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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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: 11265
Quoting Tropicsweatherpr:
Ummm,they dropped the % for 96L. Maybe the models are seeing unfavorable conditions ahead and that is why GFS and Euro drop it.


GFS and EURO dropped it because it runs into land.

I figured they would drop the odds, 96L lost model support overnight.
Member Since: July 8, 2005 Posts: 259 Comments: 24167
Quoting Tropicsweatherpr:
Ummm,they dropped the % for 96L. Maybe the models are seeing unfavorable conditions ahead and that is why GFS and Euro drop it.


Yep:

ENVIRONMENTAL CONDITIONS APPEAR TO BE A LITTLE BIT LESS
FAVORABLE FOR A TROPICAL DEPRESSION TO FORM DURING THE NEXT DAY OR
TWO.
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Ummm,they dropped the % for 96L. Maybe the models are seeing unfavorable conditions ahead and that is why GFS and Euro drop it.
Member Since: April 29, 2009 Posts: 75 Comments: 14315
they lowered it to 60
Member Since: July 21, 2010 Posts: 0 Comments: 1177
cant help wonder if dry air in the GOM will be a problem
Member Since: July 21, 2010 Posts: 0 Comments: 1177
BNT20 KNHC 221131
TWOAT

TROPICAL WEATHER OUTLOOK
NWS NATIONAL HURRICANE CENTER MIAMI FL
800 AM EDT SAT OCT 22 2011

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

CLOUDINESS AND THUNDERSTORMS ASSOCIATED WITH A NEARLY STATIONARY
AREA OF LOW PRESSURE IN THE SOUTHWESTERN CARIBBEAN SEA NEAR SAN
ANDRES ISLAND HAVE NOT BECOME ANY BETTER ORGANIZED SINCE YESTERDAY.
ALTHOUGH SURFACE PRESSURES HAVE CONTINUED TO FALL IN THE
AREA...ENVIRONMENTAL CONDITIONS APPEAR TO BE A LITTLE BIT LESS
FAVORABLE FOR A TROPICAL DEPRESSION TO FORM DURING THE NEXT DAY OR
TWO. HOWEVER...THIS SYSTEM STILL HAS A HIGH CHANCE...60 PERCENT...
OF BECOMING A TROPICAL CYCLONE DURING THE NEXT 48 HOURS.

A BROAD AREA OF LOW PRESSURE LOCATED SEVERAL HUNDRED MILES EAST OF
THE SOUTHERN WINDWARD ISLANDS IS PRODUCING DISORGANIZED CLOUDINESS
AND THUNDERSTORMS. THIS ACTIVITY HAS BEEN GRADUALLY DECREASING
SINCE YESTERDAY...AND DEVELOPMENT...IF ANY...WILL BE SLOW TO OCCUR.
THIS SYSTEM HAS A LOW CHANCE...10 PERCENT...OF BECOMING A TROPICAL
CYCLONE DURING THE NEXT 48 HOURS AS IT MOVES SLOWLY TOWARD THE
WEST-NORTHWEST.

ELSEWHERE...TROPICAL CYCLONE FORMATION IS NOT EXPECTED DURING THE
NEXT 48 HOURS.

$$
FORECASTER AVILA
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Miami NWS Discussion

LATE IN THE PERIOD... IT JUST WOULDN`T BE RIGHT IF MY LAST SHIFT
AT WFO MIAMI/SOUTH FLORIDA DIDN`T HAVE A POTENTIAL TROPICAL
CYCLONE LURKING IN THE EXTENDED. THE GFS DEPICTS A TROPICAL
CYCLONE SPINNING UP FROM WHAT IS NOW THE DISTURBANCE NORTH OF
PANAMA AND SLOWLY LIFTING NORTH AND INTERACTING WITH A STRONG COLD
FRONT AS IT PASSES NEAR THE AREA. THE 0Z ECMWF NOW KEEPS THE TC IN
THE CARIBBEAN AND POSSIBLY INTERACTING OR BEING ABSORBED BY
ANOTHER SYSTEM MOVING IN FROM THE EAST. THE BOTTOM LINE IS THAT
THERE MAY BE A SYSTEM DEVELOPING IN THE WEST CARIBBEAN OVER THE
NEXT FEW DAYS, BUT UNCERTAINTY IS HIGH REGARDING THE EVOLUTION OF
THE TC.
Member Since: September 10, 2007 Posts: 0 Comments: 11265
Quoting Tropicsweatherpr:


Good morning pottery.

That big upper level low to the north caused the weakening of 97L to the point that there is almost anything left. Yesterday morning,it looked very omminous down there with those black areas,but the tropics change constantly and here we are.

True!
I was anticipating a rained-out weekend.
Not looking that way, right now.
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Quoting stormwatcherCI:
Good morning. Is it windy down there ?
Hi- A bit gusty here on North Sound, but seems to have dropped from last night somewhat. Looks like we might get a bit of a break from the rain for a short while anyway. I see the 00 Nogaps puts 96L into Honduras/ Belize next week, but develops what appears to be influence from 97L over us & Jam' after mid-week
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Quoting stormwatcherCI:
Good morning Pottery. 97L looks to have consolidated pretty good over night but is a very small area. NHC latest surface map does not show a low there any longer though so I don't know what is going on with it.

Yeah, it seems less of a rain-threat now.
Winds here were West and NW yesterday afternoon, which was interesting.
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Member Since: September 10, 2007 Posts: 0 Comments: 11265
Quoting pottery:
Good Morning.
Pretty dawn this morning, which surprised me. I was expecting cloudy sky and the chance of rain from 97L.
Looks like everything might move North of us.
Still expect to get some showers, but not as much as it looked like, last night.


Good morning pottery.

That big upper level low to the north caused the weakening of 97L to the point that there is almost anything left. Yesterday morning,it looked very omminous down there with those black areas,but the tropics change constantly and here we are.
Member Since: April 29, 2009 Posts: 75 Comments: 14315
Quoting pottery:
Good Morning.
Pretty dawn this morning, which surprised me. I was expecting cloudy sky and the chance of rain from 97L.
Looks like everything might move North of us.
Still expect to get some showers, but not as much as it looked like, last night.
Good morning Pottery. 97L looks to have consolidated pretty good over night but is a very small area. NHC latest surface map does not show a low there any longer though so I don't know what is going on with it.
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51°F around Carrollwood, Tampa this morning !!!
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I guess us people here in Cayman are early birds
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Quoting superpete:
You always see people in Cayman up very early in times such as these...LOL Good Morning!!
Good morning. Is it windy down there ?
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Good Morning.
Pretty dawn this morning, which surprised me. I was expecting cloudy sky and the chance of rain from 97L.
Looks like everything might move North of us.
Still expect to get some showers, but not as much as it looked like, last night.
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Quoting stormwatcherCI:
Good morning. Strong breeze, rain off and on and lots of lightning and thunder up here.
You always see people in Cayman up very early in times such as these...LOL Good Morning!!
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Quoting Tropicsweatherpr:
Good morning to all.

Ok,now what? The 00z Euro almost doesn't show it and 06Z GFS drops it.
Most likely because it hasn't developed as quickly as they originally thought it would. I put a lot of stock in kmanislander and when he says we most likely will get development from this I think we will. He has never that I can remember been wrong and definitely does not hype any system.
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Quoting TropicTraveler:
Good morning island people. You are up way to early for a Saturday morning, but then, nothing like a sunrise over the water to start the day right. I'm mad cause I started to work and forgot my coffee!!! Grr. Late yesterday our resident grump was complaining that we all get excited when a storm cranks up. After I logged off I laughed because of course we get excited when a storm cranks up. This is a tropical weather blog and we are tropical weather junkies so that's what we do.......I'd say it beats being crabby and picking on us weather nuts for being who we are. Wonder why the guy even logs on here. Just saying.
Good morning. I am normally an early riser and I think we definitely need to watch 96L in the Cayman Islands. The blog has gone to the dogs over the past few weeks but I just ignore the trolls. It serves no purpose arguing with them since that is their whole purpose for coming on here.
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Good morning to all.

Ok,now what in terms of the models and 96L? The 00z Euro almost doesn't show it and 06Z GFS drops it.
Member Since: April 29, 2009 Posts: 75 Comments: 14315
Good morning island people. You are up way to early for a Saturday morning, but then, nothing like a sunrise over the water to start the day right. I'm mad cause I started to work and forgot my coffee!!! Grr. Late yesterday our resident grump was complaining that we all get excited when a storm cranks up. After I logged off I laughed because of course we get excited when a storm cranks up. This is a tropical weather blog and we are tropical weather junkies so that's what we do.......I'd say it beats being crabby and picking on us weather nuts for being who we are. Wonder why the guy even logs on here. Just saying.
Member Since: July 24, 2007 Posts: 2 Comments: 927
Quoting wunderkidcayman:
Good morn it dark but you can still see cloud still hanging around
Good morning. Strong breeze, rain off and on and lots of lightning and thunder up here.
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Good morn it dark but you can still see cloud still hanging around
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Quoting MahFL:
Hi all, working an extra half shift tonight, I saw 1 meteor earlier, but am warming up as it's 46 F out.
Good morning, 54 here at 5am, no wind to speak of, going up to 74 this afternoon, nice day ahead at last
Member Since: August 6, 2011 Posts: 4 Comments: 39144
506. MahFL
Hi all, working an extra half shift tonight, I saw 1 meteor earlier, but am warming up as it's 46 F out.
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If the NHC wanted people to read their messages, they wouldn't post 'em in ALL-CAPs.
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Why are you highlighting sections? You excited? I'm sure people can read it normal
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TROPICAL WEATHER OUTLOOK
NWS NATIONAL HURRICANE CENTER MIAMI FL
200 AM EDT SAT OCT 22 2011

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

AN AREA OF LOW PRESSURE...LOCATED OVER THE SOUTHWESTERN CARIBBEAN
SEA NEAR SAN ANDRES ISLAND...CONTINUES TO PRODUCE WIDESPREAD
CLOUDINESS AND THUNDERSTORMS. ALTHOUGH THERE HAS BEEN LITTLE CHANGE
IN THE ORGANIZATION OF THIS DISTURBANCE DURING THE PAST SEVERAL
HOURS...UPPER-LEVEL WINDS ARE FORECAST TO BE FAVORABLE FOR THE
DEVELOPMENT OF A TROPICAL DEPRESSION DURING THE NEXT DAY OR TWO.
THIS SYSTEM HAS A HIGH CHANCE...70 PERCENT...OF BECOMING A TROPICAL
CYCLONE DURING THE NEXT 48 HOURS AS IT DRIFTS SLOWLY NORTHWARD.
SHOWERS AND THUNDERSTORMS REMAIN LIMITED IN ASSOCIATION WITH A BROAD
AREA OF LOW PRESSURE LOCATED SEVERAL HUNDRED MILES EAST OF THE
WINDWARD ISLANDS. UPPER-LEVEL WINDS ARE EXPECTED TO BECOME MORE
FAVORABLE DURING THE NEXT DAY OR TWO...AND SOME SLOW DEVELOPMENT OF
THIS DISTURBANCE IS POSSIBLE. THIS SYSTEM HAS A LOW CHANCE... 20
PERCENT...OF BECOMING A TROPICAL CYCLONE DURING THE NEXT 48 HOURS
AS IT MOVES SLOWLY WEST-NORTHWESTWARD.
REGARDLESS OF DEVELOPMENT...
CLOUDINESS AND HEAVY RAINS COULD SPREAD OVER PORTIONS OF THE
WINDWARD ISLANDS AND NORTHERN VENEZUELA DURING THE NEXT FEW DAYS.

ELSEWHERE...TROPICAL CYCLONE FORMATION IS NOT EXPECTED DURING THE
NEXT 48 HOURS.

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502. D6X
Looks like that strong ULL north of PR is starting to slowly move north now. It has been responsible for strong northerly upper level winds on the east side of 96L, and tearing up 97L. It looks to me like things will begin to improve for 96L now in terms of organization, while 97L will still be under the ULLs influence.
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Dueling spins in 97L?
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Quoting Skyepony:


It looks closed at the surface..
I thought i wasnt going crazy. Im thinking if it stays the same we could see a td in the morning.
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Quoting WatchingThisOne:


Warm day or not, I think you should put some pants on. lol :)

I do.
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Quoting Skyepony:


Thanks, noticed updating my blog. I didn't get to read back more than a few pages. No mention. Probably about to get shredded anyways. Good to see we (as a group) aren't missing these the moment they come out.




they did say 96 and 97 have a ch



good night
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497. Skyepony (Mod)
Quoting bigwes6844:
is that what i think it might be?????????????


It looks closed at the surface..
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496. Skyepony (Mod)
I can't wait any longer on Oceansat. It just caught up with 97L..
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Quoting Skyepony:
Look what windsat just caught..
is that what i think it might be?????????????
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Almost getting there
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493. Skyepony (Mod)
Look what windsat just caught..
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Link Almost getting there
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491. Skyepony (Mod)
Quoting Tazmanian:


a little late are we skye? we had 97L for a few hrs now


Thanks, noticed updating my blog. I didn't get to read back more than a few pages. No mention. Probably about to get shredded anyways. Good to see we (as a group) aren't missing these the moment they come out.
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Hadn't expected to post another mapping so soon, but since the previous mapping for 21Oct_6pmGMT :
6pmGMT's D(istur)B(ance) has been re-evaluated&altered to (closed)LO(w) for Invest97L's_12amGMT_ATCF, and
8.5n54.4w, 8.6n54.8w, 8.7n55.2w, 8.8n55.7w, 9.0n56.2w have been re-evaluated&altered to
9.4n53.4w, 9.5n53.9w, 9.7n54.5w, 10.0n55.0w, 10.6n55.7w, 11.4n56.3w being the most recent positions
Starting 20Oct_6pmGMT and ending 22Oct_12amGMT

The 5 line-segments represent Invest97L's northwestward path

Copy&paste pos, bgi, 9.4n53.4w-9.5n53.9w, 9.5n53.9w-9.7n54.5w, 9.7n54.5w-10.0n55.0w, 10.0n55.0w-10.6n55.7w, 10.6n55.7w-11.4n56.3w, bbq into the GreatCircleMapper for more info
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Quoting Skyepony:
I see we have 97L..


a little late are we skye? we had 97L for a few hrs now
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Quoting AussieStorm:

I'm sitting here watching the V8's on the Gold Coast on tv wearing only shorts. It's a lovely warm day here.


Warm day or not, I think you should put some pants on. lol :)
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487. Skyepony (Mod)
I see we have 97L..
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486. Skyepony (Mod)
There is a rapidly rising volcano in South America.
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485. Skyepony (Mod)
A flash flood in central Myanmar on Friday left dozens of people missing as homes along a river bank were swept away, government officials in the military-dominated country said. "About 60 people are missing so far because of the flood" in Pakokku township, an official who did not want to be named, said. "Some houses and a monastery along the river bank were swept away and a bridge was destroyed as the water rose up," he said. There were no confirmed reports of deaths, a second official said. A monk in Pakokku said the water was believed to have risen to about three metres (10 feet) high. "Some people, animals, houses and a monastery were swept away when the water rose up. The water level is back to normal now," he said. "We had torrential rain in previous days." State media reported roads, bridges and buildings were damaged because of strong winds and heavy rains in some parts of the country. Southeast Asia has been battered by particularly severe monsoon rains this year. According to the United Nations, more than 700 people have been killed across Thailand, Cambodia, Vietnam, Laos and the Philippines, and eight million have been affected. Thailand has been particularly severely hit, with more than 300 people dead and Bangkok on alert for flooding.
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484. Skyepony (Mod)
Tsunami has been observed following the M7.4 magnitude earthquake in Raoul Island, Kermadec Island, New Zealand at 18:16 Zulu. The observed tsunami waves 10 centimeters high. Other information not available yet.
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483. Skyepony (Mod)
Kinda odd almost 2 dueling ULL North of the Leeward Islands, wrapped in a layer of dry air. Should do the trick to disrupt the stationary front, completely cut off that low & give it a little tug north as it goes.

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Quoting Seastep:
And, what the heck are you doing up at this hour?

Genuinely curious about the V8's. I have a case in my fridge, but don't know beyond that.

it's 3:45pm here. you should be in bed.
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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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