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: 1805 - 1755

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

1805. Droab
There was a post about the levee around the lake. I think currently it is around a foot above average. And I think it was within the last 2 weeks in one of the major south Fl newspapers that the Army corp of Engineer did have 6 areas of concern for substantial failure on the levee. What that meant I don't know, cause for panic or concern ?? Also being not far from the Jupiter Inlet I can only imagine what another dump from the lake will do to Indian River Lagoon and our inlet.
Member Since: Posts: Comments:
Quoting 1796. beell:
97L may be getting involved in a mid-level tug-of-war this evening as an inverted 500mb trough passes by to the north. Probably enough to pull the wave axis north towards this weakness or at the least, towards retreating 500 mb heights.

After it dampens out on Tuesday or Wednesday, 97L would be free to continue towards the west but with a resulting track over/near Hispaniola and Cuba. This would agree with the current model consensus.

But we still do not have a system capable of being resolved by any model with any degree of reliability.
So...


09/01 18Z GFS 500 mb Vort-Valid 12Z 09/02

Some northward pull of the mid levels noted along 57W.


(click for full image loop)



VERY NICE POST!!!!!
Member Since: Posts: Comments:
1803. WoodyFL
Quoting 1796. beell:
97L may be getting involved in a mid-level tug-of-war this evening as an inverted 500mb trough passes by to the north. Probably enough to pull the wave axis north towards this weakness or at the least, towards retreating 500 mb heights.

After it dampens out on Tuesday or Wednesday, 97L would be free to continue towards the west but with a resulting track over/near Hispaniola and Cuba. This would agree with the current model consensus.

But we still do not have a system capable of being resolved by any model with any degree of reliability.
So...


09/01 18Z GFS 500 mb Vort-Valid 12Z 09/02

Some northward pull of the mid levels noted along 57W.


(click for full image loop)



Almost all of the latest models agree with that. I guess how strong it is will determine where it really goes too.
Member Since: Posts: Comments:
Quoting 1788. Gearsts:


Huh? Finally some 500mb vorticity? No way. ;)
Member Since: Posts: Comments:
1801. beell
Quoting 1797. will40:
nice observation beell


We'll see. More I stare at all this stuff, the less I know!
(thx)
Member Since: Posts: Comments:
Quoting 1794. Gearsts:
Dmax should be interesting.


Dmax and the next few days :-)))))
Member Since: Posts: Comments:
Quoting 1791. Tropicsweatherpr:


What rules?


Actually what models are showing.. especially those sending 97L into the W CARIB.

I mean that 97L might behave VERY differently. But we will see XD
Member Since: Posts: Comments:
Quoting 1783. WoodyFL:


yeah, other models too are moving more north and nw



That could be a center relocation seeing as it is over the mountains of Hispanola.
Member Since: August 2, 2011 Posts: 0 Comments: 2093
1797. will40
nice observation beell
Member Since: Posts: Comments:
1796. beell
97L may be getting involved in a mid-level tug-of-war this evening as an inverted 500mb trough passes by to the north. Probably enough to pull the wave axis north towards this weakness or at the least, towards retreating 500 mb heights.

After it dampens out on Tuesday or Wednesday, 97L would be free to continue towards the west but with a resulting track over/near Hispaniola and Cuba. This would agree with the current model consensus.

But we still do not have a system capable of being resolved by any model with any degree of reliability.
So...


09/01 18Z GFS 500 mb Vort-Valid 12Z 09/02

Some northward pull of the mid levels noted along 57W.


(click for full image loop)

Member Since: Posts: Comments:
1795. ncstorm
00z NAM last frame-84 hours..

Member Since: Posts: Comments:
1794. Gearsts
Quoting 1790. CaribBoy:
LOOP

97L could break all the rules... who knows...
Dmax should be interesting.
Member Since: Posts: Comments:
1793. WoodyFL
Quoting 1787. unknowncomic:
With that ridge, if it survives Hispanola, looks like an Isaac like path through the Fl straits to me.



some models go over the windward passage

Member Since: Posts: Comments:

Quoting 1777. FIUStormChaser:
I hate to be that guy, but really? How many times have the models suggested a storm was going to hit Florida this year and how many have verified minus Andrea?
Well you have to understand the blog has been starved of precious tropical activity during August, and this idea is quite plausible so no doubt they will jump on it. 
Though I do remember the blog arguing about whether Chantal would hit Florida or South Carolina LOL. 
Member Since: Posts: Comments:
Quoting 1790. CaribBoy:
LOOP

97L could break all the rules... who knows...


What rules?
Member Since: Posts: Comments:
LOOP

97L could break all the rules... who knows...
Member Since: Posts: Comments:
1789. WoodyFL
Member Since: Posts: Comments:
1788. Gearsts
Member Since: Posts: Comments:
With that ridge, if it survives Hispanola, looks like an Isaac like path through the Fl straits to me.

Member Since: August 2, 2011 Posts: 0 Comments: 2093
Buenos Noches.
Member Since: Posts: Comments:
1785. WoodyFL
Member Since: Posts: Comments:
Member Since: Posts: Comments:
1783. WoodyFL
Quoting 1771. unknowncomic:
Looks like its moving Looks to be heading toward Florida, no.


yeah, other models too are moving more north and nw



Member Since: Posts: Comments:
Quoting 1776. GTstormChaserCaleb:
Could get Gabrielle and Hermine out of these 2 AOI's, especially considering we are closing in on the climatological peak of hurricane season where things can just develop out of nowhere and fast too.


That's VERY exciting XD
Member Since: Posts: Comments:
Quoting 1777. FIUStormChaser:
I hate to be that guy, but really? How many times have the models suggested a storm was going to hit Florida this year and how many have verified minus Andrea?
Just one I believe which was Chantal and considering we have only had 6 storms to this point. We'll see as always is the case let's see how this system looks like when it enter the Eastern Caribbean tomorrow and then if it does develop how it interacts with the mountains of Hispaniola, then we can talk about what impacts if any this will have to the US.
Member Since: Posts: Comments:
lOOKS LIKE QUITE THE RIDGE AT 75 HRS.

Member Since: August 2, 2011 Posts: 0 Comments: 2093
VERY complex setting east of the Lesser Antilles

Member Since: Posts: Comments:
1778. FOREX
Quoting 1750. Tropicsweatherpr:


Good observation about how are things doing in the upper levels.


I'm happy it won't be going into the Gulf.
Member Since: Posts: Comments:
I hate to be that guy, but really? How many times have the models suggested a storm was going to hit Florida this year and how many have verified minus Andrea?
Member Since: Posts: Comments:
Quoting 1773. CaribBoy:
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE SAN JUAN PR
906 PM AST SUN SEP 1 2013

.SYNOPSIS...MID-UPPER LEVEL RIDGE WILL BUILD OVER THE REGION LABOR
DAY AND HOLD THROUGH THE END OF THE WEEK. WEAK ELONGATED AREA OF
LOW PRES OVER THE WINDWARD ISLANDS WILL MOVE ACROSS THE ERN CARIB
SEA MON-WED BRINGING SIG RAINS TO ERN PR AND USVI TUE-WED.

&&

.DISCUSSION...QUIET WX NEXT 12 HRS UNDER BUILDING UPPER LEVEL
RIDGE...DRY AIR AND NEGATIVE H85 THETAE AIR ADVECTION. MOISTURE
BEGINS TO INCREASE MON WITH SCT AFTERNOON TSRA EXPECTED ACROSS
SOUTHERN PR UNDER A NE STEERING FLOW.

BIG SLUG OF MOISTURE ASSOCIATED WITH WEAK AREA OF LOW PRES AND
TROPICAL WAVE ALONG 61W WILL BEGIN TO REACH ERN PR AND THE USVI
TUE MORNING WITH SIG FLOODING RAINS LIKELY.
ECMWF AND GFS CONTINUE
TO DIFFER ON EXACT TIMING OF HEAVIEST RAINS BUT BOTH PAINT A VERY
WET SCENARIO FOR ERN PR...CULEBRA...VIEQUES AND THE USVI MID WEEK.
WAVE AXIS IS EXPECTED TO REACH 70W BY 12Z WED WITH WX LIKELY TO
IMPROVE BY LATE WED ACCORDING TO 18Z GFS AND GEFS GUIDANCE ALTHOUGH
ECMWF IS SLOWER BY 24 HRS WITH HEAVY RAINS LINGERING THRU THU.

ANOTHER FEATURE OF INTEREST IS A WEAK AREA OF LOW PRES ALONG 48W.
SOME GEFS ENSEMBLE MEMBERS TRY TO DEVELOP THIS LOW. RIGHT NOW
CONVECTION IS VERY LIMITED AND SFC OBS INDICATE BEST 24-HR PRES
FALLS ARE OCCURRING OVER THE LESSER ANTILES SO THIS SCENARIO DOES
NOT APPEAR LIKELY.


Could get Gabrielle and Hermine out of these 2 AOI's, especially considering we are closing in on the climatological peak of hurricane season where things can just develop out of nowhere and fast too.
Member Since: Posts: Comments:
if a mod is around you are needed in the chat room
Member Since: Posts: Comments:
good night everybody
Member Since: September 8, 2010 Posts: 0 Comments: 2218
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE SAN JUAN PR
906 PM AST SUN SEP 1 2013

.SYNOPSIS...MID-UPPER LEVEL RIDGE WILL BUILD OVER THE REGION LABOR
DAY AND HOLD THROUGH THE END OF THE WEEK. WEAK ELONGATED AREA OF
LOW PRES OVER THE WINDWARD ISLANDS WILL MOVE ACROSS THE ERN CARIB
SEA MON-WED BRINGING SIG RAINS TO ERN PR AND USVI TUE-WED.

&&

.DISCUSSION...QUIET WX NEXT 12 HRS UNDER BUILDING UPPER LEVEL
RIDGE...DRY AIR AND NEGATIVE H85 THETAE AIR ADVECTION. MOISTURE
BEGINS TO INCREASE MON WITH SCT AFTERNOON TSRA EXPECTED ACROSS
SOUTHERN PR UNDER A NE STEERING FLOW.

BIG SLUG OF MOISTURE ASSOCIATED WITH WEAK AREA OF LOW PRES AND
TROPICAL WAVE ALONG 61W WILL BEGIN TO REACH ERN PR AND THE USVI
TUE MORNING WITH SIG FLOODING RAINS LIKELY.
ECMWF AND GFS CONTINUE
TO DIFFER ON EXACT TIMING OF HEAVIEST RAINS BUT BOTH PAINT A VERY
WET SCENARIO FOR ERN PR...CULEBRA...VIEQUES AND THE USVI MID WEEK.
WAVE AXIS IS EXPECTED TO REACH 70W BY 12Z WED WITH WX LIKELY TO
IMPROVE BY LATE WED ACCORDING TO 18Z GFS AND GEFS GUIDANCE ALTHOUGH
ECMWF IS SLOWER BY 24 HRS WITH HEAVY RAINS LINGERING THRU THU.

ANOTHER FEATURE OF INTEREST IS A WEAK AREA OF LOW PRES ALONG 48W.
SOME GEFS ENSEMBLE MEMBERS TRY TO DEVELOP THIS LOW. RIGHT NOW
CONVECTION IS VERY LIMITED AND SFC OBS INDICATE BEST 24-HR PRES
FALLS ARE OCCURRING OVER THE LESSER ANTILES SO THIS SCENARIO DOES
NOT APPEAR LIKELY.


Member Since: Posts: Comments:
Quoting 1766. airmet3:
??????????????
I'm talking about the HWRF and the other model that begins with a G and the LGEM.They were forecasting the both Dorian and Chantal to make land Fall as a major in the U.S.That never happened thank goodness.
Member Since: Posts: Comments:
Quoting 1761. GTstormChaserCaleb:
18z Experimental FIM-9 takes 97L over Hispaniola and starts strengthening it closer to the Bahamas:



Looks like its moving
Quoting 1761. GTstormChaserCaleb:
18z Experimental FIM-9 takes 97L over Hispaniola and starts strengthening it closer to the Bahamas:



Looks to be heading toward Florida, no.
Member Since: August 2, 2011 Posts: 0 Comments: 2093
TROPICAL STORM KIKO DISCUSSION NUMBER 9
NWS NATIONAL HURRICANE CENTER MIAMI FL EP112013
800 PM PDT SUN SEP 01 2013

DEEP CONVECTION ASSOCIATED WITH KIKO IS FADING...AND DVORAK DATA
T-NUMBERS ARE COMING DOWN FAST. OUT OF RESPECT FOR THE EARLIER
SCATTEROMETER DATA AND THE DVORAK CURRENT INTENSITY RULE...THE
ADVISORY WIND SPEED IS SET...PERHAPS GENEROUSLY...AT 45 KT. KIKO
IS MOVING OVER PROGRESSIVELY COOLER WATERS AND INTO A MORE STABLE
AIR MASS. THESE FACTORS SHOULD CAUSE CONTINUED WEAKENING...AND THE
SYSTEM WILL PROBABLY BECOME A DEPRESSION WITHIN 24 HOURS AND
DEGENERATE INTO A REMNANT LOW IN 36 HOURS...OR SOONER. THE NHC
INTENSITY FORECAST IS NOT FAR FROM THE MODEL CONSENSUS OR THE
PREVIOUS OFFICIAL FORECAST.

LAST-LIGHT VISIBLE SATELLITE IMAGERY INDICATES THAT THE STORM HAS
ALREADY TURNED TOWARD THE NORTH-NORTHWEST AND THE INITIAL MOTION IS
ABOUT 340/5. A WEAK MID- TO LOW-LEVEL RIDGE TO THE NORTHEAST OF
THE CYCLONE SHOULD MAINTAIN A NORTH-NORTHWESTWARD MOTION FOR THE
NEXT COUPLE OF DAYS. WITH THE SYSTEM EXPECTED TO BECOME A SHALLOW
CYCLONE IN A DAY OR SO...THE FORWARD SPEED IS LIKELY TO SLOW TO A
CRAWL WITHIN THE WEAK LOW-LEVEL STEERING CURRENTS TO THE WEST OF
THE BAJA CALIFORNIA PENINSULA. THE OFFICIAL TRACK FORECAST IS
CLOSE TO THE LATEST DYNAMICAL MODEL CONSENSUS AND JUST A TAD TO THE
WEST OF THE PREVIOUS NHC FORECAST.

FORECAST POSITIONS AND MAX WINDS

INIT 02/0300Z 22.5N 116.1W 45 KT 50 MPH
12H 02/1200Z 23.1N 116.3W 40 KT 45 MPH
24H 03/0000Z 23.5N 116.5W 30 KT 35 MPH
36H 03/1200Z 23.9N 116.7W 25 KT 30 MPH...POST-TROP/REMNT LOW
48H 04/0000Z 24.1N 116.8W 20 KT 25 MPH...POST-TROP/REMNT LOW
72H 05/0000Z 24.2N 117.0W 20 KT 25 MPH...POST-TROP/REMNT LOW
96H 06/0000Z...DISSIPATED

$$
FORECASTER PASCH
Member Since: Posts: Comments:
97L and convection popping in the Western Caribbean. TAwx13 referenced this area earlier today.

Member Since: Posts: Comments:
BULLETIN
TROPICAL STORM KIKO ADVISORY NUMBER 9
NWS NATIONAL HURRICANE CENTER MIAMI FL EP112013
800 PM PDT SUN SEP 01 2013

...KIKO CONTINUES TO WEAKEN WHILE MOVING SLOWLY
NORTH-NORTHWESTWARD...


SUMMARY OF 800 PM PDT...0300 UTC...INFORMATION
----------------------------------------------
LOCATION...22.5N 116.1W
ABOUT 395 MI...640 KM W OF THE SOUTHERN TIP OF BAJA CALIFORNIA
MAXIMUM SUSTAINED WINDS...50 MPH...85 KM/H
PRESENT MOVEMENT...NNW OR 340 DEGREES AT 6 MPH...9 KM/H
MINIMUM CENTRAL PRESSURE...1000 MB...29.53 INCHES
Member Since: Posts: Comments:
97L no strengthening at all unit it get to Bahamas
Member Since: Posts: Comments:
1766. airmet3
Quoting 1590. washingtonian115:
Yeah...those same models also showed Chantal and Dorian going into the U.S as majors...(fast forward)we still have yet to get a hurricane...LOL GMAB...
??????????????
Member Since: Posts: Comments:
Quoting 1758. allancalderini:
Greta was a central American storm.
Sorry I meant Gracie.
Member Since: Posts: Comments:
Latest NAM 45HRS.

Member Since: August 2, 2011 Posts: 0 Comments: 2093
1763. will40
Quoting 1759. Skyepony:

It can. Usually once they build up height they keep it til they weaken. It's good to know for the steering maps. Usually a weak storm is so shallow you'd look more at the 850-700mb steering. Where this pass would having me looking at 500mb too.


My thoughts exactly Skye
Member Since: Posts: Comments:
1762. xcool
lol
Member Since: Posts: Comments:
18z Experimental FIM-9 takes 97L over Hispaniola and starts strengthening it closer to the Bahamas:



Member Since: Posts: Comments:
Take your pick..

Member Since: Posts: Comments:
1759. Skyepony (Mod)
Quoting 1751. docrod:


- thanks Skye - cannot that vertical structure change quickly (shear?)

It can. Usually once they build up height they keep it til they weaken. It's good to know for the steering maps. Usually a weak storm is so shallow you'd look more at the 850-700mb steering. Where this pass would having me looking at 500mb too.
Member Since: Posts: Comments:
Quoting 1690. GTstormChaserCaleb:
4 of the 6 on that list were Caribbean storms. Gloria and Greta were East Coast US storms. By the way Gabrielle has been on the Atlantic Hurricane Season list since 1989. Fast forward to 24 years. Could this be the year?
Greta was a central American storm.
Member Since: Posts: Comments:
1757. will40
the vertical height may be what the models are seeing
Member Since: Posts: Comments:
Quoting 1720. weatherlover94:
All GFS Ensemble models call for OTS




the GFS Ensemble is a outliner like the gfs
Member Since: Posts: Comments:
Quoting 1726. Chicklit:
Evening, folks. 97L makes you go hmmm....

Also at 40% with NHC, so word to the wise is to expect the worst and hope for the best.
notting going to happern with invest 97L ONLY a rain storm or maying nottting at all if it die out tonight.
Member Since: Posts: Comments:

Viewing: 1805 - 1755

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
49 °F
Overcast