Caribbean disturbance 94L dumping heavy rains on Jamaica

By: Dr. Jeff Masters , 4:44 PM GMT on June 05, 2011

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A large, wet, and disorganized tropical disturbance (Invest 94L) continues to spread heavy rain to the Central Caribbean near Jamaica. Rain has fallen continuously at Jamaica's Kingston Norman Manley Airport since midnight, with 1.89" having fallen from midnight to noon local time. Sustained winds of 24 mph also affected Kingston between 7am and 8am this morning. Satellite-estimated rainfall amounts of 1.4" per hour occurred in ocean regions 100 miles to the southeast of Kingston this morning, and heavy rains of up to 1/2" per hour are probably affecting portions of Jamaica early this afternoon, judging by the recent increase in heavy thunderstorm activity seen on visible satellite loops. This imagery also shows a slow increase in organization of 94L in recent hours, with spiral bands beginning to develop to the southeast of the center. There is a broad, poorly-defined circulation apparent that is not well enough defined to make 94L a tropical depression. Water vapor satellite loops show a region of dry air on the west side of 94L, and this dry air is interfering with the storm's organization. However, upper air balloon soundings from Kingston and the Cayman Islands taken at 8am EDT this morning show much moister air at mid levels of the atmosphere compared to Saturday (2% humidity at 500 mb on Saturday, compared to 49% this morning at Grand Cayman), and 94L appears to be gradually overcoming its dry air issues. Wind shear remains in the moderate range, 15 - 20 knots, and is predicted by the SHIPS model to remain below 20 knots through Tuesday morning. Water temperatures in the Central Caribbean are about 1°C above average, 28 - 28.5°C, which is 2°C above the threshold needed to support development of a tropical storm.


Figure 1. Rainfall rates of up to 1.4" per hour (pink colors) were estimated by the F-15 satellite for 94L at 6:02am EDT Jun 5, 2011.

Since 94L is so large and is battling dry air, it is taking its sweet time to develop, and today's mission by the Hurricane Hunters has been cancelled. A new mission is scheduled for Monday afternoon at 2pm EDT. This morning's 06Z model runs are pretty unimpressed with 94L, with most of them showing little or no development. At 2pm EDT on Sunday, NHC gave the disturbance a 40% of developing into a tropical depression by Tuesday. If 94L stays to the south, its chances of development are greater, since a band of very high wind shear of 30 - 50 knots lies over Cuba and the southern Bahama Islands. The disturbance is expected to meander slowly westward or northward over the next two days, with Jamaica and southeastern Cuba being the primary targets for very heavy rains of 4 - 8 inches through Tuesday. Haiti and Central Cuba can expect somewhat lesser rains of 3 - 6 inches. If 94L does develop into a tropical depression and moves northwards over Cuba by Wednesday, I don't see the storm attaining hurricane strength, due to the high wind shear. The primary threat from 94L will be very heavy rains, capable of causing life-threatening flash flooding.


Figure 2. Afternoon satellite image of the Central Caribbean disturbance 94L.

Jeff Masters

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1597. Walshy
Points of Origin



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Bay of Bengal huh, anyone have a link to the disturbance in there dam sst's there are very hot, better not be another developing cyclone nargis.Dam worst human tradgedy of the modern era, may 2008 with stay with me forever looking at that aftermath and death toll there, to this day they are still pulling up skeleto remains from the river banks and rice fields.
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Quoting Ylee:
I always liked that card game.....


Mornin Ylee....Hope u not workin too hard!!
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1594. Ylee
I always liked that card game.....
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Quoting KoritheMan:

The what? :)
You know, the place where a certain black bird is found.
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1592. Walshy
Convection exploding as one would expect.

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Quoting Mikla:
I may be in the minority, but I don't think there was a LLC S of Jamaica in the past 12 hours. It appears the upper level winds gives the appearence of a spin as the heat is vented off to the E from the anti-cyclone.

Also, the decending ASCAT pass shows no sign of a previous LLC...

But I have been wrong once before...

In any case, I think the NHC will go ahead with the afternoon recon flight.


If you look carefully, you can see a slight curvature of the wind barbs at about 77.8W, 15.8N, that could be the infamous LLC. I don't think that LLC is nearly as well defined as a lot of others do though.
Member Since: August 10, 2010 Posts: 2 Comments: 1971
1590. HadesGodWyvern (Mod)
India Meteorological Department
Tropical Cyclone Outlook
11:30 AM IST June 6 2011
==================================

Bay Of Bengal
-------------

Broken intense to very intense convection over Bay of Bengal south of 11.0N east of 83.0E and between 12.5N to 15.5N and 82.5E to 91.0E, northeast Andaman Sea. Broken low/medium clouds with embedded moderate to intense convection over northeast Bay of Bengal and Arkan coast and rest Bay of Bengal south of 18.0N east of 83.0E, gulf of Martaban, Tenasserim coast, and rest Andaman Sea.

Arabian Sea
------------------

Low level circulation over Arabian Sea off Maharastra coast has intensified into a low pressure area over central and adjoining northeast Arabian Sea. The vortex is the INSAT imagery is centered near 19.0N 71.5E with Dvorak intensity of 1.0. The chance of this low pressure to intensify further into a depression during the next 24 hours is MODERATE.

Associated broken intense to very intense convection over Arabian Sea (Cloud Top Temperatures -80C) north of 12.5N east of 68.0E and adjoining exterior south Guj and adjoining Gulf of Cambay.
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1589. Mikla
I may be in the minority, but I don't think there was a LLC S of Jamaica in the past 12 hours. It appears the upper level winds gives the appearence of a spin as the heat is vented off to the E from the anti-cyclone.

Also, the decending ASCAT pass shows no sign of a previous LLC...

But I have been wrong once before...

In any case, I think the NHC will go ahead with the afternoon recon flight.
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Quoting Hugo7:

 They are not going off what of the lower level winds.
I've been following the low cloud motions all evening. There is still a broad circulation in that vicinity, I agree. But it appears to be quite diffuse and is losing its luster. Whereas there was evidence of weak cyclonic banding in the vicinity of the mid-level circulation several hours ago.

If I am indeed incorrect in my thinking, I will be the first to admit it.
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1587. Hugo7
Quoting Mikla:
Folks keep talking about the LLC being to the East, but the ASCAT pass does not support that. It is still around 81W, 16.5N...


People are going off of the visual circulation of cloud tops. They are not going off what of the lower level winds.
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1586. ackee
Quoting alfabob:
Strong circulation clearly evident between the convection just south of jamaica and the convection below the small gap to the south of that. (77.6W, 17.2N)
I agree with dont see the centre where the NHC has it too hope recon will go out there later
Member Since: July 15, 2008 Posts: 0 Comments: 1372
Given Satellite loops, the coc was very clearly South of Jamaica before convection fired there... it is quite obvious, given that a few hours ago before convection fired there, you could see the spin....
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1584. Mikla
Folks keep talking about the LLC being to the East, but the ASCAT pass does not support that. It is still around 81W, 16.5N...
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Quoting NICycloneChaser:


Shear on the up, unfortunately for 94L. Anti-cylcone aloft is moving away from 94L.
If indeed that convection isn't the signification of a possible center reformation, then I think it's safe to bid adieu to 94L.
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Shear on the up, unfortunately for 94L. Anti-cylcone aloft is moving away from 94L.
Member Since: August 10, 2010 Posts: 2 Comments: 1971

Quoting TomTaylor:
the Rooky mountains
The what? :)
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It's raining in San Diego right now!

Pretty rare to see rain in June, but thanks to that cut off low sitting off of central California, were getting a few showers. Sierra Nevadas are likely getting some more snow on the 8000 ft plus peeks which is really out of season and is coming in addition to what is already a record year in terms of snow for the entire mountain range as well much of the Rooky mountains
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1578. Walshy
Quoting xcool:
wow 94L


wow
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1577. xcool
wow 94L
Member Since: September 26, 2009 Posts: 2 Comments: 15670
Quoting Walshy:


hmm interesting. 2 weeks out. But still interesting
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1575. emguy
Hurricane Center pretty much has this nailed. Satellite imagery is pretty telling. Based on appearance, best convection is off to the east and northeast and removed from the center. Mean time, being a broad low pressure system, there is no per say center of circulation and there will not be one for some time (that is if it even gets itself together). Only thing to track is a "point" of lowest pressure, which will likely bounce around erratically within this broad area in the coming days. Either way, a nice broad system would be awesome news in Florida because it could provide widespread, but very beneficial rainfall with no additional affects. If development did occur, It would need to tighten up quickly before the shear returns in 2 days. Either way, this is a true June atttempt. Something everyone gets excited about, but little to no chance of being more than a 50-60 mph deal at peak if it actually did manage to get together, which it has no signs of doing so now.
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Look at this, possibly the first cyclone of the 2011 pacific hurricane season:
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1573. HadesGodWyvern (Mod)
RSMC Miami National Hurricane Center
Tropical Cyclone Outlook
11:00 PM PDT June 5 2011
==================================

Satellite images during the past few hours indicate that the area of disturbed weather centered about 450 miles south of Acapulco, Mexico has changed little in organization. However, environmental conditions remains very favorable for development.

Tropical Cyclone Formation Potential
======================================
There is a HIGH chance of this disturbance to form into a tropical cyclone within the next 48 hours
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1572. Walshy
Down the Road...
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1571. xcool
Member Since: September 26, 2009 Posts: 2 Comments: 15670
1570. JLPR2
Quoting alfabob:
It doesn't make sense why NHC is watching the old circulation which is evident by that update and where they drew the circle. The old LLC is elongated and headed into 40-50kt shear (its not even a circulation anymore), there should be a 20% of that area or less. If on the other-hand they moved it over to the new area and a new LLC actually exists, I would give it a 60% by looking at the current convection. That would all depend on if the convection persists throughout the night though. Potentially dangerous situation.


There is no concrete proof that a new LLC exists, I guess that's why they kept the circle with the old LLC. If by tomorrow it becomes evident a new circulation formed they will then move the circle and up the probability.
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Quoting alfabob:
It doesn't make sense why NHC is watching the old circulation which is evident by that update and where they drew the circle. The old LLC is elongated and headed into 40-50kt shear (its not even a circulation anymore), there should be a 20% of that area or less. If on the other-hand the moved it over to the new area and a new LLC actually exists, I would give it a 60% by looking at the current convection. That would all depend on if the convection persists throughout the night though.

I think that they don't know what to do so they just left it at 40% I think they know about reformation of the COC but they want to wait for convection to increase and for them to get the first vis sat image and also that the old COC is nearly dead in the water
Member Since: June 13, 2009 Posts: 2 Comments: 11978
1567. xcool
;
Member Since: September 26, 2009 Posts: 2 Comments: 15670
Hey, everybody. Just checking in 4 two minutes - can't sleep for some reason.

Quoting Levi32:
As fresh as they come:

It would seem that the low remains broad and has not relocated yet.

This is basically what I saw before I left this p.m..... the area of low pressure was still too broad to allow any serious development. It really needs to tighten up tonight if it's going to get going anytime soon.

Are models still not putting 94L N of Cuba before the end of the week?
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been watching the continuous cycles of organization and convection that is 94L... Good monday to all, bye
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Good early morning everyone... Going to sleep... very weary O.O
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I think Recon will fly into 94L, its looking much better, Cmon 94L! Keep it up, so Recon can fly, and answer some of the questions that you keep making us ask.
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1560. JLPR2
Quoting MiamiHurricanes09:
000
ABNT20 KNHC 060541
TWOAT

TROPICAL WEATHER OUTLOOK
NWS NATIONAL HURRICANE CENTER MIAMI FL
200 AM EDT MON JUN 6 2011

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

A LARGE BUT DISORGANIZED AREA OF DISTURBED WEATHER ASSOCIATED WITH A
BROAD AREA OF LOW PRESSURE CONTINUES OVER A LARGE PORTION OF THE
CENTRAL AND WESTERN CARIBBEAN SEA. THE AREA OF LOWEST PRESSURE IS
LOCATED ABOUT 175 MILES SOUTH OF GRAND CAYMAN AND REMAINS SEPARATED
FROM THE STRONGEST THUNDERSTORM ACTIVITY. HOWEVER...SOME
DEVELOPMENT OF THIS SYSTEM IS POSSIBLE DURING THE NEXT DAY OR SO
BEFORE UPPER-LEVEL WINDS BECOME UNFAVORABLE. THERE IS A MEDIUM
CHANCE...40 PERCENT...OF THIS SYSTEM BECOMING A TROPICAL CYCLONE
DURING THE NEXT 48 HOURS. AN AIR FORCE RESERVE HURRICANE HUNTER
AIRCRAFT IS SCHEDULED TO INVESTIGATE THE SYSTEM LATER TODAY...IF
NECESSARY. REGARDLESS OF DEVELOPMENT... HEAVY RAINS COULD CAUSE
FLASH FLOODS AND MUD SLIDES OVER PORTIONS OF HAITI AND JAMAICA AS
THE SYSTEM MOVES SLOWLY TOWARD THE NORTHWEST OR NORTH OVER THE NEXT
COUPLE OF DAYS.

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

$$
FORECASTER AVILA


ha! Seems appropriate considering we have no idea if a new circulation is cooking underneath the convection.
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1559. JRRP
would be interesting to see in the morning
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40% Chance Still, pretty agreeable move i have to say by the NHC, need to see a surface circulation form under the convection South of Jamaica, then youll see the NHC up the %
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Quoting wunderkidcayman:

its D-Max but I am sure that is what you ment
I meant blog dmin. Like the time of minimal activity on the blog in terms of posting
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1556. xcool
Twinkster - cmc flip-flopping.
Member Since: September 26, 2009 Posts: 2 Comments: 15670
1554. JLPR2
Quoting sunlinepr:
Nice weather here....Rainy... Good for sleeping...







Yeah, going to do that soon.
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DANGIT MIAMI
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the organization and structure looking at the visible would coax me to think that it could be 60%, but the most likely % is 50%
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Quoting xcool:



cmc is crazy
Member Since: Posts: Comments:
000
ABNT20 KNHC 060541
TWOAT

TROPICAL WEATHER OUTLOOK
NWS NATIONAL HURRICANE CENTER MIAMI FL
200 AM EDT MON JUN 6 2011

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

A LARGE BUT DISORGANIZED AREA OF DISTURBED WEATHER ASSOCIATED WITH A
BROAD AREA OF LOW PRESSURE CONTINUES OVER A LARGE PORTION OF THE
CENTRAL AND WESTERN CARIBBEAN SEA. THE AREA OF LOWEST PRESSURE IS
LOCATED ABOUT 175 MILES SOUTH OF GRAND CAYMAN AND REMAINS SEPARATED
FROM THE STRONGEST THUNDERSTORM ACTIVITY. HOWEVER...SOME
DEVELOPMENT OF THIS SYSTEM IS POSSIBLE DURING THE NEXT DAY OR SO
BEFORE UPPER-LEVEL WINDS BECOME UNFAVORABLE. THERE IS A MEDIUM
CHANCE...40 PERCENT...OF THIS SYSTEM BECOMING A TROPICAL CYCLONE
DURING THE NEXT 48 HOURS. AN AIR FORCE RESERVE HURRICANE HUNTER
AIRCRAFT IS SCHEDULED TO INVESTIGATE THE SYSTEM LATER TODAY...IF
NECESSARY. REGARDLESS OF DEVELOPMENT... HEAVY RAINS COULD CAUSE
FLASH FLOODS AND MUD SLIDES OVER PORTIONS OF HAITI AND JAMAICA AS
THE SYSTEM MOVES SLOWLY TOWARD THE NORTHWEST OR NORTH OVER THE NEXT
COUPLE OF DAYS.

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

$$
FORECASTER AVILA
Member Since: Posts: Comments:
000
ABNT20 KNHC 060541
TWOAT

TROPICAL WEATHER OUTLOOK
NWS NATIONAL HURRICANE CENTER MIAMI FL
200 AM EDT MON JUN 6 2011

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

A LARGE BUT DISORGANIZED AREA OF DISTURBED WEATHER ASSOCIATED WITH A
BROAD AREA OF LOW PRESSURE CONTINUES OVER A LARGE PORTION OF THE
CENTRAL AND WESTERN CARIBBEAN SEA. THE AREA OF LOWEST PRESSURE IS
LOCATED ABOUT 175 MILES SOUTH OF GRAND CAYMAN AND REMAINS SEPARATED
FROM THE STRONGEST THUNDERSTORM ACTIVITY. HOWEVER...SOME
DEVELOPMENT OF THIS SYSTEM IS POSSIBLE DURING THE NEXT DAY OR SO
BEFORE UPPER-LEVEL WINDS BECOME UNFAVORABLE. THERE IS A MEDIUM
CHANCE...40 PERCENT...OF THIS SYSTEM BECOMING A TROPICAL CYCLONE
DURING THE NEXT 48 HOURS. AN AIR FORCE RESERVE HURRICANE HUNTER
AIRCRAFT IS SCHEDULED TO INVESTIGATE THE SYSTEM LATER TODAY...IF
NECESSARY. REGARDLESS OF DEVELOPMENT... HEAVY RAINS COULD CAUSE
FLASH FLOODS AND MUD SLIDES OVER PORTIONS OF HAITI AND JAMAICA AS
THE SYSTEM MOVES SLOWLY TOWARD THE NORTHWEST OR NORTH OVER THE NEXT
COUPLE OF DAYS.

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

$$
FORECASTER AVILA
Member Since: September 2, 2009 Posts: 130 Comments: 21193
Nice weather here....Rainy... Good for sleeping...





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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.