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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1347. Levi32
Quoting kmanislander:


Maybe, but that area near 17 / 77 sure looks like a center relocation to me.


We won't really know until daylight or a possible ASCAT pass coming up shortly.
Member Since: November 24, 2005 Posts: 635 Comments: 26700
Quoting kmanislander:
Back on for a bit. I just ran the IR2 loop and the low center from earlier is no longer evident. I see a new low near 17N and 77W.

I hate these monsoon lows.


I been saying the same thing for past few hours also!
Member Since: April 29, 2007 Posts: 0 Comments: 8134
1345. Patrap
Member Since: July 3, 2005 Posts: 428 Comments: 129903
Quoting Levi32:


I still see it, elongated though it is. The low-level clouds at 15N, 80W are still moving out of the SW.


Maybe, but that area near 17 / 77 sure looks like a center relocation to me.
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1343. Patrap
Member Since: July 3, 2005 Posts: 428 Comments: 129903
looks like WX obs from Jamaica on the sat loop supports a developing LLC south of the Islands
Member Since: June 13, 2009 Posts: 2 Comments: 12719
1341. Patrap
Member Since: July 3, 2005 Posts: 428 Comments: 129903
1339. Levi32
Quoting kmanislander:
Back on for a bit. I just ran the IR2 loop and the low center from earlier is no longer evident. I see a new low near 17N and 77W.

I hate these monsoon lows.


I still see it, elongated though it is. The low-level clouds at 15N, 80W are still moving out of the SW.
Member Since: November 24, 2005 Posts: 635 Comments: 26700
1337. beell
Unenhanced IR Loop
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1336. Levi32
Quoting alfabob:
This is a buoy by the old LLC, winds dropping to near 0kts while pressure is increasing; like I've said that isn't just a MLC south of Jamaica.


The current pressure rise is due to the diurnal cycle. The overall trend is currently down. Hopefully we will get a nearly direct pressure measurement on 94L tonight. The center is currently a bit shy of 81W, and the buoy is at 81.5W.
Member Since: November 24, 2005 Posts: 635 Comments: 26700
Back on for a bit. I just ran the IR2 loop and the low center from earlier is no longer evident. I see a new low near 17N and 77W.

I hate these monsoon lows.
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Quoting sammywammybamy:
94L Re-Organizing...




Dry air appears to have lessened considerably since yesterday, which makes me think it might actually make it before upper-level winds become less favorable.
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Good night to let 94L fester on it's own. A lot of details to work out yet and time is running out. I see tomorrow as a make or break day for the storm and it's chances of development. Should it choose not, I just hope it brings some rain with it's remnants. Rain for anyone in the coastal south, doesn't matter, we all need it.
Member Since: January 30, 2010 Posts: 0 Comments: 3259
Quoting KanKunKid:


There was a little more to it than that, but that will suffice.


Yeah, a lot more - just wanted to keep it simple.
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It looks like we may see TD-1E in the Eastern Pacific by tomorrow morning...or sooner. TD-1 in the Caribbean has some chance of coming up tomorrow but for now TD-1E is still much closer to TD status. However the TD-1 has shown quite some signs of organization so I wouldn't be surprised to see a code red tomorrow morning.
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1326. beell
Quoting Levi32:
Invest 94L is definitely not close to becoming a tropical depression. It is decoupled with a mid-level circulation back underneath the center of the upper anticyclone east of the surface low, which is a classic setup. The surface circulation may or may not reform further east, but for now it seems quite well-defined, and it will be a long time before it reforms if it is going to. We will have to see if convection refires during the diurnal maximum tonight and if 94L can acquire some more organization. It doesn't have more than 48 hours before wind shear will again become a major problem.


Probably the best, most even-handed synopsis I have read today (fwiw, of course)!
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Quoting sunlinepr


Very helpful. You can really see the LLC vs. the MLC in that loop. Thanks.
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Quoting galvestonhurricane:


Anyone mind telling me?


He got mad, said things he shouldn't have -> banned.
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Logging on from the Miami and Dallas game... Heat wins. Yay.

Anyway,

Last few satellite images is showing convective flare ups all around. Invest will experience its best health during this DMAX. Lets see if its enough to edge it towards the side of solid development, becoming a depression. For now the storm is not so impressive but can be with this dmax cycle.
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Quoting galvestonhurricane:


Does that have any chance of developing?

JTWC gives the indian invest a Medium chance



The invest in the WPAC hasn't been given a chance yet since the JTWC hasn't updated their page to include the invest
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I'll probably end up wrong, but I am going to stay with my prediction that the Jamaica MLC will take over and strengthen.
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Quoting jasonweatherman2010:


vorticity has gone down significantly, that cant just be from DMIN can it?
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Quoting FLdewey:
Me thinks I saw Rufus on a poster at the post office.

Chance of rain for Mon and Tuesday just went *poof*

There's always Wed. :-#



Had to look it up in the dictionary, memory failing me.
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1315. xcool
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Quoting ShenValleyFlyFish:
"Whom the gods would destroy the first make mad" Sad story best not told. Goggle him he is still out there.


Anyone mind telling me?
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Quoting sailingallover:
The convection has fallen off to the East and started reforming more to the west over the center.
This is also over new warm water....
The Tropical waves is going to be over the center of the LLC by morning judging by the MSLP on the floaters.
I'm going to predict we wake up to an almost storm for the day...


I hate to be rude or skeptical, but how many times have we said, "let's just wait for the next day," on this invest?
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Quoting galvestonhurricane:


Remember TS Allison?
Yep.
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1309. Levi32
Quoting galvestonhurricane:


Does that have any chance of developing?


The Indian blob looks good. I haven't really looked at either of them, for obvious reasons.
Member Since: November 24, 2005 Posts: 635 Comments: 26700
Quoting galvestonhurricane:


Where's Storm?
"Whom the gods would destroy the first make mad" Sad story best not told. Goggle him he is still out there.
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The convection has fallen off to the East and started reforming more to the west over the center.
This is also over new warm water....
The Tropical waves is going to be over the center of the LLC by morning judging by the MSLP on the floaters.
I'm going to predict we wake up to an almost storm for the day...
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Quoting KoritheMan:

It's June 5. No.


Remember TS Allison?
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Quoting Levi32:






Does that have any chance of developing?
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Quoting sunlinepr:


I always love how those Artic lows dwarf any tropical so called monsters.
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Quoting galvestonhurricane:
Anything else to watch besides 94L and 91E?
It's June 5. No.
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1301. Levi32
Quoting galvestonhurricane:
Anything else to watch besides 94L and 91E?




Member Since: November 24, 2005 Posts: 635 Comments: 26700
1300. Levi32
Invest 94L is definitely not close to becoming a tropical depression. It is decoupled with a mid-level circulation back underneath the center of the upper anticyclone east of the surface low, which is a classic setup. The surface circulation may or may not reform further east, but for now it seems quite well-defined, and it will be a long time before it reforms if it is going to. We will have to see if convection refires during the diurnal maximum tonight and if 94L can acquire some more organization. It doesn't have more than 48 hours before wind shear will again become a major problem.
Member Since: November 24, 2005 Posts: 635 Comments: 26700
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Quoting PcolaDan:

In Ocean.


Very funny
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Anything else to watch besides 94L and 91E?
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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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