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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good afternoon everyone, regardless of development at least we have something to talk about besides global warming LOL
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new shear map out, shear increasing right by the system

I have to say the NHC is right with this system, dont expect that yellow circle to change at 8pm

Sorry to kill everyone's spirits lol
There's a LLC, most evident on vis...QuikSCAT should be interesting.

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Quoting hunkerdown:
Ok everybody, please deactivate your capslock (you will see the light go off on the top right corner of your keyboard).
nothing like looking important
Member Since: July 15, 2006 Posts: 174 Comments: 54473
Quoting scottsvb:
You guys are like kids jumping up and down in the back seat of the car... this is just a strong tropical wave... yes its close to TD status.. but right now this has no model support .. (Which means) this will probably get sheared later tonight into Monday



How does no model support equate to a system getting sheared?
Member Since: July 7, 2005 Posts: 0 Comments: 5351
Quoting WaterWitch11:


YOU KNOW I STAYED UP HALF THE NIGHT WITH A CHILD WHO WAS UPSET, I'M A LITTLE TIRED!


Did you get your PhD in trollogy?
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Drak! But he's here already, I saw him.

I thought he was banned for life.
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Quoting WaterWitch11:


YOU KNOW I STAYED UP HALF THE NIGHT WITH A CHILD WHO WAS UPSET, I'M A LITTLE TIRED!


You don't have to type in all caps. At least it isn't all caps and bold too though.
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Ok everybody, please deactivate your capslock (you will see the light go off on the top right corner of your keyboard).
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703. eye
If it does develop, it will be a tiny system.
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Quoting plywoodstatenative:
Patrap, love the images you post. Where do you find em?


NOAA Floater Page

97L Floater 1 Imagery
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Quoting Stormchaser2007:


Whoa..I think my ears are bleeding.


YOU KNOW I STAYED UP HALF THE NIGHT WITH A CHILD WHO WAS UPSET, I'M A LITTLE TIRED!
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Quoting plywoodstatenative:
Patrap, love the images you post. Where do you find em?
Walmart.
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Patrap, love the images you post. Where do you find em?
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Quoting WaterWitch11:
AT STORM OR DRAK

OK I SOUNDED LIKE A RETARD IN THAT LAST POST. I JUST WANTED TO KNOW WHERE WEATHER UNDERGROUND GETS THE INFO FOR THE FORECAST MODELS.

THANKS GUYS!


45
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ws, who?
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are ya enjoying the afternoon entertainment pull up a chair stay awhile press it should get even more fun as the afternoon wears on with a fake two's and all
Member Since: July 15, 2006 Posts: 174 Comments: 54473


97L Floater 1 Imagery

Enhancement Descriptions:
Abbreviation Full Name Description
AVN
Aviation color enhancement
BD
Dvorak Dvorak enhancement - used for Tropical Classifications with the Dvorak Technique
FT
Funktop Funktop enhancement - developed by Ted Funk for assistance with Precipitation analysis
IR2
Shortwave Channel 2 Infrared imagery - Shortwave, sometimes considered "night visible"
IR4
Unenhanced Channel 4 Infrared Imagery
JSL
JSL2 enhancement - developed by Jim Lynch for use with tropical classifications
RB
Rainbow Rainbow enhancement curve - pretty color enhancement
RGB
Combination of Visible and IR using a three channel technique to make features stand out
VIS
Visible Unenhanced Visible imagery that transitions to IR2 overnight.
WV
Water Vapor Infrared Channel 3 with color enhancement
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Quoting plywoodstatenative:
Press, ease off the sugar
Maybe he hasn't really awaken from his nap.
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Quoting eye:
Be careful following moonlight's prediction, he bought his crystal ball at a buy one get one free yard sale!


LOL, why don't you actually "contribute" something to the discussion and give reasons for your statements? Try that or just shut up.

...another one finds the ignore button. One yesterday, now one, today too. It's much easier reading cognizant, conscientious posts without the loose-lathered lips. ;)
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OK, who set out the troll bait?
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Press, ease off the sugar
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Quoting presslord:
THE LATE BIILY MAYS HERE!!! FOR DR. JEFF MASTERS WEATHER UNGROUND BLOG!!!!

YOU WANT OPINIONS?!?!?!?!

WE'VE GOT 'EM!!!!!!!!!!!

AND THEY CAN BE YOURS!!! FOR THE INCREDIBLY LOW PRICE OF...WELL...NOTHING, REALLY!!!!!!!

BUT WAIT!!!!!!! THERE'S MORE!!!!!!!!

WE'LL EVEN THROW IN EGOTISM...SARCASM...AND MONOMANIA!!!!!!!!!

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you forgot to mention the deluxe package, with extra goodies for just $10.
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yo
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Quoting BurnedAfterPosting:
well ok scott I will go eat my chicken fingers on my finding nemo plate and leave it to the experts lol


RIP 97L because scott thinks so obviously


Hahaha! Bubbles!!
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afternoon press
Member Since: July 15, 2006 Posts: 174 Comments: 54473


Tropical Cyclone Model Guidance
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Afternoon all,

97L looks like a mid level circulation to me.
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Quoting WaterWitch11:
AT STORM OR DRAK

O


Poof.
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New shear map should be out in 10 mins.
Member Since: May 16, 2009 Posts: 1 Comments: 1231
Quoting msphar:
Lifting in lattitude, will be contacting shear soon.
Its the convection that is expanding to the north. Don't watch the direction of convective bursts, with the "center of circulation". It is easier seen on the visible sat. While the rainbow gives a more dramatic effect, it may be harder to interperet in some circumstances.
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AT STORM OR DRAK

OK I SOUNDED LIKE A RETARD IN THAT LAST POST. I JUST WANTED TO KNOW WHERE WEATHER UNDERGROUND GETS THE INFO FOR THE FORECAST MODELS.

THANKS GUYS!
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18 UTC SHIPS for 97L

Looking at the sats this morning before I went to work (4:50am) gave me a little smile. My money's on the shear *shrugs*

(((( All y'all ...good to see ya's)))
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Quoting WaterWitch11:
AT STORM W OR DRAK

PLEASE LET ME KNOW IF WHERE THE LINK IS THE THIS WEBSITE GETS THE FORECAST MODELS FROM

THANK YOU


Whoa..I think my ears are bleeding.
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Atlantic Ocean View (Updated ~3 hours)
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670. eye
Be careful following moonlight's prediction, he bought his crystal ball at a buy one get one free yard sale!
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Getting close to the time were you expect convection to wane. And its doing so because its a week system. Its NOT gaining any latitude, its moving a W-SW direction.
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Quoting msphar:
Lifting in lattitude, will be contacting shear soon.


It isnt gaining latitude at all, moving just south of due west right now


AT STORM W OR DRAK

PLEASE LET ME KNOW IF WHERE THE LINK IS THE THIS WEBSITE GETS THE FORECAST MODELS FROM

THANK YOU
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The structure is impressive. Kinda looks like Gustav over Cuba.


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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.