Lesser Antilles Disturbance 97L Still Disorganized

By: Dr. Jeff Masters , 2:34 PM GMT on September 03, 2013

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A tropical wave over the Lesser Antilles Islands (Invest 97L) is moving west-northwest at 10 mph, and is bringing sporadic heavy rain showers to the islands. Top sustained winds observed in the islands as of 10 am AST Tuesday were mostly below 15 mph. Heavy thunderstorm activity has been low since Monday, and is spread out, as seen on satellite loops. The thunderstorms are poorly organized, and there is no sign of a well-organized surface circulation. Martinique radar shows little evidence of rotation to the echoes, and no low-level spiral bands forming. Upper level winds are favorable for development, with wind shear a low 5 - 10 knots, and an upper-level anticyclone overhead. An area of dry air from the Saharan Air Layer (SAL) surrounds 97L and is interfering with development, though the the 12Z Tuesday balloon sounding from Guadeloupe near the center of 97L showed moist air through the entire depth of the atmosphere.


Figure 1. Latest satellite image of Invest 97L.

Forecast for 97L
Wind shear is expected to be low through Friday, and ocean temperatures will be warm, 29°C. The disturbance has not been able to generate enough thunderstorms to moisten the surrounding atmosphere much, and dry air may continue to slow down development over the next few days. The models take 97L to the west-northwest, bringing it near or over Puerto Rico or Hispaniola on Wednesday night. A track over the high mountains of Hispaniola would disrupt the circulation of 97L, forcing the storm to regroup on Thursday over the Southeast Bahamas and Turks and Caicos Islands. The best chance for development of 97L would appear to be on Friday, after the storm has finished its encounter with Hispaniola. This morning's 00Z run of the experimental GFDL ensemble--which produces 10 simulations with slightly varying initial conditions to create a plume of potential storm tracks--foresees that once 97L organizes into a tropical depression, it might take only two days for it to intensify into a hurricane to the north of Hispaniola. The wave will bring heavy rain showers to the Lesser Antilles islands on Tuesday and Wednesday, and this activity will likely spread to Puerto Rico, the Virgin Islands, the Dominican Republic, and Haiti on Wednesday and Thursday. These rains will be capable of causing life-threatening flash flooding and mudslides in mountainous regions of 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 over the Central Bahamas on Saturday. There will be a strong trough of low pressure along the U.S. East Coast this weekend, which will be capable of turning 97L to the north before the storm can hit the U.S. In their 8 am EDT Tuesday Tropical Weather Outlook, NHC left the 5-day odds of formation of 97L at 50%, and 2-day odds at 20%. The Hurricane Hunters are on call to investigate 97L Wednesday afternoon. The flight scheduled for today will likely be cancelled. The Hurricane and Severe Storm Sentinel Mission, a 5-year field project utilizing two remotely crewed Global Hawk aircraft to overfly tropical storms and hurricanes, will have one of their aircraft investigate 97L today, and again on Wednesday. You can follow the progress of the aircraft using NASA's live-plane tracker map (Global Hawk AV6 is tail number NASA872, and Global Hawk AV1 is tail number NASA871.)

98L off the coast of Africa and a Yucatan Peninsula tropical wave
A tropical wave that emerged from the coast of Africa on Monday (Invest 98L) is expected to track northwest over the Cape Verde Islands. This course will take 98L into a region of ocean where historically, very few tropical cyclones have made the long journey across the Atlantic to affect North America. In their 8 am EDT Tuesday Tropical Weather Outlook, NHC put the 5-day odds of development at 20%.

A tropical wave over Mexico's Yucatan Peninsula has a respectable area of heavy thunderstorms associated with it that is bringing heavy rains. This activity will push over the extreme Southern Gulf of Mexico's Bay of Campeche on Wednesday. The wave will have two days over water to develop before moving ashore on the Mexican coast between Veracruz and Tampico on Friday. In their 8 am EDT Tuesday Tropical Weather Outlook, NHC put the 5-day odds of development at 30%, and 2-day odds at 20%.

Jeff Masters

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Quoting 161. LargoFl:
BAMS continues to say 97 is headed to the gulf......


Even so all them models are out the door and in the trash because of where the BEST track data plotted the location which was incorrect
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Quoting 97. CaneHunter031472:


A Windows based storm destroyer in 05? That would explain Katrina and Rita. Actually the whole 2005 season.


Or the eight (so far) subsequent seasons.
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Quoting 136. GTstormChaserCaleb:
Seriously, the GFS still has this problem even after being carried over to the Supercomputer?


No, the computer did not change the fundamental problems that the GFS has always had. These issues with northeast feedback in the tropics have been around for years.
Member Since: November 24, 2005 Posts: 635 Comments: 26700
Quoting 156. redwagon:


Look at the vort maps GT posted: the Western blob is fully stacked, the Eastern not... also noticible is the vortexes are discrete now.
The blob moving south of PR has 2 centers
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Hello bloggers , Have all of you seen the MSNBC story , on this years hurricane season , the forecasters , they are still calling for an above average season !
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Quoting 154. GatorWX:
I thought I read that the NWS said this was a open low/wave?

14.25n/63.5w.


They were either looking at the wrong thing or NWS made this statement before sunrise
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BAMS continues to say 97 is headed to the gulf......
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Quoting 154. GatorWX:
I thought I read that the NWS said this was a open low/wave?

14.25n/63.5w.




It might be open I think its borderline closed with very weak west winds somewere.
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Quoting 105. wunderkidcayman:


Actually that's WSW look at it again from as soon as first daylight image comes up to now you can see it goes from 14.6N 62.7W to 14.2N 63.2W




I am in agreement...with the difficulty locating the true LLC these models are pointless. If 97L remains weak and disorganized the western traverse is a real possibility.
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Quoting 146. Gearsts:
I see we have 2 centers and the best looking one is south of the convection but seems to be rotating towards it.

I only see one and that's confirmed on the satellite, radar, and suggested by surface obs and buoy data
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Member Since: June 30, 2013 Posts: 12 Comments: 8774
Quoting 146. Gearsts:
I see we have 2 centers and the best looking one is south of the convection but seems to be rotating towards it.


Look at the vort maps GT posted: the Western blob is fully stacked, the Eastern not... also noticible is the vortexes are discrete now.
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155. JRRP
Quoting wunderkidcayman:


The whole rotation is moving W-WSW not WNW



Yep



Umm no not even close to 16N try 14N


ah .. i see it..
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I thought I read that the NWS said this was a open low/wave?

14.25n/63.5w.

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Quoting 145. GTstormChaserCaleb:
I agree the system keeps moving west and defying the models.


I still believe recurve east of FL in the end very close to dorians track.
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Folks in South florida..heed your local warnings today..stay safe..............
...THUNDERSTORMS DEVELOPING, FOCUSED INTERIOR-GULF COAST...
...HEAVY RAINFALL AND LOCALIZED FLOODING POSSIBLE...

THIS HAZARDOUS WEATHER OUTLOOK IS FOR SOUTH FLORIDA.

.DAY ONE...TODAY AND TONIGHT

THUNDERSTORMS: THUNDERSTORMS WILL DEVELOP THIS AFTERNOON, FOCUSED
ACROSS THE INTERIOR AND GULF COAST, WHERE STORMS ARE EXPECTED TO
BECOME NUMEROUS. THUNDERSTORMS WILL BE MORE ISOLATED ALONG THE
ATLANTIC COAST. THE THUNDERSTORMS WILL BE CAPABLE OF PRODUCING
FREQUENT LIGHTNING, HEAVY RAINFALL, AND GUSTY WINDS.

FLOODING...STREET FLOODING AND FLOODING OF POORLY DRAINED LOCALES IS
POSSIBLE THIS AFTERNOON INTO THIS EVENING DUE TO SLOW THUNDERSTORM
MOVEMENT.

WIND: GUSTY WINDS OF 40 TO 50 MPH WILL BE POSSIBLE IN THE STRONGEST
THUNDERSTORMS THIS AFTERNOON.

WATERSPOUTS: THERE IS A RISK OF WATERSPOUTS OVER THE LOCAL
COASTAL WATERS DUE TO LIGHT WINDS.

TEMPERATURES: MAXIMUM AFTERNOON HEAT INDEX READINGS ARE EXPECTED
TO RANGE FROM NEAR 100 DEGREES MOST LOCALES, BUT AROUND 105 DEGREES
ACROSS INLAND COLLIER COUNTY.

.DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY

SCATTERED TO NUMEROUS AFTERNOON AND EARLY EVENING THUNDERSTORMS
ARE EXPECTED EACH DAY, ESPECIALLY OVER THE INTERIOR, WITH THE MAIN
THREATS BEING FREQUENT LIGHTNING STRIKES AND LOCALLY HEAVY RAINFALL.

.SPOTTER INFORMATION STATEMENT...

WIDESPREAD SPOTTER ACTIVATION IS NOT ANTICIPATED, HOWEVER
INDIVIDUAL SPOTTERS ARE ENCOURAGED TO REPORT HIGH WIND, HAIL AND
FLOODING TO THE NATIONAL WEATHER SERVICE FORECAST OFFICE IN
MIAMI.

FOR MORE INFORMATION...VISIT THE NATIONAL WEATHER SERVICE IN
MIAMI WEBSITE AT WWW.WEATHER.GOV/MIAMI.

$$

GREGORIA
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So thankful for the quiet season. Hopefully we won't see a hurricane at all this year in the Atlantic.
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The GFS wants to develop the disturbance behind 97L and here comes the next system off the coast of Africa.

Link
Member Since: June 30, 2013 Posts: 12 Comments: 8774
Quoting 140. chrisdscane:



this will likely change I still think recurve but much more west than forecasted.


If BEST track data can plot the location correctly we should see a fairly decent jump S and W from the models
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trade winds still very fast out of the east ( the orange/ yellow clouds on visible) not allowing deep convection to erupt.
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Quoting 142. ncstorm:


accordingly to Joe yes..but I only see initialization errors on the previous model diagnostic discussions about the GFS on the WPC site..I haven't checked today though..
Oh ok gotcha, it may just be his personal opinion in that case, but I guess we will see.

Member Since: June 30, 2013 Posts: 12 Comments: 8774
I see we have 2 centers and the best looking one is south of the convection but seems to be rotating towards it.
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Quoting 140. chrisdscane:



this will likely change I still think recurve but much more west than forecasted.
I agree the system keeps moving west and defying the models.
Member Since: June 30, 2013 Posts: 12 Comments: 8774
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Member Since: July 3, 2005 Posts: 428 Comments: 129780
Quoting 136. GTstormChaserCaleb:
Seriously, the GFS still has this problem even after being carried over to the Supercomputer?


accordingly to Joe yes..but I only see initialization errors on the previous model diagnostic discussions about the GFS on the WPC site..I haven't checked today though..
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TIRED with the GFS feedbacks
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this will likely change I still think recurve but much more west than forecasted.
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Quoting 135. ncstorm:


Quiet for him..please..I had to scroll through a whole bunch of "other stuff" to find the Tropical Weather tweets..


LOL - get the feeling that with JB there never is a moment of quiet contemplation? He seems to be a ball of energy, to say the least.
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Thank you Dr. Masters and Good Morning Class!
Member Since: September 18, 2010 Posts: 0 Comments: 5248
Flood Advisory

------------------------------------------------- -------------------------------
FLOOD ADVISORY
NATIONAL WEATHER SERVICE TAMPA BAY AREA - RUSKIN FL
1147 AM EDT TUE SEP 3 2013

FLC015-115-031745-
/O.NEW.KTBW.FA.Y.0108.130903T1547Z-130903T1745Z/
/00000.N.ER.000000T0000Z.000000T0000Z.000000T0000 Z.OO/
SARASOTA FL-CHARLOTTE FL-
1147 AM EDT TUE SEP 3 2013

THE NATIONAL WEATHER SERVICE IN RUSKIN HAS ISSUED AN

* URBAN AND SMALL STREAM FLOOD ADVISORY FOR...
NORTHWESTERN CHARLOTTE COUNTY IN FLORIDA.
SOUTHERN SARASOTA COUNTY IN FLORIDA.
THIS INCLUDES THE CITY OF ENGLEWOOD


* UNTIL 145 PM EDT

* AT 1146 AM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED
RAINFALL RATES OF TWO TO THREE INCHES PER HOUR ASSOCIATED WITH
THUNDERSTORMS OVER THE ADVISED AREA...LOCALIZED FLOODING IS IMMINENT
OR OCCURRING.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

KEEP CHILDREN FROM BEING SWEPT AWAY IN FLOODED DITCHES AND DRAINS.
FLOOD WATERS ARE USUALLY DEEPER THAN THEY APPEAR AND MAY STALL YOUR
VEHICLE. JUST ONE FOOT OF FLOWING WATER IS POWERFUL ENOUGH TO SWEEP
VEHICLES OFF THE ROAD. TURN AROUND...DONT DROWN.

&&

LAT...LON 2686 8233 2692 8237 2704 8237 2704 8217
2686 8217

$$


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Quoting 122. ncstorm:
Joe Bastardi %u200F@BigJoeBastardi 1h

Nam looks alot like UKMET idea on complex situation in Caribbean pic.twitter.com/o16cLQmAbN

Joe Bastardi %u200F@BigJoeBastardi 43s

They'll never fix the GFS feedback problem and so its trying to take disturbance out to ne, and will try to recurve bigger storm in 10 days
Seriously, the GFS still has this problem even after being carried over to the Supercomputer?
Member Since: June 30, 2013 Posts: 12 Comments: 8774
Quoting 129. daddyjames:


Well, the first statement has been pretty obvious - even to those of us not schooled in met.

The second is well described.

Must be quiet time at the office.


Quiet for him..please..I had to scroll through a whole bunch of "other stuff" to find the Tropical Weather tweets..
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Regarding whether advanced technology has been developed to alter weather on the scale of steering storms or influencing their development, a study of U. S. Patent 4,686,605, particularly the applications and/or potential uses, should be quite revealing. The facilities with the potential to perform "experiments" along these lines have already been built and have been in operation for many years, and not all of them are under the control of the United States.
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Quoting 108. HuracandelCaribe:


Don't focus in the little swirl, focus in the whole rotation that is moving WNW.


The whole rotation is moving W-WSW not WNW

Quoting 109. GTstormChaserCaleb:
These products tend to agree with your guys thinking.

850 mb. vort.



700 mb. vort.



500 mb. vort.



Anti-Cyclone over top of it.



Lower convergence still strung out, which has been one of the problems with this system.



Yep

Quoting 117. JRRP:
97L
16.5n
63.5w
Link

Link


Umm no not even close to 16N try 14N

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1998 Atlantic Hurricane Season, now mind you by this time we had 3 hurricanes, the point I want everyone to know is that the 2 bad ones of that season were Georges and Mitch which didn't come until later.

Member Since: June 30, 2013 Posts: 12 Comments: 8774
FLOOD ADVISORY
NATIONAL WEATHER SERVICE TAMPA BAY AREA - RUSKIN FL
1147 AM EDT TUE SEP 3 2013

FLC015-115-031745-
/O.NEW.KTBW.FA.Y.0108.130903T1547Z-130903T1745Z/
/00000.N.ER.000000T0000Z.000000T0000Z.000000T0000Z .OO/
SARASOTA FL-CHARLOTTE FL-
1147 AM EDT TUE SEP 3 2013

THE NATIONAL WEATHER SERVICE IN RUSKIN HAS ISSUED AN

* URBAN AND SMALL STREAM FLOOD ADVISORY FOR...
NORTHWESTERN CHARLOTTE COUNTY IN FLORIDA.
SOUTHERN SARASOTA COUNTY IN FLORIDA.
THIS INCLUDES THE CITY OF ENGLEWOOD


* UNTIL 145 PM EDT

* AT 1146 AM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED
RAINFALL RATES OF TWO TO THREE INCHES PER HOUR ASSOCIATED WITH
THUNDERSTORMS OVER THE ADVISED AREA...LOCALIZED FLOODING IS IMMINENT
OR OCCURRING.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

KEEP CHILDREN FROM BEING SWEPT AWAY IN FLOODED DITCHES AND DRAINS.
FLOOD WATERS ARE USUALLY DEEPER THAN THEY APPEAR AND MAY STALL YOUR
VEHICLE. JUST ONE FOOT OF FLOWING WATER IS POWERFUL ENOUGH TO SWEEP
VEHICLES OFF THE ROAD. TURN AROUND...DONT DROWN.

&&

LAT...LON 2686 8233 2692 8237 2704 8237 2704 8217
2686 8217
Member Since: Posts: Comments:



PR could recieve some gusty storms later today but nothing more than a strong afternoon thundershower.
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Quoting 122. ncstorm:
Joe Bastardi %u200F@BigJoeBastardi 1h

Nam looks alot like UKMET idea on complex situation in Caribbean pic.twitter.com/o16cLQmAbN

Joe Bastardi %u200F@BigJoeBastardi 43s

They'll never fix the GFS feedback problem and so its trying to take disturbance out to ne, and will try to recurve bigger storm in 10 days


Well, the first statement has been pretty obvious - even to those of us not schooled in met.

The second is well described.

Must be quiet time at the office.
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Click to enlarge
Look at the concentration of the circulating precipitable water and the fact that the circulation of the wave behind maybe overrun and digest 97L soon, dragging it to the northwest? Just a guess of course ;)
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Those who toss around the word "Crap" should consider mental health for that, as it can really sink a Job interview.
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Quoting 109. GTstormChaserCaleb:
These products tend to agree with your guys thinking.

850 mb. vort.



700 mb. vort.



500 mb. vort.



Anti-Cyclone over top of it.



Lower convergence still strung out, which has been one of the problems with this system.



And your evidence is strongly suggesting mitosis is nearly complete. One goes W, the other to FL.
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Quoting 94. hurricanes2018:
invest 98L MOVE back to the sw at the end


Like ERIN or DORIAN = BUST
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many islands reporting south and sw winds this is the best low lvl structure 97l has ever had even though the system remains rather weak.
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Joe Bastardi %u200F@BigJoeBastardi 1h

Nam looks alot like UKMET idea on complex situation in Caribbean pic.twitter.com/o16cLQmAbN

Joe Bastardi %u200F@BigJoeBastardi 43s

They'll never fix the GFS feedback problem and so its trying to take disturbance out to ne, and will try to recurve bigger storm in 10 days
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Quoting 115. CaneHunter031472:
I just find this season mind blowing. We are just 7 days from the highest point of the peak of this season, and there's nothing significant to talk about. I just wonder what completely threw a wrench on this season and if it's going to hold. This season it's going to be one for the books regarding lack of formation.
We may not live up to the numbers the weather agencies are predicting, who knows? but the season is far from over. And like I was saying yesterday this is the month where things can develop without the models even noticing it.
Member Since: June 30, 2013 Posts: 12 Comments: 8774
120. JLPR2


97L is looking anemic but its lower level structure underwent some changes and is looking healthier. We actually have a good wind shift showing and what appears to be a weak band of convection wrapping in to the SE of the system.

If this thing can develop some decent convection over the center we might actually have a decent looking invest.

The center (the little swirl) is very weak and will jump around and reform in the area, specially if convection develops close to it.
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97L should continue to move towards Haiti-Jamaica-Eastern Cuba in the next 2-3days. I'm more with the Euro on this unless the LLC reforms further NE tomorrow
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97l has a closed low in my opinion it needs to sustain some thunderstorms near or over it in order of HH to fly in tommoro thats all that can be said at this time.
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117. JRRP
97L
16.5n
63.5w
Link

Link
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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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