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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1465. Drakoen
"same ol' boring bickering..."
Member Since: October 28, 2006 Posts: 57 Comments: 30562
Quoting alaina1085:


Yup! Especially because some of the models keep hinting at a development. You never know..

As Nole said as well, the pattern down here in the Gulf States has been so weird this year. First it was over 100 for 5 days in a row which never happens until August...lack of sea breeze but maybe a handful of times this year, and now a solid front passing through and temps have been really low to the point when we had a solid land breeze a few days ago.
Member Since: May 20, 2009 Posts: 0 Comments: 1640
1463. Drakoen
Quoting IKE:


Exactly. Just the same stuff over and over and over.

Jeez...go take a walk...mow the yard...play with your kids...



lol
Member Since: October 28, 2006 Posts: 57 Comments: 30562
1462. Patrap
..dosent anyone look at the current thread anymore before we get TWOat-ted to death here...?



LOL
Member Since: Posts: Comments:
1461. IKE
Quoting hurricane23:
I was surprised to see it come back to life early this morning it seemed to be organizing rapidly and was /is close to depression status---at least at some level near the surface. BUT, various loops appear to show that it is about to run into a NW upper flow brick wall within hours, and its head will be torn asunder.Maybe it will re fire up in a couple of days in the central carib, if the upper flow improves like the GFS indicates it might. But, as i have often stated, the 200mb progs are the most likely to not verify than all the other levels lower down.

Adrian


You need to read the TWO.
Member Since: Posts: Comments:
Latest frames are showing an emerging convection pulse. If this continues within the next 3hrs, watch the blog make a 180. lol
Member Since: Posts: Comments:
000
ABNT20 KNHC 192350
TWOAT
TROPICAL WEATHER OUTLOOK
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
800 PM EDT SUN JUL 19 2009

FOR THE NORTH ATLANTIC...CARIBBEAN SEA AND THE GULF OF MEXICO...

SHOWER AND THUNDERSTORM ACTIVITY ASSOCIATED WITH A TROPICAL WAVE
LOCATED ABOUT 400 MILES EAST OF THE WINDWARD ISLANDS CONTINUES TO
SHOW SIGNS OF ORGANIZATION. UPPER-LEVEL WINDS ARE EXPECTED TO
BECOME LESS FAVORABLE FOR THE DEVELOPMENT OF THIS SYSTEM OVER THE
NEXT 24 TO 48 HOURS. REGARDLESS OF DEVELOPMENT...LOCALLY HEAVY
RAINFALL AND GUSTY WINDS COULD AFFECT THE WINDWARD ISLANDS ON
MONDAY AS THE WAVE MOVES WESTWARD AT 15 TO 20 MPH. THERE IS A LOW
CHANCE...LESS THAN 30 PERCENT...OF THIS SYSTEM BECOMING A TROPICAL
CYCLONE DURING THE NEXT 48 HOURS.

ELSEWHERE...TROPICAL CYCLONE FORMATION IS NOT EXPECTED DURING THE
NEXT 48 HOURS.

$$
FORECASTER PASCH

I guess it a yellow circle for now
Member Since: June 13, 2009 Posts: 2 Comments: 12147
I was surprised to see it come back to life early this morning it seemed to be organizing rapidly and was /is close to depression status---at least at some level near the surface. BUT, various loops appear to show that it is about to run into a NW upper flow brick wall within hours, and its head will be torn asunder.Maybe it will re fire up in a couple of days in the central carib, if the upper flow improves like the GFS indicates it might. But, as i have often stated, the 200mb progs are the most likely to not verify than all the other levels lower down.

Adrian
Member Since: May 14, 2006 Posts: 8 Comments: 13804
1457. eye
000
ABNT20 KNHC 192350
TWOAT
TROPICAL WEATHER OUTLOOK
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
800 PM EDT SUN JUL 19 2009

FOR THE NORTH ATLANTIC...CARIBBEAN SEA AND THE GULF OF MEXICO...

SHOWER AND THUNDERSTORM ACTIVITY ASSOCIATED WITH A TROPICAL WAVE
LOCATED ABOUT 400 MILES EAST OF THE WINDWARD ISLANDS CONTINUES TO
SHOW SIGNS OF ORGANIZATION. UPPER-LEVEL WINDS ARE EXPECTED TO
BECOME LESS FAVORABLE FOR THE DEVELOPMENT OF THIS SYSTEM OVER THE
NEXT 24 TO 48 HOURS. REGARDLESS OF DEVELOPMENT...LOCALLY HEAVY
RAINFALL AND GUSTY WINDS COULD AFFECT THE WINDWARD ISLANDS ON
MONDAY AS THE WAVE MOVES WESTWARD AT 15 TO 20 MPH. THERE IS A LOW
CHANCE...LESS THAN 30 PERCENT...OF THIS SYSTEM BECOMING A TROPICAL
CYCLONE DURING THE NEXT 48 HOURS.

ELSEWHERE...TROPICAL CYCLONE FORMATION IS NOT EXPECTED DURING THE
NEXT 48 HOURS.

$$
FORECASTER PASCH




Member Since: August 21, 2006 Posts: 0 Comments: 147
lol Didn't we went though this last night?
Member Since: July 24, 2005 Posts: 407 Comments: 19076
Quoting HaboobsRsweet:

I am with you...it is the right time of year for it and the water is ready. That front is still producing some solid thunderstorms. watch the shear line for something to spin when it stalls out.


Yup! Especially because some of the models keep hinting at a development. You never know..
Member Since: Posts: Comments:
1454. IKE
That TWO seemed more encouraging for development and gave it 24 to 48 hours before sheer rips it apart and it's still old yeller?????????
Member Since: Posts: Comments:
1453. Patrap


We gots da Funktop Animated Loop too...baby.

Floater 1 - Funktop Color Infrared Loop

Member Since: Posts: Comments:
Blog Update
Reflector site for those at work, which includes Weather456, daily update.


AOI

AOI

AOI
Member Since: Posts: Comments:
Quoting TerraNova:


Agreed.

Appreciate that, TN.

Catch up with y'all later. I hope it dissipates, but it is certainly interesting to watch - guess that's why most of us are here.
Member Since: Posts: Comments:
.
Member Since: May 14, 2006 Posts: 8 Comments: 13804
000
ABNT20 KNHC 192350
TWOAT
TROPICAL WEATHER OUTLOOK
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
800 PM EDT SUN JUL 19 2009

FOR THE NORTH ATLANTIC...CARIBBEAN SEA AND THE GULF OF MEXICO...

SHOWER AND THUNDERSTORM ACTIVITY ASSOCIATED WITH A TROPICAL WAVE
LOCATED ABOUT 400 MILES EAST OF THE WINDWARD ISLANDS CONTINUES TO
SHOW SIGNS OF ORGANIZATION. UPPER-LEVEL WINDS ARE EXPECTED TO
BECOME LESS FAVORABLE FOR THE DEVELOPMENT OF THIS SYSTEM OVER THE
NEXT 24 TO 48 HOURS. REGARDLESS OF DEVELOPMENT...LOCALLY HEAVY
RAINFALL AND GUSTY WINDS COULD AFFECT THE WINDWARD ISLANDS ON
MONDAY AS THE WAVE MOVES WESTWARD AT 15 TO 20 MPH. THERE IS A LOW
CHANCE...LESS THAN 30 PERCENT...OF THIS SYSTEM BECOMING A TROPICAL
CYCLONE DURING THE NEXT 48 HOURS.

ELSEWHERE...TROPICAL CYCLONE FORMATION IS NOT EXPECTED DURING THE
NEXT 48 HOURS.

$$
FORECASTER PASCH


Member Since: Posts: Comments:
Quoting weatherwatcher12:

Sure. No problem.
Link


cool, thank you
Member Since: Posts: Comments:
Quoting CaicosRetiredSailor:
ABNT20 KNHC 192350
TWOAT
TROPICAL WEATHER OUTLOOK
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
800 PM EDT SUN JUL 19 2009

FOR THE NORTH ATLANTIC...CARIBBEAN SEA AND THE GULF OF MEXICO...

SHOWER AND THUNDERSTORM ACTIVITY ASSOCIATED WITH A TROPICAL WAVE
LOCATED ABOUT 400 MILES EAST OF THE WINDWARD ISLANDS CONTINUES TO
SHOW SIGNS OF ORGANIZATION. UPPER-LEVEL WINDS ARE EXPECTED TO
BECOME LESS FAVORABLE FOR THE DEVELOPMENT OF THIS SYSTEM OVER THE
NEXT 24 TO 48 HOURS. REGARDLESS OF DEVELOPMENT...LOCALLY HEAVY
RAINFALL AND GUSTY WINDS COULD AFFECT THE WINDWARD ISLANDS ON
MONDAY AS THE WAVE MOVES WESTWARD AT 15 TO 20 MPH. THERE IS A LOW
CHANCE...LESS THAN 30 PERCENT...OF THIS SYSTEM BECOMING A TROPICAL
CYCLONE DURING THE NEXT 48 HOURS.

ELSEWHERE...TROPICAL CYCLONE FORMATION IS NOT EXPECTED DURING THE
NEXT 48 HOURS.

$$
FORECASTER PASCH
WWWW


very interesting working, seems they have backed off on the shear unfavorable and the system has become better organized

but that shear variable is a good reason to keep it yellow
1446. KEEPEROFTHEGATE (Mod)
1
Member Since: Posts: Comments:
000
ABNT20 KNHC 192350
TWOAT
TROPICAL WEATHER OUTLOOK
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
800 PM EDT SUN JUL 19 2009

FOR THE NORTH ATLANTIC...CARIBBEAN SEA AND THE GULF OF MEXICO...

SHOWER AND THUNDERSTORM ACTIVITY ASSOCIATED WITH A TROPICAL WAVE
LOCATED ABOUT 400 MILES EAST OF THE WINDWARD ISLANDS CONTINUES TO
SHOW SIGNS OF ORGANIZATION. UPPER-LEVEL WINDS ARE EXPECTED TO
BECOME LESS FAVORABLE FOR THE DEVELOPMENT OF THIS SYSTEM OVER THE
NEXT 24 TO 48 HOURS. REGARDLESS OF DEVELOPMENT...LOCALLY HEAVY
RAINFALL AND GUSTY WINDS COULD AFFECT THE WINDWARD ISLANDS ON
MONDAY AS THE WAVE MOVES WESTWARD AT 15 TO 20 MPH. THERE IS A LOW
CHANCE...LESS THAN 30 PERCENT...OF THIS SYSTEM BECOMING A TROPICAL
CYCLONE DURING THE NEXT 48 HOURS.

ELSEWHERE...TROPICAL CYCLONE FORMATION IS NOT EXPECTED DURING THE
NEXT 48 HOURS.

$$
FORECASTER PASCH

Member Since: May 16, 2009 Posts: 1 Comments: 1231
1443. IKE
OLD YELLER!

ruff! ruff!

OMG...LOL.
Member Since: Posts: Comments:
Quoting NHC:
000
192334
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT SUN JUL 19 2009

TROPICAL WEATHER DISCUSSION

A TROPICAL WAVE IS ALONG 52W S OF 18N MOVG W NEAR 15 KT. THIS
WAVE COINCIDES WITH A LOW TO MIDDLE LEVEL CYCLONIC CIRCULATION
NEAR THE WAVE AXIS AT 13N. SCATTERED MODERATE CONVECTION IS FROM
12N-15N BETWEEN 51W-54W.

$$
WALTON



Member Since: Posts: Comments:
I GUARANTEE POOF!
Member Since: Posts: Comments:
Quoting alaina1085:
Ahh, Pat I am just waiting for something to brew in the Gulf everytime you post those images! lol...

I am with you...it is the right time of year for it and the water is ready. That front is still producing some solid thunderstorms. watch the shear line for something to spin when it stalls out.
Member Since: May 20, 2009 Posts: 0 Comments: 1640
Quoting IKE:


Exactly. Just the same stuff over and over and over.

Jeez...go take a walk...mow the yard...play with your kids...


Good point, Ike. Think I'll run some errands and come back later on when 97L is a naked swirl. I like my crow served sweet and plentiful.

Ya'll have fun "swirl" watchin'! ;)
Member Since: Posts: Comments:
1405. HaboobsRsweet 11:45 PM GMT on July 19, 2009
Quoting Nolehead:
do any of the models suggest anything developing from this frontal boundary that's draped in the GOM right now?? weird front for July...very hot waters right now..things might start popping up before we know it...

Wondered that myself. Have to watch the shear line. The clouds down here have been weird lately. Still having a hard time setting up a solid sea breeze which is odd for this time of year.


i know it almost feels like late Sept not JULY!!! weird stuff..
Member Since: June 3, 2008 Posts: 0 Comments: 1932
ABNT20 KNHC 192350
TWOAT
TROPICAL WEATHER OUTLOOK
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
800 PM EDT SUN JUL 19 2009

FOR THE NORTH ATLANTIC...CARIBBEAN SEA AND THE GULF OF MEXICO...

SHOWER AND THUNDERSTORM ACTIVITY ASSOCIATED WITH A TROPICAL WAVE
LOCATED ABOUT 400 MILES EAST OF THE WINDWARD ISLANDS CONTINUES TO
SHOW SIGNS OF ORGANIZATION. UPPER-LEVEL WINDS ARE EXPECTED TO
BECOME LESS FAVORABLE FOR THE DEVELOPMENT OF THIS SYSTEM OVER THE
NEXT 24 TO 48 HOURS. REGARDLESS OF DEVELOPMENT...LOCALLY HEAVY
RAINFALL AND GUSTY WINDS COULD AFFECT THE WINDWARD ISLANDS ON
MONDAY AS THE WAVE MOVES WESTWARD AT 15 TO 20 MPH. THERE IS A LOW
CHANCE...LESS THAN 30 PERCENT...OF THIS SYSTEM BECOMING A TROPICAL
CYCLONE DURING THE NEXT 48 HOURS.


ELSEWHERE...TROPICAL CYCLONE FORMATION IS NOT EXPECTED DURING THE
NEXT 48 HOURS.

$$
FORECASTER PASCH
WWWW



Member Since: Posts: Comments:
Quoting KimberlyB:
thnx weatherwatcher

no problem.
Member Since: May 16, 2009 Posts: 1 Comments: 1231
.
Member Since: May 14, 2006 Posts: 8 Comments: 13804
It's still a wave, albeit a well organized one. Waves flare up and down throughout the day until they can develop a low level circulation and fend for themselves. There isn't enough evidence to determine if this one has a well-defined low level center (QS will tell us that, whenever). I strongly doubt it'll go "poof", it has good satellite presentation and at least a tightening mid level center.
Member Since: Posts: Comments:
1433. amd
the end is near with 97L. Earlier I thought that 15 north would be the separating line between high and low shear, but it seems that the TUTT has become elongated due to the the upper level high trying to build in from the south west.

This has caused the shear levels associated with the TUTT to increase substantially, especially in the region between 12 and 15 degrees north and east of the lesser antilies. That is why some shear maps have shown a 20+ knot increase in shear in this region, and why many experts, including the NHC, do not think 97L will develop.
Member Since: August 29, 2005 Posts: 0 Comments: 1024
thnx weatherwatcher & keeper
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1431. Patrap
NexSat Se Coast
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1430. KEEPEROFTHEGATE (Mod)
Quoting KimberlyB:
Lurker with a question.....

"llc" is low level circulation, correct?
yes
Member Since: Posts: Comments:
I rememeber Fay last year, the invest that became Fay was dead as a doornail for days, came back to life, died again and then finally developed

If anyone pretends they think they know 100% what will happen, they are pulling your leg.
Quoting hurricaneseason2006:
Hurricane23 and the other poofers and downcasters are feeding on the DMIN. Realise they never high and mighty aorund DMAX like this morning.

YOu can go back and check but I have been a downcaster since the beginning. never thought it had a shot to survive the shear and still dont. I think I am one day off on when I thought it would get there. I thought it would have been there today but looks like tomorrow is the day we will see it go totally poof.
Member Since: May 20, 2009 Posts: 0 Comments: 1640
1404. BurnedAfterPosting 11:45 PM GMT on July 19, 2009
WS we said shear was affecting it, doesnt meant to forget about it and look at a wave 2000 miles to its east that will take days and days to develop


is this WS..... JFW, just wondering..
Member Since: June 3, 2008 Posts: 0 Comments: 1932
Ahh, Pat I am just waiting for something to brew in the Gulf everytime you post those images! lol...
Member Since: Posts: Comments:
Quoting KimberlyB:
Lurker with a question.....

"llc" is low level circulation, correct?

yes
Member Since: May 16, 2009 Posts: 1 Comments: 1231
1424. Patrap
JSL Channel



Floater 1 - JSL Color Infrared Loop
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1423. eye
moonlightcowboy, when u go to bed tonight, pray for our waves survival....it is gonna get blasted by shear and looks terrible now (and the main shear is further away) This small wave dosent have a chance...
Member Since: August 21, 2006 Posts: 0 Comments: 147
Quoting weatherwatcher12:

Sure. No problem.
Link


looks like we should be watching the east coast for development.
Member Since: July 7, 2008 Posts: 2 Comments: 3237
Pretty decent flare-up in the sw Caribbean for the past few hours.
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lol It is amusing watching everyone poofing it, and then seeing them get excited about convection flare ups. It's all the same everyday.
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1419. IKE
Quoting Drakoen:


I took a nap. No sense in hearing the same redundant info over and over again.


Exactly. Just the same stuff over and over and over.

Jeez...go take a walk...mow the yard...play with your kids...
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POOF!
Member Since: Posts: Comments:
Lurker with a question.....

"llc" is low level circulation, correct?
Member Since: Posts: Comments:
1416. Drakoen
Quoting IKE:


They are.

I see everyone is still in place arguing over 97L.

I'm on the right blog.


I took a nap. No sense in hearing the same redundant info over and over again.
Member Since: October 28, 2006 Posts: 57 Comments: 30562
1415. Patrap
Member Since: Posts: Comments:

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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.