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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847. xcool


Member Since: September 26, 2009 Posts: 2 Comments: 15672
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CIMSS TPW imagery is hinting at some dry air being drawn to the south of Cuba in the NW quad of 94L's circulation.

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Quoting Levi32:


Every season has the potential to see deadly destruction. You mentioned Andrew...1992 was a very quiet season overall, yet one of the costliest in history. In general, I expect the U.S. is more prone to landfalls, certainly more so than last year, when everything avoided the United States.


Besides tropical [thunder]storm Bonnie, but that was a typical rainy day in the sunshine state.
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Quoting TxHurricanedude11:

exactly different set up this year
"We dodge a cannonball".You'll think it's funny once you see where the joke comes from....
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If you right-click view image on the image I posted in post 831 you should get a bigger picture. I'd estimate the pressure with 94L to be around 1006mb, which is a nice low pressure for an invest/disturbance.
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Quoting galvestonhurricane:


Where I live south of Houston, we have had only 1 day of rain (.20") in more than 3 months. That is why we are complaining.


You guys need it worse than we do (Fl). The national news a few weeks ago was reporting animals falling out of trees and dying because they had no water????
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Quoting troy1993:
Levi32..do you think that we have the potential to see deadly destructive hurricanes hitting the United States this year..like(Katrina,Andrew, Ike)


Every season has the potential to see deadly destruction. You mentioned Andrew...1992 was a very quiet season overall, yet one of the costliest in history. In general, I expect the U.S. is more prone to landfalls this season, certainly more so than last year, when everything avoided the United States.
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Quoting scott39:
Good to see you too Taco. Did you experience that extreme lightning, wind, hail and rain storm on Friday Afternoon? It came up very fast and it was intense where I am!


Sorry I missed this but the only thing we got on Friday was "Lightning" no rain....

I do hope you got some today I know I did not get any as of yet, but it is Thundering to my East right now and hope it moves to the west....

Taco :o)
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Levi32..do you think that we have the potential to see deadly destructive hurricanes hitting the United States this year..like(Katrina,Andrew, Ike)
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Quoting CybrTeddy:
Drak is back! :) Welcome back!
Let's all throw a parade.Here no I'll go get the confetti...
Quoting TxHurricanedude11:

For now yes the high is not going to sit there the whole season lol...someone along the gulf coast will get hit this year the question is where along the gulfcoast.
That pattern that helped block storms along the U.S last year is not in place this year.
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834. xcool
damm blog all mess upp
Member Since: September 26, 2009 Posts: 2 Comments: 15672
The buoy directly west of 94L is certainly sensing the invest's approach. It will be interesting if we can get a nearly direct central pressure reading tonight when 94L drifts nearly overhead of the buoy.

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Quoting PlazaRed:
Quite a lot of people are going to get a severe drenching with rain out of this 94L!

All these impatient people in Florida and Texas and nearby states are going to have to wait your turns, I am sure your share has been ordered for later this season. This conglomeration is going to head north and its no doubt got a few brothers and sisters to follow!!

Oh, evening everybody!


Where I live south of Houston, we have had only 1 day of rain (.20") in more than 3 months. That is why we are complaining.
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Quoting Levi32:
The surface circulation is clearly evident here.

 That placement is correct and supported by the surface observations using NOAA's nowCOAST.


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Aquak9, here you go. It's the rain dance!!

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Quite a lot of people are going to get a severe drenching with rain out of this 94L!

All these impatient people in Florida and Texas and nearby states are going to have to wait your turns, I am sure your share has been ordered for later this season. This conglomeration is going to head north and its no doubt got a few brothers and sisters to follow!!

Oh, evening everybody!
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Quoting Grothar:


DRAK! You're back. I hope you don't mind me calling you Drak?


Good to read you again Drak! BTW Gro...you can call me Mr. Tibbs.
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Quoting CyclonicVoyage:


And so true.

Retired DJ here, you know the song??
I think it's called tonight is the night.It's on one of my CDs called dance mix usa.It has alot of dance songs aand then they mix into each other going into the end of the song.
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Quoting eliteforecaster:
so then why was the pressure min during the day? Is that because the bouy was not under the storm?


There's a difference between "DMIN" and diurnal pressure cycles. The former is what Hurry was talking about, with the air being the warmest during the day, decreasing the instability between the warm ocean surface and the atmosphere above.

Diurnal pressure cycles have a minimum pressure in the afternoon which is thought to be caused by solar heating and expansion of the upper atmosphere, which lowers the pressure at the surface during the height of the day. There is also a secondary diurnal cycle which has a pressure minimum just before sunrise.
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Drak is back! :) Welcome back!
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Always good to have as many knowledgeable level heads as you can around here.

Welcome back Drak.
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Finally Drak is back.

Good to see you.
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Quoting MrstormX:
94E will soon be 01-E, very impressive satellite image.


You mean 91E.
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Ok I see the LLC, but I think its more 16.5/79.1
Member Since: April 29, 2007 Posts: 0 Comments: 7862
Quoting Drakoen:

 I've always kind of been here. :)



welcome back
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Quoting Grothar:


DRAK! You're back. I hope you don't mind me calling you Drak?
Not at all!


Hey everyone! Good to see you guys keeping things alive here
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Quoting washingtonian115:

Tonight is the night,is the night of fun.
Forever and ever is never enough

Forever and ever is never enough.
It's from a song on one of my old Dance mix CDs.


And so true.

Retired DJ here, you know the song??
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Quoting Drakoen:
Satellite imagery shows a strong mid level rotation south of Jamaica. The RGB imagery is really good for seeing the distinction between the low level cloud movements and the mid to upper level clouds. Notice that the surface flow is southwesterly underneath the mid level center. Going to be interesting to see whether or not this mid level low can better align itself with the surface center.The upper level anticyclone is not directly overhead 94L judging from the CIMSS Wind shear maps. The clockwise flow around the high is producing marginally favorable upper level conditions. Water vapor imagery shows sinking air in the vicinity of the system which is helping to inhibit convection on the western side of the system. Global computer models show that this upper high may move more to the north and position itself better with the system over the next couple of days.

You're back! :D
Nice observation BTW.
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Quoting Levi32:


Great to see ya here Drak.
 I've always kind of been here. :)
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ohs Randrewl?
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Quoting TxHurricanedude11:

no its going to be much different US landfall wise this year than last year...btw the season just barely started


Why do you think that this year will be different? I noticed that whenever there is a huge high pressure area sitting over the S.E U.S that tends to block storms from entering the Gulf?
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Quoting Drakoen:
Satellite imagery shows a strong mid level rotation south of Jamaica. The RGB imagery is really good for seeing the distinction between the low level cloud movements and the mid to upper level clouds. Notice that the surface flow is southwesterly underneath the mid level center. Going to be interesting to see whether or not this mid level low can better align itself with the surface center.The upper level anticyclone is not directly overhead 94L judging from the CIMSS Wind shear maps. The clockwise flow around the high is producing marginally favorable upper level conditions. Water vapor imagery shows sinking air in the vicinity of the system which is helping to inhibit convection on the western side of the system. Global computer models show that this upper high may move more to the north and position itself better with the system over the next couple of days.
good write up hows college for ya going
Member Since: July 15, 2006 Posts: 171 Comments: 53846
91E will soon be 01-E, very impressive satellite image.
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Quoting Drakoen:
Satellite imagery shows a strong mid level rotation south of Jamaica. The RGB imagery is really good for seeing the distinction between the low level cloud movements and the mid to upper level clouds. Notice that the surface flow is southwesterly underneath the mid level center. Going to be interesting to see whether or not this mid level low can better align itself with the surface center.The upper level anticyclone is not directly overhead 94L judging from the CIMSS Wind shear maps. The clockwise flow around the high is producing marginally favorable upper level conditions. Water vapor imagery shows sinking air in the vicinity of the system which is helping to inhibit convection on the western side of the system. Global computer models show that this upper high may move more to the north and position itself better with the system over the next couple of days.


Great to see ya here Drak.
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Quoting Hurrykane:

No..because the environment in relation to the storm, or rising tropical air is warmer per se, thereby decreasing the lapse rate, or how fast the air can rise then condense into clouds.
so then why was the pressure min during the day? Is that because the bouy was not under the storm?
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Quoting CyclonicVoyage:


Getting there, that's for sure. 94L should make a solid run tonight..

Tonight is the night,is the night of fun.
Forever and ever is never enough

Forever and ever is never enough.
It's from a song on one of my old Dance mix CDs.
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Quoting txjac:



Houston, Texas

Temperature
106.0 °F
Feels Like 113 °F


Wow
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The surface circulation is clearly evident here.

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I say 50 or 60% for 94L.
Anyone know if the tropical number index has changed?
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..were back in Drak,..

And I'm beatin' the flak
Nobody's gonna get me on another rap
Member Since: July 3, 2005 Posts: 424 Comments: 128344

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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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