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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GEEZ if these storms hold together the west coast of florida is in for it..
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Quoting 798. GTstormChaserCaleb:
Once this develops you're pretty much going to hear this..."It's going west, no it's going north, no it's taken a dive towards the southwest, wait it's beginning to recurve OTS the US is safe from another one."


Oh, and stationary.
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I need that bouys pressure to continue to dip...its leveled off at the same place it did earlier today...

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Quoting 799. stormpetrol:


For now, imo its moving due west or 270 degrees, of course that could change.

I say after a small tug NEward with the convection it's back to W with maybe slight jog S of due W

Also new map suggest more WSW movement last map suggested more W movement

New


Old
Member Since: June 13, 2009 Posts: 2 Comments: 11951

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Quoting 806. LargoFl:
be extra creful..lightning killed a guy in south florida a few days ago..put 2 more in the hospital...scary this storm season is..regular storms not tropical.
Thanks, I probably need to move away from my computer by the window :O
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I don't think there is any correlation between a previous years storm numbers and the current one.
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808. FOREX
Quoting 805. scott39:
97L is moving forward.


Westward forward with maybe a slight, and I mean very slight WNW movement.lol
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Quoting 797. scott39:
Im going through it now. Many lightning strikes in SW Al.
be extra creful..lightning killed a guy in south florida a few days ago..put 2 more in the hospital...scary this storm season is..regular storms not tropical.
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97L is moving forward.
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We've talked about 97L cause it's the most threatening thing so far, but what about the yellow circle over the Yucatan?
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It's an S!
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Quoting 798. GTstormChaserCaleb:
Once this develops you're pretty much going to hear this..."It's going west, no it's going north, no it's taken a dive towards the southwest, wait it's beginning to recurve OTS the US is safe from another one."
go west young man go west lol
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Quoting 780. stormpetrol:
14.9N/63.8W, just my take.

Yeah I'd agree
Member Since: June 13, 2009 Posts: 2 Comments: 11951
anybody want a good laugh. look at #7 and see what Category they put down

Link
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Quoting 790. FOREX:


Looks more of a westward than WNW movement. Your opinion??


For now, imo its moving due west or 270 degrees, of course that could change.
Member Since: April 29, 2007 Posts: 0 Comments: 7862
Once this develops you're pretty much going to hear this..."It's going west, no it's going north, no it's taken a dive towards the southwest, wait it's beginning to recurve OTS the US is safe from another one."
Member Since: June 30, 2013 Posts: 12 Comments: 8194
Quoting 783. catastropheadjuster:
Boy it's wicked outside right know, it's black as a ace of spades. Lightning everywhere. It's scarey.

sheri
Im going through it now. Many lightning strikes in SW Al.
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796. Relix
Hahaha the usual WNW-West debate we have every time. Usually I am against the west movement but this time, I believe its moving at 285 degrees. The convective mass is spinning that way.
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Quoting 776. scott39:
2100 vorticity maps still show 97L stretched out like silly putty. Lower convergence is lousy too.


The vorticity maps are deceiving. While it looks elongated, it isn't at all. 97L and the low to the NE are pretty isolated in terms of their respective LLCs. They're not fighting with each other. There may be a little bit of N-S elongation in 97L itself, but it's very minor. The two lows in close proximity makes it seem like it's one stretched low, when it's just the former - two lows very close to each other. Each circulation is closed and nearly circular. The only competition between these two lows seems to be that they are taking each other's convergence away, but they should get farther as the Eastern one tracks NW and 97L tracks W-WNW.
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panhandle getting storms this afternoon...............
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Quoting 783. catastropheadjuster:
Boy it's wicked outside right know, it's black as a ace of spades. Lightning everywhere. It's scarey.

sheri
Stay safe over there Sheri.
Member Since: June 30, 2013 Posts: 12 Comments: 8194
Quoting 775. CybrTeddy:


A very impressive ULAC. I do think 97L will develop, I'm just curious to see how strong it gets. The 12z GFS showed it splitting - convective feedback perhaps - and the northern low becoming a 1000mb storm, I imagine if the energy remains piled up it could become a moderate to strong TS. The intensity model consensus is quite a bit higher, so that tells me the conditions in the western Atlantic are favorable to support 97L as it goes out to sea assuming that's the path it takes.

not going ots but that would be nice
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it looks like a lot of dry air is around 97. correct me if im wrong. I know you want to.


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790. FOREX
Quoting 780. stormpetrol:
14.9N/63.8W, just my take.


Looks more of a westward than WNW movement. Your opinion??
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Those models are tracking a TC.....not an Invest.
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Quoting 783. catastropheadjuster:
Boy it's wicked outside right know, it's black as a ace of spades. Lightning everywhere. It's scarey.

sheri
Where are you Sheri?
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over 90 mph no way!
Member Since: March 12, 2013 Posts: 15 Comments: 28481
Quoting 781. Patrap:
Looks like it is starting to turn towards the northwest.
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Quoting 772. wunderkidcayman:

It could shift W again
bams says it wil, has said that all along..we'll see, i just do not want this going into the gulf with that storm gasoline hot water there..
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Boy it's wicked outside right know, it's black as a ace of spades. Lightning everywhere. It's scarey.

sheri
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Looks like the only way to go slow movement between 2 ULLs


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14.9N/63.8W, just my take.
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Quoting 774. TropicalAnalystwx13:

It wouldn't be an accurate hypothesis.
As they say in "Family Feud" Good answer
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Arctic Warming is Altering Weather Patterns, Study Shows



Member Since: June 30, 2013 Posts: 12 Comments: 8194
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2100 vorticity maps still show 97L stretched out like silly putty. Lower convergence is lousy too.
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Quoting 765. JLPR2:
97L took over the ULAC, so the disturbance to the east related to the other TW is getting shredded by wind-shear.



A very impressive ULAC. I do think 97L will develop, I'm just curious to see how strong it gets. The 12z GFS showed it splitting - convective feedback perhaps - and the northern low becoming a 1000mb storm, I imagine if the energy remains piled up it could become a moderate to strong TS. The intensity model consensus is quite a bit higher, so that tells me the conditions in the western Atlantic are favorable to support 97L as it goes out to sea assuming that's the path it takes.
Member Since: July 8, 2005 Posts: 259 Comments: 24016
Quoting 759. FunnelVortex:


Me and a few other bloggers speculate that if this season doesn't use up enough of the energy, then it will be left over and boost next season.

It wouldn't be an accurate hypothesis.
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773. JLPR2
Quoting 764. WoodyFL:
some models shifted back west a little






Despite that I think 97L will make its way to E-DR or try to pass though the Mona Channel.
The second spin to the east is interacting with our invest which should add a bit of northward motion as they dance around each other. At least that's what I think...

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Quoting 764. WoodyFL:
some models shifted back west a little





It could shift W again
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Quoting 762. IKE:

we are getting hammered in LA.
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Quoting 766. TXCWC:


Looking good.
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earlier they were all over Puerto rico

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Quoting 756. CybrTeddy:


Not in 19 years, and that was a deep El Nino.
This could be very well our first another record I want to broke. last year only two reach MH and only for 6 hours each.
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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.