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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Quoting 901. K8eCane:




By Christmas, at which time I become known as CandyCane
Good one! Good sense of humor. :D
Member Since: June 30, 2013 Posts: 11 Comments: 7464
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T.C.F.A
97L/INV/XX/XX

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Quoting 885. BahaHurican:
Is is wrong to be jealous of other islands who now have their radars online? After all, we were the first "small island", and even beat one of the "big islands".... lol

that radar imaging is from last month. It's broken now. If that makes you feel better. :)
I always find it hard to believe that the Bahamas has no working radar.
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Quoting 888. ackee:
if 97L was to be upgrade to a TD/ TS when do u guys think this would happen ?

A 24 HOURS
B 48 HOURS
C 72 HOURS
D 96 HOURS
E 120 Hours




By Christmas, at which time I become known as CandyCane
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Quoting 887. BrandenCordeiro:
Does anyone have an reccomendations on good accurate personal weather stations I could buy? I would prefer somethinh below $230...

Any suggestions thanks!


Below $230 ??. Not sure what you can get for that.

I have a Davis Vantage Pro 2 with a rain collector etc.
Gives you all the bells and whistles and comes either as a cabled or wireless system. Cost depends on what you add on, just like buying a car. Fancy software etc to link your station to the internet adds to cost.

Try visiting their site at WWW.Davis.Com

This is not a plug or ad for the company, just trying to be helpful.
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Good Evening... 97L fairing well so far.
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Why are you instigating?.If your not going to help keep shut and stay on the sidelines.This is not directed at you PBW KEEP and Art.
Member Since: August 14, 2010 Posts: 10 Comments: 16383
Quoting 885. BahaHurican:
Is is wrong to be jealous of other islands who now have their radars online? After all, we were the first "small island", and even beat one of the "big islands".... lol



I want to do all of the islands (big/small) if I ever get the $$$.
Member Since: September 8, 2005 Posts: 0 Comments: 274
Quoting 888. ackee:
if 97L was to be upgrade to a TD/ TS when do u guys think this would happen ?

A 24 HOURS
B 48 HOURS
C 72 HOURS
D 96 HOURS
E 120 Hours
less.
Member Since: Posts: Comments:
895. FOREX
Quoting 888. ackee:
if 97L was to be upgrade to a TD/ TS when do u guys think this would happen ?

A 24 HOURS
B 48 HOURS
C 72 HOURS
D 96 HOURS
E 120 Hours


D
Member Since: Posts: Comments:
894. beell
97L seems to be continuing its habit of forming forward-propagating thunderstorms (towards the S or SW) along the convergence boundary separating the low-level westerlies from the southeasterlies.
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Quoting 892. PalmBeachWeather:
Articuno.....You did nothing.........I did nothing....A certain mod did something...Don't worry about it...I will take care of it...Thanks



can you plse get back too the weather
Member Since: May 21, 2006 Posts: 5091 Comments: 114705
Quoting 843. Articuno:

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.
Articuno.....You did nothing.........I did nothing....A certain mod did something...Don't worry about it...I will take care of it...Thanks
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Member Since: August 19, 2006 Posts: 13 Comments: 14412
Quoting 876. Kowaliga:
Surf's up in Barbados!

that loop is old
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Quoting 843. Articuno:

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.
Articuno.....You did nothing.........I did nothing....A certain mod did something...Don't worry abount it...I will take care of it...Thanks
Member Since: Posts: Comments:
888. ackee
if 97L was to be upgrade to a TD/ TS when do u guys think this would happen ?

A 24 HOURS
B 48 HOURS
C 72 HOURS
D 96 HOURS
E 120 Hours
Member Since: Posts: Comments:
Does anyone have an reccomendations on good accurate personal weather stations I could buy? I would prefer somethinh below $230...

Any suggestions thanks!
Member Since: Posts: Comments:
Quoting 878. washingtonian115:
So have the doom predictions of "this is going to be the next _____(Insert name here) major hurricane begun?.Have the doom predictions of a cat 5 running into the gulf started yet or am I ahead of the game?.
Oh well it is still within my cone of doom. :D

Member Since: June 30, 2013 Posts: 11 Comments: 7464
Quoting 876. Kowaliga:
Surf's up in Barbados!

Is is wrong to be jealous of other islands who now have their radars online? After all, we were the first "small island", and even beat one of the "big islands".... lol

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pbw if ya upset take it to this blog pls

iam being more than reasonable

Link
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Quoting 62901IL:

Me!
Might be but without reckon, imposible to confirm...
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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


It looks like some of others want to go to the bahamas

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97L has slowed down considerably today meaning trade winds are slow ahead of the system. The recent slowdown will cause more rain and squally weather than previously expected for the Lesser Antilles. The forward motion will help it tremendously by allowing the easterlies to the west of the system in the Central Atlantic to pile up rather than move west naturally into the Caribbean. The Lesser Antilles needs to watch it carefully as it might ramp up overnight as more instability returns.

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Quoting 875. ncstorm:


Gro was on earlier? GREAT!

Yeah he dropped a quick comment a few pages back. I'm running 100 posts per page so it maybe a couple of hundred posts earlier. We have official "blobs" if I remember correctly..lol
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Come on @863/865...what could you possibly be basing that on?
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So have the doom predictions of "this is going to be the next _____(Insert name here) major hurricane begun?.Have the doom predictions of a cat 5 running into the gulf started yet or am I ahead of the game?.
Member Since: August 14, 2010 Posts: 10 Comments: 16383
877. ackee
97L is the first invest this seasons that is moving under 17 mph its just moving at 8pmh wow which I am thinking could work in 97L favor shear seem to be lowering in the Eastern Caribbean , so my guess tonight will be a interesting night for 97L will it close off before it reach entering eastern Caribbean
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Surf's up in Barbados!

Member Since: September 8, 2005 Posts: 0 Comments: 274
Quoting 874. 954FtLCane:
It was nice to see Gro on here earlier clarifying that this was a blob. :-)


Gro was on earlier? GREAT!
Member Since: August 19, 2006 Posts: 13 Comments: 14412
And here I thought the Green Mod Bold note next to the name up top meant that I had modified my statement. This is something I do often because I'm always going back and modifying my posts due to misspelling.
It was nice to see Gro on here earlier clarifying that this was a blob. :-)
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Quoting 864. RascalNag:
I think we'll see a good deep burst out of 97L soon.
Doubt this'll happen before dark, about 4 hours from now...
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Quoting 863. HurricaneAndre:
Who thinks 97L is a TD.
I DO,DO YOU.

Not quite yet
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870. JRRP
Quoting HurricaneAndre:
Who thinks 97L is a TD.
I DO,DO YOU.

no
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Quoting 864. RascalNag:
I think we'll see a good deep burst out of 97L soon.
I think so too.
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Quoting 855. PalmBeachWeather:
"Waiting for a response from whitewabit" an apology or ban me.........GOT IT...
pbw from what I see you have done nothing but quote a comment that you were asked to remove nicely you refused so it got remove for you and the ban ended right after removal but now you are making it a point to make it personal towards wab and all he was trying to do was keep it civil come on girl please don't make us do something that really had nothing to do with ya in the first place other than a quoted comment

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Quoting 860. Gearsts:
Is just going to keep developing convection the other way lol Is like wave is moving East.


It's like a lobster, all the meat is in the tail.
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Quoting 863. HurricaneAndre:
Who thinks 97L is a TD.
I DO,DO YOU.

Me!
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I think we'll see a good deep burst out of 97L soon.
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Who thinks 97L is a TD.
I DO,DO YOU.
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Quoting 852. Articuno:

If I would've kept my mouth shut none of this would've happened.
You did just fine Art...It was needed
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Quoting 860. Gearsts:
Is just going to keep developing convection the other way lol Is like wave is moving East.


shes reorganizing
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Is just going to keep developing convection the other way lol Is like wave is moving East.
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Quoting 854. VAbeachhurricanes:


None of this is your fault, its been brewing for a while.
nothing brewing but that which one wants to brew
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Quoting 849. KEEPEROFTHEGATE:
I don't know whats going on I just got back had to step out give me a minute


Never mind Keep.
Edited
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from the left hand side please
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"Waiting for a response from whitewabit" an apology or ban me.........GOT IT...
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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.