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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867. BahaHurican
3:26 AM GMT on September 04, 2013
Interestingly enough, after yesterday's gully-washers, we've so far had a clear and mostly sunny day.
Member Since: October 25, 2005 Posts: 19 Comments: 22143
866. prweatherwatcher
11:00 PM GMT on September 03, 2013
A suspicious windy afternoon here in PR. It looks like a storm is coming our way...
Member Since: July 29, 2011 Posts: 0 Comments: 90
865. ncstorm
10:37 PM GMT on September 03, 2013
Quoting 858. Chucktown:


There is no ridging. There is a deep trough that will be digging across the east coast of the US, but it's the weakness that is created ahead of the trough that will steer 97L NW, N, then eventually NE. Notice where the axis of the trough is by this Sunday. I also think the ULL just west of 97L is playing a small part of ejecting a NW "bump" into it. If the trough is delayed or 97L somehow picks up speed, then it may venture a little further west before turning. However, with all this said, I think the NAM does seem a little quick in the turn.

Link


Chuck, according to the WPC (if I am reading it correctly), some of the models have back off on the deepening of the trough, especially the Euro..

THE CRITICAL DIVERGENCE IS WITH
REGARD TO THE SECOND BATCH OF CONTINENTAL POLAR AIR SLATED TO
CROSS SOUTHEASTERN CANADA DAYS 5 THROUGH 7. THE 00Z/03 EC GUIDANCE
IS MUCH LESS AMPLIFIED WITH THIS WAVE THAN THE RECENT GFS RUNS,
GEFS MEANS, AND CMCE MEANS. FURTHERMORE, THE 00Z/03 ECMWF BROKE
CONTINUITY WITH ITS PREVIOUS RUNS IN THIS REGARD, AND THE LAST
FOUR ECENS MEANS HAVE BEEN UNUSUALLY UNSTABLE. SUCH INSTABILITY IN
RELIABLE GUIDANCE SUCH AS THE ECENS MEAN LIKELY SIGNALS A
DECEPTIVELY COMPLEX FLOW COMING DOWN THE PIPE
Member Since: August 19, 2006 Posts: 13 Comments: 15317
864. HuracanTaino
10:35 PM GMT on September 03, 2013
Quoting Patrap:
It Is heading WNW towards the Mona canal very close to the SW corner of Puerto Rico....
Quoting Tropicsweatherpr:


I think is too far south at this point that it will be difficult for the low to cross PR. But plenty of rain will come anyway.
Member Since: May 31, 2011 Posts: 0 Comments: 877
863. HuracanTaino
10:27 PM GMT on September 03, 2013
Quoting JrWeathermanFL:
We've talked about 97L cause it's the most threatening thing so far, but what about the yellow circle over the Yucatan?
That one would probably intensify fast,a short life though , probably to an strong TS, before it hit Tampico, after a day or so on the waters of Campeche...
Member Since: May 31, 2011 Posts: 0 Comments: 877
862. RascalNag
10:27 PM GMT on September 03, 2013
Quoting 858. Chucktown:


There is no ridging. There is a deep trough that will be digging across the east coast of the US, but it's the weakness that is created ahead of the trough that will steer 97L NW, N, then eventually NE. Notice where the axis of the trough is by this Sunday. I also think the ULL just west of 97L is playing a small part of ejecting a NW "bump" into it. If the trough is delayed or 97L somehow picks up speed, then it may venture a little further west before turning. However, with all this said, I think the NAM does seem a little quick in the turn.

Link


The main thing that puzzles me is that it starts moving NW before the trough gets to it, as if the other low (which is being steered northwest) drags it along. Steering winds though would seem to indicate that before the trough gets there it would move WSW, not WNW.
Member Since: October 24, 2012 Posts: 0 Comments: 207
860. wunderkidcayman
10:22 PM GMT on September 03, 2013
Quoting 853. GTstormChaserCaleb:
You're wishcasting wunderkid.

No wishcasting just laying down the facts that it

Member Since: June 13, 2009 Posts: 2 Comments: 12038
859. RascalNag
10:22 PM GMT on September 03, 2013
Hmm...

Is it possible that the proximity of the two lows, 97L and the one to its NE, is making some models treat it like one system? Because for right now, I definitely can see the area to the East of the LEsser Antilles going out to sea, but the same can't be said for 97L. The GFS at least seems to have them dance around as two vorts in one system for a while. That's the only thing I can come up with for right now to explain why the models are taking it so drastically NW when steering and ridging suggests the opposite - the system to the NE drags it along with it. I'm highly skeptical of this to say the least, since one of them is only an invest atm (maybe a depression, definitely close to one) and the other looks a bit weaker. I'm not sure if they could pull off the perhaps fujiwhara sort of interaction that would allow the north eastern system to drag 97L away to the north.

Member Since: October 24, 2012 Posts: 0 Comments: 207
858. Chucktown
10:21 PM GMT on September 03, 2013
Quoting 844. RascalNag:
Really don't see anything to move 97L to the NW like the models keep claiming... Steering and ridging wouldn't support that at all.


There is no ridging. There is a deep trough that will be digging across the east coast of the US, but it's the weakness that is created ahead of the trough that will steer 97L NW, N, then eventually NE. Notice where the axis of the trough is by this Sunday. I also think the ULL just west of 97L is playing a small part of ejecting a NW "bump" into it. If the trough is delayed or 97L somehow picks up speed, then it may venture a little further west before turning. However, with all this said, I think the NAM does seem a little quick in the turn.

Link
Member Since: August 27, 2006 Posts: 0 Comments: 1765
857. blewmyfuse
10:20 PM GMT on September 03, 2013
Good evening,

Looks like 97l is going to make a run at a name in the next day or so. My uneducated for cast is west of the forcast points, as a tropical storm hitting southern florida. Unless it can stay way west of the forcasts, there is just to much in the way for it really get going. Where it would most likely not strengthen into a Cat 1 until its headed out to sea. Trade winds are still holding her back right now, but we should see a great cyclonic feature look tomorrow evening and they relax. My 2 cents
Member Since: July 31, 2011 Posts: 0 Comments: 9
856. Sfloridacat5
10:19 PM GMT on September 03, 2013
GFS at 141 hours. 97L stretched out to the northeast. Only hope for 97L is if it can stay far enough south to miss being picked up by the trough.
Member Since: September 16, 2007 Posts: 0 Comments: 6916
855. washingtonian115
10:18 PM GMT on September 03, 2013
I've been in lurk mode most of the day.Not gonna waste time taking about a disabled invest and models again forecasting doom here and there.Well see ya.
Member Since: August 14, 2010 Posts: 10 Comments: 16981
854. TXCWC
10:16 PM GMT on September 03, 2013
Tough to tell where the actual low would be based solely on ASCAT pass couple hours ago. Has a way to go before reaching any type of storm status.

Member Since: May 18, 2012 Posts: 0 Comments: 521
853. GTstormChaserCaleb
10:15 PM GMT on September 03, 2013
Quoting 846. wunderkidcayman:


You got that right
Before it showed more W movement now it's gone back to W-WSW

You're wishcasting wunderkid.
Member Since: June 30, 2013 Posts: 12 Comments: 8323
852. Patrap
10:15 PM GMT on September 03, 2013
Member Since: July 3, 2005 Posts: 424 Comments: 128348
851. watchingnva
10:15 PM GMT on September 03, 2013
Quoting 835. hurricanes2018:
that right and going out to the sea with the fish


quoted, so tonight if the models shift west and you start warning the east coast, I can sit back and laugh...lol
Member Since: September 7, 2005 Posts: 7 Comments: 1516
850. Relix
10:15 PM GMT on September 03, 2013
Its not moving WSW... come on. Guys. Come on. Be real. Its not moving WSW at all.
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849. GTstormChaserCaleb
10:15 PM GMT on September 03, 2013
Captain trough has returned to the East Coast.

Member Since: June 30, 2013 Posts: 12 Comments: 8323
848. WunderAlertBot (Admin)
10:14 PM GMT on September 03, 2013
JeffMasters has created a new entry.
847. Sfloridacat5
10:14 PM GMT on September 03, 2013
High pressure building into the East coast is what turns 97L abruptly to the north. There's also another front that builds in right behind the one currently pushing offshore.
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846. wunderkidcayman
10:13 PM GMT on September 03, 2013
Quoting 844. RascalNag:
Really don't see anything to move 97L to the NW like the models keep claiming... Steering and ridging wouldn't support that at all.


You got that right
Before it showed more W movement now it's gone back to W-WSW

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845. Patrap
10:12 PM GMT on September 03, 2013
Member Since: July 3, 2005 Posts: 424 Comments: 128348
844. RascalNag
10:10 PM GMT on September 03, 2013
Really don't see anything to move 97L to the NW like the models keep claiming... Steering and ridging wouldn't support that at all.
Member Since: October 24, 2012 Posts: 0 Comments: 207
843. allancalderini
10:10 PM GMT on September 03, 2013
Quoting 840. hurricanes2018:
no threatening for the east coast
Mexico is land where people live not just the east coast you know.
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842. SLU
10:09 PM GMT on September 03, 2013
Don't count out 98L. The ridge is strengthening to its north too.

Member Since: July 13, 2006 Posts: 13 Comments: 5164
841. wunderkidcayman
10:09 PM GMT on September 03, 2013
Quoting 830. WoodyFL:


I think you may be right. After it turns completely north it could move more to the west.

Lol no
Member Since: June 13, 2009 Posts: 2 Comments: 12038
840. hurricanes2018
10:08 PM GMT on September 03, 2013
Quoting 804. JrWeathermanFL:
We've talked about 97L cause it's the most threatening thing so far, but what about the yellow circle over the Yucatan?
no threatening for the east coast
Member Since: March 12, 2013 Posts: 18 Comments: 35583
839. GTstormChaserCaleb
10:08 PM GMT on September 03, 2013
Quoting 833. RufusBaker:


And its going out to sea toooo....
LOL point proven in post 798. Want to predict anything else going OTS while you're at it? ;)
Member Since: June 30, 2013 Posts: 12 Comments: 8323
838. Tazmanian
10:07 PM GMT on September 03, 2013
Quoting 829. GTstormChaserCaleb:
98L is that you on the GFS?




no am hiding I got a dress on so am hiding fro you



that's what 98L said to you
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837. Patrap
10:07 PM GMT on September 03, 2013
NASA Global Hawk still on station with 97L
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836. PalmBeachWeather
10:07 PM GMT on September 03, 2013
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.
That was terrible Largo...They took shelter under a tractor trailer...
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835. hurricanes2018
10:06 PM GMT on September 03, 2013
Quoting 820. hurricanewatcher61:
I guess this thing would have to take a hard right turn soon to stay with models, correct?
that right and going out to the sea with the fish
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834. GTstormChaserCaleb
10:06 PM GMT on September 03, 2013
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833. RufusBaker
10:05 PM GMT on September 03, 2013
Quoting 829. GTstormChaserCaleb:
98L is that you on the GFS?



And its going out to sea toooo....
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832. watchingnva
10:05 PM GMT on September 03, 2013


pretty.
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831. hurricanes2018
10:05 PM GMT on September 03, 2013
INVEST 97L going to to sea the east east will be safe this year.. nice fall weather for the northeast this week
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830. WoodyFL
10:05 PM GMT on September 03, 2013
Quoting 772. wunderkidcayman:

It could shift W again


I think you may be right. After it turns completely north it could move more to the west.
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829. GTstormChaserCaleb
10:04 PM GMT on September 03, 2013
98L is that you on the GFS?

Member Since: June 30, 2013 Posts: 12 Comments: 8323
828. rmbjoe1954
10:03 PM GMT on September 03, 2013
Quoting 805. scott39:
97L is moving forward.


"forward"? What direction is that?
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827. hurricanes2018
10:03 PM GMT on September 03, 2013
I was right about invest 97L GOING OUT TO SEA. I SAID IT WAS GOING OUT TO SEA A FEW DAYS AGO.
Member Since: March 12, 2013 Posts: 18 Comments: 35583
826. LargoFl
10:03 PM GMT on September 03, 2013
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825. unknowncomic
10:02 PM GMT on September 03, 2013
Could be two systems pouch 30L and pouch 25L.
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824. hurricanes2018
10:02 PM GMT on September 03, 2013
Quoting 823. RufusBaker:
97l= another complete US miss and fall apart
ITS GOING OUT TO SEA.
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823. RufusBaker
10:01 PM GMT on September 03, 2013
97l= another complete US miss and fall apart
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822. wunderkidcayman
10:01 PM GMT on September 03, 2013
Quoting 820. hurricanewatcher61:
I guess this thing would have to take a hard right turn soon to stay with models, correct?

Yeah pretty much
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821. LargoFl
10:00 PM GMT on September 03, 2013
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820. hurricanewatcher61
9:59 PM GMT on September 03, 2013
I guess this thing would have to take a hard right turn soon to stay with models, correct?
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819. Sfloridacat5
9:59 PM GMT on September 03, 2013
GFS at 90 hours puts 97L just north of Haiti.
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818. watchingnva
9:58 PM GMT on September 03, 2013
btw, good afternoon everyone...i see 97l is still looking pretty rough...

and i had a question...if there isn't dry air affecting the system, why does it look like there are outflow boundary's EVERYWHERE! ...lol
Member Since: September 7, 2005 Posts: 7 Comments: 1516
817. LargoFl
9:58 PM GMT on September 03, 2013
GEEZ if these storms hold together the west coast of florida is in for 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.