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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Some nice showers....every little bit helps :)

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Quoting Patrap:
Note the ULL forcing the Inland T-storms in Louisiana and Miss

Gulf Of Mexico - Rainbow Loop







And LOTS of high level cloud cover now in Tampa, with a nice breeze. First clouds and breeze of the day.
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hey hey hey ya'll in SFla- we need the rain up here in N Fla, too.
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Quoting scott39:
That cooled us off by 15 degrees, in NW Mobile county today....More better!!

Yes it did cool us off but we had no Rain at all....
Good to see ya on here again Scott39

"ugh"

Taco :o)
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Quoting watercayman:
Just got off the ocean. Winds in Cayman pretty consistent, hovering around 20kts out of the NE. Just a spit or two of rain, but skies darkening off and on throughout the day.
Where exactly are you ? Been having heavy showers off and on in East End all day and very overcast.
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Quoting watercayman:
Just got off the ocean. Winds in Cayman pretty consistent, hovering around 20kts out of the NE. Just a spit or two of rain, but skies darkening off and on throughout the day.


Keep us posted. It might get wetter over there later tonight.
Member Since: November 24, 2005 Posts: 635 Comments: 26659
Quoting hurricane23:


Very unlikely this thing does anything significant if it moves into the gulf as it would have to contend with 40-50 knot westerlies near cuban coast. If it wants to develope it still has a small window to so in the nw caribbean sea were conditions are decent but not great by any means.
Some of us are saying 45-65 mph TS at some point in its life. IMO conditions would really have to change greatly for anything more.
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Per Tropical Atlamtic...94L... 16.8N 79.6W Moisture looks to be filling in.
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Gomex SSTs:
Looking at buoy data, most of the mid gulf is around 82 at night to 85 in the day, trending higher.
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Quoting washingtonian115:
With my magical powers I'll give rain..with no wind.Should be coming in a few days.


Auntie Samantha is that you ?
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Quoting jasonweatherman2010:
winds up to 100 mph in 78 hours.
why is it so much easier for EPAC storms to get going than Atlantic storms??

Most epac storms don't even form from t waves like they do in the Atlantic which just shows that storms in the Atlantic often need the pre existing moisture, vorticity, and convection to form in the first place.
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Quoting hurricane23:


Very unlikely this thing does anything significant if it moves into the gulf as it would have to contend with 40-50 knot westerlies near cuban coast. If it wants to develope it still has a small window to so in the nw caribbean sea were conditions are decent but not great by any means.


Could this just develop into a weak TS and then park itself over South Florida for a couple of days ? We need the rain badly.

Please excuse any ignorance of the weather I am no expert but just a worry-wort about hurricanes, as I went through Andrew in South Dade and never want to experience that again.
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Quoting orthodoxkc:


I usually don't wish for a storm, but darn it my lawn here in Miami looks horrid too. WE NEED THE RAIN. Just no wind please ?
With my magical powers I'll give rain..with no wind.Should be coming in a few days.
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Just got off the ocean. Winds in Cayman pretty consistent, hovering around 20kts out of the NE. Just a spit or two of rain, but skies darkening off and on throughout the day.
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Pull up the latest RGB image, you can see the intense wrapping the system is under. The problem with models is that all of them have been all over the place with forecasting.
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Quoting NICycloneChaser:


Just to be awkward, I'm gonna go down the middle and say Wednesday :P
Wednesday is actually not at all unreasonable.

Quoting NICycloneChaser:
Looks like the EPAC is just going to beat the Atlantic to the first storm of the season. NOAA predicts 15 in both basins, so we have something of a competition on the cards.... Haha
I'm not surprised that we may see 91E form earlier. There's been a lot of monsoonal activity over there since before the start of the ATL season, with a couple of AOIs that looked fairly impressive. Furthermore, EPac usually has activity earlier than ATL because conditions become favorable there earlier than they do in our basin. That's one reason why their season opening date is 15 May.


Quoting SouthDadeFish:
IR looking pretty ragged....

Anybody besides me see what looks like a pattern on Tstorm formation all around a large central low? Clouds on the w side are near the Central American coast....

I've got to go, but I'm agreeing with the pple keeping this at 40% [or at most, 50%] for now. Everything with 94L seems to be slow burning. The low area is still pretty broad; there's a lot of consolidation left to be done; there are competing circulations. Maybe another 24 hours will bring this up to TCFA status....

Later all.
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Quoting NICycloneChaser:
The GFS shear forecast has the shear very high in the GoM in 4-5 days, would need to be a strong system to cope with that and get near the US as a decent storm.


Very unlikely this thing does anything significant if it moves into the gulf as it would have to contend with 40-50 knot westerlies near cuban coast. If it wants to develope it still has a small window to so in the nw caribbean sea were conditions are decent but not great by any means.
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Quoting sunlinepr:


In this loop it looks as if the systems showers are getting dispersed over a larger area, but less white (intense), is this a good or bad thing.

Remember to me a bad thing is if a storm develops.
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665:
What kind of shear was that system facing? It takes a major hurricane to put up a fight vs a Jet. Again, all shear is not created equal.
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Quoting wunderkidcayman:


I say its a bit more east than what you have it now
I concur kid.
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Quoting IKE:



Eeek. But we do need the rain... badly.
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Quoting pottery:
94L is a great start to the season.
It's irrational and confounding and has everyone tizzik!
Just like Tropical Weather is supposed to be.
Good Stuff!
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Definitely enough energy in the Carib to support intensification:

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THE NATIONAL WEATHER SERVICE IN LEAGUE CITY HAS ISSUED A

* TORNADO WARNING FOR...
NORTHWESTERN AUSTIN COUNTY IN SOUTHEAST TEXAS...
WASHINGTON COUNTY IN SOUTHEAST TEXAS...

* UNTIL 500 PM CDT

* AT 433 PM CDT...WASHINGTON COUNTY SHERIFFS OFFICE REPORTED A
TORNADO IN CHAPPEL HILL. THE SHERIFFS OFFICE REPORTED ROOF DAMAGE
AND DAMAGE TO A TV TOWER. THE STORM WAS MOVING SOUTHWEST AT 15
MPH.

* LOCATIONS IN THE TORNADO WARNING INCLUDE BUT ARE NOT LIMITED TO
SHELBY...INDUSTRY...CAT SPRING AND BELLVILLE.
Member Since: August 22, 2008 Posts: 12 Comments: 6010
Quoting tropicfreak:


Thankyou for that.Sst in the gulf getting awefully high thanks to that 90+ degree heat.Without any clouds either.Maybe if we have considerable cloudinous over the gulf that should keep it from warming up so much...
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Quoting congaline:
Another wishcaster for SFL landfall of TS Arlene the lawn looks like a nuke exploded on it! Rain, yes please!


I usually don't wish for a storm, but darn it my lawn here in Miami looks horrid too. WE NEED THE RAIN. Just no wind please ?
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670. HCW
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Member Since: August 2, 2010 Posts: 21 Comments: 9821


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Quoting eyestalker:

Which means it's still quite a bit lopsided to the east, but it's not as terribly disorganized as it was the last few days and if we see an enhancement of convection near this COC we should have a depression tomorrow.
I have to disagree on this position. I think the COC has moved to the east, or at least one has formed in that area. I see spin to the east of your original location.
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Quoting SouthALWX:
Also, An upper level anticyclone will only fend off that much shear if the system below it is pumping considerable amounts of air into it. With a marginal hurricane, and shear induced by a jet, no way it fends off 80-90% of it as you claim. Add to that that not all shear is created equal, (shear at differing heights affects the storm differently) and your statement is a hard one to argue for. Oth, this system has the potential to be a large one, and that would tend to help it against shear.


While I mostly agree, TS Barry established a small but albeit an effective anticyclone to find off from 40-50 knots of shear in the Gulf

and Barry was by no means a well developed system
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Where is everybody?.Everytime I get on people dissapear.Hmm maybe I do have magic after all.
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Quoting washingtonian115:
Can someone post the sst for the GOM.


Member Since: September 2, 2006 Posts: 110 Comments: 6878
Also, An upper level anticyclone will only fend off that much shear if the system below it is pumping considerable amounts of air into it. With a marginal hurricane, and shear induced by a jet, no way it fends off 80-90% of it as you claim. Add to that that not all shear is created equal, (shear at differing heights affects the storm differently) and your statement is a hard one to argue for. Oth, this system has the potential to be a large one, and that would tend to help it against shear.
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94L sure to be round in some form in 100 hours and more.

One to watch Long term,,for a drought buster somewhere.
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Can someone post the sst for the GOM.
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94L is a great start to the season.
It's irrational and confounding and has everyone tizzik!
Just like Tropical Weather is supposed to be.
Good Stuff!
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656. j2008
Quoting Inactivity:


I think it will go to about 50% at 8pm but the D-Max tonight will probably bring it up to a red 60% or 70% by 8am tomorrow morning, plus I think the conditions may get slightly better for development over the next 12-24 hours. Anyone agree with me?

I think you have a good point, we will have to see what happens tonight though.
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next TWO will probably be 50 %
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Quoting Patrap:
Note the ULL forcing the Inland T-storms in Louisiana and Miss

Gulf Of Mexico - Rainbow Loop





That cooled us off by 15 degrees, in NW Mobile county today....More better!!
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LOL Pat
The modeling reminds me of those champagne party poppers.
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Quoting eyestalker:

true, Cindy was pretty ugly too especially at first, Alberto and Barry looked horrible....Alex was an exception though.
Their have been some other ugly systems to.And they were not in June...such as Danny.Ewwww..just ew.
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You would be surprised: there can be very significant drops in wind speed over that last 33 feet.
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convection continues to increase near the midlevel center south of jamaica and i notice its tightening up, but i also see what levi is talking about a LLC SW of jamaica but it is very broad. quite frankly i have no clue what will happen
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Note the ULL forcing the Inland T-storms in Louisiana and Miss

Gulf Of Mexico - Rainbow Loop





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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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