97L growing more organized, will bring heavy rain to the Lesser Antilles

By: Dr. Jeff Masters , 3:55 PM GMT on July 19, 2009

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The tropical wave near 12N 52W, about 600 miles east of the Lesser Antilles Islands (97 L), has grown more organized this morning as it tracks west at about 20 mph. This wave is surrounded by an area of very dry air from the Sahara Desert, but 97L has been able to steadily moisten a large region of the atmosphere over the past day, insulating itself from the dry air. This moistening process has been aided by sea surface temperatures (SSTs) that have steadily increased from 26.5°C to 27.5°C, plus the presence of only 10 knots of wind shear. The system now has a small area of intense thunderstorms near its center, with some rotation of the cloud pattern evident at mid-levels of the atmosphere. An upper-level outflow channel has opened to the north, and there is evidence that surface spiral bands are beginning to form. This morning's QuikSCAT pass missed 97L, so we don't know what is happening at the surface.

Wind shear is a modest 10 knots over the disturbance, and is forecast to remain in the moderate 10 - 15 knot range through Monday morning. This should allow further development to occur today, and 97L could be approaching tropical depression strength on Monday as it moves through the central Lesser Antilles Islands. Monday night, shear is expected to rise to 20 - 30 knots, thanks to the presence of a trough of low pressure at upper levels of the atmosphere over the eastern Caribbean. Since 97L is a relatively small system, it is very vulnerable to wind shear. This shear may be able to drive some of the dry air west of 97L deep into its interior, significantly disrupting the disturbance. Shear will remain high along 97L's path through Thursday, when the storm should be in the western Caribbean near Cuba. If there is anything left of 97L by then, some development is possible. The National Hurricane Center gave 97L a low (less than 30% chance) of developing into a tropical depression in the next 48 hours in their 8am Tropical Weather Outlook. However, I'd say the odds are now in the medium range (30 - 50%).

None of the computer models are forecasting tropical storm development over the next seven days.


Figure 1. Current satellite image of African wave 97L.

I'll have an update Monday morning. As 97L approaches the islands, you may want to follow local observations there using our wundermap for 97L.

Jeff Masters

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latest 103 pm est
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Quoting reedzone:
Hey everyone, I told you not to underestimate 97L, it looks like chances will be at medium 30-50% by the next TWO. It's looking good :)


Yeah you were the only one I knew that was not RIPING it like everybody else was saying.
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Member Since: May 16, 2009 Posts: 1 Comments: 1231
It looks like it trying to wrap the low level cloud field.
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251. Chicklit 5:13 PM GMT on July 19, 2009
Quoting BurnedAfterPosting:
In other news, we may be about to see something incredible

Tom Watson at 59 years of age, is leading the British Open by 1 shot with 1 hole to play

Westwood has a long putt to tie for the lead on 18

Go Watson!


just play PAR golf Tom and it's all your's at age 59...incrediable!!!
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Quoting StormFreakyisher:

Thank you, that is the wave I was talking about.
Look at the, SAL loop the dust will not let it out of the ITCZ.
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Early Track Guidance

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The NHC doesnt usually get on the bandwagon with rapid development of systems they look for consistency i think they will give it one more day to see if it can hold together like this through the night...
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Hi Chicklit.
I was never too good at telling the future LOL. A lot of variables in the short/medium term.
Except, I can deffinitely predict, that when I send this post, I will have a cold beer. I am 100% sure of that.
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12Z CMC Develops a system off the SE FL coast but definitely not related to 97L.
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253. IKE
Quoting BurnedAfterPosting:
In other news, we may be about to see something incredible

Tom Watson at 59 years of age, is leading the British Open by 1 shot with 1 hole to play

Westwood has a long putt to tie for the lead on 18


Perfect drive...59 yrs. old...unbelievable.
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Hey everyone, I told you not to underestimate 97L, it looks like chances will be at medium 30-50% by the next TWO. It's looking good :)

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Quoting BurnedAfterPosting:
In other news, we may be about to see something incredible

Tom Watson at 59 years of age, is leading the British Open by 1 shot with 1 hole to play

Westwood has a long putt to tie for the lead on 18

Go Watson! With Tiger out the Old Goat's got a chance.
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250. XL
Quoting Chicklit:
KmanIslander must be out golfing.
ShortWave
Will be interested to hear what he has to say, too! What d'ya think, Pottery?
Will 97L crash into shear and give the Cayman Islands golf courses a good drenching?


Chicklit

He is on holiday, so nothing dare threaten Cayman!!
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Quoting jasoniscoolman09:
All the images you post are fine, but please do say something as to your thoughts/ideas/opinions/reasonings for posting the image.
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In other news, we may be about to see something incredible

Tom Watson at 59 years of age, is leading the British Open by 1 shot with 1 hole to play

Westwood has a long putt to tie for the lead on 18
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Quoting jasoniscoolman09:

Thank you, that is the wave I was talking about.
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I don't think they ran GFDL and HWRF this cycle. I think the vortex from GFS is too weak and they would dissipate the storm quickly and stop running. Next upgrade to HWRF will allow them to restart and continue the model when that happens.
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245. Relix
Are the models in good agreement about the track?
Member Since: August 3, 2006 Posts: 0 Comments: 2639
I'll have a Fries with a Coke,..please.

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KmanIslander must be out golfing.
ShortWave
Will be interested to hear what he has to say, too! What d'ya think, Pottery?
Will 97L crash into shear and just give the Cayman Islands golf courses a good drenching?
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241. IKE
My final vote is B+....with an emphasis on possibility of C by 7 pm CDST if the current trend continues.
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240. CUBWF
B
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Floater 1 - JSL Color Infrared Loop

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Quoting StormFreakyisher:

B-Orange because of its relatively small size of the storm and could be sheared apart if it doesn't stay south of the ridge.


Poll is already over, sorry you missed it lol
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Member Since: May 16, 2009 Posts: 1 Comments: 1231
Quoting BurnedAfterPosting:
Poll Results

Which color will the circle be on the 2pm TWO?
Votes
A Yellow.........................7
B Orange.........................20
C Red............................7
D Circle will be removed.........0

Total votes..............34

B-Orange because of its relatively small size of the storm and could be sheared apart if it doesn't stay south of the ridge.
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...so this thing is going to be a tropical depression for a short time and then die?
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It's still building convection as we start getting close to dmin in CATL and looks like no affect from trough through Monday morning. Seams to have found sweet spot for now.
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Quoting btwntx08:

its in the itcz
And appears to be suppressed by the expanding SAL.
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2PM TWO should be out in 40 to 45 min. The suspense builds up... hehe...
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Quoting Drakoen:
They really should get buoys at a lower latitude a fair amount of systems pass south of the current buoys.

Agreed, Drak.
Member Since: July 9, 2006 Posts: 184 Comments: 29594
Poll Results

Which color will the circle be on the 2pm TWO?
Votes
A Yellow.......................................7
B Orange....................................20
C Red..........................................7
D Circle will be removed.........0

Total votes................................34
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Quoting hunkerdown:
It has actually been getting its act together since just after midnight.


Ya I agree, but I am just saying from when I woke up to now it looks so much better.
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They really should get buoys at a lower latitude a fair amount of systems pass south of the current buoys.
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Quoting alaina1085:
Amazing what 97L looks like now compared to just 5 hours ago.
It has actually been getting its act together since just after midnight.
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that wave at 30W is really far south lol

maybe something to watch in a few days, but nothing imminent
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Amazing what 97L looks like now compared to just 5 hours ago.
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Quoting aquak9:
sngalla, gamma- no, stormno is not using all caps anymore. But I bet he will before Season™ is over.

STORMMASTERG is not Lenny.


He won't be able to hold back, once the first big one forms. Lol!
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poll is now closed, I will post the results in a few minutes
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217. CUBWF
True weatherwat. My bad. I stated before I have problems reading english. Sorry
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Quoting BurnedAfterPosting:


East or West?

I see nothing else in the Atlantic other than 97L, if you mean the area in the Caribbean, that convection is shear induced

This right off the coast of Africa.
East of 97L
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WHXX01 KWBC 191217

CHGHUR

TROPICAL CYCLONE GUIDANCE MESSAGE

ATTENTION...NATIONAL HURRICANE CENTER

1217 UTC SUN JUL 19 2009



DISCLAIMER...NUMERICAL MODELS ARE SUBJECT TO LARGE ERRORS.

PLEASE REFER TO NHC OFFICIAL FORECASTS FOR TROPICAL CYCLONE

AND SUBTROPICAL CYCLONE INFORMATION.



ATLANTIC OBJECTIVE AIDS FOR



DISTURBANCE INVEST (AL972009) 20090719 1200 UTC



...00 HRS... ...12 HRS... ...24 HRS. .. ...36 HRS...

090719 1200 090720 0000 090720 1200 090721 0000



LAT LON LAT LON LAT LON LAT LON

BAMS 12.4N 50.2W 13.0N 54.0W 13.9N 58.2W 15.3N 62.2W

BAMD 12.4N 50.2W 12.5N 52.8W 12.7N 55.1W 13.1N 57.6W

BAMM 12.4N 50.2W 12.8N 53.1W 13.3N 56.2W 14.0N 59.2W

LBAR 12.4N 50.2W 12.6N 53.7W 12.9N 57.5W 13.6N 61.3W

SHIP 20KTS 24KTS 29KTS 32KTS

DSHP 20KTS 24KTS 29KTS 32KTS



...48 HRS... ...72 HRS... ...96 HRS. .. ..120 HRS...

090721 1200 090722 1200 090723 1200 090724 1200



LAT LON LAT LON LAT LON LAT LON

BAMS 16.6N 66.7W 19.8N 74.8W 22.9N 80.3W 25.4N 82.4W

BAMD 13.4N 60.5W 14.0N 67.8W 14.5N 76.1W 14.2N 84.8W

BAMM 14.9N 62.7W 17.1N 70.5W 19.3N 78.1W 20.8N 84.1W

LBAR 14.3N 65.3W 16.1N 72.7W .0N .0W .0N .0W

SHIP 35KTS 37KTS 42KTS 53KTS

DSHP 35KTS 37KTS 42KTS 52KTS



...INITIAL CONDITIONS...

LATCUR = 12.4N LONCUR = 50.2W DIRCUR = 270DEG SPDCUR = 20KT

LATM12 = 12.3N LONM12 = 46.2W DIRM12 = 272DEG SPDM12 = 20KT

LATM24 = 12.0N LONM24 = 42.0W

WNDCUR = 20KT RMAXWD = 40NM WNDM12 = 20KT

CENPRS = 1013MB OUTPRS = 1014MB OUTRAD = 100NM SDEPTH = S

RD34NE = 0NM RD34SE = 0NM RD34SW = 0NM RD34NW = 0NM



$$

NNNN


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About JeffMasters

Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.