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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Oye...

Member Since: September 10, 2007 Posts: 0 Comments: 11098
Member Since: March 12, 2013 Posts: 12 Comments: 20000
2353. guygee
Personally I am rooting for the record, just to stir it up a bit across the spectrum. That's just me obviously. (P.S. Well maybe not just me, but it is my personal preference).
Member Since: September 16, 2005 Posts: 0 Comments: 3148
2352. WoodyFL
Quoting 2291. CybrTeddy:
LMAO HWRF. 134kts.



I believe on that model, 134 knots is not the surface winds. It would be winds at 950mb. To convert to estimated surface winds I usually reduce that amount by 20% and it will give approximate surface level winds. In this case roughly 100 knots. (still laughable at the moment)

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2351. IKE
Strip-tease taking place east of the islands.....


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Quoting 2309. allancalderini:
Would be cool to break the record for latest hurricane,rooting for 97L to be just a ts.
I'd personally like us to go the rest of the year without any further named storms whatsoever. Now that would be something to see...

Assuming no storm will be named by midnight, 2013 will be six storms behind 2012 and 1995, and seven storms behind 2011 and 2005, by the end of the day. ACE-wise, the current tally of eight is fewer than half that of the 1983 season, which featured the lowest ACE (17) in the years from 1950 through 2012. However, while that season saw only four storms form, three of those were hurricanes, and one (August's Alicia) went on to become a major. IOW, the odds are increasingly favoring a historically low accumulation of ACE this year (though it should of course be noted that a single large and/or longlasting storm could quickly banish that possibility). (To put things in perspective, 2013's current ACE is just 3.23% of 2005's final tally.)

2013

2013
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2349. guygee
No hint of expected 97L effects in the long-range forecast section of this mornings MLB-AFD. Emphasis on the ridge axis moving farther north of us as the week progresses.


AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MELBOURNE FL
427 AM EDT MON SEP 2 2013

.DISCUSSION...
[,,,]
[...]
THU-SUN...SUBTROPICAL RIDGE AXIS CONTINUES TO SHIFT NORTHWARD INTO LATE WEEK AND EVENTUALLY MERGES WITH A STRONGER AREA OF HIGH PRESSURE NEAR THE MID ATLANTIC COAST. THIS PROVIDES A PERSISTENT ONSHORE FLOW THROUGH THE PERIOD WITH GREATEST RAIN CHANCES ACROSS THE INTERIOR...UP TO 40 PERCENT. EARLIER DEVELOPMENT OF THE EAST COAST SEA BREEZE WILL KEEP MAX TEMPS NEAR THE COAST CONFINED TO THE
UPPER 80S/AROUND 90 DEGREES WITH LOW 90S ACROSS THE INTERIOR.
&&
[...]
&&
.MARINE...
[...]
TUE-FRI...HIGH PRESSURE RIDGE AXIS NEAR LAKE OKEECHOBEE TUESDAY WILL GRADUALLY SHIFT NORTHWARD THROUGH LATE WEEK WITH S/SW WINDS BECOMING ONSHORE INTO LATE WEEK. WIND SPEEDS WILL REMAIN BELOW 15 KNOTS WITH SEAS 2-3 FEET.
Member Since: September 16, 2005 Posts: 0 Comments: 3148
Joe Bastardi ‏
US hurricane models so far doing poor job. HWRF turns tropical system over Caribbean into cat 4 hurricane in Bahamas

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2347. IKE

1h
Long slow drawn out process likely to have storm in Bahamas in several days, but doubt its near what the HWRF has
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Quoting 2340. CybrTeddy:


It'll be the opposite of yesterday, irrationally in despair that there won't be a hurricane for another 10 years.
I think it was to early to decide the strength of 97L blowing up into a major.It had multiple voticies and models struggle badly with those kind of storms.
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Good Morning!
Sunday, 7:46 PM (23:46 GMT)

Last night's sunset in Lantana, Florida.

Sunrise, sunset
Sunrise, sunset

Is this the little girl I carried?
Is this the little boy at play?
I don't remember growing older
When did they?

When did she get to be a beauty?
When did he grow to be so tall?
Wasn't it yesterday
When they were small?

Sunrise, sunset
Sunrise, sunset
Swiftly flow the days
Seedlings turn overnight to sunflowers
Blossoming even as they gaze

Sunrise, sunset
Sunrise, sunset
Swiftly fly the years
One season following another
Laden with happiness and tears

One season following another
Laden with happiness and tears
Sunrise, sunset
Sunrise, sunset


6:39 am (10:39 GMT)

The little white sliver is the moon...

6:49 am


Toadfish!

AKA, 'Chicken of the Sea', there are currently thousands of them around Boynton Inlet according to a local fisherman. The meat is all white, but knowledge of proper cleaning is necessary to avoid poisoning. Not for commercial sale in the US, but I'm told they fetch $18 per pound for export. They are quite delicious.

7:13 am


7:31 am

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2344. ncstorm
NEW TROPICAL STORM FORECAST TO DEVELOP AFTER 84 HOURS

FORECAST POSITION AT T+ 84 : 19.8N 68.8W



VERIFYING TIME POSITION STRENGTH TENDENCY

-------------- -------- -------- --------

12UTC 05.09.2013 19.8N 68.8W WEAK

00UTC 06.09.2013 20.7N 71.3W MODERATE LITTLE CHANGE

12UTC 06.09.2013 21.7N 73.0W MODERATE LITTLE CHANGE

00UTC 07.09.2013 22.4N 74.7W MODERATE LITTLE CHANGE

12UTC 07.09.2013 23.2N 76.6W MODERATE LITTLE CHANGE

00UTC 08.09.2013 24.2N 77.1W MODERATE INTENSIFYING SLIGHTLY





THIS INFORMATION IS PROVIDED AS GUIDANCE FOR TROPICAL CYCLONE

RSMCS. IT REQUIRES INTERPRETATION BY TROPICAL CYCLONE SPECIALISTS

AND SHOULD NOT BE CONSIDERED AS A FINAL PRODUCT





MET OFFICE, EXETER, UK



TOO 020514
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Charley started at a very low latitude. That kept it clear of the Islands, and Charley quickly crossed the the Western (flat) part of Cuba.
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This is definitely a positive step in the right direction for 97L compared to yesterday.
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It is amazing people want to satisfy themselves at the death and destruction of others... SAD!!!
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Quoting 2325. washingtonian115:
So are we still predicting impending doom? or can I blog where people are thinking more rational today?.Please let it be the latter..


It'll be the opposite of yesterday, irrationally in despair that there won't be a hurricane for another 10 years.
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Quoting 2325. washingtonian115:
So are we still predicting impending doom? or can I blog where people are thinking more rational today?.Please let it be the latter..
I think we can start with a ban on the models for labor day. Let them stay home and think about what they have done.... :)
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I would have loved to be in Martinique yesterday to see the cloud motion...weak low level swirls all around...probably looked interesting...
Member Since: September 7, 2005 Posts: 7 Comments: 1494
2337. JRRP
Member Since: August 16, 2007 Posts: 0 Comments: 5683
Quoting 2331. Sfloridacat5:
A weaker system and an eastward shift in the model track over night?

We're lucky 97L isn't sitting a little further south (latitude) or we could have been looking at a Charley type track.



I was thinking the same thing yesterday but it looks like the path has shifted east so maybe NOT a Charley type track after all.

Eric
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2335. WoodyFL
Quoting 2306. Bluestorm5:


This is why I'm little stubborn about westward direction, but I don't know if the steering is the reason though. The models are also strengthening the storm fast which is almost impossible in East Caribbean, lol. The trough will pick a strong storm, but not a storm this messy :)



I'm right and you're wrong! LOL. Weak tropical systems are usually steered by low level winds and strong systems are normally steered by upper level winds. A common misconception is that if a storm is weak, it will just keep moving west. I think the low level winds on this will move it to a more NW motion.
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Quoting 2319. allancalderini:
Just 9 more days :D.Do you want this season to break the record? I am just sad that we are in September and it looks like are we are not getting Cape verde storms this year.
http://
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lol...good morning everyone...

i find it funny that the nhc is just gonna clump the approaching tw from the east in together...no wonder models cant get a hold on this mess. A weak vort with limited convection barely moving being overtaken by a much larger tw with alot more convection at this time...
Member Since: September 7, 2005 Posts: 7 Comments: 1494
Quoting 2327. PensacolaDoug:
Please let it be the latter..



Dare to dream!
Lol.

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A weaker system and an eastward shift in the model track over night?

We're lucky 97L isn't sitting a little further south (latitude) or we could have been looking at a Charley type track.
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2330. ncstorm
00z Euro with 97L and a CV system..last frame

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2329. ackee
Quoting 2316. RGVtropicalWx13:
I don't believe that record is going to fall. We will get our hurricane in western Caribbean with all that tchp there.
agree I think 97L will stay weak in the Eastern Caribbean models are too aggressive in strengthen the system in the eastern Caribbean a weak system like this will not be influence by the ULL pressure as even gone up to 1009 now and winds are down to 30 now
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2309: didn't you say you wanted Gabrielle to be a major? Why different tone now lol
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Please let it be the latter..



Dare to dream!
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2326. ncstorm
Quoting 2321. PensacolaDoug:



Will the real 97L please stand up?


LOL..if the blogger chriscances (sic) who has the pic of eminem as his avatar had wrote that, would have been classic..
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So are we still predicting impending doom? or can I blog where people are thinking more rational today?.Please let it be the latter..
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Almost stationary.

LATCUR = 14.3N LONCUR = 59.4W DIRCUR = 270DEG SPDCUR = 3KT
Member Since: April 29, 2009 Posts: 75 Comments: 14209
Quoting 2317. ackee:
Looking at 97L right now how do u guys think 97L will track ?

A WEST
B WNW
C NW
D NNW










B
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2322. ncstorm
06z GFDL Ensembles

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Quoting 2311. ncstorm:
Good Morning all..

Joe Bastardi ‏@BigJoeBastardi 6m

Dry air not the problem anymore with system in Caribbean. We have 3 separate waves fighting with each other, so energy cant bundle.



Will the real 97L please stand up?
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2320. VR46L
Very intense cloud near Belize Associated with TW




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Quoting 2312. CybrTeddy:


Entirely possible, if not likely. Judging by this seasons track record I'd say it probably will happen.
Just 9 more days :D.Do you want this season to break the record? I am just sad that we are in September and it looks like are we are not getting Cape verde storms this year.
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2318. GatorWX
Member Since: January 1, 2008 Posts: 0 Comments: 2825
2317. ackee
Looking at 97L right now how do u guys think 97L will track ?

A WEST
B WNW
C NW
D NNW






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I don't believe that record is going to fall. We will get our hurricane in western Caribbean with all that tchp there.
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2315. JRRP
Member Since: August 16, 2007 Posts: 0 Comments: 5683
2314. ncstorm
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I see the ULL is still sitting over Haiti. I thought that thing was moving quickly out of the way? It's moving, but seems to be taking its time.
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Quoting 2309. allancalderini:
Would be cool to break the record for latest hurricane,rooting for 97L to be just a ts.


Entirely possible, if not likely. Judging by this seasons track record I'd say it probably will happen.
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2311. ncstorm
Good Morning all..

Joe Bastardi ‏@BigJoeBastardi 6m

Dry air not the problem anymore with system in Caribbean. We have 3 separate waves fighting with each other, so energy cant bundle.
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2310. JRRP
Member Since: August 16, 2007 Posts: 0 Comments: 5683
Would be cool to break the record for latest hurricane,rooting for 97L to be just a ts.
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2308. JRRP
Member Since: August 16, 2007 Posts: 0 Comments: 5683
12z Best Track for 97L.

AL, 97, 2013090212, , BEST, 0, 143N, 594W, 25, 1009, LO
Member Since: April 29, 2009 Posts: 75 Comments: 14209
Quoting 2299. WoodyFL:


I think with this one, the strength doesn't matter that much because of the trough. All of the models like HWFI, FIM9, AEMI, GFDL all seem to be in the same direction. I think the CMC is the outlier cause it moves it directly north which i don't think is possible right now. because of the way this looks its hard to tell direction



This is why I'm little stubborn about westward direction, but I don't know if the steering is the reason though. The models are also strengthening the storm fast which is almost impossible in East Caribbean, lol. The trough will pick a strong storm, but not a storm this messy :)

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People shouldn't feel bad. Even the NHC was pretty hyped over 97L yesterday.
But one thing I noticed was a lot of people had no idea where the center was yesterday. They were fooled by all the convection to the north and east of the center. The center was there (could be seen south and east) of where most people thought it was.

This morning 97L has a nice circulation and definitely has a real chance of development if it can stay away from the main islands (Haiti/DR/East Cuba).
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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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