Lesser Antilles Disturbance 97L a Threat to Develop

By: Dr. Jeff Masters , 2:46 PM GMT on September 01, 2013

Share this Blog
70
+

A tropical wave over the Lesser Antilles Islands (Invest 97L) is moving westward at 15 mph, and is bringing heavy rains and gusty winds to the islands. Top sustained winds in the islands as of 10 am AST Sunday were 26 mph at Monserrat. Heavy thunderstorm activity has sharply increased since Saturday, as seen on satellite loops. A large circulation is evident, with some westerly winds blowing to the south of the disturbance. However, the thunderstorms are poorly organized, and there is no sign of a well-organized surface circulation. Martinique radar shows some rotation to the echoes, though well-organized spiral bands are not evident, and do not appear to be forming. Wind shear has dropped to a moderate 10 - 20 knots over the system. An area of dry air from the Saharan Air Layer (SAL) surrounds 97L and is interfering with development.


Figure 1. Latest satellite image of Invest 97L.

Forecast for 97L
Wind shear is expected to be in the low to moderate range for the next five days, and ocean temperatures will be warm, 28 - 29°C. The disturbance is steadily moistening the atmosphere and is moving into a moister environment, so dry air will be less of an impediment to development as the week progresses. The main factor keeping the disturbance from developing over the next two days would appear to be the fact that 97L is quite large, and is stretched out from east to west over a wide expanse. Large, elongated systems like 97L usually take several days to consolidate and spin up. Another factor that will likely retard development is the presence of strong surface trade winds over the Eastern Caribbean ahead of 97L, south of the Dominican Republic. These strong trade winds are a common feature of the Eastern Caribbean, and make the region something of a hurricane graveyard. As the surface wind flow to the west of 97L accelerates into this wind max, air will be sucked from aloft downward towards the surface, creating sinking air, interfering with the formation of thunderstorm updrafts. The best chance for development of 97L would appear to be on Wednesday or Thursday, when the disturbance reaches the Central Caribbean. The wave will likely spread heavy rains to Puerto Rico, the Virgin Islands, and the Dominican Republic by Tuesday, and to Haiti by Wednesday. These rains will be capable of causing life-threatening flash flooding and mudslides in mountainous regions in Puerto Rico and Hispaniola. Of our three reliable models for predicting genesis, the UKMET, GFS, and European models, only the UKMET model develops the disturbance, predicting it will become a tropical depression south of Haiti on Wednesday, and near Jamaica on Thursday. In their 8 am EDT Sunday Tropical Weather Outlook, NHC boosted the 5-day odds of formation of 97L to 30%, and the 2-day odds to 20%.


Video 1. You can see why landslides triggered by heavy rains from a tropical cyclone are among the most dangerous hazards of these storms, thanks to a dashboard cam that caught this extraordinary rock slide in Northeast Taiwan on August 31, 2013, after heavy rains from a cold front drenched the island with up to 200 mm (7.87") of rain in 24 hours. The rains fell upon soils already saturated by Thursday's torrential rains from Tropical Storm Kong-Rey, which dumped up to 482 mm (19") of rain on Taiwan, killing three people. The driver of the car caught in the rock slide survived with minor injuries. Thanks go to wunderground member Robert Speta for bringing this video to my attention. A separate video showing the damage to the car and the course of the rock slide is here.

Jeff Masters

Reader Comments

Comments will take a few seconds to appear.

Post Your Comments

Please sign in to post comments.

or Join

Not only will you be able to leave comments on this blog, but you'll also have the ability to upload and share your photos in our Wunder Photos section.

Display: 0, 50, 100, 200 Sort: Newest First - Order Posted

Viewing: 1405 - 1355

Page: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30 | 31 | 32 | 33 | 34 | 35 | 36 | 37 | 38 | 39 | 40 | 41 | 42 | 43 | 44 | 45 | 46 | 47 | 48 | 49 | 50Blog Index

TROPICAL WEATHER OUTLOOK
NWS NATIONAL HURRICANE CENTER MIAMI FL
800 PM EDT SUN SEP 1 2013

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

AN AREA OF LOW PRESSURE IS LOCATED NEAR THE LESSER ANTILLES.
SHOWERS AND THUNDERSTORMS ASSOCIATED WITH THIS SYSTEM HAVE
DECREASED THIS EVENING...AND SURFACE OBSERVATIONS INDICATE THAT THE
CIRCULATION IS RATHER ELONGATED. ALTHOUGH UPPER-LEVEL WINDS APPEAR
TO BE CONDUCIVE...THE PROXIMITY TO DRY AIR IN THE MIDDLE LEVELS OF
THE ATMOSPHERE COULD INHIBIT DEVELOPMENT OF THIS DISTURBANCE. THIS
SYSTEM HAS A MEDIUM CHANCE...40 PERCENT...OF BECOMING A TROPICAL
CYCLONE DURING THE NEXT 48 HOURS...AND A MEDIUM CHANCE...50
PERCENT...OF BECOMING A TROPICAL CYCLONE DURING THE NEXT 5 DAYS
WHILE IT MOVES WESTWARD TO WEST-NORTHWESTWARD AT 10 TO 15 MPH OVER
THE CARIBBEAN SEA...AND NEAR OR OVER HISPANIOLA. REGARDLESS OF
WHETHER OR NOT A TROPICAL CYCLONE FORMS...LOCALLY HEAVY RAINFALL
AND STRONG GUSTY WINDS ARE EXPECTED TO AFFECT PORTIONS OF THE
LESSER ANTILLES THROUGH MONDAY.
Member Since: Posts: Comments:
1404. LargoFl
once it passes the small islands there is a spot that could weaken it some..then it gets under cuba and Bam..regeneration..
Member Since: Posts: Comments:
1403. scott39
Its going to be the same
Member Since: Posts: Comments:
Quoting 1394. LargoFl:
exactly..it stays the same,hasnt gotten any stronger and..it may go back down to 30%..we'll have to wait and see....anyway todays numbers dont mean much..thurs-fri..thats the important ones


We will have to wait and see. We could at least have a depression by then.
Member Since: Posts: Comments:
Quoting 1385. Tazmanian:



you are vary late
Season hurricanes forecast is garbage.
Member Since: June 23, 2011 Posts: 0 Comments: 1252
50/60% for me
Member Since: Posts: Comments:
keep it at 40% at 8pm!
Member Since: Posts: Comments:
Quoting 1388. MiamiHurricanes09:
That's what I'm thinking.


There is another specialist as optimistic as Stewart?
Member Since: September 23, 2005 Posts: 15 Comments: 11342
70/90
Member Since: Posts: Comments:
Another possible analog, track wise:

Member Since: Posts: Comments:
Its being hold by the interaction of the ULL over DR and the huge ULL in the north.... The thing is if it will develop under those conditions.... GFS doesnt shows any development yet....

Member Since: Posts: Comments:
1394. LargoFl
Quoting 1387. FunnelVortex:


lol, 40% is exactly what the NHC has it at.
exactly..it stays the same,hasnt gotten any stronger and..it may go back down to 30%..we'll have to wait and see....anyway todays numbers dont mean much..thurs-fri..thats the important ones
Member Since: Posts: Comments:
Hi everyone, quick in and out...

I have just loaded up a bunch of pictures from today's
Sugarland Rally in Clewiston, FL about all our
polluted water and drainage problems.

Dr Master's was talking about this last week in one of his blog threads.

Our Very Own, IndianRiverGuy was one of the speakers and he was just great.
He really cares about out waters and it was nice to meet him in person.

If you want to see any of the pictures they are in my blog header.

Have a great Labor Day Weekend!

Member Since: Posts: Comments:
50/50 for NHC
Member Since: Posts: Comments:
Member Since: Posts: Comments:
Quoting 1377. CaribBoy:


YES XD
So,Dmin is the other guy,no wonder you hated it.
Member Since: June 23, 2011 Posts: 0 Comments: 1252
1389. ackee
I say 50/60 at 8pm
Member Since: July 15, 2008 Posts: 0 Comments: 1376
Quoting 1378. islander101010:
nochange.%
That's what I'm thinking.
Member Since: Posts: Comments:
Quoting 1380. LargoFl:
i say 40% tonight...its early yet...............


lol, 40% is exactly what the NHC has it at.
Member Since: Posts: Comments:
Member Since: Posts: Comments:
Quoting 1382. FunnelVortex:
Up to 40%

Looks like the season isn't dead after all! (Hear that, Wash?).




you are vary late
Member Since: May 21, 2006 Posts: 5091 Comments: 115454
Quoting 1351. hydrus:
You see that upper low moving across Hispaniola.? I cannot remember the year, but I saw one do that same thing, and the interaction with land helped bring the system to the surface and it became a tropical storm. I wish I could remember the name.



I don't remember either.... But the ULL N of it is bigger and it's making it stationary
Member Since: Posts: Comments:
Quoting 1334. sunlinepr:
Geez... that ULL is pulling up masses of convection over Hispaniola... not good if 97L does indeed track that way.... :o/
Member Since: Posts: Comments:
Up to 40%

Looks like the season isn't dead after all! (Hear that, Wash?).

Member Since: Posts: Comments:
Quoting 1364. unknowncomic:
Mystery about what is happening with 97L. I wonder if the LLC isn't moving west and leaving the convection behind like we've seen with past storms.

We need TrollTrackerScott to analyzed this mystery.
Member Since: June 23, 2011 Posts: 0 Comments: 1252
1380. LargoFl
i say 40% tonight...its early yet...............
Member Since: Posts: Comments:
1379. scott39
Quoting 1354. weatherlover94:



But I think it will get together before then. My worry now is where it goes after 5 days and how strong it will be
Too soon to speculate.
Member Since: Posts: Comments:
nochange.%
Member Since: Posts: Comments:
Quoting 1376. prcane4you:
You are in love with Dmax?


YES XD
Member Since: October 6, 2007 Posts: 0 Comments: 6455
Quoting 1360. CaribBoy:
I HATE DMIN
You are in love with Dmax?
Member Since: June 23, 2011 Posts: 0 Comments: 1252
1375. scott39
I would be tempted to go 40/60 like keeper, but the E Caribbean has such a strong track record of limiting developement, and killing of organizing systems. Im torn but Im sticking with 40/50.
Member Since: Posts: Comments:
1374. LargoFl
Member Since: Posts: Comments:
If I recall, Cuba does not always inhibit a storm's development. Wasn't there this little storm named Sandy that crossed Cuba and remained not only intact, but continued to slowly strengthen? So if 97l does develop and track across Cuba as some models have indicated, then there is no guarantee that it will be ripped apart!

Edit: that is of course if it develops at all!
Member Since: Posts: Comments:
1372. KYDan
Quoting unknowncomic:
Mystery about what is happening with 97L. I wonder if the LLC isn't moving west and leaving the convection behind like we've seen with past storms.



Pretty sure that is an accurate assessment.
Member Since: Posts: Comments:
1371. LargoFl
Member Since: Posts: Comments:
50/60 or that it stays the same.
Member Since: Posts: Comments:
Quoting 1367. JRRP:

no no CaribBoy
Dmin is funny jejeje


+ WE LOSE VISIBLE :(
Member Since: October 6, 2007 Posts: 0 Comments: 6455
Quoting 1339. TexasHurricane05:


Strong TS or cat 1 in the Western GOM

He asked for the date not strength of model run. Of course now the model doesn't show that anymore.
Member Since: Posts: Comments:
1367. JRRP
Quoting CaribBoy:
I HATE DMIN

no no CaribBoy
Dmin is funny jejeje
Member Since: August 16, 2007 Posts: 0 Comments: 6213
1366. scott39
Quoting 1348. TexasHurricane05:


hmmm, interesting. Course I realize this isn't written in stone and probably will change. I don't know. I would be surprised if TX actually got something. Not that I am wishing a major hurricane because I am not. Just a good rain maker for TX
A rain soaking TS would be good.
Member Since: Posts: Comments:
For the TWO I say 50 and 70
Member Since: Posts: Comments:
Mystery about what is happening with 97L. I wonder if the LLC isn't moving west and leaving the convection behind like we've seen with past storms.

Member Since: Posts: Comments:
I don't know what odds the NHC will give at 8 p.m. but I think the odds should be 40% in 48 hours and 70% in 120 hours.
Member Since: June 29, 2013 Posts: 36 Comments: 2596
Quoting 1360. CaribBoy:
I HATE DMIN

I think we all do.. :P
Member Since: Posts: Comments:
I would go with 50% and 60% for the next 5 days
Member Since: Posts: Comments:
I HATE DMIN
Member Since: October 6, 2007 Posts: 0 Comments: 6455
Quoting 1355. KEEPEROFTHEGATE:
I will say 40 60

50/60
Member Since: Posts: Comments:
Quoting 1347. MiamiHurricanes09:
*Charley.

Hurricane Charlie (not Charley) also seems like a good analog because it's the same place Invest 97L is in right now, but the track sent it through Mexico.
Member Since: Posts: Comments:
1357. beell
Convergence may be weak but "confluence" is not.
Member Since: Posts: Comments:
1356. scott39
I think that 97L has a shot at being the first hurricane of the season.
Member Since: Posts: Comments:
1355. KEEPEROFTHEGATE (Mod)
Quoting 1350. weatherlover94:
I do think we will go into Red mode at 8:00
I will say 40 60
Member Since: July 15, 2006 Posts: 178 Comments: 56020

Viewing: 1405 - 1355

Page: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30 | 31 | 32 | 33 | 34 | 35 | 36 | 37 | 38 | 39 | 40 | 41 | 42 | 43 | 44 | 45 | 46 | 47 | 48 | 49 | 50Blog Index

Top of Page

About

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

Local Weather

Overcast
26 °F
Overcast

JeffMasters's Recent Photos

Lake Effort Snow Shower Over Windsor, Ontario
Sunset on Dunham Lake
Pictured Rocks Sunset
Sunset on Lake Huron