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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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).
Member Since: September 16, 2007 Posts: 0 Comments: 8248
Why is this storm, if you want to call it that, not moving at all?
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Quoting 2257. CaneHunter031472:


Other than dry air, conditions seem to be favorable. I guess we'll see.
Nice icon...sums up a huge portion of this season. :)
Member Since: August 18, 2011 Posts: 0 Comments: 994
Looks like with this development process it's in, there's no choice that the models have to move south and more west. Fyi the hwrf has gone insane!!!! No way that happens in two and half days!! Lol!!
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2301. GatorWX
Another thing that don't seem to be moving...

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The GFDL shows a slightly less unrealistic 100kts in the Bahamas, which may have been possible in any other season, just not in "the hurricane season that never was" 2013.
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2299. WoodyFL
Quoting 2280. PanhandleChuck:


It will definitely go furrher West now that it isn't developing as fast as it was. The models should be heading bac West on the next few runs.


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

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Quoting 2271. ackee:
Base on what the NHC is saying the shower at 50W is a part of 97L and looking at the weak state 97L is now I can't see this weak system moving over Hispaniola a more likely track is westward into the western Caribbean that where I think 97L will show its true color

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2297. pottery
I'm gone.
Stuff and Whatnot to do.

Stay Safe, all.
And enjoy your Holiday.
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2296. pottery
Quoting CybrTeddy:
LMAO HWRF. 134kts.

That would be a complete Disaster. Haiti.
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Quoting 2286. PanhandleChuck:


Don't go back to lurking, but you do have to have some thick skin in these parts.

if you really want to get bashed, just make a few posts about how GW is political rhetoric and get ready to gst a beat down. LOL


Good one! lol
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2294. VR46L
Quoting 2278. Neapolitan:
Another sign of the quiet Atlantic season: looking at thunderstorms over Sudan and speculating, "Maybe?"

2013


Errr I think you are looking at the couple of showers in the extreme SE South Sudan and Ethiopia ..there is one Shower in Sudan :)

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2293. pottery
Quoting GatorWX:
It could go to The Caymans?



Let's see what else is stirring...


With the amount of Blobs, Blobbettes and Bloblets out there, Grothar has probably had to go back to bed.......
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2292. Dakster
I see overnight didn't help out 97L...

Member Since: March 10, 2006 Posts: 0 Comments: 10572
LMAO HWRF. 134kts.
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2290. GatorWX
It could go to The Caymans?



Let's see what else is stirring...

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2289. pottery
Anyone considering the possibility of the center moving back East a couple hundred miles ?
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2288. WxLogic
Good Morning
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2287. pottery
Quoting PanhandleChuck:


It will definitely go furrher West now that it isn't developing as fast as it was. The models should be heading bac West on the next few runs.

I think so too.

IF it can get moving at all !
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Quoting 2279. WoodyFL:


I hope i didn't say something wrong. It took me long enough years to post wondiering who's gonna attack me on the blog. I know sometimes you all can get rough. maybe i'll go back to lurking. lol


Don't go back to lurking, but you do have to have some thick skin in these parts.

if you really want to get bashed, just make a few posts about how GW is political rhetoric and get ready to gst a beat down. LOL
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2285. GatorWX
Quoting 2279. WoodyFL:


I hope i didn't say something wrong. It took me long enough years to post wondiering who's gonna attack me on the blog. I know sometimes you all can get rough. maybe i'll go back to lurking. lol


Inside joke I guess, you're good. Most likely you're right with it not going to The Caymans. Looks like Hispaniola right now, maybe Eastern Cuba. I think a lot has to do with the influence from the ull.
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2284. pottery
Quoting WoodyFL:


I hope i didn't say something wrong. It took me long enough years to post wondiering who's gonna attack me on the blog. I know sometimes you all can get rough. maybe i'll go back to lurking. lol

Nah, you didn't say anything wrong.

In fact, one of the people who has been saying that 97 will end up in Cayman may prove to be correct. Again !

:):))
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2283. barbamz
Don't want this to happen over Fukushima ...



Youtube Info: Tornado hits near Tokyo
02 September 2013

KOSHIGAYA, Japan (AFP) - Several dozen people were injured when a tornado ripped through parts of eastern Japan on Monday, tearing off roofs and uprooting buildings.

Footage on public broadcaster NHK showed a number of homes destroyed, upturned cars, schools with shattered windows and a warehouse that had been lifted from its foundations and hurled into other buildings in Koshigaya, north of Tokyo.

An AFP journalist in the city saw roof tiles scattered all over the streets, with locals outside inspecting their battered homes and emergency vehicles at the scene.

Residents were being prevented from re-entering their houses for fear of collapse.

Some electricity poles had been snapped and a number of them had hit houses as they fell, worsening the damage.

The Koshigaya city hall said 29 people were injured, three of them seriously, in the city alone.

Jiji Press agency said most of the injured were members of a volleyball team at a local middle school.

"We are preparing evacuation shelters, while also readying emergency supplies," said an official of the fire department in Koshigaya.

The electricity supply was cut for some 33,000 households in the region, mainly in Saitama prefecture, probably after lightning strikes, according to utility Tokyo Electric Power which provides power in the area.

"Weather conditions in the region today have been very unstable," said a meteorologist at Japan's weather agency.

"In flatter parts of the region particularly, warm, wet air can come inland and spark tornados. This is especially the case when there is a typhoon developing in the south," he said.
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Quoting 2278. Neapolitan:
Another sign of the quiet Atlantic season: looking at thunderstorms over Sudan and speculating, "Maybe?"

2013
look like your 7-0-0 wish might come true, Nea :P
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Quoting 2279. WoodyFL:


I hope i didn't say something wrong. It took me long enough years to post wondiering who's gonna attack me on the blog. I know sometimes you all can get rough. maybe i'll go back to lurking. lol
lol you didn't. I'm confused why the models are showing the track over Hispaniola so they might be onto something. From the current condition I see, though, I see it unlikely but the game changes fast.
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Quoting 2266. WoodyFL:
All the models have been shifting back to east since yesterday morning. Everytime I posted them there was a blogger who said that would change and move west toward Jamaica and the cayman islands. With the trough there how was that possible.





It will definitely go furrher West now that it isn't developing as fast as it was. The models should be heading bac West on the next few runs.
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2279. WoodyFL
Quoting 2272. pottery:

Well, it certainly gave me a chuckle.
Thanks !


I hope i didn't say something wrong. It took me long enough years to post wondiering who's gonna attack me on the blog. I know sometimes you all can get rough. maybe i'll go back to lurking. lol
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Another sign of the quiet Atlantic season: looking at thunderstorms over Sudan and speculating, "Maybe?"

2013
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2277. GatorWX
Barbados

Yesterday:



Today:

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Reason for models going toward northward over Hispaniola is because they are strengthening the storm in East Caribbean.

* ATLANTIC SHIPS INTENSITY FORECAST *
* GOES AVAILABLE, OHC AVAILABLE *
* INVEST AL972013 09/02/13 06 UTC *

TIME (HR) 0 6 12 18 24 36 48 60 72 84 96 108 120
V (KT) NO LAND 30 32 35 39 44 54 64 74 82 88 92 94 93
V (KT) LAND 30 32 35 39 44 54 64 74 82 88 74 83 82
V (KT) LGE mod 30 31 33 36 39 47 59 72 87 101 87 102 104
Storm Type TROP TROP TROP TROP TROP TROP TROP TROP TROP TROP TROP TROP TROP

SHEAR (KT) 8 4 5 6 5 7 2 4 4 4 1 4 11
SHEAR ADJ (KT) -3 -1 0 -1 -2 0 -1 -2 -2 -1 2 -2 0
SHEAR DIR 136 114 82 119 113 87 154 37 321 63 306 195 237
SST (C) 28.8 28.9 28.9 29.0 29.0 29.1 29.1 29.1 29.1 29.1 29.2 29.4 29.5
POT. INT. (KT) 146 148 149 151 151 153 153 154 154 153 155 158 159
ADJ. POT. INT. 138 141 142 144 144 147 148 148 148 146 145 147 146
200 MB T (C) -54.0 -54.0 -53.3 -53.3 -53.7 -53.4 -53.3 -53.1 -53.1 -53.0 -53.0 -53.0 -53.0
TH_E DEV (C) 10 10 10 10 9 10 9 10 10 11 11 11 11
700-500 MB RH 59 59 61 63 64 62 66 65 64 63 62 62 61
GFS VTEX (KT) 7 7 8 8 8 9 9 8 7 6 5 5 4
850 MB ENV VOR 47 50 58 70 72 69 73 67 73 67 63 50 44
200 MB DIV 54 18 16 34 38 33 52 42 29 20 13 35 9
700-850 TADV 0 1 1 0 0 3 2 3 4 4 -1 2 -1
LAND (KM) 382 373 377 396 411 394 288 213 144 36 -2 78 22
LAT (DEG N) 14.0 14.1 14.2 14.3 14.4 14.9 15.4 16.2 17.0 17.8 18.5 19.1 19.6
LONG(DEG W) 59.7 60.4 61.0 61.8 62.5 64.1 65.9 67.9 69.9 72.0 73.8 75.6 77.0
STM SPEED (KT) 5 6 7 7 8 9 10 10 11 10 9 8 7
HEAT CONTENT 42 46 33 42 40 49 47 35 29 35 12 44 49
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boring? i find this yr exciting not knowing what to expect.
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Well we may have something to watch. It's been very quite...
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Quoting 2270. WoodyFL:



did i say something funny?
This is what I deal with from the local weather forecast station.
Clear with a chance of a thunderstorm. High of 93F. Winds from the ENE at 5 to 10 mph. Chance of rain 40%.
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2272. pottery
Quoting WoodyFL:



did i say something funny?

Well, it certainly gave me a chuckle.
Thanks !
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2271. ackee
Base on what the NHC is saying the shower at 50W is a part of 97L and looking at the weak state 97L is now I can't see this weak system moving over Hispaniola a more likely track is westward into the western Caribbean that where I think 97L will show its true color
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2270. WoodyFL
Quoting 2268. GatorWX:


lol



did i say something funny?
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2269. WoodyFL
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2268. GatorWX
Quoting 2266. WoodyFL:
All the models have been shifting back to east since yesterday morning. Everytime I posted them there was a blogger who said that would change and move west toward Jamaica and the cayman islands. With the trough there how was that possible.





lol
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2267. barbamz

TPW, click to enlarge. Hmm, center of the wave's circulation (97L) looks a bit void of moisture in the last frames.
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2266. WoodyFL
All the models have been shifting back to east since yesterday morning. Everytime I posted them there was a blogger who said that would change and move west toward Jamaica and the cayman islands. With the trough there how was that possible.



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Happy Labor Day, all! Pouring rain here, although the rain in Maine is plainly on the wane.

I think the photo in this link summarizes somebody's opinion on the hurricane season:

http://weather.aol.com/2013/08/29/cloudspotting-i s-this-cloud-angry-at-the-world/?icid=maing-grid7%7 Cmain5%7Cdl3%7Csec1_lnk3%26pLid%3D366756

Have a safe holiday, all.
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2264. pottery
Quoting IKE:
LOL....they lowered the odds. Watched pot never boils. The incredible season rocks on.....

6-0-0.

NOTE: I thought they might raise the odds to 50% and 60%.


More like a slow dance, to Frank Sinatra music.
Enough to put a man to sleep.....
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2263. pottery
Quoting CybrTeddy:
Down to 20% in the next 48 hours, holding strong at 50% in 5 days. Clearly the NHC still thinks this has a good chance to develop.


Based entirely on Climate, I guess.
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2262. GatorWX
Quoting 2261. IKE:





97 has reminded me more of a low embedded in the itcz than a tropical wave. Strange how it's basically back-built the last 24 hours.
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2261. IKE



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Quoting 2251. pottery:


Barbados.


LOL!
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2259. pottery
Quoting GatorWX:


hahahha, funny guy!

Morning Pott

Greetings.
Hazy and still as a tomb here.

I trust that you all have lots of Labour planned today?
That's the idea, isn't it ?
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2258. IKE

Quoting SLU:


Sums up 2013 so far when Stewart has lost all optimism.
Good point.
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Quoting 2253. CybrTeddy:
Down to 20% in the next 48 hours, holding strong at 50% in 5 days. Clearly the NHC still thinks this has a good chance to develop.


Other than dry air, conditions seem to be favorable. I guess we'll see.
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2256. GatorWX
Quoting 2251. pottery:


Barbados.


hahahha, funny guy!

Morning Pott
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2255. SLU
Quoting 2252. IKE:
TROPICAL WEATHER OUTLOOK
NWS NATIONAL HURRICANE CENTER MIAMI FL
800 AM EDT MON SEP 2 2013

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

DISORGANIZED CLOUDINESS AND SHOWERS IN ASSOCIATION WITH AN ELONGATED
AREA OF LOW PRESSURE EXTEND FROM THE EASTERN CARIBBEAN SEA ACROSS
THE LESSER ANTILLES AND INTO THE TROPICAL ATLANTIC. ALTHOUGH
UPPER-LEVEL WINDS ARE FAVORABLE...THE PROXIMITY TO DRY AIR IN THE
MIDDLE LEVELS OF THE ATMOSPHERE IS INHIBITING DEVELOPMENT OF THIS
DISTURBANCE. THIS SYSTEM HAS A LOW CHANCE...20 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 TO WEST-NORTHWESTWARD AT AROUND
10 MPH OVER THE CARIBBEAN SEA...AND NEAR OR OVER HISPANIOLA.
REGARDLESS OF WHETHER OR NOT A TROPICAL CYCLONE FORMS...BRIEF
PERIODS OF LOCALLY HEAVY RAINFALL AND GUSTY WINDS ARE EXPECTED TO
AFFECT PORTIONS OF THE LESSER ANTILLES OVER THE NEXT DAY OR SO.

OTHER SYSTEMS WITH FORMATION POTENTIAL BEYOND 48 HOURS...

A TROPICAL WAVE LOCATED OVER THE NORTHWESTERN CARIBBEAN SEA IS
MOVING WEST-NORTHWESTWARD AT ABOUT 10 MPH. THIS SYSTEM IS EXPECTED
TO MOVE ACROSS THE YUCATAN PENINSULA TODAY AND INTO THE BAY OF
CAMPECHE TUESDAY THROUGH THURSDAY...WHERE SOME DEVELOPMENT IS
POSSIBLE LATER IN THE WEEK. THIS SYSTEM HAS A LOW CHANCE...NEAR 0
PERCENT..
.OF BECOMING A TROPICAL CYCLONE DURING THE NEXT 48
HOURS...AND A LOW CHANCE...20 PERCENT...OF BECOMING A TROPICAL
CYCLONE DURING THE NEXT 5 DAYS.

&&

FIVE-DAY FORMATION PROBABILITIES ARE EXPERIMENTAL IN 2013. COMMENTS
ON THE EXPERIMENTAL FORECASTS CAN BE PROVIDED AT...

WWW.NWS.NOAA.GOV/SURVEY/NWS-SURVEY.PHP?CODE=ETWO

$$
FORECASTER STEWART


Sums up 2013 so far when Stewart has lost all optimism.
Member Since: July 13, 2006 Posts: 13 Comments: 5356

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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.