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 txjac:
http://www.drought.unl.edu/dm/DM_south.htm


Test, first time trying to post an image.


Well, that didnt work ...lol


Here you Go:



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Quoting wunderkidcayman:

I see what you are seeing and telling us. but with every image it seems to be getting weaker, most likely because a new COC is forming or already formed, and it is stronger, so it is steeling the COC that you are looking at. so the location of where this next COC is well... the only place I could find was right underneath the MLC, and plus the vort map show the COC that you are eyeing on at 850mb so what about vort at 925mb how do they look


The 925 mb vort map confirms what I have been saying

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94L starting too look good



do you guys think 94L will look good in a drss?
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Anyway I see that our system is almost taking advantage of it's surroundings now.We could could see a tropical depression by Thursday/friday.But I still have my doubts.
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393. IKE

Quoting xcool:


12z uk
998mb by tomorrow....
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Anyone remember this little sucker?

Mid June 2010
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Quoting Grothar:


I don't believe the low will move over South Florida, but as stated by the most current observations, there will be very increased rain chances and even wind conditions will probably change. Remember, in MOST systems, the heavy weather is normally in the western section of an organized system. One could therefore deduce that the even if the system were to move to the west of the penisula, there could be sufficient weather to the east.
the east side is the dirty side of the system the western side normally is the weaker , but that depends from system to system
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It will be interesting to see if this buoy bottoms out in the diurnal valley lower than the previous cycle:

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Quoting kmanislander:


The fact that it is hard to find is an indication that convection is building over the low and obscuring it from clear observation. Run the RGB loop and cover the mid level spin by placing a sheet of paper over it on your computer screen. This will prevent your eyes being distracted by the mid level rotation.

You can then see the inflow from the South West into that cluster of storms I was referring to and then above them you will see the cloud field rotating to the West. Those clouds are where the surface low is.

I see what you are seeing and telling us. but with every image it seems to be getting weaker, most likely because a new COC is forming or already formed, and it is stronger, so it is steeling the COC that you are looking at. so the location of where this next COC is well... the only place I could find was right underneath the MLC, and plus the vort map show the COC that you are eyeing on at 850mb so what about vort at 925mb how do they look
Member Since: June 13, 2009 Posts: 2 Comments: 12710
Quoting sammywammybamy:


Gro...

Do you still Belive this will hit South Florida?

I Favor a track that slowly travels over the Gulf of Mexico Skirting Florida's West Coast.... and finally making landfall in the panhandle?





I don't believe the low will move over South Florida, but as stated by the most current observations, there will be very increased rain chances and even wind conditions will probably change. Remember, in MOST systems, the heavy weather is normally in the eastern section of an organized system. One could therefore deduce that the even if the system were to move to the west of the penisula, there could be sufficient weather to the east.
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387. IKE
Quoting sammywammybamy:


Ike... Judging by that picture...

If 94L moves North towards the Panhandle.. west of the Peninsula of Florida...

Would it still drag all that rain that is East of 94L Currently Over the Peninsula?

If that is the case then count me in!
Here's the 6-10 day precip. outlook....shows above normal for the peninsula of Florida....


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386. xcool


12z uk
Member Since: September 26, 2009 Posts: 2 Comments: 15684
Quoting kmanislander:
Charcoal colour showing up now in the thunderstorm complex.



That means its going to bubble over now. If that happens and it covers the llc; just before darkness covers the visible it should bubble up one last time like with Richard last year.
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Quoting IKE:
Looks like a flooding issue....with 94L....a lot of moisture.....




Ike... Judging by that picture...

If 94L moves North towards the Panhandle.. west of the Peninsula of Florida...

Would it still drag all that rain that is East of 94L Currently Over the Peninsula?

If that is the case then count me in!
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Quoting Bitmap7:


The peak of dmin.


Not today I don't think. Dmin is only about 3 hours away and the thunderstorms continue to build.
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Quoting IKE:
Looks like a flooding issue....with 94L....a lot of moisture.....




Ike, that long tail moving from the South will reach Puerto Rico and cause even more flooding issues tonight and Monday. PR is under a flash flood watch until Tuesday afternoon.
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Quoting kmanislander:
Charcoal colour showing up now in the thunderstorm complex.

all we need is for the convection to increase alot more over the center but the current convection is fairing quite well
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380. txjac
http://www.drought.unl.edu/dm/DM_south.htm


Test, first time trying to post an image.


Well, that didnt work ...lol
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Quoting kmanislander:


I don't think it is still that far removed based upon the inflow to that cluster of thunderstorms. One thing seems certain and that is the low center is on the way to being covered over unless something happens to slow it down.


The peak of dmin.
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Charcoal colour showing up now in the thunderstorm complex.

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Quoting CosmicEvents:
Stop kvetching about the lack of recon. We can look at what's going on with the satellite and radar. If it looks like a
.
.

.
.
it's a
.
.


The info from recon is so much more accurate and completely outweighs anything we would see ourselves from satellite images
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i can't comment
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Quoting Levi32:


If you get really zoomed in I still see the center of the broad low clearly west of the convection. The uncertainty right now lies in the area you described on the western edge of the convection where the vorticity is strengthening towards, indicating that the low may eventually refocus to that location. It's always hard to pick out centers within a broad circulation that can have multiple vortices.


I don't think it is still that far removed based upon the inflow to that cluster of thunderstorms. One thing seems certain and that is the low center is on the way to being covered over unless something happens to slow it down.
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373. xcool
IKE thanks.
Member Since: September 26, 2009 Posts: 2 Comments: 15684
372. ackee
Quoting wunderkidcayman:

I agree with you it seem this way
I think you right been noticing that too seem like covention growing over the centre for the first time
Member Since: July 15, 2008 Posts: 0 Comments: 1376
371. IKE
Looks like a flooding issue....with 94L....a lot of moisture.....


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Quoting HurricaneHunterJoe:
are we on the death bandwagon or live long and prosper bandwagon with regards to 94L?


For the benefit of the southern US, somewhere inbetween, I think.
Member Since: August 10, 2010 Posts: 2 Comments: 1971
Quoting FLdewey:
Just got down off the roof... I think I can can just barely see the feeder bands to the South.

Time to test the emergency beverage center... ya know just to ensure we still have freshness.



contrails
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Quoting FLdewey:
Just got down off the roof... I think I can can just barely see the feeder bands to the South.

Time to test the emergency beverage center... ya know just to ensure we still have freshness.



LOL
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Quoting Seflhurricane:
levi does it look like the midlevel center Se of jamaica is trying to become the dominant center


I doubt it. Those features are common after convection has died in the area, and they rarely do anything in terms of working down to the surface.
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Quoting kmanislander:


The fact that it is hard to find is an indication that convection is building over the low and obscuring it from clear observation. Run the RGB loop and cover the mid level spin in the mid levels by placing a sheet of paper over it on your compuetr screen. This will prevent your eyes being distracted by the mid level rotation.

You can then see the inflow from the South West into that cluster of storms I was referring to and then above them you will see the cloud field rotating to the West. Those clouds are where the surface low is.


If you get really zoomed in I still see the center of the broad low clearly west of the convection. The uncertainty right now lies in the area you described on the western edge of the convection where the vorticity is strengthening towards, indicating that the low may eventually refocus to that location. It's always hard to pick out centers within a broad circulation that can have multiple vortices.
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364. IKE

Quoting kmanislander:


I agree with that. See my post 357
I saw that and agreed.
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Quoting MarcoIslandCat5:
Evening all, Can someone tell me what affect 94l is having on sea temp's underneath it does such a system remove heat from the ocean at all??

It does remove some heat, but not a substantial amount. Another system would have no problem forming after 94L left the area if conditions permitted. I'm sure someone else can go into more details on how strong systems usually are to have a noticeable effect on SST's.
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Quoting kmanislander:


The fact that it is hard to find is an indication that convection is building over the low and obscuring it from clear observation. Run the RGB loop and cover the mid level spin in the mid levels by placing a sheet of paper over it on your compuetr screen. This will prevent your eyes being distracted by the mid level rotation.

You can then see the inflow from the South West into that cluster of storms I was referring to and then above them you will see the cloud field rotating to the West. Those clouds are where the surface low is.
thanks i see it now convection is firing right over the center
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are we on the death bandwagon or live long and prosper bandwagon with regards to 94L?
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Quoting Grothar:
Sorry, but I see the system moving more NW than WNW at this time. Depending on the strength and the position of the ridge to the North, this will most likely move over Western or central Cuba first. Just take a slow look at it now.

Link


Gro...

Do you still Belive this will hit South Florida?

I Favor a track that slowly travels over the Gulf of Mexico Skirting Florida's West Coast.... and finally making landfall in the panhandle?



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359. IKE
Key West discussion....

EXTENDED...THURSDAY THROUGH SUNDAY...BOTH 12Z ECMWF AND GFS BRING
THE UPPER LOW EASTWARD INTO THE CENTRAL GULF. THIS IN TURN BEGINS TO
PULL UP MID AND HIGH LEVEL MOISTURE OUT OF THE CARIBBEAN SEA ON
THURSDAY. BOTH 12Z GFS AND ECMWF PULL REMNANTS OF THE LOW PRESSURE
SYSTEM NOW LOCATED 150 MILES SOUTHWEST OF JAMAICA NORTHWARD THURSDAY
AND FRIDAY...THEN ACROSS WESTERN CUBA ON SATURDAY AND INTO THE
SOUTHEASTERN GULF OF MEXICO ON SUNDAY. 12Z GFS MODEL FORECAST
SOUNDINGS ARE ILLUSTRATING PWAT RISING TO 1.50 ON THURSDAY...BETWEEN
1.50 AND 2.00 INCHES ON FRIDAY...AND ABOVE 2.00 INCHES FRIDAY AND
SATURDAY. THE 12Z ECMWF IS ALSO ILLUSTRATING EVEN DEEPER MOISTENING
THAN THIS. GIVEN THE UNCERTAINTIES WITH THIS SYSTEM AM STILL GOING
TO MAINTAIN LOW CHANCE POPS FRIDAY THROUGH THE WEEKEND...BUT RAIN
CHANCES MAY NEED TO BE RAISED IF THERE IS ADDITIONAL RUN CONSISTENCY
IS OBSERVED DURING THE NEXT COUPLE OF CYCLES. HAVE ELECTED TO
INCREASE OVERALL SHOWER AND THUNDERSTORM COVERAGE FRIDAY THROUGH
SUNDAY. IN ADDITION TO INCREASED MOISTURE...THE COMBINATION OF THE
WEAK LOW PRESSURE MOVING ACROSS WESTERN CUBA AND RIDGING TO THE
NORTH WILL ONCE AGAIN INCREASE THE LOCAL GRADIENT ACROSS THE KEYS
AND ADJOINING WATERS. HAVE ALREADY INCREASED WINDS ONE CATEGORY
HIGHER FROM WEDNESDAY THROUGH THE WEEKEND. AGAIN IF MODELS REMAIN
CONSISTENT WITH THE TRACK OF THIS WAVE/TROUGH...MIGHT NEED TO
INTRODUCE BREEZY CONDITIONS FOR THURSDAY THROUGH THE WEEKEND. STAY
TUNED.
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Quoting IKE:
Looks like convection is popping near or over the center now.


I agree with that. See my post 357
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Quoting Seflhurricane:
thanks kman as always. i am trying to find the dominant low center but it is hard tofind on visible but i do see what you mean SW of jamaica


The fact that it is hard to find is an indication that convection is building over the low and obscuring it from clear observation. Run the RGB loop and cover the mid level spin by placing a sheet of paper over it on your computer screen. This will prevent your eyes being distracted by the mid level rotation.

You can then see the inflow from the South West into that cluster of storms I was referring to and then above them you will see the cloud field rotating to the West. Those clouds are where the surface low is.
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356. IKE

Quoting xcool:
dose any ONE have Visible for 94L FROM rammb.cira.colostate.edu
I've been looking, but they haven't put a floater on it.
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good day everybody
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Just got down off the roof... I think I can can just barely see the feeder bands to the South.

Time to test the emergency beverage center... ya know just to ensure we still have freshness.

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Are you at the met office today wunderkid?
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352. IKE
Looks like convection is popping near or over the center now.
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351. hamla
it seems like 94l is gaining a lot more outflow in the higher ups and the shear is starting to weaken some what
which will be the dominating feature in thge coming hours/days???
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Quoting wunderkidcayman:

I agree with you it seem this way


I agree as well.
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Quoting BLee2333:
Looks like we have a little action out there.

I made it safely to Iraq...

Just wanted to say "Hi", and let you all know I may be in and out a lot this season. I'll post as the internet and situation permits!
Stay safe over there.
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348. xcool
dose any ONE have Visible for 94L FROM rammb.cira.colostate.edu
Member Since: September 26, 2009 Posts: 2 Comments: 15684
Quoting Seflhurricane:
looking at visible images it appears the midlevel center is taking over look closely as convection is refiring up and how convection is wraping around the west side , what it appears to me is that the circulation off the SW jamaica may be weak and the new center getting stronger

I agree with you it seem this way
Member Since: June 13, 2009 Posts: 2 Comments: 12710

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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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