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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Quoting 2095. daddyjames:
Interestingly enough, if I am reading this correctly, the NHC has 34 kt winds in the Northeast Quadrant. If I am not reading it correctly, let me know.

We could have a TD in the morning - if the convection picks up.

Center fix is still south at 14N

AL, 97, 2013090200, , BEST, 0, 140N, 607W, 30, 1008, LO, 34, NEQ, 0, 0, 0, 0, 1011, 200, 70, 0, 0, L, 0, , 0, 0, INVEST, M,

Nope...need persistant convection for 18-24hrs
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2104. JRRP
Member Since: August 16, 2007 Posts: 0 Comments: 6213
Quoting 2099. Camille33:
img src="">

Big storm forming from 97l soon!!!

i hope you are wrong!!
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Quoting 2092. scottsvb:
First I'm getting tired of seeing that stupid video playing every time I refresh the page,, anyone else getting that feed?



What video? Get adblock and popup blocker. I don't get any video starting when I refresh.
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2101. JRRP
Member Since: August 16, 2007 Posts: 0 Comments: 6213
Quoting 2091. Some1Has2BtheRookie:
No jokes from me tonight.

Fukushima's radioactive ocean plume due to reach US waters in 2014

Radiation spikes to lethal levels at Japan's Fukushima nuclear plant

Radioactive water seeping into Pacific from Fukushima is 'emergency,' official says

This link has a correction noted at the bottom stating these high levels are not considered to be lethal


I thought that the levels at Fukishima were lethal if exposed for 4 hours. That coming to the US is not lethal thugh, correct?
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img src="">

Big storm forming from 97l soon!!!
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2098. scott39
Quoting 2060. sar2401:
For those of you who have already forgotten Dr.Master's Blog of August 29, I suggest you read it again. Models are generally not good at genesis of storms, just some are worse than others. They tend to be really poor on track when we have a weak, shallow low, and ridiculously bad when it comes to intensity. When we have at least a TD and it's within 4 or 5 days of landfall, then it's time to pay attention to models, especially the ensemble. For intensity, the models have less that a 50/50 chance of being within one category of being right within three days before landfall. Showing models predicting a cat 4 now is like showing models from a guy who claims he can predict winning lotto numbers.
I did read this. He also said in 2011 that the best GFS, EURO, UKMET ect... predicted TC genesis 9% to 23% of the entire season. thats means 77% to 91% of the time they didnt.
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2097. ackee
97L seem to be too elongated to Develop anytime soon large system like 97L will take very long to get a tight LLC right now it just a wait and see for 97L
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97L, now that its stripped for us, shows some very impressive lines. Really shows the look of a system that's not that far off at all from forming. I know being void of any deep convection at the moment doesn't look good, but convection will fill back in later this morning into tomorrow, I think this may well be a TS by Tuesday afternoon if not sooner.
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Interestingly enough, if I am reading this correctly, the NHC has 34 kt winds in the Northeast Quadrant. If I am not reading it correctly, let me know.

We could have a TD in the morning - if the convection picks up.

Center fix is still south at 14N

AL, 97, 2013090200, , BEST, 0, 140N, 607W, 30, 1008, LO, 34, NEQ, 0, 0, 0, 0, 1011, 200, 70, 0, 0, L, 0, , 0, 0, INVEST, M,
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2094. JRRP
Quoting scott39:
Is the GFS and EURO in agreement on a more NW track for 97L?

may be yes


Member Since: August 16, 2007 Posts: 0 Comments: 6213
Quoting 2088. scott39:
Is the GFS and EURO in agreement on a more NW track for 97L?


I believe so - an elongated vorticity splitting into two. Northern portion going over Hispaniola/PR. Southern part going west, south of or into Cuba.
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First I'm getting tired of seeing that stupid video playing every time I refresh the page,, anyone else getting that feed?

Next... again, year after year I always post. Don't go with any model after 5 days. GFS is decent out to 72hrs and the Euro on days 4-5 but again, doesn't mean if will verify..

Now with 97L. The T-Storms fell apart as I mentioned it will earlier today cause they were enhanced by 2 upper lows causing rising air. If this system wants to have it's own energy, it will need the drier air in the midlevels to fade out. Unfortunatly, the odds are 30% it will. Still though I see the midlevel moisture streaming N of Puerto Rico in 2-3 days. GFS is correct out to 3 days(60%) that midlevel moisture and a trough of LP will develop and move WNW towards the eastern Bahamas by day 5. Current 97L LLC-Vortex will move through the central carribean. Hard to tell if it will survive or not in the dry air that will follow it in the midlevels. After day 5.,, Depends on how strong the ridge is to the north of the Bahamas and how much developed the system east of the Bahamas is will determine the next few days movement.
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Center trying to form around 59 x 15;
That seems to be in agreement with the latest models run taking the "thing" north of PR.

The TW coming behind 97 maybe add some needed fuel or this "thing" may die all together.

I need surf on the Florida east coast !

Link

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2089. sar2401
Quoting Civicane49:

What a tremendous waste of time. Not you Civicane, but producing tracks and intensity when we don't even have a Best track, the GFS, or even an NHC official. Then we have one model going absolutely crazy with intensity. Total waste of money and resources they claim they don't have.
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2088. scott39
Is the GFS and EURO in agreement on a more NW track for 97L?
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2087. scott39
Quoting 2084. JRRP:
That seems unreal in 60 hours from now.Wind shear would be favorable for a NW track.
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2085. scott39
Quoting 2080. sar2401:

It's very interesting on satellite. The appearance of 97L has not improved, but the amount of thunderstorm activity in the wave has increased markedly. It looks like the wave is actually cannibalizing 97L
maybe, Or vice versa. I would think 97L would win that tug of war. You never know in the tropics. Thats why I find it so interesting. Wind shear looks to be rough for 97L if it stays south of 16N in the Eastern Caribbean.
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2084. JRRP
Member Since: August 16, 2007 Posts: 0 Comments: 6213
Quoting 2078. daddyjames:


Hey TS - correct west to east in my quote, so I don't look so dumb ;D



ya I think you was right on...I just enforcing your thoughts...:)
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nice tropical wave here
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TROPICAL WEATHER OUTLOOK
NWS NATIONAL HURRICANE CENTER MIAMI FL
200 AM EDT MON SEP 2 2013

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

1. CLOUDINESS AND SHOWERS REMAIN DISORGANIZED IN ASSOCIATION WITH AN
ELONGATED AREA OF LOW PRESSURE EXTENDING FROM THE EASTERN CARIBBEAN
ACROSS THE LESSER ANTILLES AND INTO THE TROPICAL ATLANTIC. ALTHOUGH
UPPER-LEVEL WINDS APPEAR TO BE CONDUCIVE...THE PROXIMITY TO DRY AIR
IN THE MIDDLE LEVELS OF THE ATMOSPHERE COULD INHIBIT DEVELOPMENT OF
THIS DISTURBANCE. THIS SYSTEM HAS A MEDIUM CHANCE...40 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...LOCALLY
HEAVY RAINFALL AND STRONG GUSTY WINDS ARE EXPECTED TO AFFECT
PORTIONS OF THE LESSER ANTILLES OVER THE NEXT DAY OR SO.

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2080. sar2401
Quoting scott39:
It looks like that wave behind 97L is going to feed it some convection :)

It's very interesting on satellite. The appearance of 97L has not improved, but the amount of thunderstorm activity in the wave has increased markedly. It looks like the wave is actually cannibalizing 97L
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2079. scott39
It looks like that wave behind 97L is going to feed it some convection :)
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Quoting 2073. TampaSpin:


More likely the Vorticity return possibly!



Hey TS - correct west to east in my quote, so I don't look so dumb ;D
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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 OVER 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.
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Good night everyone.

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Member Since: July 9, 2006 Posts: 184 Comments: 29610
Quoting 2071. GTstormChaserCaleb:
CLOUDINESS AND SHOWERS REMAIN DISORGANIZED IN ASSOCIATION WITH AN
ELONGATED AREA OF LOW PRESSURE EXTENDING FROM THE EASTERN CARIBBEAN
ACROSS THE LESSER ANTILLES AND INTO THE TROPICAL ATLANTIC.

I believe they are acknowledging that TW aproaching 97L.

Umm no they are just including that extra convection that's off on its E side which the whole of 97L is elongated with it extending from the lesser Antilles into the tropical Atlantic that tropical wave E of 97L is its own entity
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Quoting 2072. daddyjames:


Everything to the west and north of the Antilles is considered the Tropical Atlantic.


More likely the Vorticity return possibly!

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Quoting 2071. GTstormChaserCaleb:
CLOUDINESS AND SHOWERS REMAIN DISORGANIZED IN ASSOCIATION WITH AN
ELONGATED AREA OF LOW PRESSURE EXTENDING FROM THE EASTERN CARIBBEAN
ACROSS THE LESSER ANTILLES AND INTO THE TROPICAL ATLANTIC.

I believe they are acknowledging that TW aproaching 97L.


Everything to the east and north of the Antilles is considered the Tropical Atlantic.

corrected
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CLOUDINESS AND SHOWERS REMAIN DISORGANIZED IN ASSOCIATION WITH AN
ELONGATED AREA OF LOW PRESSURE EXTENDING FROM THE EASTERN CARIBBEAN
ACROSS THE LESSER ANTILLES AND INTO THE TROPICAL ATLANTIC.

I believe they are acknowledging that TW aproaching 97L.
Member Since: June 30, 2013 Posts: 12 Comments: 8774
No change which is the right thing to do

000
ABNT20 KNHC 020538
TWOAT

TROPICAL WEATHER OUTLOOK
NWS NATIONAL HURRICANE CENTER MIAMI FL
200 AM EDT MON SEP 2 2013

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

CLOUDINESS AND SHOWERS REMAIN DISORGANIZED IN ASSOCIATION WITH AN
ELONGATED AREA OF LOW PRESSURE EXTENDING FROM THE EASTERN CARIBBEAN
ACROSS THE LESSER ANTILLES AND INTO THE TROPICAL ATLANTIC. ALTHOUGH
UPPER-LEVEL WINDS APPEAR TO BE CONDUCIVE...THE PROXIMITY TO DRY AIR
IN THE MIDDLE LEVELS OF THE ATMOSPHERE COULD INHIBIT DEVELOPMENT OF
THIS DISTURBANCE. THIS SYSTEM HAS A MEDIUM CHANCE...40 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...LOCALLY
HEAVY RAINFALL AND STRONG GUSTY WINDS ARE EXPECTED TO AFFECT
PORTIONS OF THE LESSER ANTILLES OVER THE NEXT DAY OR SO
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Quoting 2061. scott39:
Looks like we have a "little" thunderstorm action popping around the broad center of 97L.

Yep as D-max starts to fade in that will continue to build

Also I seem to have found a LLCOC I'm tracking it however I am waiting for a few more satellite images to come then I will publish my finding with graphics on this blog
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2068. scott39
If dry air in the mid levels sticks around....its going to be a long few days for 97L.
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1. CLOUDINESS AND SHOWERS REMAIN DISORGANIZED IN ASSOCIATION WITH AN
ELONGATED AREA OF LOW PRESSURE EXTENDING FROM THE EASTERN CARIBBEAN
ACROSS THE LESSER ANTILLES AND INTO THE TROPICAL ATLANTIC. ALTHOUGH
UPPER-LEVEL WINDS APPEAR TO BE CONDUCIVE...THE PROXIMITY TO DRY AIR
IN THE MIDDLE LEVELS OF THE ATMOSPHERE COULD INHIBIT DEVELOPMENT OF
THIS DISTURBANCE. THIS SYSTEM HAS A MEDIUM CHANCE...40 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...LOCALLY
HEAVY RAINFALL AND STRONG GUSTY WINDS ARE EXPECTED TO AFFECT
PORTIONS OF THE LESSER ANTILLES OVER THE NEXT DAY OR SO.
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the CMC has a big recurve but now sorta the same look the GFS just showed. The CMC speeds it up while the GFS has it moving very slow...GFS just might be more accurate! MAYBE

here is 144hrs out

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Quoting 2057. Astrometeor:


Well, if I had to choose a storm to represent this season, I would have to go with T.S. Jose. No idea where this season has gone.


Yeah, I chose Ophelia for the reasons on my latest blog and also cause I think that the most impressive storm we will get this year will be like Ophelia.
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...And I thought I had seen EVERYTHING on the GFS week 2.......prints a TS trapped under a ridge in the Bahamas for days and days and.......

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2063. scott39
Quoting 2059. TampaSpin:



LOL...I knew someone would say something...I was ready tho....HEHEHEHE
97L is what made me Lol.
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Quoting 2039. GTstormChaserCaleb:
I'm just really frustrated with the models right now, even in the short range which shows development and a strengthening system one run only for the next run to kill it off completely. It really does come down to nowcasting now and a good look at the surface charts, and cimss products, along with the actual satellite imagery.


Bravo, GT, you've become the wiser.
Member Since: July 9, 2006 Posts: 184 Comments: 29610
2061. scott39
Looks like we have a "little" thunderstorm action popping around the broad center of 97L.
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2060. sar2401
For those of you who have already forgotten Dr.Master's Blog of August 29, I suggest you read it again. Models are generally not good at genesis of storms, just some are worse than others. They tend to be really poor on track when we have a weak, shallow low, and ridiculously bad when it comes to intensity. When we have at least a TD and it's within 4 or 5 days of landfall, then it's time to pay attention to models, especially the ensemble. For intensity, the models have less that a 50/50 chance of being within one category of being right within three days before landfall. Showing models predicting a cat 4 now is like showing models from a guy who claims he can predict winning lotto numbers.
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Quoting 2056. moonlightcowboy:


TS, come on, man! 384 hours out?



LOL...I knew someone would say something...I was ready tho....HEHEHEHE
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That's my point and I'm not saying anymore. Later folks.
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Quoting 2037. opal92nwf:
Hurricane Ophelia is my poster-child for the 2013 Atlantic Hurricane Season, what's yours?

What a beauty


Well, if I had to choose a storm to represent this season, I would have to go with T.S. Jose. No idea where this season has gone.

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Quoting 2047. TampaSpin:
I hate to even post this GFS current run at 384hrs out...but it shows a Carolina system from 97L




TS, come on, man! 384 hours out?
Member Since: July 9, 2006 Posts: 184 Comments: 29610
Quoting 2039. GTstormChaserCaleb:
I do remember you stating that earlier in the season and currently that is what is going on as we have this persistent trough off the East Coast. By the way I wasn't jumping on Scottsvb I'm just really frustrated with the models right now, even in the short range which shows development and a strengthening system one run only for the next run to kill it off completely. It really does come down to nowcasting now and a good look at the surface charts, and cimss products, along with the actual satellite imagery.


bro, I never look at just one run on any model....I only look at a persistent run of all the models. I look at the consensus of them all to even try to determine anything. Seems the NHC does much the same although, they do have their favorite models more than others I do believe.
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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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