Lesser Antilles Disturbance 97L a Threat to Develop

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

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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

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"Waiting for a response from whitewabit" an apology or ban me.........GOT IT...
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Quoting 852. Articuno:

If I would've kept my mouth shut none of this would've happened.


None of this is your fault, its been brewing for a while.
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When comments bark and nag
don't quote just flag!
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Quoting 847. seer2012:
Go, PBW! Tell it like it is!

If I would've kept my mouth shut none of this would've happened.
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Quoting 840. DonnieBwkGA:
thanks for answering my question kmanislander!


You're welcome
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Quoting 846. Tropicsweatherpr:


That is wave behind 97L.


thanks Tropic..you right..so its splitting up as the CMC has been showing
Member Since: August 19, 2006 Posts: 13 Comments: 16222
Quoting 842. Jamiekins:


So we shouldnt quote things like this?
Or a couple others that happened today?
I don't know whats going on I just got back had to step out give me a minute
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848. JRRP
Member Since: August 16, 2007 Posts: 0 Comments: 6213
Go, PBW! Tell it like it is!
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Quoting 838. ncstorm:
So the Navgem is back into play into bringing a 1008mb storm over the bahamas..

however Levi site has 1004 mb


That is wave behind 97L.
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Quoting 836. ncstorm:
butter or salt free anyone?
I like plain, low fat, myself...

Hmmm... speaking of POPPING up....



I may need to run outside for a minute or two...
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Quoting 839. kmanislander:
The center of 97L has still not made it past Martinique which is showing NNE winds. This thing has really slowed down.


this is giving it a chance to get better organized
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Quoting 832. PalmBeachWeather:
I may be banned forever here, BUT, I am going to have my say...Just because someone called "whitewabit" in freekin" green letters thinks he or she is god here is a bunch of crap....I did nothing to no one...And I see I have support...What a bunch a BS that someone that is picked out of thin air thinks that they are in "Charge" and know what the hell they are talkin' about can actually make choices of whom stays or not....REPEAT....I did nothing wrong and was banned.....How freekin' dare you "whitewabit" You have not heard the end of this this you freekin' green biased mod...Got it???

You don't deserved to be banned, I do.
I did get banned but I should still be banned, and if anything it's my fault your banned.
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Oh nevermind!
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Quoting 837. catastropheadjuster:
When I access the page the enternet explorer keeps shutting me down saying it has blocked cross-site scripting attacks then it says send error report then closes everything. Is anyone else having any trouble or what does this mean? I'm sorry this is off subject just didn't know if anyone else is having trouble.

sheri

some others that run IE mentioned earlier that they were getting bad reports. I run Firefox and haven't had any issues though.
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thanks for answering my question kmanislander!
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The center of 97L has still not made it past Martinique which is showing NNE winds. This thing has really slowed down.
Member Since: Posts: Comments:
So the Navgem is back into play into bringing a 1008mb storm over the bahamas..

however Levi site has 1004 mb
Member Since: August 19, 2006 Posts: 13 Comments: 16222
When I access the page the enternet explorer keeps shutting me down saying it has blocked cross-site scripting attacks then it says send error report then closes everything. Is anyone else having any trouble or what does this mean? I'm sorry this is off subject just didn't know if anyone else is having trouble.

sheri
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butter or salt free anyone?
Member Since: August 19, 2006 Posts: 13 Comments: 16222
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Quoting 828. GTstormChaserCaleb:
LOL I guess I was so caught up in Stephanie Abrams news feed, that I lost track. :D
Good one.... lol

U better go read the topper, quick... lol
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for our california friends..........
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Quoting 830. BahaHurican:
That looks to stay pretty far west, and therefore seems unlikely to impact Gro... I got caught in one of these downpours last week out just N of I-595... almost had to pull off the road it was so bad...
TY so he'll be ok...
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Quoting 816. LargoFl:
maybe GRO is getting some of this................Special Weather Statement

------------------------------------------------- -------------------------------
SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE MIAMI FL
335 PM EDT SUN SEP 1 2013

FLZ071-073-012000-
INLAND BROWARD COUNTY FL INLAND MIAMI-DADE COUNTY FL
335 PM EDT SUN SEP 1 2013

...A SIGNIFICANT WEATHER ADVISORY IS IN EFFECT FOR SOUTHWESTERN
BROWARD COUNTY...NORTHWESTERN MIAMI-DADE COUNTY...FOR FREQUENT TO
EXCESSIVE LIGHTNING AND GUSTY WINDS OF 45 TO 55 MPH...

$$
KONARIK
That looks to stay pretty far west, and therefore seems unlikely to impact Gro... I got caught in one of these downpours last week out just N of I-595... almost had to pull off the road it was so bad...
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829. SLU
Quoting 796. Gearsts:
Trades south of PR are really fast and can kill the system by pulling the center west leaving behind the convection.


Ok.. near the islands the trades have been below 10kts recently.
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Quoting 773. BahaHurican:
U realize this is the video in the doc's blog, right?
LOL I guess I was so caught up in Stephanie Abrams news feed, that I lost track. :D
Member Since: June 30, 2013 Posts: 12 Comments: 8774
Quoting 776. Gearsts:
So is this thing moving?


It looks like its moving but the NHC is backing it East.
Relocate ?
Or reconcile ?
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Quoting 824. VAbeachhurricanes:


I hope this is oozing with sarcasm.

I'm serious, I'm sorry.
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Convection isn't quite as deep as earlier, but it's hanging on. There is some new convection as well forming to the West, but that may actually be a bad thing because it may try to steal away the LLC and put a reset on all the hard work that was done to tighten it up some this morning. Unless of course the eastern sector brings out a burst as well, as if a wave of energy is travelling across the system from W to E.
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Quoting 820. Articuno:
I'm sorry I'm such a horrible person guys, I deserve no respect on here whatsoever because of what I did, I'm sorry everyone here took it offensively, and I realize I did something wrong, and please just bombard me with all the words you can because I deserve it.


I hope this is oozing with sarcasm.
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Quoting 821. GTstormChaserCaleb:
I see a few of the ensemble members bringing it up towards Tampa Bay.


yes..NCEP ensemble members have been trending west with it..very interesting..
Member Since: August 19, 2006 Posts: 13 Comments: 16222
822. whitewabit (Mod)
Quoting 818. Bluestorm5:
Which one, please.



Please do not quote content that violates the community standards.

Edit .. Also - Personnel attacks are not allowed in the blog!
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Quoting 811. ncstorm:
I see 97L is slowly coming along..I also see the CMC hasnt wavered either..

I see a few of the ensemble members bringing it up towards Tampa Bay.
Member Since: June 30, 2013 Posts: 12 Comments: 8774
I'm sorry I'm such a horrible person guys, I deserve no respect on here whatsoever because of what I did, I'm sorry everyone here took it offensively, and I realize I did something wrong, and please just bombard me with all the words you can because I deserve it.
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819. SLU
Quoting 792. kwad:


Aircraft at Hewanorra Airport St Lucia are flying out in the opposite direction.


Yes I. Looks like we will be getting some heavy stuff tomorrow.
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Quoting 809. whitewabit:


against community standards
Which one, please.
Member Since: August 1, 2011 Posts: 28 Comments: 8074
Quoting 813. Tazmanian:



this is a comet

Uh... Taz....

BTW... weren't several models showing us 96L diving to the SW? So take a look at this...



It would be ironic if it does go on to become a storm somewhat down the road instead of near Africa...
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maybe GRO is getting some of this................Special Weather Statement

------------------------------------------------- -------------------------------
SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE MIAMI FL
335 PM EDT SUN SEP 1 2013

FLZ071-073-012000-
INLAND BROWARD COUNTY FL INLAND MIAMI-DADE COUNTY FL
335 PM EDT SUN SEP 1 2013

...A SIGNIFICANT WEATHER ADVISORY IS IN EFFECT FOR SOUTHWESTERN
BROWARD COUNTY...NORTHWESTERN MIAMI-DADE COUNTY...FOR FREQUENT TO
EXCESSIVE LIGHTNING AND GUSTY WINDS OF 45 TO 55 MPH...

* UNTIL 400 PM EDT

* AT 330 PM EDT...NATIONAL WEATHER SERVICE METEOROLOGISTS DETECTED A
STRONG THUNDERSTORM 9 MILES NORTHEAST OF DADE-COLLIER TRAINING
AIRPORT...AND MOVING NORTHEAST AT 10 MPH.

* THE STORM WILL AFFECT...
RURAL NORTHWESTERN MIAMI-DADE COUNTY.

THE PRIMARY IMPACTS WILL BE FREQUENT TO EXCESSIVE LIGHTNING AND GUSTY
WINDS OF 45 TO 55 MPH. LIGHTNING IS THE NUMBER ONE WEATHER RELATED
KILLER IN FLORIDA. TREES AND OPEN SHELTERS OFFER NO PROTECTION. THESE
WINDS CAN DOWN SMALL TREE LIMBS AND BRANCHES...AND BLOW AROUND
UNSECURED SMALL OBJECTS. SEEK SHELTER IN A SAFE BUILDING UNTIL THE
STORM PASSES.

LAT...LON 2619 8086 2610 8053 2581 8073 2586 8087
TIME...MOT...LOC 1935Z 205DEG 8KT 2593 8077

$$
KONARIK
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NHC says dry air in the mid to upper levels with 97L may inhibit development.
Looks like this system is steadily wrapping up.

The water vapor loop does not appear to indicate this.

http://www.ssd.noaa.gov/goes/east/tatl/flash-wv.h tml

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

A WELL-DEFINED LOW PRESSURE SYSTEM IS LOCATED ABOUT 100 MILES EAST
OF THE CENTRAL LESSER ANTILLES. SATELLITE IMAGERY INDICATES THAT
THE ASSOCIATED THUNDERSTORM ACTIVITY HAS INCREASED AND IS SHOWING
SIGNS OF ORGANIZATION. UPPER-LEVEL WINDS ARE QUITE CONDUCIVE...
BUT PROXIMITY TO DRY AIR IN THE MIDDLE- AND UPPER-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 AT 10 TO 15 MPH ACROSS THE CARIBBEAN SEA.
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 TODAY THROUGH MONDAY.
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97L is more elongated now that it was 3 hours ago.Vort/convergence & divergence spread out on the east/west convection

Cimss

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Quoting 806. Camille33:

what is a comet?



this is a comet

Member Since: May 21, 2006 Posts: 5091 Comments: 115453
Quoting 747. DonnieBwkGA:
The eastern Caribbean is usually not very good for storms to organize in. Are there any reasons why that may not be the case now?


Waves that do not become TDs by 63W tend to struggle until 75W and typically do not become cyclones until after 75. However, if they do become Tds BEFORE approximatley 63 W then they can and do intensify regardless of being in the Eastern Caribbean. The point is whether or not they get classified before reaching that mark. 97L does not appear to be to be moving at 10 to 15 MPH. If anything less than 10 IMO.

This relatively slow motion is giving it time to possibly get classified before getting into the main portion of the basin. It has great upper level support from an anticyclone
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I see 97L is slowly coming along..I also see the CMC hasnt wavered either..

Member Since: August 19, 2006 Posts: 13 Comments: 16222
Quoting 723. txjac:
Are annular hurricanes worse than "regular" hurricanes? I can see the difference ..but if they impact land is it the same as a "regular" one?
Annular hurricanes are more dangerous because they are hard to kill. They can withstand high shear with little or no weakening. They maintain there strength for a much longer period than regular hurricanes when making landfall.. Good thing they are quite rare.
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809. whitewabit (Mod)
Quoting 804. Bluestorm5:
I don't see a reason why?


against community standards
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Passing along the message from Levi on Twitter...

@TropicalTidbits 4m
The wind shear cited as a problem for 97L by many is not an issue. Why? Zonal TUTTs split in the face of heat. Convection was all it needed.
Member Since: August 1, 2011 Posts: 28 Comments: 8074
Quoting 795. taco2me61:

nope you have not missed anything :o( I was just making a funny on where this may go that's all :o)

Taco :o)


Thank you, I'm trying to catch up with the blog and when I read your post I thought i had missed something. Back to learning!
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Quoting 780. Tazmanian:
commet re move


what is a comet?
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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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