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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1546. JLPR2
The vort maps have me confused, just at what level is the circulation south of Jamaica? Thought it was mid-level but no decent reflection at the 500mb level. :\

Sheesh 94L is a confusing invest.
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alfabob, not the least 60%, more like the most. Poll that the NHC is dealing with right now...
40%: 23% Chance
50%: 57% Chance
60%: 19% Chance
70%: 1% Chance
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Quoting TomTaylor:
Its because we're approaching the blog dmin.

Lol. And tomorrow is a work day

its D-Max but I am sure that is what you ment
Member Since: June 13, 2009 Posts: 2 Comments: 11019
tygor, LOL yeah remind me not to drive an hour to San Antonio. Here the drought is just as bad. although i guess were a bit lucky. we saw some heat showers that produced about a tenth of rain(or less) Southeast texas got some decent showers today(gulf produced of coarse) WE NEED A TROPICAL STORM NOW!!!!!
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1541. docrod
Quoting Patrap:
le pays des merveilles de bonne nuit


bonne nuit
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Quoting alfabob:


the MLC should worl itself down to the surface while continuing to drag current LLc into the MLC that is why it looks elongated
Member Since: June 13, 2009 Posts: 2 Comments: 11019


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1538. xcool
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Quoting HurricaneDean07:
blog is slowing down a bit...
Its because we're approaching the blog dmin.

Lol. And tomorrow is a work day
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1536. Tygor
We were kind of hoping 93L or 94L would come to Texas, but it doesn't look like it's in the cards. 3/4" of rain in San Antonio since the first week of the year and people are starting to worry about the water supply. Already approaching Tier 3 of water restrictions and 0% of rain the next 10 days (which you can obviously take as a grain of salt). I'm not sure what stage 4 is but we might have a bunch of stinky people walking around ;)
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alfabob, seem that the circulation that the ascat caught is dissipating and a new circulation is forming south of Jamaica, near the convection, organization has increased a bit with 94L in the past few hours, so be interesting to see what the NHC has to say.
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1534. xcool
;)
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blog is slowing down a bit...
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the center should be relocated by 8AM or so.
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1530. xcool



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Most of what you guys see is just above the surface from 2,500 feet up to 10,000 feet above the surface
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Its not at the surface..latest surface reports has this still near 17N and 80.4W
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very impressive Circulation forming under the strong convection. should see a 50% or 60% at the TWO
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Nice convection popping up! :)

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1523. beell
IR Loop

Select the "Fronts" checkbox!
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1522. JRRP
este sistema se ha tragado 2 ondas tropicales
y no ha hecho absolutamente nada!
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I noticed it this afternoon on the 200mb from CIMSS however, it was just a tiny little speck at the time and I didn't think anything of it. It's definitely growing, evident just by clicking the -3hrs tab. Have to sleep on this one though, interested to see what it brings to the table.
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Quoting sammywammybamy:


Thank you very much!


My Thoughts:



I like it!!! Great graphic!
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Quoting alfabob:
It looks like any ULL more the the south is dissipating from the upper-level outflow being established. I think CIMSS is also off on the vorticity as there is a clear circulation established just south of Jamaica, which it says nothing about on any layer.


Looking at WV, it is clearly evident and last few frames you can see the moisture drying up around it.
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Quoting SouthDadeFish:
I agree. I have no idea where that came from?



Has to come up at 12:45am, lol. It will still be there in the morning. Have to think about this one...
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Quoting tennisgirl08:
KORITHE MAN - nice blog post. it really answered some of my questions. why do we think the track will shift east? to me the models are still pretty spread at this point..
If the center relocates farther east, it would lie in closer proximity to the mid-oceanic trough, and the weakness in the western Atlantic ridge. Hence a more poleward track.

And I disagree about the models being spread. Even the GFS, which is the only one not sending this into the Gulf as an organized entity, does at least foresee some weak 850 mb energy making its way into the Gulf.
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Why, thank you
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Levi or Drak, did you guys pick up on the ULL organizing to the south of 94L, any input on that??
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Quoting CyclonicVoyage:


This is news to me, not sure what it will do in the matter. I don't remember seeing or missed this in the models I looked at today.
No, it hasn't been shown in their upper vorticity forecasts.
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Quoting CyclonicVoyage:


This is news to me, not sure what it will do in the matter. I don't remember seeing or missed this in the models I looked at today.
I agree. I have no idea where that came from?
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Quoting ColoradoBob1:
105F in Houston Sunday , beat the old daily record by 7 degrees. 16 degrees above the average, and a new record high for the month of June.
Ouch.
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1508. beell
Quoting kmanislander:


A riddle within an enigma. Time to turn in. The convection is steadily expanding tonight so let's see where we stand tomorrow. We know that an intense cluster of thunderstorms has the capability to create a new area of lowest pressure underneath it.

Back in the morning.

Good night all.


Sounds like a plan, kman. Nite.
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Quoting KoritheMan:

That could complicate things...


This is news to me, not sure what it will do in the matter. I don't remember seeing or missed this in the models I looked at today.
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Quoting tennisgirl08:
KORITHE MAN - nice blog post. it really answered some of my questions. why do we think the track will shift east? to me the models are still pretty spread at this point..


I agree with this, LT could go any where at this point....




Taco:0)
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Complete Update

TS BUSTED FORECAST ALIBI






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1504. Patrap
le pays des merveilles de bonne nuit
Member Since: July 3, 2005 Posts: 420 Comments: 127549
105F in Houston Sunday , beat the old daily record by 7 degrees. 16 degrees above the average, and a new record high for the month of June.
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1502. KEEPEROFTHEGATE (Mod)
Member Since: July 15, 2006 Posts: 169 Comments: 53296
Quoting Patrap:
Most of the tourist flourish here in the Vieux Carre at Night easily.

Most fizzle after dawn as well.
That's French Quarter to most. When you go to the doctor for an earache hopefully he says your ear is infected or has a swimmer's ear rather than an otitis media/ externa. Always use the term most folks will understand, just saying. :)
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Quoting CyclonicVoyage:
Seems there is an upper level low organizing to the south of 94L. Also visible in WV.

200mb


That could complicate things...
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1499. KEEPEROFTHEGATE (Mod)
well iam out as well later bloggers 7 am comes fast
Member Since: July 15, 2006 Posts: 169 Comments: 53296
Quoting pottery:

Seen.


Member Since: August 19, 2006 Posts: 0 Comments: 15725
1497. pottery
Quoting kmanislander:


A riddle within an enigma. Time to turn in. The convection is steadily expanding tonight so let's see where we stand tomorrow. We know that an intense cluster of thunderstorms has the capability to create a new area of lowest pressure underneath it.

Back in the morning.

Good night all.

Seen.
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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.