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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1705. ncstorm
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1704. ncstorm
Quoting 1687. Levi32:
Good evening.

Blog update:

Late Sunday video discussion on Invest 97L


Hey Levi,

Great video as usual but in your video you said none of the models were picking up on 97L, actually the CMC did pick up 97L and also first at depicting the same scenario as the Euro and GFS with two energies splitting..

I know the CMC is not admired on here but you have to say thats pretty good for that model sniffing out 97L first before the "reliable" models..no? or will I get the clock quote :)
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1703. Patrap
Member Since: July 3, 2005 Posts: 421 Comments: 127569
1702. Patrap

Member Since: July 3, 2005 Posts: 421 Comments: 127569
Oh wow the two things I said would make it struggle just happen to be in the TWO... Dry air and elongated vort. This system still has a while to go.
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Quoting 1694. GTstormChaserCaleb:
Gordon and Grace?

Oh, ok then, 3.
Member Since: June 2, 2013 Posts: 8 Comments: 1097
Levi, I understand it's quite a long ways out and it's very difficult to predict these things (from experience I know), but I'm curious to hear your thoughts on a "worst case scenario" if 97L manages to get named in the western Caribbean.
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97l is dead the low level wave axis is ahead of the mid level convection.
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1697. HadesGodWyvern (Mod)
Gordon and Grace?


looks like it

Grace 1991
Gordon 1994
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Quoting 1621. beell:
Maybe some evidence of mid-level dry air between 500-600 mb on the RGB. Could just be a coincidence or a short-term oddity. Some dry-ish mid-level westerlies on the evening sounding from Barbados



Ok, sounds right, but what's your take, Beell, on what's happening overall, and what's your thinking of what, if anything, 97L will do? By now, considering the position, lack of inhibiting shear especially at the mid-levels, I thought we'd have a system coming together, but seems to be far from it. And, I'm starting to have my doubt, but confounded somewhat as to why. What's the skinny here, bud? ;)
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NHC track brought it into the E Carib...
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Quoting 1686. TylerStanfield:

No, there's 2 veteran G storms left.
Gordon and Grace?
Member Since: June 30, 2013 Posts: 11 Comments: 7473
Wouldn't surprise me if we have 98L real soon. Perhaps Monday or Tuesday.
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1692. JLPR2
Quoting 1683. Tropicsweatherpr:


Yeah,that image always is like doom.


In there it looks like a tropical storm already. That IR makes everything look nice. XD
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Thanks for the update Levi
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Quoting 1672. wunderkidcayman:


Now out of those put up the ones that was Caribbean hurricanes
4 of the 6 on that list were Caribbean storms. Gloria and Greta were East Coast US storms. By the way Gabrielle has been on the Atlantic Hurricane Season list since 1989. Fast forward to 24 years. Could this be the year?
Member Since: June 30, 2013 Posts: 11 Comments: 7473
Quoting 1685. RGVtropicalWx13:
Reread my post Cayman "Mexico or not" don't you get it!! Might have affects for my location.

Ok yes fine whatever you win
Member Since: June 13, 2009 Posts: 2 Comments: 11049
Quoting 1677. stormpetrol:

What I think as the convection dies down so would that mid level spin and it would redevelop closer to where the low level vort is which is just about where BEST track data has it as convection redevelops later tonight
Member Since: June 13, 2009 Posts: 2 Comments: 11049
1687. Levi32
Good evening.

Blog update:

Late Sunday video discussion on Invest 97L
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Quoting 1679. allancalderini:
That means Gabrielle is the last veteran *G* storm?

No, there's 2 veteran G storms left.
Member Since: June 2, 2013 Posts: 8 Comments: 1097
Reread my post Cayman "Mexico or not" don't you get it!! Might have affects for my location.
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Quoting 1680. prcane4you:
This is enough for today.This blog is a theraphy.I really enjoy so many funny people around.Good Evening all and keep waiting D-MAX.


G NIGHT :)
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Quoting 1673. JLPR2:
Time to post the satellite image of doom:



Yeah,that image always is like doom.
Member Since: April 29, 2009 Posts: 75 Comments: 14019
Quoting 1658. Relix:


I apparently have my bearings messed up but... there's not a lot of shear looking at that. My bad :P! I thought the overall raged and "cut" look (to the north) meant there was shear from the north but alas its not much. My bad!

Diurnal Minimum is in Full-swing right now so It will look ragged for a bit, and the "Fanning look" (Cut-look) is actually the outflow of the storm, which is a healthy sign for the invest.
It's no big deal, but this is a valuable site to look at for Atmospheric conditions.
Member Since: June 2, 2013 Posts: 8 Comments: 1097
HURRICANE IRIS 1995.... was supposed to enter the E Caribbean....



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This is enough for today.This blog is a theraphy.I really enjoy so many funny people around.Good Evening all and keep waiting D-MAX.
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Quoting 1666. GTstormChaserCaleb:
Gabrielle is the next name on the list. List of "G" names to be retired: Gustav (2008), (Georges 1998), (Gilbert (1988), Gloria (1985), Greta (1978), and Gracie (1959).











That means Gabrielle is the last veteran *G* storm?
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Quoting 1669. RGVtropicalWx13:

Mexico or not we still have to watch it. Might be a bit north where Fernand went.


A bit N of where Fernand went is still Mexico
Member Since: June 13, 2009 Posts: 2 Comments: 11049
Member Since: April 29, 2007 Posts: 0 Comments: 7669
Quoting 1665. wunderkidcayman:

No not at all


Its obvious. The system is not going to develop.
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Number of recorded storms affecting Florida


Month

Number of storms


January


0

February


1

March


0

April


1

May


9

June


51

July


35

August


97

September


160

October


117

November


17

December


2
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This is why no one is saying this storm is going to dies out...

Member Since: August 1, 2011 Posts: 28 Comments: 7903
1673. JLPR2
Time to post the satellite image of doom:

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Quoting 1666. GTstormChaserCaleb:
Gabrielle is the next name on the list. List of "G" names to be retired: Gustav (2008), (Georges 1998), (Gilbert (1988), Gloria (1985), Greta (1978), and Gracie (1959).













Now out of those put up the ones that was Caribbean hurricanes
Member Since: June 13, 2009 Posts: 2 Comments: 11049
Quoting 1625. prcane4you:
Why? 97L likes the french islands nearby? Maybe is on vacation. What is you reasoning for that?


My reasoning well... intuition + experience XD

But seriously several tracks have been influenced by the bigger islands (i.e Martinique, Dominica, and Guadeloupe) in the past. This has been the case for IRIS (95), Marilyn (95), and Jose (99)... models kept showing a stupid W track into the E Carib, while either the center stalled east of the islands or slowly moved NW/NNW across most of the islands. NHC's tracks were big fails for all of these storms!

...and 97L might just do the same LOL.
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Quoting 1650. Skyepony:
Average model error for 97L recap.. ave error (nm or kts) 0hr & 24hr..

Forecast track top performers..
GFDL 22.2 13.1
AEMN 28.1 21.2
CMC 24.7 34.8

Intensity Top Performers..
DSHP 0 1.7
SHIP 0 1.7
IVCN 0 2.0
LGEM 0 1.7

Hey Skye :)
Member Since: June 2, 2013 Posts: 8 Comments: 1097
Quoting 1659. victoria780:

OTHER SYSTEMS WITH FORMATION POTENTIAL BEYOND 48 HOURS...

A TROPICAL WAVE OVER THE NORTHWESTERN CARIBBEAN SEA IS FORECAST TO
MOVE ACROSS THE YUCATAN PENINSULA AND INTO THE BAY OF CAMPECHE IN A
COUPLE OF DAYS WHERE ENVIRONMENTAL CONDITIONS ARE EXPECTED TO
BECOME MARGINALLY FAVORABLE FOR DEVELOPMENT. 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...AS IT MOVES
WEST-NORTHWESTWARD AT 10 MPH.

Mexico or not we still have to watch it. Might be a bit north where Fernand went.
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1668. JLPR2
Quoting 1658. Relix:


I apparently have my bearings messed up but... there's not a lot of shear looking at that. My bad :P! I thought the overall raged and "cut" look (to the north) meant there was shear from the north but alas its not much. My bad!


Yep, just the effect of a strong ULAC, the great divergence with 97L evidences this.

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1667. Skyepony (Mod)
On 97L HWRF has overshot it's average 24hr forecast by 6kts, GFDL by 7kts.
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Gabrielle is the next name on the list. List of "G" names to be retired: Gustav (2008), (Georges 1998), (Gilbert (1988), Gloria (1985), Greta (1978), and Gracie (1959).











Member Since: June 30, 2013 Posts: 11 Comments: 7473
Quoting 1657. interpreter:

Its worse than you think!

No not at all

Member Since: June 13, 2009 Posts: 2 Comments: 11049
1664. HadesGodWyvern (Mod)
Japan Meteorological Agency
Tropical Cyclone Advisory #9
Gale Warning
TROPICAL STORM YUTU (T1316)
9:00 AM JST September 2 2013
==============================

Midway Island Waters

At 0:00 AM UTC, Tropical Storm Yutu (1004 hPa) located at 33.7N 177.0E has 10 minute sustained winds of 35 knots with gusts of 50 knots. The cyclone is reported as almost stationary.

Gale Force Winds
=================
180 NM from the center in southeast quadrant
120 NM from the center in northwest quadrant

Dvorak Intensity: T2.5

Forecast and Intensity
========================
24 HRS: 34.3N 179.1E - 35 knots (CAT 1/Tropical Storm) Midway Island Waters
48 HRS: 35.4N 176.0W - 35 knots (CAT 1/Tropical Storm) South Of Aleutian Island
72 HRS: 35.7N 171.1W - Extratropical Low South Of Aleutian Island

Japan Meteorological Agency
Tropical Cyclone Advisory #11
Gale Warning
TROPICAL STORM TORAJI (T1317)
9:00 AM JST September 2 2013
==============================

Near Okinawa Island

At 0:00 AM UTC, Tropical Storm Toraji (1000 hPa) located at 26.6N 125.5E has 10 minute sustained winds of 35 knots with gusts of 50 knots. The cyclone is reported as moving east northeast at 6 knots.

Gale Force Winds
===============
90 NM from the center

Dvorak Intensity: T2.5

Forecast and Intensity
========================
24 HRS: 28.2N 126.8E - 40 knots (CAT 1/Tropical Storm) Amami Islands
48 HRS: 29.1N 127.5E - 45 knots (CAT 1/Tropical Storm) East China Sea
72 HRS: 29.7N 127.7E - 45 knots (CAT 1/Tropical Storm) East China Sea
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Quoting 1659. victoria780:

OTHER SYSTEMS WITH FORMATION POTENTIAL BEYOND 48 HOURS...

A TROPICAL WAVE OVER THE NORTHWESTERN CARIBBEAN SEA IS FORECAST TO
MOVE ACROSS THE YUCATAN PENINSULA AND INTO THE BAY OF CAMPECHE IN A
COUPLE OF DAYS WHERE ENVIRONMENTAL CONDITIONS ARE EXPECTED TO
BECOME MARGINALLY FAVORABLE FOR DEVELOPMENT. 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...AS IT MOVES
WEST-NORTHWESTWARD AT 10 MPH.




what was your point in reposting that isn't that what I this said that it would be heading for MX most likey
Member Since: May 21, 2006 Posts: 5091 Comments: 114731
Quoting 1631. SouthCentralTx:
Could Lake O handle a hurricane if these models were become true?
NO we would have a severe Breach in the levee especially with the west season we have been having
Member Since: July 14, 2009 Posts: 0 Comments: 2990
1661. ackee
My preDiction for this season is 13 name storm with 3 cane and 2 major I think if 97L takes a more western track I think it could bed our first cane in the western Caribbean
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Quoting 1651. RGVtropicalWx13:
Btw did we not forget about the nw Caribbean wave that's expected to move across the Yucatan and into the Boc? It does have a 20% chance after 48 hrs. If you don't keep an eye on it then I'll surprise a lot of all.

Not a anything to look at or be concerned about for a good couple of days and we got more important thing to look at
Member Since: June 13, 2009 Posts: 2 Comments: 11049
Quoting 1653. Tazmanian:



its heading for mx

OTHER SYSTEMS WITH FORMATION POTENTIAL BEYOND 48 HOURS...

A TROPICAL WAVE OVER THE NORTHWESTERN CARIBBEAN SEA IS FORECAST TO
MOVE ACROSS THE YUCATAN PENINSULA AND INTO THE BAY OF CAMPECHE IN A
COUPLE OF DAYS WHERE ENVIRONMENTAL CONDITIONS ARE EXPECTED TO
BECOME MARGINALLY FAVORABLE FOR DEVELOPMENT. 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...AS IT MOVES
WEST-NORTHWESTWARD AT 10 MPH.
Member Since: July 20, 2008 Posts: 0 Comments: 326
1658. Relix
Quoting 1638. TylerStanfield:

Explain?


I don't see much shear, and if there is, it's definitely not from the North.


I apparently have my bearings messed up but... there's not a lot of shear looking at that. My bad :P! I thought the overall raged and "cut" look (to the north) meant there was shear from the north but alas its not much. My bad!
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Quoting 1646. wunderkidcayman:

Oh yeah 97L is getting pounded by very light shear oh I wonder how its to survive the very light shear lol good joke Relix

Its worse than you think!
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Quoting 1620. Stormchaser121:
I pretty much have a good idea what AL97 is gonna do but im not gonna say what it is yet.
Here we go again.Poof due to dry air and shear.Others says is D-Min.This season is really........
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Quoting 1622. wunderkidcayman:

Well it's been a while that Florida had anything catastrophic so it could be a good thing not that anything catastrophic is good but it's a good way to see if the state of Florida is prepared for a strong hurricane it's been a wile and I bet some people have become laid back
the issue is we have had a very very wet season here and we are having major issues with lake Okeechobee's levee which can breech with any tropical system at this point , they have been lowering the lake thus far and that has been causing catastrophic algae blooms on both coasts.
Member Since: July 14, 2009 Posts: 0 Comments: 2990

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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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