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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Been raining non-stop in jupiter, FL since 5 or so.

TORNADO WARNING
FLC086-310100-
/O.NEW.KMFL.TO.W.0011.111031T0026Z-111031T0100Z/




BULLETIN - EAS ACTIVATION REQUESTED
TORNADO WARNING
NATIONAL WEATHER SERVICE MIAMI FL
826 PM EDT SUN OCT 30 2011

THE NATIONAL WEATHER SERVICE IN MIAMI HAS ISSUED A

* TORNADO WARNING FOR...
EAST CENTRAL MIAMI-DADE COUNTY IN SOUTHEAST FLORIDA...

* UNTIL 900 PM EDT

* AT 818 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED
A POSSIBLE TORNADO 1 MILE EAST OF BLACK POINT...MOVING NORTHWEST
AT 5 MPH.
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The GoM is a little dry.
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I see the low-level center. Pretty obvious in this image.
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Look at the low-level clouds. There's SOMETHING going on in there.
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Quoting kmanislander:


They are seeing a "shallower" system, that is one that remains weak, which would not be drawn to the N by a trough or front. This is the solution that the NOGAPS has been touting for some time.

Also, the position used to initialise each set of model runs is a factor. Assuming the initial position for each recent runs is the 81.7 W position then the models assume the feature to have been moving in that direction since the prior runs which would be towards the coast. In fact, with no real center any so called motion is more a meandering around but the models do not necessarily pick up on that.



Thank you for that clear explanation. This is another excample of why the tropics change not from day to day,but in only a few hours,from a monster cane that the models had in yesterdays runs to today.There are many variables that occur in the tropical regions of the world that can make things look good for a time,but change to not good later in a matter of hours.
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Quoting scott39:
Is land interaction the biggest culprit in regards to developement of 96L?


A number of factors really including upper level atmospheric conditions which are very stable at the moment. The entire season has seen below climo instability which discourages quick development. 96L is also still caught up in the monsoon trough which is another deterrent to development. The surface map below shows it tagged to that trough.

Proximity to land does not help but we have seen many powerful systems start out just like this at or close to the same coordinates.

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Wilma comparisons were re: track, not intensity.

However, I think there is also a point already made by other bloggers with regard to the possibility of RI, which was also seen in Wilma's case.

This is a situation where patience is key, but also containing a great deal of volatility.
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96L reminds me of the system that became Paula. NHC dropped the odds substantially on it because the models backed off on it as it moved over Central America. Became a Category 2 hurricane. Situation might be similar here..
Member Since: July 8, 2005 Posts: 259 Comments: 24574
NEW BLOG
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Quoting capelookout:

You think it has a chance of affecting the U.S.?


A chance of the Fla. Keys or South Florida but I do not see anything further N than that at this time.
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lol, the NHC lowers it chances of development slightly, and everybody acts like it has a Near 0% change of developing. Yes, it has become a little less organized since yesterday...So? Systems will struggle every once in a while. As for the models, just because they switched in one night, that means that our opinion should just change drastically too? No.

96L still has the potential to become a dangerous system...In case you have forgot...



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Quoting Tropicsweatherpr:


Kman,why the sudden change by the models sending it to CA? You think the lack of vertical inestability may play a roll?


They are seeing a "shallower" system, that is one that remains weak, which would not be drawn to the N by a trough or front. This is the solution that the NOGAPS has been touting for some time.

Also, the position used to initialise each set of model runs is a factor. Assuming the initial position for each recent runs is the 81.7 W position then the models assume the feature to have been moving in that direction since the prior runs which would be towards the coast. In fact, with no real center any so called motion is more a meandering around but the models do not necessarily pick up on that.

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Quoting TropicalAnalystwx13:
96L yesterday afternoon:



Now:

What?
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Quoting kmanislander:


Absolutely. See the post I just put up at 609.
Is land interaction the biggest culprit in regards to developement of 96L?
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Quoting reedzone:
NHC making a big mistake canceling recon, but it is what it is.. Just like when they made the mistake of not naming 93L which was clearly a Subtropical Storm that made landfall in Cape Canaveral, FL. Off to work, not surprised by the actions of the NHC lately, not surprised at all.


It's been struggling since yesterday, but will you give it a rest with 93L and bashing the NHC already!
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Quoting TropicalAnalystwx13:

Yeah, I wish they wouldn't have cancelled recon..Even if it is slightly less organized than yesterday, its still a strong disturbance that has the potential to become a tropical system over the next 48 hours. It would have been nice to see what recon found.

Oh well...


It's not going anywhere fast anytime soon...what is the point? It's a waste of money. They have all the tools they need for 96L right now.
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616. Skyepony (Mod)
Oceansat's pass, after I fell out lastnight, shows 96L came undone a bit after Windsat's pass.

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Quoting SLU:

lol..Its basically devoid of convection right now...The NHC will drop it to ~0% at 2PM, but then it will fire a lot more convection later on, and they will up it to 10%.

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Quoting kmanislander:


Don't trust the models before we have a closed low. I still see this meandering around until probably tomorrow and then a drift to the N or NNW. I put up the current steering back at post 571 I believe. 96L is not going anywhere any time soon.

I agree.
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Quoting reedzone:
NHC making a big mistake canceling recon, but it is what it is.. Just like when they made the mistake of not naming 93L which was clearly a Subtropical Storm that made landfall in Cape Canaveral, FL. Off to work, not surprised by the actions of the NHC lately, not surprised at all.

Yeah, I wish they wouldn't have cancelled recon..Even if it is slightly less organized than yesterday, its still a strong disturbance that has the potential to become a tropical system over the next 48 hours. It would have been nice to see what recon found.

Oh well...
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Quoting scott39:
Thanks,When an invest has not developed, is it best to go with real time than Model support? To me they seem to swing quite a bit in a short amount of time, coming out of the Caribbean this season.


Absolutely. See the post I just put up at 609.
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610. SLU
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Quoting TropicalAnalystwx13:

What's your opinion?


Don't trust the models before we have a closed low. I still see this meandering around until probably tomorrow and then a drift to the N or NNW. I put up the current steering back at post 571 I believe. 96L is not going anywhere any time soon.
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Quoting kmanislander:


Because they are now taking it inland across Nicaragua
Thanks,When an invest has not developed, is it best to go with real time than Model support? To me they seem to swing quite a bit in a short amount of time, coming out of the Caribbean this season.
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Quoting kmanislander:


Because they are now taking it inland across Nicaragua


Kman,why the sudden change by the models sending it to CA? You think the lack of vertical inestability may play a roll?
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Another reason why it may continue to struggle...

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Quoting reedzone:
NHC making a big mistake canceling recon, but it is what it is.. Just like when they made the mistake of not naming 93L which was clearly a Subtropical Storm that made landfall in Cape Canaveral, FL. Off to work, not surprised by the actions of the NHC lately, not surprised at all.


Your kidding right? lol
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Quoting kmanislander:


Because they are now taking it inland across Nicaragua

What's your opinion?
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96L yesterday afternoon:



Now:

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Quoting scott39:
Goodmorning, Looks like the models have a back off quite a bit with intensity of 96L. I wonder why?


Because they are now taking it inland across Nicaragua
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NHC making a big mistake canceling recon, but it is what it is.. Just like when they made the mistake of not naming 93L which was clearly a Subtropical Storm that made landfall in Cape Canaveral, FL. Off to work, not surprised by the actions of the NHC lately, not surprised at all.
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Almost posted at same time the recon info.
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No Recon today...

WEATHER RECONNAISSANCE FLIGHTS
CARCAH, NATIONAL HURRICANE CENTER, MIAMI, FL.
1030 AM EDT SAT 22 OCTOBER 2011
SUBJECT: TROPICAL CYCLONE PLAN OF THE DAY (TCPOD)
VALID 23/1100Z TO 24/1100Z OCTOBER 2011
TCPOD NUMBER.....11-144

I. ATLANTIC REQUIREMENTS
1. SUSPECT AREA (WESTERN CARIBBEAN)
FLIGHT ONE -- TEAL 70
A. 23/1900Z
B. AFXXX 01KKA INVEST
C. 23/1500Z
D. 14.6N 82.5W
E. 23/1830Z TO 23/2230Z
F. SFC TO 10,000 FT

2. OUTLOOK FOR SUCCEEDING DAY: BEGIN 6-HRLY FIXES AT
24/1800Z NEAR 16.5N 84.0W IF SYSTEM DEVELOPS.
3. REMARK: LOW-LEVEL INVEST FOR 22/2000Z CANCELED BY
NHC AT 22/1205Z.
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Im sure you have heard the phrase....a watched pot never boils. Lol
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Quoting shawn26:
What time will the hurricane hunters be to the system?

There isn't any...

3. REMARK: LOW-LEVEL INVEST FOR 22/2000Z CANCELED BY
NHC AT 22/1205Z.
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Looking at all the info 96l will not be a TD today circulation is still broad and convection is lacking on the east side among many things
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Member Since: April 29, 2007 Posts: 0 Comments: 8134
TCs are so fickeled. Got to love it!
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Member Since: April 29, 2007 Posts: 0 Comments: 8134


Vorticity further south , more spread out and not as close to land
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What time will the hurricane hunters be to the system?
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Quoting robert88:
I think if it even develops..it won't be until Monday. It's looking less organized and could easily follow the convection inland and die.

We'll have to see what recon finds.
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Is the lack of vertical inestibility do harm to the development of 96L?

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Goodmorning, Looks like the models have a back off quite a bit with intensity of 96L. I wonder why?
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Member Since: April 29, 2007 Posts: 0 Comments: 8134
I think if it even develops..it won't be until Monday. It's looking less organized and could easily follow the convection inland and die.
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Quoting hunkerdown:
I just love what texting has done...


Ain't that the truth. At this rate, it will be harder to interpert than raw METAR data. :)
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I see the GFS now moves 96L into Central America. Yesterday the GFS had 96L crossing Cuba. Big Change over night.
Member Since: September 16, 2007 Posts: 0 Comments: 9234
Invest 96L is looking good...I think the NHC will find the invest very close to, or, a, tropical depression.

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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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