Western Caribbean disturbance 96L growing more organized

By: Dr. Jeff Masters , 5:14 PM GMT on October 21, 2011

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A region of disturbed weather in the Western Caribbean (Invest 96L) is bringing heavy rains to coastal Nicaragua, and has the potential to develop into a tropical depression this weekend. Visible satellite loops show that 96L is beginning to show signs of organization. Some rotation is apparent, and the upper-level cirrus clouds streaming away from the center indicate that 96L is establishing an upper-level outflow channel to the east. The heavy thunderstorm activity is quite limited at present, because a large region of dry air to the east of 96L is interfering with development, as seen on water vapor satellite loops. An ASCAT pass at 11:05 am EDT showed no signs of a surface circulation, with surface winds in the 25 - 30 mph range. Surface pressures are slowly falling at San Andres Island, near the center of 96L. Wind shear is a moderate 10 - 20 knots in the region, and is expected remain in the moderate range through Monday. Water temperatures are very warm, 29 - 30°C, and these warm waters extend to great depth.


Figure 1. Afternoon satellite image of 96L.

Forecast for 96L
The moderate wind shear and warm waters should allow some modest development of 96L over the next few days, though this will be slowed by the dry air to the storm's east. The models are quite enthusiastic about developing 96L into a tropical depression, and our top four reliable models for forecasting genesis--the ECMWF, GFS, UKMET, and NOGAPS--have all been predicting formation of a tropical depression by Monday in one or more of their runs over the past day. 96L is in an area of weak steering currents, and will move little over the next three days. On Tuesday and Wednesday, a strong trough of low pressure will be passing over the Eastern U.S., and this trough has the potential to turn 96L northwards into Cuba. This is more likely to happen if 96L is stronger and deeper, and thus able to "feel" the upper-level winds the trough will bring. The 12Z run of the GFS model and 00Z runs of the ECMWF and UKMET models predict 96L will develop into a tropical storm that hits Western Cuba on Wednesday or Thursday, and potentially affecting the Cayman Islands, South Florida, and the Bahamas as well. If 96L remains a weak and shallow system, it is more likely to stay trapped in the Western Caribbean and make landfall in Nicaragua. This is the solution of the NOGAPS model, which has 96L moving ashore on Tuesday over Nicaragua as a weak system. NHC gave 96L a 30% chance of developing into a tropical depression by Sunday in their 8 am Tropical Weather Outlook. A hurricane hunter mission is scheduled to investigate 96L Saturday afternoon.

I'll have a new post on Saturday, but might wait until the afternoon, when the hurricane hunter data becomes available.

Jeff Masters

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Invest 96L is looking good...I think the NHC will find the invest very close to, or, a, tropical depression.

Member Since: July 6, 2010 Posts: 113 Comments: 31451
Quoting stormpetrol:


I think We could very be dealing with a Paloma like scenario and just as strong, only I think 96L will be more of threat to us here in Grand Cayman, rather than the sister islands,having said that all saved us from a direct hit from Paloma was a last minute wobble to the East, I remember Kman & I were the first to remark about it on this blog.
I was very thankful for that eastward jog or we were going to get a direct hit in East End. After all the damage we had up here from Ivan we sure didn't need that.
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Quoting stormwatcherCI:
Paloma developed at 81.7W and 13.7N from a broad area of low pressure. I would not underestimate the possibility of 96L developing just yet. For a few days before she developed she had intermittent convection.


I think We could very be dealing with a Paloma like scenario and just as strong, only I think 96L will be more of threat to us here in Grand Cayman, rather than the sister islands,having said that all saved us from a direct hit from Paloma was a last minute wobble to the East, I remember Kman & I were the first to remark about it on this blog.
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Paloma developed at 81.7W and 13.7N from a broad area of low pressure. I would not underestimate the possibility of 96L developing just yet. For a few days before she developed she had intermittent convection.
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Quoting stormwatcherCI:
I am not sure but to my untrained eye I see the spin just to the NE of the co-ordinates they are giving when I look at the shortwave loop.


I see the low about mid way between the 80 W line and the coast. I have centered that with the image below.

Have to run out for a bit

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Quoting kmanislander:
Good morning

I see that the NHC have come back down to 60%. That is probably where they should have left this at when they opted to go to 70% late yesterday.

One persistent feature of this low is that the convection has always been on the West side of the low strung out linearly from N to S. This may account in part for the drift closer to the coast as the low tries to follow the deepest convection.

Continued meandering is to be expected over the next 24 hours IMO.
Morning kman does it look like we may have a TD later tonight or tomorrow
Member Since: July 14, 2009 Posts: 0 Comments: 2990
I have the center of 96L at around 12.5N/81.7W
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Latest observations from San Andres island shows the low NW from there.

METAR text: SKSP 221300Z 24015KT 9999 SCT015 BKN080 25/23 A2975 REDZ
Conditions at: SKSP (SAN ANDRES ISLAN, CO) observed 1300 UTC 22 October 2011
Temperature: 25.0°C (77°F)
Dewpoint: 23.0°C (73°F) [RH = 89%]
Pressure (altimeter): 29.75 inches Hg (1007.5 mb)
Winds: from the WSW (240 degrees) at 17 MPH (15 knots; 7.8 m/s)
Visibility: 6 or more miles (10+ km)
Ceiling: 8000 feet AGL
Clouds: scattered clouds at 1500 feet AGL
broken clouds at 8000 feet AGL
Weather: no significant weather observed at this time


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Have a wonderful day blogging.
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Quoting kmanislander:
Good morning

I see that the NHC have come back down to 60%. That is probably where they should have left this at when they opted to go to 70% late yesterday.

One persistent feature of this low is that the convection has always been on the West side of the low strung out linearly from N to S. This may account in part for the drift closer to the coast as the low tries to follow the deepest convection.

Continued meandering is to be expected over the next 24 hours IMO.
I am not sure but to my untrained eye I see the spin just to the NE of the co-ordinates they are giving when I look at the shortwave loop.
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Good Morning.
96L looks the same as yesterday. But with an ever-so-slightly better defined center.
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Very weak steering currents still prevailing

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Good morning

I see that the NHC have come back down to 60%. That is probably where they should have left this at when they opted to go to 70% late yesterday.

One persistent feature of this low is that the convection has always been on the West side of the low strung out linearly from N to S. This may account in part for the drift closer to the coast as the low tries to follow the deepest convection.

Continued meandering is to be expected over the next 24 hours IMO.
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Quoting chrisdscane:
what r the cords for its llc any1 know?
I just love what texting has done...
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So my non-weather experienced family member said " I guess the season's over" Gasp - dare this be said. My other family member proceeded to tell them that they now jinxed us and have steered one of these new systems our way.
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AL, 97, 2011102212, , BEST, 0, 98N, 558W, 20, 1007, LO

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96L should start to move NNE if that movement haven't started already
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So whats with the talk of 96l being Wilma like? I think at best it will become a strong cat1, then again iv not put much time into checking the condition the storm will be under in the future, but thats just my guess.
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Quoting GTcooliebai:
They didn't drop it, they just show a weaker system, and aren't bullish with intensification. Anything past 3 days should be taken with a grain of salt where track and intensification apply.
I have to agree with that, so far its just a blob close to land, something to watch thats all
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No change in pressure or windspeed; moved WNW since the last update:

AL, 96, 2011102212, , BEST, 0, 128N, 817W, 25, 1007, LO, 34, NEQ, 0, 0, 0, 0, 1012, 175, 60, 0, 0, L, 0, , 0, 0, INVEST, M,
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Link

Good discussion from Crown Weather this morning and a look at model predictions. Most, if not all do not develop this until at least Sunday.
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could this be rina "the lil sister" of wilma
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Quoting BahaHurican:
Here in Nassau we are still dismal [overcast] with winds from the N to NNW at about 10 mph... a relatively wintry day, in fact.

I agree with Kman that 96L is going to be a slow developer... he was putting formation chances sometime between this afternoon and tomorrow afternoon. It'll be interesting to see how far north this whole mess drifts before we get anything more consolidated.

NHC surface map shows it drifting NE so I am guessing once it pulls a little further from land it has a better shot at developing.
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Quoting stormpetrol:


Pressures are significantly lower across the region than yesterday, and 96L is about 1006.3mb according to this!
That's where the surface low should form, convergence and divergence seem good in that area, anticyclone almost right over it, and vorticity is increasing.

Member Since: August 31, 2009 Posts: 0 Comments: 5628
Quoting Tropicsweatherpr:


That is a big mess right now.I really dont think recon will fly this afternoon. I also want to see what our friend Kman thinks today about 96L.
Why should they change their plans just off of satellite presentation, they didn't do that for 95L, and I see know reason why they should cancel here.
Member Since: August 31, 2009 Posts: 0 Comments: 5628
Quoting BahaHurican:


Morning all...

Eck! What is THAT?
Member Since: August 18, 2011 Posts: 0 Comments: 994
Quoting BahaHurican:


Morning all...



That is a big mess right now.I really dont think recon will fly this afternoon. I also want to see what our friend Kman thinks today about 96L.
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Quoting wunderweatherman123:
well shear has increased a bit. 6z gfs and euro drop it. i dont pay attention to that. if 96L starts geting convection around its center its a td
They didn't drop it, they just show a weaker system, and aren't bullish with intensification. Anything past 3 days should be taken with a grain of salt where track and intensification apply.
Member Since: August 31, 2009 Posts: 0 Comments: 5628
Here in Nassau we are still dismal [overcast] with winds from the N to NNW at about 10 mph... a relatively wintry day, in fact.

I agree with Kman that 96L is going to be a slow developer... he was putting formation chances sometime between this afternoon and tomorrow afternoon. It'll be interesting to see how far north this whole mess drifts before we get anything more consolidated.

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well shear has increased a bit. 6z gfs and euro drop it. i dont pay attention to that. if 96L starts geting convection around its center its a td
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Morning all...

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Quoting CybrTeddy:


GFS and EURO dropped it because it runs into land.

I figured they would drop the odds, 96L lost model support overnight.


And that track is a big change from the one they had going thru in past runs. The question is,why the change of track?
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000
NOUS42 KNHC 211430
WEATHER RECONNAISSANCE FLIGHTS
CARCAH, NATIONAL HURRICANE CENTER, MIAMI, FL.
1030 AM EDT FRI 21 OCTOBER 2011
SUBJECT: TROPICAL CYCLONE PLAN OF THE DAY (TCPOD)
VALID 22/1100Z TO 23/1100Z OCTOBER 2011
TCPOD NUMBER.....11-143

I. ATLANTIC REQUIREMENTS
1. SUSPECT AREA (WESTERN CARIBBEAN)
FLIGHT ONE --TEAL 70--
A. 22/2000Z
B. AFXXX 01KKA INVEST
C. 22/1530Z
D. 13.5N 80.0W
E. 22/1930Z TO 22/2230Z
F. SFC TO 10,000 FT

2. OUTLOOK FOR SUCCEEDING DAY: FIX SYSTEM AT 23/1800Z
NEAR 14.5N 80.5W.

II. PACIFIC REQUIREMENTS
1. NEGATIVE RECONNAISSANCE REQUIREMENTS.
2. SUCCEEDING DAY OUTLOOK....NEGATIVE.
JWP

Hopefully its still a go for the HHs
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Quoting wunderkidcayman:
hey stormpetrol u know that those are old scats from very early this morn


Yep I know, man I can't believe how hung up on models some people are! 96L is already a TD IMO.
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Pressures are significantly lower across the region than yesterday, and 96L is about 1006.3mb according to this!
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Quoting stormpetrol:
IMO it has also started a Northward drift, maybe even a little bit east of due North.

well that was expected 96L was to have a NE run before his NNW walk
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IMO it has also started a Northward drift, maybe even a little bit east of due North.
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545. wpb
6z gfs no tc from 96l
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hey stormpetrol u know that those are old scats from very early this morn
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Hi all...please raise the South Florida shields as I am heading to Key West monday for a week....I deserve beautiful weather lol... Thanks for any input
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Good Morning, 96L still has a high chance of becoming a tropical cyclone, actually I think the surface low is much better defined than yesterday, I suspect when the HHs fly into it this PM , we'll have a TD or maybe even a TS.
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soon they will rase 96L up to about 80/90% by 12 then possible TD/TS by 5pm or 8 today convection is now starting to blow up and pop and 96L has that ULAC almost on top so give it some time to get just right
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96l not looking veary healthy may we have dodged a bullet?
Member Since: July 21, 2010 Posts: 0 Comments: 1065
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Quoting chrisdscane:
what r the cords for its llc any1 know?
This is the latest but should be updated in about an hour so not sure now.


127N-807W.


22/0545 UTC 12.7N 81.0W T1.5/1.5 96L -- Atlantic
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39 here in Florida.
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what r the cords for its llc any1 know?
Member Since: July 21, 2010 Posts: 0 Comments: 1065
Key West NWS Discussion

LONG TERM (TUESDAY THROUGH FRIDAY)...
CONSIDERABLE UNCERTAINTY CLOUDS THE LONG-TERM PORTION OF THIS
FORECAST...AS MODEL INCONSISTENCY REGARDING THE DEVELOPING LOW
PRESSURE CENTER CURRENTLY OVER THE SOUTHWESTERN CARIBBEAN SEA
PERSISTS. THERE APPEARS TO BE LITTLE IN THE WAY OF STEERING FLOW OVER
THE WESTERN CARIBBEAN DURING THE EARLY AND MIDDLE PORTIONS OF THE
UPCOMING WEEK...AND THE PROXIMITY OF THE ORGANIZING LOW PRESSURE
CENTER TO THE CENTRAL AMERICAN COAST WILL LIKELY DICTATE HOW MUCH
DEVELOPMENT OCCURS. A PROGRESSIVE TROUGH TRAVERSING THE WESTERN AND
CENTRAL UNITED STATES MAY SHARPEN ENOUGH TO PULL THIS SYSTEM
NORTHWARD BY LATE NEXT WEEK. HOWEVER...THE ECMWF HAS FLIP-FLOPPED
FROM ITS PRIOR SOLUTION ON ITS 00Z RUN AND NO LONGER SHOWS A TROPICAL
CYCLONE EMERGING INTO THE SOUTHEASTERN GULF OF MEXICO.
Member Since: September 10, 2007 Posts: 0 Comments: 10972

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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.