93L slow to develop, but bringing heavy rains to Haiti

By: Dr. Jeff Masters , 1:50 PM GMT on June 22, 2010

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A modest region of intense thunderstorms (Invest 93L) is over the central Caribbean, a few hundred miles south of Hispaniola. This disturbance has the best chance to become Tropical Storm Alex of any system we've seen so far this year. We don't have any buoys near 93L, but pressures at the ground stations surrounding the storm are not falling. A pass of the ASCAT satellite over the Central Caribbean at 9:45 pm EDT last night revealed a modest wind shift associated with 93L, but nothing at all close to a surface circulation. Top surface winds seen by ASCAT were 15 - 20 mph. Water vapor satellite loops show that 93L is embedded in a large region of moist air. The atmosphere over the Caribbean has moistened over the past day, which should aid development of 93L. Wind shear is a low 5 - 10 knots. The high wind shear associated with the strong winds of the subtropical jet stream are over the northern Caribbean, too far north to interfere with development, but close enough to provide good upper-level outflow for the storm. Visible satellite loops show high level cirrus clouds streaming away from 93L to the northeast, evidence of the upper-level outflow channel that is developing to the storm's north. Sea Surface Temperatures are plenty warm, a record 29 - 30°C. The Madden-Julian oscillation (MJO) currently favors upward motion over the Caribbean, which will act to increase the chances of tropical storm formation this week. The Madden-Julian oscillation is a pattern of enhanced rainfall that travels along the Equator from west to east. The pattern has a wet phase with large-scale rising air and enhanced thunderstorm activity, followed by a dry phase with large-scale sinking air and suppressed thunderstorm activity. Each cycle lasts approximately 30 - 60 days. When the Madden-Julian oscillation is in its wet phase over a hurricane-prone region, the chances for tropical storm activity are greatly increased. The main negative for 93L continues to be lack of spin. The University of Wisconsin 850 mb relative vorticity analysis is showing that spin at 850 mb (roughly 5,000 feet in altitude) has increased over the past day, but 93L needs to acquire additional spin before it can grow more organized. I speculate that it is this lack of spin that contributed to the loss of much of 93L's heavy thunderstorm activity last night. The storm is now going through a cycle where it is building another respectable mass of heavy thunderstorms, and the increased inflow of low-level air that will feed these thunderstorms will likely enhance 93L's spin today. The Hurricane Hunters are on call to investigate 93L on Wednesday afternoon.


Figure 1. Morning visible satellite image of the central Caribbean disturbance 93L.

Forecast for 93L
NHC is giving 93L a 40% chance of developing into a tropical depression by Thursday morning, which is a reasonable forecast. Given the storm's current lack of spin and relatively modest amount of heavy thunderstorms, the earliest I'd expect 93L to become a tropical depression would be Wednesday afternoon, with Thursday more likely. Wind shear is expected to be low, less than 10 knots, over the central and western Caribbean this week. Water temperatures will be warm, dry air absent, and the MJO favorable. I don't see any major impediments to the storm becoming a tropical depression by Thursday, and it is a bit of a surprise to me that the computer models have been reluctant to develop 93L. The GFS, NOGAPS, and UKMET models do not develop 93L, and the ECMWF model doesn't develop 93L until after it crosses the Yucatan Peninsula and enters the Gulf of Mexico in a about a week. The current (2am EDT) run of the GFDL model predicts 93L will be a weak tropical storm in the Gulf of Mexico in five days; its previous run had 93L as a major hurricane in the Gulf. Given all this model reluctance and the current disorganization of 93L, I give the storm a low (less than 20% chance) of becoming a hurricane in the Caribbean. Expect 93L to bring flooding rains of 3 - 6 inches to Jamaica, eastern Cuba, and southwestern Haiti today through Wednesday. These rains will spread to the Cayman Islands and central Cuba by Thursday, and western Cuba and Mexico's Yucatan Peninsula on Friday. The current run of the SHIPS model has 93L slowing down late this week to a forward speed of just 6 knots (7 mph) from its current speed of about 10 mph, in response to a weakening in the steering currents. A trough of low pressure is expected to swing down over the Eastern U.S. early next week. If this trough is strong enough and 93L develops significantly, the storm could get pulled northwards and make landfall along the northern Gulf of Mexico coast in the oil spill region. This is the solution of the Canadian GEM model. If 93L stays weak and/or the trough is not so strong, the storm would get pushed west-northwestwards towards the Texas coast. This is the solution of the ECMWF model. The amount of wind shear in the Gulf of Mexico next week is highly uncertain. There is currently a band of high shear near 30 knots over the Gulf, and some of the models predict this shear will remain over the Gulf over the next 7 - 10 days. However, other models predict that this band of high shear will retreat northwards and leave the Gulf nearly shear-free. The long-term fate of 93L remains very murky. My main concerns at this point are the potential for 3 - 6 inches of rain in Haiti over the next two days, and the possibility 93L could become a hurricane in the Gulf of Mexico next week.

Elsewhere in the tropics
None of the reliable computer models is calling for tropical cyclone formation elsewhere in the Atlantic over the next seven days.

Floods in China and Burma kill over 250
The deadliest and most destructive weather-related disaster on the planet so far this year is occurring in southern China and northern Burma, where a week of heavy rains has caused flooding that has claimed over 250 lives. The heavy rains and floods ravaging 10 southern Chinese provinces had killed 199 and left 123 missing as of 11:00 a.m. Tuesday, a Ministry of Civil Affairs statement said. Damage is estimated at $6.2 billion. Floods and landslides in neighboring areas of Myanmar (Burma) have claimed at least 63 lives in the past week.


Figure 2. Paramilitary policemen help evacuate residents from Wanjia village of Fuzhou City, East China's Jiangxi province, June 22, 2010. Days of heavy rain burst the Changkai Dike of Fu River on June 21, threatening the lives of 145,000 local people. Local authorities have ordered immediate evacuation, and the army and paramilitary police have begun conducting rescue operations. Image credit: Xinhua.

Wind and ocean current forecast for the BP oil disaster
Southeast to east winds less than 10 knots will blow in the northern Gulf of Mexico today through Saturday, according to the latest marine forecast from NOAA. The resulting weak ocean currents should cause little motion of the oil slick, according to the latest trajectory forecasts from NOAA and the State of Louisiana. The long range outlook is uncertain, and will depend upon what 93L does.

Resources for the BP oil disaster
My post, What a hurricane would do the Deepwater Horizon oil spill
My post on the Southwest Florida "Forbidden Zone" where surface oil will rarely go
My post on what oil might do to a hurricane
NOAA's interactive mapping tool allows one to overlay wind and ocean current forecasts, oil locations, etc.
Gulf Oil Blog from the UGA Department of Marine Sciences
Oil Spill Academic Task Force
University of South Florida Ocean Circulation Group oil spill forecasts
ROFFS Deepwater Horizon page
Synthetic Aperture Radar (SAR) imagery from the University of Miami

"Hurricane Haven" airing again this afternoon
Tune into another airing of my live Internet radio show, "Hurricane Haven", at 4pm EDT today. Listeners will be able to call in and ask questions. The call in number is 415-983-2634, or you can post a question in the comments area on my blog. You can also email the questions to me today before the show: jmasters@wunderground.com. Be sure to include "Hurricane Haven question" in the subject line. Some topics I'll cover today on the show:

1) The latest on 93L
2) Which model is the most reliable?

Today's show will be 30 - 40 minutes, and you can tune in at http://www.wunderground.com/wxradio/wubroadcast.h tml. The show will be recorded and stored as a podcast.

Jeff Masters

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Quoting alaina1085:


Well I personally rather the over hype and to be let down then the under hype and be caught totally off guard. You have to respect the fact that these mets are doing the best that they can with very little tools. So until I have been 100% in there shoes, Im just grateful with the info available. Just my oppinion.


I agree 100%. Under-hype is more dangerous than the other way around. We had local media telling people not to evacuate from Ike on the morning of the 11th. While water was already cutting off some roads. Ridiculous!!!
Member Since: August 15, 2008 Posts: 10 Comments: 3665
1995. DehSoBe
you are right, but i think most people that hear 20% does not know that is only for a 48 hr period. Once the storm is on top of them they up the percentage... a little too late
Member Since: Posts: Comments:
The GFDL run doesn't really "get it together" until it's almost at Yucatan. It's a broad and/or weak vortex until then. Considering how sloppy this thing still is, I wouldn't doubt that. The models may or may not be out to lunch with the ultimate track and landfall site, but the general idea of it taking a while to pull its circulation together and spin down to the surface seems on target.
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At its current status, the NHC is totally correct with the 48 hour forecast.
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Quoting RecordSeason:
Wow...GFDL is verifying the borderline cat3/cat4 status south of NOLA at end of run again. And once again, that's before it even hits the "hot spot" right on the coast.

where can i find the gfdl run you are looking at. can oyu post a link? thanks in advance:)
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Quoting StormW:


Is this showing it run right into the Yucatan and continue due west?
Member Since: August 15, 2008 Posts: 10 Comments: 3665
Quoting Hurricanes101:


Honestly I doubt the majority of non weather nerds even knows the NHC releases a tropical weather outlook lol
Funny,but sad.
The EPAC is about to spit out another. If all of this EPAC action was in the Atlantic, this blog would explode.

Expect Celia and Five-E at 11 for the EPAC.
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Quoting MrMarcus:


Nope, not my style...


Well I personally rather the over hype and to be let down then the under hype and be caught totally off guard. You have to respect the fact that these mets are doing the best that they can with very little tools. So until I have been 100% in there shoes, Im just grateful with the info available. Just my oppinion.
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Quoting Drakoen:


I agree as well now that we know where the low pressure center is


did 93l pull off the llc thing today? wow i had it still 24 hrs away from pulling that off.
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1986. DehSoBe
I definitly see rotation on that image
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It looks like it's already about time to make plans to evacuate.
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Mr.Marcus what is your take on 93L.Do you think it has a chance to develope.
Quoting Hurricanes101:


Honestly I doubt the majority of non weather nerds even knows the NHC releases a tropical weather outlook lol


That's a sad truth...
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23:15 frame says it all.
Member Since: June 13, 2010 Posts: 0 Comments: 2336
Quoting antonio28:


Oh nooo...!! NOLA not again.


with that track, maybe. could be waveland, ms again however. the 20 people that still live there would probably puke if they saw that run.
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Quoting Floodman:


I'm sure you'll remind us, huh?


Nope, not my style...
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1978. Drakoen
Quoting Stormchaser2007:


I completely agree with the NHC. Its a chance of developing in 48 hours. Not overall.


I agree as well now that we know where the low pressure center is
Member Since: October 28, 2006 Posts: 57 Comments: 30615
Quoting DehSoBe:
Does anyone feel by keeping the chances at 20% by the NHC is giving the residents along the GOM a false since of the possible? Im sure they dont want to cause alarm, but come on...


Honestly I doubt the majority of non weather nerds even knows the NHC releases a tropical weather outlook lol
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Quoting MrMarcus:


Personally, I think Professor Panic (Masters) and the rest of the 'experts' have done a fine job of scaring the public into believing Armageddon is coming every hurricane season. Sure, if you yell 'Fire' in a crowded theater enough times, you'll actually get lucky once in a while. But, if you compare the predictions with the results over the past few years, they have continually missed the mark.

Now, not having the millions of dollars in equipment and other resources to work from, I have to rely on less 'scientific' methods (observation), or at least perceived as less scientific by the all knowing masses.

Sure, we don't have the benefit of the El Nino we had last season (Most models call for an ENSO neutral year), and that continual batch of dry air off the African coast we had last summer will probably not make a repeat appearance. But, with that said, I'm expecting (guessing - let's call it what it is) a fairly normal season. Whatever we get this year, will mostly happen in late summer (August/September). The early storms we've seen thus far (if you can really call them that) have little bearing on the overall season.

Sure, I could be way off, and I'm positive that someone will be there to remind me of it, but no one will remember if I'm right.

BTW - I've been in Florida since '98, so I've seen a few of these storms up close and personal (was actually in the eye of Charlie).


I'm sure you'll remind us, huh?
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.

Member Since: June 9, 2007 Posts: 4 Comments: 15946
Quoting RecordSeason:
Wow...GFDL is verifying the borderline cat3/cat4 status south of NOLA at end of run again. And once again, that's before it even hits the "hot spot" right on the coast.



DOOM I SAY HERE ALL DOOM
Member Since: May 21, 2006 Posts: 5091 Comments: 115354
1973. Patrap
Quoting NASA101:

Stop scaring people; 900 hPa is NOT the surface pressure!!


Lighten up Francis..


Its a inside joke with some here.


Press to ATO on someone else Astro..
Member Since: July 3, 2005 Posts: 426 Comments: 129090
Quoting MiamiHurricanes09:
GFDL 18z 126 hours.



Oh nooo...!! NOLA not again.
Member Since: July 15, 2008 Posts: 0 Comments: 799
Quoting DehSoBe:
Does anyone feel by keeping the chances at 20% by the NHC is giving the residents along the GOM a false since of the possible? Im sure they dont want to cause alarm, but come on...


I completely agree with the NHC. Its a chance of developing in 48 hours. Not overall.
Member Since: June 9, 2007 Posts: 4 Comments: 15946
Quoting Floodman:


Yes, it does...Patrap! LOL

Ha! (note to self: move far away from Patrap!)
Good to see you Flood.
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1967. Patrap
Quoting alaina1085:

There just being conservative. They dont want to have to jump back and forth with there percentages. Once they see the consistency in 93L's development they will up the percentage. Im not really suprised at all.


Exactly..the climo favored area is west and it wont get there till Thursday /Friday,and then the better organized system expected will have a full Juicy GOM Ahead of it.

One to watch.
Member Since: July 3, 2005 Posts: 426 Comments: 129090
1965. NASA101
Quoting Patrap:
900mb is insanity

Stop scaring people; 900 hPa is NOT the surface pressure!!
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Wow...GFDL is verifying the borderline cat3/cat4 status south of NOLA at end of run again. And once again, that's before it even hits the "hot spot" right on the coast.
Member Since: June 13, 2010 Posts: 0 Comments: 2336
1963. DehSoBe
Does anyone feel by keeping the chances at 20% by the NHC is giving the residents along the GOM a false since of the possible? Im sure they dont want to cause alarm, but come on...
Member Since: Posts: Comments:
latest model runs?
Member Since: August 24, 2006 Posts: 0 Comments: 1867
Minute convention keeps on trying to pop over the new low, but they quickly die out. 93L needs a good DMAX. Ill be back after 10.
Member Since: June 9, 2007 Posts: 4 Comments: 15946
1960. ATL
Quoting Tazmanian:




NOT GOOD

Who are you trying to fool, 90 percent of this blog is crapping their pants every time a model run comes out forecasting a hurricane.
Quoting Tazmanian:
000
ABNT20 KNHC 222333
TWOAT
TROPICAL WEATHER OUTLOOK
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
800 PM EDT TUE JUN 22 2010

FOR THE NORTH ATLANTIC...CARIBBEAN SEA AND THE GULF OF MEXICO...

A TROPICAL WAVE OVER THE CENTRAL CARIBBEAN SEA IS MOVING WESTWARD
ABOUT 10 MPH AND IS SPREADING CLOUDINESS AND THUNDERSTORMS OVER
PORTIONS OF THE DOMINICAN REPUBLIC...HAITI... JAMAICA...AND EASTERN
CUBA. THIS SYSTEM HAS CHANGED LITTLE IN ORGANIZATION TODAY BUT
ENVIRONMENTAL CONDITIONS ARE FORECAST TO BECOME MORE FAVORABLE FOR
SLOW DEVELOPMENT AS THE WAVE REACHES THE WESTERN CARIBBEAN SEA IN A
DAY OR TWO. THERE IS A LOW CHANCE...20 PERCENT...OF THIS SYSTEM
BECOMING A TROPICAL CYCLONE DURING THE NEXT 48 HOURS.

ELSEWHERE...TROPICAL CYCLONE FORMATION IS NOT EXPECTED DURING THE
NEXT 48 HOURS.

$$
FORECASTER AVILA/ROBERT

ok i didnt do this lol *laughs* why is my name on there lol
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Quoting Tazmanian:



this saying you can get banned for posting fish photo has some one found out


i do not get it. if something else out there had a south eye and north eye i would have used it instead. if i get banned for making a silly like that to illustrate a need for people to start watching the gulf then this forum needs some cleansing from below.
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Quoting alaina1085:

Did you seriously have to post that!?!? You know your only an hour away!! lol. My hot wings dont sound so good anymore.

And lets hope that HWRF doesnt pan out. Does LA have a target on it or something?


Yes, it does...Patrap! LOL
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These big track shifts today are interesting. Most of them are now pointing at the Central Gulf Coast states since they are now strengthening 93L into a potent storm. This large shift east in the tracks could end up putting the West Coast of Florida in the bull's eye. Such a large shift is usually followed by more shifts, especially this early in the game.

However, it is all dependent on how strong 93L gets and right now, we still have a long way to go.
Member Since: July 15, 2006 Posts: 17 Comments: 10284
Quoting ecflweatherfan:
Wow... surprised they did not up it a tad... but oh well!

There just being conservative. They dont want to have to jump back and forth with there percentages. Once they see the consistency in 93L's development they will up the percentage. Im not really suprised at all.
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i say BP get a move on
Member Since: May 21, 2006 Posts: 5091 Comments: 115354
Quoting Stormchaser2007:


A Cat 2 is a monster?


In my eyes.. it is. Ike and Isabel for example. Actually i thought that was a stronger system, was about to edit my post.
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NHC keeps 93L at 20%.
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Quoting MiamiHurricanes09:
GFDL 18z 126 hours.



instead of 93l, that could be the gulf disturbance it is seeing. just saying
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Quoting CybrTeddy:
GFDL and HWRF make a monster.


A weak Cat 2 is a monster?
Member Since: June 9, 2007 Posts: 4 Comments: 15946
Quoting Stormchaser2007:
A TROPICAL WAVE OVER THE CENTRAL CARIBBEAN SEA IS MOVING WESTWARD
ABOUT 10 MPH AND IS SPREADING CLOUDINESS AND THUNDERSTORMS OVER
PORTIONS OF THE DOMINICAN REPUBLIC...HAITI... JAMAICA...AND EASTERN
CUBA. THIS SYSTEM HAS CHANGED LITTLE IN ORGANIZATION TODAY BUT
ENVIRONMENTAL CONDITIONS ARE FORECAST TO BECOME MORE FAVORABLE FOR
SLOW DEVELOPMENT AS THE WAVE REACHES THE WESTERN CARIBBEAN SEA IN A
DAY OR TWO.
THERE IS A LOW CHANCE...20 PERCENT...OF THIS SYSTEM
BECOMING A TROPICAL CYCLONE DURING THE NEXT 48 HOURS.


still doesnt show why they didnt up atleast to 30%

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About

Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.