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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Quoting wunderkidcayman:

I think this is going to happen it will reform under the MLC then we shall see an increase in convection and by sunrise convection should be blowing like nukes and if this continues then TD by 2pm or 8 pm

One step at a time, let's see what happens with the circulations first.
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Quoting Levi32:


I did mention that. There are a handful of wind barbs to compare that are nearly opposite of what the GFS shows, but it would be nice to have a bigger cluster to be sure. It's not a significant issue though.
ok. Well just so I can see what you were getting at, could you put it in simple terms? Were the barbs on the initialization in different directions, or were the barbs showing too strong of winds relative to the satellite observations?
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Quoting tropicfreak:


Too weak?

Apparently.
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1094. aquak9
Caneswatch- STP- I knew you were an awesome person.
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Quoting pottery:

Looks so, doesnt it ?

I think this is going to happen it will reform under the MLC then we shall see an increase in convection and by sunrise convection should be blowing like nukes and if this continues then TD by 2pm or 8 pm
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Quoting sammywammybamy:


Putting the Northern Carribean, Bahamas, South Florida, Central and Northern Florida at a High Risk First

And then when the storms make into the gulf...

Alabama, Lousiana, Mexico , Texas, Missisipi at High Risk too


Exactly. Dr. Gray (I believe it was) put South Florida's odds of getting hit by a hurricane close to 50/50, according to the Storm Prep Guide given by the Palm Beach Post.
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1090. beell
Quoting Levi32:


I see no northeast or straight northerly winds over the Gulf of Mexico here.



Ok, I was looking at to the NE not from. My bad. Sat winds may be seeing the NE flow around the ridge whereas the model is not

There was also a weak disturbance moving along the LA coast today along the ridge with a little buckle at 500mb

All in all though. Not a big difference.

MESOSCALE DISCUSSION 1099
NWS STORM PREDICTION CENTER NORMAN OK
1101 AM CDT SUN JUN 05 2011

AREAS AFFECTED...SRN LA

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE

VALID 051601Z - 051730Z

...SLIGHT RISK WILL BE ADDED TO SRN LA AT 1630Z OUTLOOK...

LATEST SATELLITE AND DIAGNOSTIC DATA CONFIRM A WEAK CIRCULATION HAS
DRIFTED TO NEAR THE SERN LA COAST...MOVING WWD AT ROUGHLY 15KT.
STRONG HEATING ALONG THE WRN/SRN PERIPHERY OF THIS LOW PRESSURE
SYSTEM IS ENHANCING INSTABILITY ACROSS SRN LA SUCH THAT STRONG
STORMS ARE BEGINNING TO EVOLVE ALONG LEADING EDGE OF WWD-MOVING
CLOUD CANOPY. WITH TEMPERATURES WARMING WELL INTO THE 90S IT WOULD
SEEM LIKELY THAT A FEW OF THESE WEAKLY SHEARED UPDRAFTS COULD POSE
AT LEAST A RISK OF LOCALLY STRONG DOWNBURSTS GIVEN THAT VERY HIGH
PWAT...APPROACHING 2 INCHES...EXISTS INVOF THIS SYSTEM.

..DARROW.. 06/05/2011
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Quoting weatherwatcher12:
05/2345 UTC 17.0N 80.2W TOO WEAK 94L -- Atlantic


Too weak?
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1088. Patrap
'days they posted on the squall

wicked the winds and water was


The Cities awashed in seas


the noble one sends the Mighty fleet'
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05/2345 UTC 17.0N 80.2W TOO WEAK 94L -- Atlantic
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00z Best Track for 94L.

AL, 94, 2011060600, , BEST, 0, 169N, 801W, 25, 1007, DB

Link
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1085. Patrap
Member Since: July 3, 2005 Posts: 426 Comments: 128654
1084. Levi32
Quoting TomTaylor:
these images look pretty similar to me, I am confused on how you're make that conclusion, since the goes 250mb winds don't even show up over most of the w half of the gulf, so idk how you can tell what the winds are doing and hen relate those winds to the gfs initialization


I did mention that. There are a handful of wind barbs to compare that are nearly opposite of what the GFS shows, but it would be nice to have a bigger cluster to be sure. It's not a significant issue though.
Member Since: November 24, 2005 Posts: 635 Comments: 26654
1083. Bitmap7


91E should be in the same position as 94l. 90% means that the system shouldn't crumble under dmin, for its able to maintain convection on its own.
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Still unchanged wind-wise and pressure-wise. Other than that, just a nudge north and a nudge west.

AL, 94, 2011060600, , BEST, 0, 169N, 801W, 25, 1007, DB, 34, NEQ, 0, 0, 0, 0, 1010, 275, 175, 0, 0, L, 0, , 0, 0, INVEST, M,
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Quoting Levi32:
Anyone else notice how most of the models forecasts (GFS here for example) show this configuration of the 200mb trough in the Gulf of Mexico for 0z (10 minutes from now), yet the GOES upper winds analysis shows the trough much farther southwest and still more dug in and amplified than the models show.

18z GFS 6-hour 200mb forecast:



22:30z GOES WV upper winds analysis:


these images look pretty similar to me, but I am confused on how you're make that conclusion, since the goes 250mb winds don't even show up over most of the w half of the gulf, so idk how you can tell what the winds are doing and hen relate those winds to the gfs initialization
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Quoting weatherlover94:
i dont think there will be any landfalling hurricanes this year


Yeah, good call Nostradamus.
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Well, lets get with it guys and figure this situation out.....~~~~~dizzying....lol
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1077. pottery
Quoting Mrsenseofhumor:


He meant to say, that it will develop west of the current MLC.

Really?
Confirm that please Cayman.
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1076. Levi32
CMC 12-hour forecast at 300mb seems farther north and less deep with the trough in the western gulf as well. It may very well mean nothing, but still interesting.

Member Since: November 24, 2005 Posts: 635 Comments: 26654
5 minutes of big, well spaced drops on the west side of Kingwood. Probably would amount to a trace. Lots of thunder to the south of us towards downtown Houston.
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1070. hotrods
Hello everyone, all these maps have me confused, been looking at them most of day, one minute is one thing the next is something else.
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Quoting PlazaRed:


Hope you get lots more than that amount of rain over the next few days into a week or so.
863. galvestonhurricane Told us how bad you were having it with the heat earlier tonight, I sure hope you get some relief soon.


Still no rain for us in Friendswood, TX.
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1067. Levi32
Quoting sammywammybamy:


Still kinda Lost...

Just got back from the Beach...

Will the Trough pick the Storm up and send it NE or N?





It's not much of a steering trough here. Its influence mainly has to do with upper-level conditions over 94L. I'm just pondering whether the model actually captures the current depth of the trough over the southern gulf or not. It may not be a big issue, but it still looks a little different.
Member Since: November 24, 2005 Posts: 635 Comments: 26654
1065. pottery
Quoting wunderkidcayman:

because they think that the LLC may reform under the MLC

Looks so, doesnt it ?
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Quoting Patrap:
..."take my hand child and come with me,.and to a castle I will take you"...
great song. I love led zep
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Quoting Levi32:
Anyone else notice how most of the models forecasts (GFS here for example) show this configuration of the 200mb trough in the Gulf of Mexico for 0z (10 minutes from now), yet the GOES upper winds analysis shows the trough much farther southwest and still more dug in and amplified than the models show.

18z GFS 6-hour 200mb forecast:



22:30z GOES WV upper winds analysis:




Good observation.
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Quoting pottery:

Post 1051.
That shows the Highest Probability just south of Jamaica, at around 75w-77w. Certainly not at 80+w.
Why ?

because they think that the LLC may reform under the MLC
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1059. Levi32
Quoting beell:


Not sure if I follow you there. Sticking to the 200mb level, plenty of NE winds on the NE side. Trough axis on both extend from near the Mississippi coast to the coast in the BOC. Pretty good model representation for me.


I see no northeast or straight northerly winds over the Gulf of Mexico here.

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1058. Patrap


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200mb Vorticity

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1056. beell
Quoting Levi32:


I'd say stronger on the GOES analysis, based on the fact that the GFS has not a single east, northeast, or northerly wind barb on that image. The upper low seems more closed on satellite, though there is some uncertainty since it would be more defined the lower you go, until about 500mb.


Not sure if I follow you there. Sticking to the 200mb level, plenty of NE winds on the NE side. Trough axis on both extend from near the Mississippi coast to the coast in the BOC. Pretty good model representation for me.
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1055. Patrap
...
As the orbit of your hips
Eclipse
You elevate my soul..
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1054. pottery
Quoting jasonweatherman2010:
NEW BLUE COLOR ON HERE!!

Post 1051.
That shows the Highest Probability just south of Jamaica, at around 75w-77w. Certainly not at 80+w.
Why ?
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Quoting jasonweatherman2010:
NEW BLUE COLOR ON HERE!!


Why's there blue in the BOC? I don't see anything there.
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Quoting weatherlover94:
i dont think there will be any landfalling hurricanes this year


There will be. It looks like the A/B High will shift west causing more landfalling hurricanes.
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Quoting Tazmanian:
this year may be more like 09


Very, very doubtful.

Maybe like of 1999, 2004, etc.
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Quoting NICycloneChaser:


We have an east-caster! Lol


yea i was on here last hurricane season but stopped blogging out of hurricane season lol...but yea im on the east coast in West Virginia
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Quoting weatherlover94:
i dont think there will be any landfalling hurricanes this year


We have an east-caster! Lol
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1047. Levi32
Quoting beell:


Based on the wind barbs, they don't look that much different. Stronger in the model.


I'd say stronger on the GOES analysis, based on the fact that the GFS has not a single east, northeast, or northerly wind barb on that image. The upper low seems more closed on satellite, though there is some uncertainty since it would be more defined the lower you go, until about 500mb.
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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.