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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Quoting Weather456:
GFS Shear

12 hrs



24 hrs



48 hrs




Whoa...Large change. Interesting since the GFS is what the NHC uses for a shear forecast. Looks pretty favorable. We'll see though.
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This gfs forcast for higher wind shear is not accurate and i don't buy into it.I expect shear to remain 5 to 15kt for the next 3 to 4 days.
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Quoting TheWeatherMan504:


Where is Futuremet?

5 Nw Fort Pierce [St. Lucie Co, FL] asos reports TSTM WND GST of M70 MPH at 04:50 PM EDT -- fort pierce airport recorded a wind gust of 270 degrees at 61 knots.



Its getting pretty nasty here...very heavy rain with a gust so far near 50mph.
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1008. centex
It survived the dry air and dust and that was not expected.
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Hi everyone, first time posting this season, this is reminding me of 2007 a bit
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GFS Shear

12 hrs



24 hrs



48 hrs


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Quoting Stormchaser2007:


Yep, looks like were in for some hail.



Where is Futuremet?

5 Nw Fort Pierce [St. Lucie Co, FL] asos reports TSTM WND GST of M70 MPH at 04:50 PM EDT -- fort pierce airport recorded a wind gust of 270 degrees at 61 knots.

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Quoting Stormchaser2007:
Hollow.


Expected as it heads into sunset, weak systems do this all the time. Betting it will blow up tonight.
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Quoting Stormchaser2007:


B with 60% confidence.


You're right 60% of the time, everytime!
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This thing needs to be upgraded to at least a td/based on it looks.tstms will keep on firing.The air keeps on spreading out due to divergence,makes air to keep rising.
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993. beell
Quoting hurricane23:
The trof of low pressure should dig deep enough to scoop up what ever is down there in the comings days. It will be fun to see what eventually comes out of this disturbance.


It is kinda funny-if you were to take this trough and 97L and move it just off the east coast everyone would be posting fish pictures...
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992. HadesGodWyvern (Mod)
The NHC TC Guidance has it a tropical storm southeast of your prediction, BurnedAfterPosting
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...we have a mini tropical storm at our house now!.... we live in Pembroke Pines...(south florida)
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Actually 30% is in the medium range. A yellow circle is 1-29%. (Talk about splitting hairs, lol)
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16N 75W

in that general vicinity is where I think this will be a TD
987. CUBWF
Cuando un cubano habla de esa manera, no dice mucho de esa persona. Eso es aguaje y guaperia, en buen cubano, y deja mucho que decear en la decencia. Solo que los mas jovenes no se dan cuenta de eso hasta que les pasa el tiempo. Any way, no tengo ningun problema con eso. Fue solo un consejo que le di a ws, porque en ingles se pasa de polite, pero en español, habla como chusmo del barrio de cayo Hueso, en la Habana. Just my opinion
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Not related to 97L

OFFSHORE WATERS FORECAST FOR THE SW AND TROPICAL N ATLANTIC AND CARIBBEAN SEA

SYNOPSIS FOR THE SW N ATLC INCLUDING THE BAHAMAS
530 PM EDT SUN JUL 19 2009

.SYNOPSIS...RIDGE FROM 29N65W TO S FLORIDA WILL CONTINUE THROUGH EARLY TONIGHT AS A WEAK FRONT MOVES OFF THE GEORGIA AND NE FLORIDA COAST. THE FRONT WILL STALL AND DISSIPATE THROUGH MON NIGHT. THE RIDGE WILL SHIFT SLIGHTLY N MON AS THE NORTHERN PORTION OF CARIBBEAN TROPICAL WAVE MOVES THROUGH S WATERS OVERNIGHT...THEN BREAKS OFF INTO TROUGH THAT MOVES N AND NE THROUGH THE BAHAMAS THROUGH TUE NIGHT. THE TROUGH IS FORECAST TO PASS ACROSS THE NW BAHAMAS AND E OF THE NE FLORIDA COAST WED INTO THU BEFORE TRACKING NE AS A POSSIBLE LOW N OF THE AREA FRI
Member Since: September 23, 2005 Posts: 15 Comments: 11347
Quoting CUBWF:
Hi ws, I don't think is correct you to talk like that. Believe me, most of the cuban, don't talk like that, I don't think Yamil does.

It's not apropiate. Take it just like an advice.
Quoting yamil20:


mi hermano estas un poco equivocado, yo hablo asi tambien,lo que aqui no hablo asi para respetar a los demas, eso es un lenguaje que los cubanos nada mas entendemos LOL

He gets his translation from babelfish...Hispanic people don't talk that way trust me I know.
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983. HadesGodWyvern (Mod)
They don't update the TWO map until around 8PM though, =P
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The storms in florida are not much.Its just 3,000 to 4,000 cape.But with less than20kt bulk shear/mainly outflow wind/collapsing and very isolated marginal hail.
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Quoting 0741:
i supprise to see that nhc didnot gave it orange circle to 97l doing 2pm outlook maybe because shear that coming


We've been saying that for 3 hours. lol
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980. beell
Quoting homelesswanderer:


Lol. I thought you had it right the first time.

Good Afternoon Everyone.

Looks like the NWS has a sense of humor as well..


TREE ROOTS ARE GETTING HIGH ENOUGH TO TRIP ON.

Lol. I just love a good pun. :)


Afternoon, homeless. Just added 2,000 lbs of topsoil to my front weedbed. Was not my idea.
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Quoting BurnedAfterPosting:
actually Adrian is right, shear is pretty hostile in the immediate vicinity and does look to be impacting this system a bit


It has nothing to do with how it looks now, the NHC is looking at what impacts the shear will have on 97L, and at this point the prospects do not look good for it.


i agree 100%. the NHC isn't the judge for a beauty contest. but they think that there is a 70% chance or greater that it will get ripped apart by shear in the next 48 hours, therefor putting a 30% chance of it not. (yellow circle)
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978. 0741
i supprise to see that nhc didnot gave it orange circle to 97l doing 2pm outlook maybe because shear that coming
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Quoting BurnedAfterPosting:
my prediction on 97L, it will not have enough time to become a TD before shear hits it

however I feel it will survive the shear and you will see a TD south of Jamaica in about 3-4 days; after that who knows lol

print it lol

lol I guess I'm in for something
Member Since: May 16, 2009 Posts: 1 Comments: 1231
As the night rolls in to save 97L.

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my prediction on 97L, it will not have enough time to become a TD before shear hits it

however I feel it will survive the shear and you will see a TD south of Jamaica in about 3-4 days; after that who knows lol

print it lol
Quoting CUBWF:
Hi ws, I don't think is correct you to talk like that. Believe me, most of the cuban, don't talk like that, I don't think Yamil does.
It's not apropiate. Take it just like an advice.


mi hermano estas un poco equivocado, yo hablo asi tambien,lo que aqui no hablo asi para respetar a los demas, eso es un lenguaje que los cubanos nada mas entendemos LOL
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973. HadesGodWyvern (Mod)


Well Marked Low Pressure along the coast of India.
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Quoting GeoffreyWPB:
It looks like 9 p.m. outside instead of 5:00 p.m.


Sure does.
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Quoting HurricaneSwirl:


lol that a boy


I'm a team player, ya' know...
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The trof of low pressure should dig deep enough to scoop up what ever is down there in the comings days. It will be fun to see what eventually comes out of this disturbance.
Member Since: May 14, 2006 Posts: 8 Comments: 13841
It looks like 9 p.m. outside instead of 5:00 p.m.
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Quoting Stormchaser2007:


Yep, looks like were in for some hail.

Multicells/mainly wind,small hail to 1inch
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actually Adrian is right, shear is pretty hostile in the immediate vicinity and does look to be impacting this system a bit


It has nothing to do with how it looks now, the NHC is looking at what impacts the shear will have on 97L, and at this point the prospects do not look good for it.
Dejavu

lol, I said about 94L in 2007


1136. Weather456 9:27 AM AST on August 30, 2007
putintang3, my doubts on 94L are waning day by day but i have not given up on it totally, becuz these things do move into more favorable enviorments and suprise us.


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Hollow.
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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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