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 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.





NOT GOOD
Member Since: Posts: Comments:
Stays at 20%... Be back in a couple minutes...
Member Since: September 2, 2009 Posts: 130 Comments: 21193
I see 2 Circulations 1 at 72 W 17.5N moving to the NW and 1 at 75W 15.5N moving to the w-wnw there is a possibility that the circulation moving to the NW could cross Hattie and form the low that the CMC is calling for on the other side of Hattie
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Quoting GreenMe2225:


so? north eye and south eye. what?



this saying you can get banned for posting fish photo has some one found out
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GFDL and HWRF make a monster.
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GFDL 00z in 126 h.


Category 3 in the gulf.
Member Since: Posts: Comments:
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.

Member Since: June 9, 2007 Posts: 4 Comments: 15889
Quoting Ameister12:
Good evening everyone.

Evening!
Member Since: August 2, 2006 Posts: 0 Comments: 1240
Wow... surprised they did not up it a tad... but oh well!
Member Since: March 19, 2010 Posts: 0 Comments: 1147
Quoting btwntx08:
someone post the gfdl at 126 hr plz thx
GFDL 18z 126 hours.

Member Since: September 2, 2009 Posts: 130 Comments: 21193
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
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18Z 93L GFDL

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Ouch

Member Since: June 9, 2007 Posts: 4 Comments: 15889
Still 20%.
Member Since: September 10, 2007 Posts: 0 Comments: 11149
Quoting GreenMe2225:
everyone needs to keep their south eye on 93l and their north eye on the gulf. that may be a depression wannabee in the making!

this image does not signify a fish storm. this is you using your south eye and north eye.




you posted a fish photo
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1926. Patrap
900mb is insanity
Member Since: July 3, 2005 Posts: 423 Comments: 128240
1925. fsumet
.
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Staying at 20%.
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the two is the same
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1922. Patrap
Quoting Drakoen:
GFDL pointing at you Patrap:



Thats becoming a nasty Habit now Drak.

The new 00Z ATCF tracks should be interesting later


Member Since: July 3, 2005 Posts: 423 Comments: 128240
Good evening everyone.
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Quoting Patrap:



We always at the mercy of the Storms strength..here..and the NOSE of the High seems.

But not this early usually.

One to watch as it approaches the Yucatan in a few days..

Oh I'll be watching. Time to whip out and stock up on the hurricane supplies.
Member Since: August 2, 2006 Posts: 0 Comments: 1240
Quoting Drakoen:
GFDL pointing at you Patrap:




oh no
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HWRF heading due North at the end of the run.

Member Since: June 9, 2007 Posts: 4 Comments: 15889
18z HWRF inner-nest at 126 hours.

Member Since: September 2, 2009 Posts: 130 Comments: 21193
1913. Drakoen
GFDL pointing at you Patrap:

Member Since: October 28, 2006 Posts: 57 Comments: 30489
I can be there in 50 minutes!!!!


Quoting Patrap:
Waiting for my Pizza Dough to rise..

Making somew deep Dish Supreme..Ol Style from Scratch
Member Since: Posts: Comments:
1911. Patrap
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?



We always at the mercy of the Storms strength..here..and the NOSE of the High seems.

But not this early usually.

One to watch as it approaches the Yucatan in a few days..
Member Since: July 3, 2005 Posts: 423 Comments: 128240
1910. DehSoBe
what does this mean?
Member Since: Posts: Comments:
Quoting GreenMe2225:
everyone needs to keep their south eye on 93l and their north eye on the gulf. that may be a depression wannabee in the making!

this image does not signify a fish storm. it is a south eye and a north eye.



seee you in 24hrs some one of the blog got banned for posting fish photos drung active periods of hurricane season
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1908. hydrus
Quoting Drakoen:
HWRF 18z

That looks bad also...
Member Since: September 27, 2007 Posts: 1 Comments: 21173
Quoting Patrap:
Waiting for my Pizza Dough to rise..

Making somew deep Dish Supreme..Ol Style from Scratch

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?
Member Since: August 2, 2006 Posts: 0 Comments: 1240
1903. Patrap
Oil-zilla is Lurking in the GOM and Caribbean TCHP.

Member Since: July 3, 2005 Posts: 423 Comments: 128240
Quoting RecordSeason:
Off the Scale Potential Intensity Along Proposed Track


SmileyCentral.com
Member Since: August 15, 2008 Posts: 10 Comments: 3665
1899. Patrap
Quoting Drakoen:
HWRF point at you Patrap


It can Point all day.

When the real one does..then Im concerned.

But its a bad trend
Member Since: July 3, 2005 Posts: 423 Comments: 128240
Quoting Patrap:
925mb

ooow-ee
ok Pat we did not need to know that.... Thats a bit stronger than we need....

Taco :o)
Member Since: July 7, 2005 Posts: 6 Comments: 3261
1897. Patrap
HWRF 18z
Member Since: July 3, 2005 Posts: 423 Comments: 128240
1896. Drakoen
HWRF point at you Patrap
Member Since: October 28, 2006 Posts: 57 Comments: 30489

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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.