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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I am going on record to say I am in Wunderkidcaymans camp on this one. I think he has presented a good analysis. With the system still rather elongated the models could truly be off with still no truly defined LLC....we shall see
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266. bwi
I've been seeing some SSW and S winds from Bonaire (easternmost of the ABC islands off the n coast of Venezuela). That's pretty impressive I think.

These large broad systems can be pretty durable if they finally get ramped up.
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Quoting 237. Abacosurf:
Yes. It looks like the vort at 14N is trying to wrap the 16N vort into it slowly. Overall 97L looks healthier than yesterday at this time and the the 2 vortices oriented from NNW to SSE are going to converge as one later today.

The overall gyre is there.




it does
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better banding on south side but 97l realy needs some CDO, im afraid that wont happen due to the trade wind flow out of the east, this may make a run at a name before interacting with the islands.
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Global Hawk is now in 97L
Link
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There is *possible* rotation west of Guadeloupe
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Quoting 257. stormpetrol:


With that loop I definitely see that the whole system is moving very slowly WNW.
Member Since: August 12, 2007 Posts: 0 Comments: 96
260. Skyepony (Mod)
Extreme Weather in USA on Tuesday, 03 September, 2013 at 03:06 (03:06 AM) UTC.
Description
A lightning strike has killed one man and injured two others in a semi-rural area southwest of Miami. Miami-Dade Fire Rescue officials said the men were outside when a major storm passed through the area Monday afternoon. They tried to hide underneath a tractor-trailer but it was struck by lightning. The energy passed through the trailer and into the men. The two injured men were taken by ambulance to a trauma center for treatment. Their condition was not immediately known.
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Quoting 240. HurricaneHunterJoe:


Thanks WKC.....I will say, not that I even like mentioning their names....Chantal and Dorian both came further west as WKC was saying at the time....if my OLD brain cells remember that correctly.



He was insisting Dorian was moving due west the entire time, contrary to everyone on the blog




Most of the models had Chantal moving west so it wasn't much of an issue



There wasn't a day he didn't write Dorian was moving due west and would be a Caribbean cruiser.


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Quoting 245. MahFL:


It's 2013, please learn how to use Google.
Insert global hawk hu into Google and it's the very first link.......


I do and I will :(
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thx doc trade winds a factor as well I agree with your 40%
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255. Skyepony (Mod)
Flash Flood in USA on Tuesday, 03 September, 2013 at 03:26 (03:26 AM) UTC.
Description
Two days of torrential rain across much of Rhode Island has led to serious flash flooding in parts of the state. In Cranston, about 60 people were evacuated from their apartments on Oaklawn when flood waters entered the 1st floor of the complex. "The water came up all the way onto the 2nd floor of that apartment complex", Mayor Allan Fung told WPRO Monday afternoon. He said residents of those apartments had to be evacuated by boat. Monday's rains, which totalled over three inches in sections of the state, came on top of more heavy rains on Sunday. Spotters report some areas of Kent County have seen up to 8 inches over rain over the last 48 hours. The torrential rains made roads impassible in parts of Cranston, Warwick, West Warwick, Coventry and other communities in the state. Rte 10 through Cranston was closed for over an hour on Monday afternoon because of high water. A flash flood watch remains in effect for Rhode Island through 11 tonight. Forecasters say there's a chance of more heavy rain, would serve to renew the area's flooding problems. The National Weather Service has also issued a flood warning for the Pawtuxet River through Tuesday morning. The River is expected to crest about a foot over flood stage late Monday caused minor flooding problems along low lying areas of river.
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Sigh.... some will never change XD HAHAHA
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Quoting 246. stormpetrol:
Link

This link clearly shows the LLC of 97L around 14.3N/63.8W moving 270degrees or due west!

Well stormpetrol see it

Quoting 247. IKE:
Instead of wishcasting a storm to you....buy a plane and fly into it.

Been there done that well I didn't buy a plane it was in the C-130

Quoting 248. HuracandelCaribe:
At this moment it looks like 97L is sucking the life of the wave behind it.

Yes it is
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Quoting 238. TideWaterWeather:


If ones forecast is always to a certain point no matter the storm or conditions, then sooner or later it will happen. Broken clock anyone?


yes or the Stormtop model
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Quoting 246. stormpetrol:
Link

This link clearly shows the LLC of 97L around 14.3N/63.8W moving 270degrees or due west!


Is barely moving.
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250. JeffMasters (Admin)
It's like a switch got turned on over 97L, and now it is starting to spin up. However, I'm seeing outflow boundaries on the convection on its north side, where dry air is getting ingested. Probably a 2-day 40% chance of development now.

Dr. M.
Quoting 239. sdswwwe:


Yes because Cayman has many brushes with storms so he is bound to be right some of the time. I don't think it is usually based off the facts though. If he dropped the bias he would be a good forecaster.

I'm not bias I go by the facts

Quoting 240. HurricaneHunterJoe:


Thanks WKC.....I will say, not that I even like mentioning their names....Chantal and Dorian both came further west as WKC was saying at the time....if my OLD brain cells remember that correctly.

That is correct
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At this moment it looks like 97L is sucking the life of the wave behind it.
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247. IKE
Instead of wishcasting a storm to you....buy a plane and fly into it.
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Link

This link clearly shows the LLC of 97L around 14.3N/63.8W moving 270degrees or due west!
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245. MahFL
Quoting 231. HurricaneHunterJoe:


... Is there a link to see what met resources/equipment Global Hawk has onboard and what tests it can perform?


It's 2013, please learn how to use Google.
Insert global hawk hu into Google and it's the very first link.......
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Looks like 98L will be around for a while.
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Good afternoon, everyone

Just got back from camping on a small (smaller than this one) island. Didn't take a computer with me so am now trying to figure out what's happening with this system I see all of you talking about.

I think I much prefer swinging in the hammock, overlooking the water, gentle breezes, warm water, lovely island beverages...I think you get my drift! ;-)

Lindy

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Quoting 231. HurricaneHunterJoe:


Good stuff Pat!......I think the the unmanned flights will help a lot and cheaper on cash resources I would think...and can stay there quite a while. Is there a link to see what met resources/equipment Global Hawk has onboard and what tests it can perform?


Published on May 15, 2013
NASA's Hurricane and Severe Storm Sentinel (HS3) mission uses NASA's Global Hawk Unmanned Aerial Vehicles (UAV) to study tropical storms and hurricanes. This nine-minute video describes the mission, reveals details about the Global Hawk aircraft, and offers a glimpse inside the command centers of both the ground-based pilots and the scientists who analyze satellite images to assist in flight navigation. The video concludes with information about getting students involved directly from the classroom through computer monitoring of the Global Hawk's flight patterns and participating in live chats with the ground-based pilots.

Educational resources about the HS3 mission can be found at the NASA Wavelength Digital Library nasawavelength.org/resource/nw-000-000-0­3-539/

For more information about HS3 and the NASA Airborne Science Program visit airbornescience.nasa.gov, and nasa.gov/hs3


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241. IKE

56m
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 228. wunderkidcayman:

Wrong


No spin at 16N



I don't think so we'll just have to wait and see


Thanks WKC.....I will say, not that I even like mentioning their names....Chantal and Dorian both came further west as WKC was saying at the time....if my OLD brain cells remember that correctly.
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Quoting 233. Relix:


To his defense that has happened a lot before and I get a good laugh haha. Sadly there's a clear movement to 285 degrees at the moment so I don't think he'll pull it off this time :p.


Yes because Cayman has many brushes with storms so he is bound to be right some of the time. I don't think it is usually based off the facts though. If he dropped the bias he would be a good forecaster.
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Quoting 233. Relix:


To his defense that has happened a lot before and I get a good laugh haha. Sadly there's a clear movement to 285 degrees at the moment so I don't think he'll pull it off this time :p.


If ones forecast is always to a certain point no matter the storm or conditions, then sooner or later it will happen. Broken clock anyone?
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Quoting 219. HurricaneHunterJoe:


I see 2 spins...14N and 16N...anyone else?
Yes. It looks like the vort at 14N is trying to wrap the 16N vort into it slowly. Overall 97L looks healthier than yesterday at this time and the the 2 vortices oriented from NNW to SSE are going to converge as one later today.

The overall gyre is there.
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Ok you guy don't see it well ok as I said before lets just wait and watch see what happens
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235. 7544
the plane should make things more clear but i think the models will shift more to the west after they get the new data so far im with levi on this one for now .
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Quoting 229. bluewaterblues:
Wunderkidcayman is going to have a lot of people eating crow if 97L stays west and avoids the trough.

If it does yes maybe lol
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233. Relix
Quoting 229. bluewaterblues:
Wunderkidcayman is going to have a lot of people eating crow if 97L stays west and avoids the trough.


To his defense that has happened a lot before and I get a good laugh haha. Sadly there's a clear movement to 285 degrees at the moment so I don't think he'll pull it off this time :p.
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Quoting 224. wunderkidcayman:


Look man not all the times BEST track is correct in fact most times it off by a couple of degrees right now the visible and radar images as well as sfc obs and buoys say different from what BEST track says


There is no N movement of the COC at all so 270 would be it anything higher would bring in a N factor into its movement and at this time there is none


Clearly show W-WSW
Lol unless your reading it backward that would be ENE lol j/k I know you ain't reading backward


This is where you shoot yourself in the foot on every storm. All the wishing and bias in the world will not make the storm come to you if that's not what mother nature wants. The southern swirl seems to be rotating into the larger COC.. and the entire system is taking on a NW component.
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Quoting 221. Patrap:

Global Hawks current position

Current Altitude, is 50K ft


Good stuff Pat!......I think the the unmanned flights will help a lot and cheaper on cash resources I would think...and can stay there quite a while. Is there a link to see what met resources/equipment Global Hawk has onboard and what tests it can perform?
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Quoting 216. Relix:


I am gonna take a guess and say its moving towards the Cayman Islands, am I right?


just the rain hurricanes are messy and bad for business well unless you sell hurricane supplies or ice or gas
or booze directly after from your garage
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Wunderkidcayman is going to have a lot of people eating crow if 97L stays west and avoids the trough.
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Quoting 216. Relix:


I am gonna take a guess and say its moving towards the Cayman Islands, am I right?

Wrong

Quoting 219. HurricaneHunterJoe:


I see 2 spins...14N and 16N...anyone else?

No spin at 16N

Quoting 222. HuracandelCaribe:
The swirl that some were following is now dissipating and a new stronger one is developing a full degree to the NE


I don't think so we'll just have to wait and see
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Looks like 97l is on the move and will affect someplace.
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Quoting 209. Levi32:


The GFS and its derivative models still look plain wrong to me, generating something out of nothing to the northeast of the main complex. I think the Bahamas will still have to deal with weather from 97L. It's not going OTS as easily as all that, but we still have to see where it's centered after dealing with Hispaniola, which can always change the game.


If the 12Z GFS is correct (not looking at 97L) the east coast trough sharpens just along 75 West or so and really doesn't "leave" until next Tuesday. I don't think this makes it into the Bahamas.

Link
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Homecasting du jour?
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Quoting 212. WoodyFL:



You most certainly did In your post#486 9/2/13 1:58 PM


QUOTE: wunderkidcayman


Look at BEST track file its moving W not E


Look man not all the times BEST track is correct in fact most times it off by a couple of degrees right now the visible and radar images as well as sfc obs and buoys say different from what BEST track says

Quoting 214. chrisdscane:


no, not 270, 280 would seep about right we dont even have a depression yet so trying to guess the movment would be difficult.

There is no N movement of the COC at all so 270 would be it anything higher would bring in a N factor into its movement and at this time there is none

Quoting 215. JRRP:

put in rock

Clearly show W-WSW
Lol unless your reading it backward that would be ENE lol j/k I know you ain't reading backward
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Quoting 197. yonzabam:


What a difference a day makes! The Azober high must have weakened awful quick.


It must have. Unless that trough that Caleb showed a little while back is what might be moving it more northerly. The models are just a little off to me. I don't see it turning that quickly north. I do believe it will be north of the DR. though.

I know it certainly isn't moving west!!
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The swirl that some were following is now dissipating and a new stronger one is developing a full degree to the NE
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Global Hawks current position

Current Altitude, is 50K ft
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Shouldn't be long till we get 99L in the Yucatan.
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Quoting 187. Torito:
97L seems to starting to become organized now...



I see 2 spins...14N and 16N...anyone else?
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South-west monsoon weakens, winter on the way: Met
Times of India, TNN | Sep 3, 2013, 02.26 AM IST

JAIPUR: The cessation of monsoon activity in all parts of the state over the past fortnight indicates the south-west monsoon has weakened.
Though the Jaipur Met office has not declared it officially, on Monday they said that the monsoon activity has come to an end. The minimum temperatures have started dipping and within a fortnight, the mornings are likely to turn nippy.
Attributing the absence of rain to the decreased moisture and dipping temperatures in the afternoons and early mornings, respectively, the met office said that there would hardly be any further monsoon activity in state.
"We are yet to make the official announcement, but the ongoing climatic pattern suggests that monsoon has vanished from the state," said SS Singh, director, Jaipur Met office on Monday.
Though partly cloudy conditions prevailed in most parts of state, the weather mainly remained dry.
"Absence of monsoon activity for over a fortnight indicates that it has bidden goodbye," said a Met official. ...




And the wave train over Africa continues looking rather anemic in the northern hemisphere.
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Levi,do you have data from the Global Hawk mission?
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About JeffMasters

Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.