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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Quoting Levi32:


Most of the time there is a cold snap during the formation of late-season Florida, Cuba, and Bahamas hurricanes.



True. But that also holds intensity down. Those cold snaps cooling shelf waters are not good for major hurricanes making landfall.

Kate in 1985 was a real outlier. She hit the panhandle as the strongest November hurricane to make landfall in our records. Kate would have made landfall as a major if she had been shoved east into the peninsula. November 1985 was a very warm month however, without strong cold snaps.

And a Cat 2 can cause a lot of problems obviously. A hurricane doesn't have to be a major to be dangerous.
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Interesting developments in the western Carib this afternoon, now upped to a 60% chance. Again, as others have mentioned, it is several days out... so nothing to worry about for the SE CONUS at this point, just a wait and see.

I do find it interesting that the other day when 95L was sitting near the Yucatan, some of the models had it progged to move southward into the western Carib. Now, here we sit with 96L in the region. Those models were hinting at something then. And sure enough, a piece of energy associated with the cold front that passed through FL and SW into the Yucatan moved eastward and interacted with a Twave, and boom goes the dynamite!

FL may have to deal with a wet midweek next week. Still plenty of time though. And things can and do change often.
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Quoting BaltimoreBrian:
Naples water temp is a bit warmer between 76 and 77. As it gets warmer the water temp may recover there as well. However even if the system becomes a major in the NW Caribbean and Gulf, it will probably be on a weakening trend if it hits Naples as well.

I wouldn't say that a major hitting FL after October 25 is impossible just because that is the record. But long duration records are difficult to break. If there hadn't been a strong cold snap this week I would say a major was a decent possibility. But the cool shelf waters after the cold snap will make that difficult now.


Most of the time there is a cold snap in the eastern United States during the formation of late-season Florida, Cuba, and Bahamas hurricanes.

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Naples water temp is a bit warmer between 76 and 77. As it gets warmer the water temp may recover there as well. However even if the system becomes a major in the NW Caribbean and Gulf, it will probably be on a weakening trend if it hits Naples as well.

I wouldn't say that a major hitting FL after October 25 is impossible just because that is the record. But long duration records are difficult to break. If there hadn't been a strong cold snap this week I would say a major making landfall in FL is a decent possibility. But the cool shelf waters after the cold snap will make that difficult now.
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From NCAR:REAL-TIME GUIDANCE FOR LOW INVEST (AL96)

At 1200 UTC, 21 October 2011, LOW INVEST (AL96) was located in the North Atlantic basin at 13.5N and 80W. The current intensity was 25 kt and the center was moving at 3 kt at a bearing of 180 degrees. The minimum central pressure was 1008 mb.

At 1800 UTC, 21 October 2011, DISTURBANCE INVEST (AL97) was located in the North Atlantic basin at 9.0N and 56.2W. The current intensity was 30 kt and the center was moving at 5 kt at a bearing of 285 degrees. The minimum central pressure was 1006 mb.
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Quoting Some1Has2BtheRookie:


Ten bucks, for gas? Are you putting it in your lawn mower?
lol yep, and even that will only cut half the lawn.
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Quoting Clearwater1:


Steering current and mid level steering winds were north and the sea surface temps between 80 and 83 degrees, as it headed into the gulf, the water temps dropped a few degrees.

Is that worth ten bucks for gas money? lol


Ten bucks, for gas? Are you putting it in your lawn mower?
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Quoting SouthDadeFish:
yeah I was being very general. I guess it is technically between Tampa and Naples area there. Still seven days out so the actual landfall point shouldn't be taken for much.


Fort myers there to be exact as a minimal ts. If you take a look at the jet entrance region south of Florida it is a prime area for development. Think this is a go.
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Euro 12z is similar to the CMC 12z run:

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Quoting hurricane23:


Futher south then tampa there closer to naples actually.


Looks like it is between Naples and Tampa lol
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Clearwater Beach water temp is between 72 and 73. That will probably recover some as the weather warms up. But I think the water will be too cool for a major landfalling hurricane if the system goes that far north.
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Quoting hurricane23:


Futher south then tampa there closer to naples actually.
yeah I was being very general. I guess it is technically between Tampa and Naples area there. Still seven days out so the actual landfall point shouldn't be taken for much.
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the waters in the caribean are warm and this warm waters extend to great deep, it coul be a hurricane by monday but what worries me is 97 l
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Quoting GTcooliebai:
Yeah I would literally give someone a million dollars if they would post the steering and sst at the time of that storm.


Steering current and mid level steering winds were north and the sea surface temps between 80 and 83 degrees, as it headed into the gulf, the water temps dropped a few degrees.

Is that worth ten bucks for gas money? lol
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If it goes as far north as Tampa has the cool snap cooled the shelf waters enough to knock it down below Cat 3 even if it becomes a major in the Gulf?
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18z..

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that near jacksonville
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TROPICAL WEATHER OUTLOOK
NWS NATIONAL HURRICANE CENTER MIAMI FL
200 PM EDT FRI OCT 21 2011

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

1. AN AREA OF LOW PRESSURE OVER THE WESTERN CARIBBEAN SEA IS CENTERED
ABOUT 170 MILES EAST OF THE COAST OF NICARAGUA. THE ASSOCIATED
SHOWER ACTIVITY HAS BECOME BETTER ORGANIZED...AND THERE IS A
LIKELIHOOD THAT A TROPICAL DEPRESSION WILL FORM DURING THE WEEKEND.

LITTLE MOTION IS ANTICIPATED IN THE SHORT TERM...BUT A SLOW
NORTHWARD DRIFT SHOULD BEGIN ON SUNDAY. THIS SYSTEM HAS A HIGH
CHANCE...60 PERCENT...OF BECOMING A TROPICAL CYCLONE DURING THE
NEXT 48 HOURS.

2. A BROAD AREA OF LOW PRESSURE HAS FORMED ABOUT 350 MILES
EAST-SOUTHEAST OF TRINIDAD IN THE SOUTHERN WINDWARD ISLANDS.
CLOUDINESS AND SHOWERS ASSOCIATED WITH THIS LOW HAVE BECOME A
LITTLE BETTER ORGANIZED AND THE POTENTIAL FOR DEVELOPMENT HAS
INCREASED. THIS SYSTEM HAS A LOW CHANCE...20 PERCENT...OF BECOMING
A TROPICAL CYCLONE DURING THE NEXT 48 HOURS. REGARDLESS OF
DEVELOPMENT...CLOUDINESS AND HEAVY RAINS WILL LIKELY SPREAD OVER
NORTHERN VENEZUELA AND THE SOUTHERN WINDWARD ISLANDS DURING THE
NEXT FEW DAYS.
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Quoting SouthDadeFish:
12Z Euro shows Tampa landfall in seven days. Keep in mind those is a long way out people:



Futher south then tampa there closer to naples actually.
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96L.


97L.
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Euro weakens it by 15mb between Days 5 and 6:

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12Z Euro has a strong Hurricane impacting FL @168hrs. Looks like it split the Yucatan channel perfectly.
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euro hits tampa in seven days as a catgory 3
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12Z Euro shows Tampa landfall in seven days. Keep in mind this is a long way out people:

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Quoting Clearwater1:
The storm was observed on October 21 while several hundred miles southwest of Jamaica. Its origin is unknown, though it possibly developed from an extratropical storm over Panama a day earlier. A high pressure system over Bermuda caused a north-northwest motion, allowing for the storm to intensify over favorable conditions. On October 22, the storm attained hurricane status shortly after passing 10 miles (16 km) east of the Swan Islands. On October 23, the hurricane entered the Yucatán Channel, with its eastern side brushing Cuba.

Of course this is the 1921 storm that hit Tampa Bay. I know, different circumstances then than now, but they do form and can head north. Hurricane season ends Nov. 30th
Yeah I would literally give someone a million dollars if they would post the steering and sst at the time of that storm.
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12Z GFS run keeps it south of FL and moves it ENE across the FL straits and the Bahamas. For what it's worth. Florida definitely is not out of the woods. There hasn't been a major hurricane making landfall in the USA after Oct 25, but records are meant to be broken.

However if it does hit Florida I think an Irene 1999 type hurricane is close to the upper bound.

Images are clickable and expandable.


168 hours



192 hours

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96L is in a fairly favorable spot for development, in the western "lobe" of an elongated area of low pressure in the central Atlantic. If you think about an eliptical-shaped low pressure region, the highest index of curvature is going to be at each end of the major axis, and thus the highest vorticity will be found there as well. High pressure to the north over the SE US and to the west over the eastern Pacific is also helping to force air towards the western Caribbean, causing air to converge and form thunderstorms. This situation is resulting in a smaller circulation than the massive 95L, which was too large to really develop. 96L is smaller and could potentially wind up into a storm in a classic fashion.

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The storm was observed on October 21 while several hundred miles southwest of Jamaica. Its origin is unknown, though it possibly developed from an extratropical storm over Panama a day earlier. A high pressure system over Bermuda caused a north-northwest motion, allowing for the storm to intensify over favorable conditions. On October 22, the storm attained hurricane status shortly after passing 10 miles (16 km) east of the Swan Islands. On October 23, the hurricane entered the Yucatán Channel, with its eastern side brushing Cuba.

Of course this is the 1921 storm that hit Tampa Bay. I know, different circumstances then than now, but they do form and can head north. Hurricane season ends Nov. 30th
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We now have invest 97 also
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Quoting SouthDadeFish:
12Z Euro at day 5 seems even farther west:



Looks like this will be a powerful hurricane.
I believe that says 973mb which typically translates to a mid-range Cat. 2 Hurricane. And notice the High Pressure to the North and the trough starting to come into the picture over Texas.
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oh noooo, more Invests !!!! I was thinking in Thanksgiving Day already. hopefully, Tampa Bay is out of the woods for the rest of the Hurricane Season.
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As of tomorrow, it will have been four weeks (28 days) since Ophelia was named. At the moment, we are one named storm behind 2010 on this date, three behind 1995, and five behind 2005. Though I have to say, for now it looks like we'll likely see Rina (#18) and possibly even Sean (#19) in the next few days.

Strictly speaking in terms of named storms, 2011 has been above average every month of the season.
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Gulf and Tropics (Updated every ~1/2 hour)

GOES-13 Low Cloud Image/Loop

..click Image for Loop


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And just when I expect it to be a TS coming here to South Florida, some models are bombing it out. Great....
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12Z Euro at day 5 seems even farther west:



Looks like this will be a powerful hurricane.
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Quoting GTcooliebai:
If I were in the Cayman Islands I would be watching this one too.


What really alarms me about these October/Nov systems they move very little giving them time to fester and intensify!
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Quoting ryang:
We might have 97L soon...

Good call...
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I think Rina is waiting to be a bad one, jmo.
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I suppose something like this can't be ruled out



or this

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The 12Z Euro has 96L becoming a hurricane in 96 hours:

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Quoting Drakoen:
Plenty of fuel to work with especially when the system gets into the Central and Northern Caribbean.

That area has gone untapped all season. If wind shear remains light enough, 96L has the potential to be a monster in a few days. Hopefully the shear will keep it in check.
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Quoting stormwatcherCI:
Don't forget Paloma. She developed the first week of November in the same area.
If I were in the Cayman Islands I would be watching this one too.
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Plenty of fuel to work with especially when the system gets into the Central and Northern Caribbean.

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Quoting SouthDadeFish:
Definitely one to watch as this looks to be shaping up te become a classic late October hurricane in the NW Carib. I also agree that it is too early to speculate on a long-range track. The point is we have a strong model consensus on 96L intensifying and moving north....
It shouldn't come as a surprise either, just looking back at some classic Oct. Hurricanes and most of them from this position has went on to hit the Western Tip of Cuba. If I were in Cuba I would keep a watchful eye on this. I think this will also come down to timing with the approaching front.
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Quoting GTcooliebai:
Is it me or does that area seem conducive for quick spin ups i.e. Mitch, Beta, & Ida?
Don't forget Paloma. She developed the first week of November in the same area.
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Btw we now have this:



BEGIN
NHC_ATCF
invest_al972011.invest
FSTDA
R
U
040
010
0000
201110211801
NONE
NOTIFY=ATRP
END
INVEST, AL, L, , , , , 97, 2011, DB, O, 2011102118, 9999999999, , , , , , METWATCH, , AL972011
AL, 97, 2011102018, , BEST, 0, 85N, 544W, 25, 1006, DB, 0, , 0, 0, 0, 0,
AL, 97, 2011102100, , BEST, 0, 86N, 548W, 25, 1006, DB, 0, , 0, 0, 0, 0,
AL, 97, 2011102106, , BEST, 0, 87N, 552W, 25, 1006, DB, 0, , 0, 0, 0, 0,
AL, 97, 2011102112, , BEST, 0, 88N, 557W, 25, 1006, DB, 0, , 0, 0, 0, 0,
AL, 97, 2011102118, , BEST, 0, 90N, 562W, 30, 1006, DB
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Quoting Drakoen:


This will definitely be one to watch as the models want to move this poleward possibly into the GOM. Some of the long range models have this impacting Florida, too early to say though.
Definitely one to watch as this looks to be shaping up te become a classic late October hurricane in the NW Carib. I also agree that it is too early to speculate on a long-range track. The point is we have a strong model consensus on 96L intensifying and moving north....
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The NHC has 96L up to 60% (RED CIRCLE)

October issue of the monthly Q & A with NHC professionals is available
Eastern Pacific Atlantic



60% Chance of Tropical Cyclone Formation (click for full outlook)
AN AREA OF LOW PRESSURE OVER THE WESTERN CARIBBEAN SEA IS CENTERED
ABOUT 170 MILES EAST OF THE COAST OF NICARAGUA. THE ASSOCIATED
SHOWER ACTIVITY HAS BECOME BETTER ORGANIZED...AND THERE IS A
LIKELIHOOD THAT A TROPICAL DEPRESSION WILL FORM DURING THE WEEKEND.
LITTLE MOTION IS ANTICIPATED IN THE SHORT TERM...BUT A SLOW
NORTHWARD DRIFT SHOULD BEGIN ON SUNDAY. THIS SYSTEM HAS A HIGH
CHANCE...60 PERCENT...OF BECOMING A TROPICAL CYCLONE DURING THE
NEXT 48 HOURS.


Graphical Tropical Weather Outlook | Active Storms | Marine Forecasts


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Quoting SouthDadeFish:
12Z GFDL and HWRF both bomb out 96L while bringing it into the NW Carib.....



This will definitely be one to watch as the models want to move this poleward possibly into the GOM. Some of the long range models have this impacting Florida, too early to say though.
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Interesting to see the NHC has given 96l a high chance for development! I haven't done much looking at it yet but I'm about to.
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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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