quoting tharpgomex:
Ike you getting any rain yet?


Not yet.

South of me....

Member Since: June 9, 2005 Posts: 23 Comments: 37858
137. CJ5
Quoting Drakoen:
The models may be leaning to a trough scenario for Bill.


I agree...though it seems later 4-5 days..agree?
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Quoting TheCaneWhisperer:
Won't the 12Z model runs for Bill be bad since the center consolidated further south than anticipated?

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.
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Quoting chevycanes:

no it doesn't.

current 12z run curves it just east of FL.


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.
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Quoting TheCaneWhisperer:
Won't the 12Z model runs for Bill be bad since the center consolidated further south than anticipated?


The runs were initialized correctly.
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Quoting IKE:


What happened to the post claiming an east Florida hit?


I posted yesterday's run by mistake.

I dont read the date, just the time. LOL
Member Since: July 31, 2006 Posts: 56 Comments: 8112
Quoting IKE:


What happened to the post claiming an east Florida hit?


LOL I never claimed a east Florida hit

are you talking about WS?
Member Since: July 19, 2008 Posts: 43 Comments: 4051
Quoting AussieStorm:

Pity you said it 1st


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.
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Quoting IKE:


Mainly a rainmaker...but the GFS is bad on intensity...maybe it could be a TD...weak TS....


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. :)
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Quoting futuremet:
Out-to-sea



So your saying bill goes north out to sea! and this from how many days out?
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128. IKE
Quoting chevycanes:
that's a big longwave trough though.

i'm not convinced it will dig that deep but i guess we'll see.


Yup...GFS is back on with a strong trough....
Member Since: June 9, 2005 Posts: 23 Comments: 37858
Surface pressures around the Keys are not falling. There is an 850mb vort maximum. There is an upper level trough in the GOM to prevent anything from getting too organized right now.
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Ike you getting any rain yet?
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Both of these systems will probably make into Caribbean from what I can tell.
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Quoting LPStormspotter:


Can you give me an idea of what the steering,high, or what ever will be next week.

Thanks
Brandy


Ridge is expected to set up over the west Atlantic, allowing Ana to follow a relatively westward track.

Member Since: July 19, 2008 Posts: 43 Comments: 4051
NEXRAD Radar
Key West, Base Reflectivity 1.45 Degree Elevation Range 124 NMI

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94. CaneLover 4:38 PM GMT on August 15, 2009
Quoting floridafisherman:
52. AussieStorm 4:30 PM GMT on August 15, 2009 Proof plz
------------

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! :)
------------

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
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Quoting mobilegirl81:

THats what i am worried about with the spin by the keys.


Lowest pressure I could find in the area is 1016mb....
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119. Relix
PR News:

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.
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118. IKE
Quoting CaneLover:


Ike, does it bring it in as a mere rain maker or something more??


Mainly a rainmaker...but the GFS is bad on intensity...maybe it could be a TD...weak TS....
Member Since: June 9, 2005 Posts: 23 Comments: 37858
Quoting Progster:


is that a recent (like today) pic?
this was 2 days ago right now we have rain/thunderstorms
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The trough scenario is as usual going to be dependent on timing and how far south of the models it tracks in the meantime. All too often we've seen it predicted but not happen. The timing has to be perfect. I wouldn't bet on it till it gets closer to the lesser antilles.
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Won't the 12Z model runs for Bill be bad since the center consolidated further south than anticipated?
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that's a big longwave trough though.

i'm not convinced it will dig that deep but i guess we'll see.
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Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.

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