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 tropicfreak:


Looks so timy and compact.


Hope it stays that way. Most models bring it Gulfward and that's the last thing we need with that gusher still spewing oil all over the GOM.
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3344. Walshy
BElieVe iN th3 John Hope Rule. don't forget it...
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Quoting DestinJeff:
HWRF @ +126



That seems to be my track toward the FL panhandle maybe as far east of Tampa but that maybe a stretch.
Member Since: November 4, 2009 Posts: 0 Comments: 6577
Quoting IKE:
*reaches for valium*


**nudges IKE**

Got an extra one of those? It's going to be an "interesting" day
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Morning Nash!
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Quoting cirrocumulus:
Anybody of the theory that the blobs will merge?


No....Fujiwhara Blob Madness........
Member Since: August 8, 2006 Posts: 0 Comments: 9317
3339. aquak9
Quoting IKE:
*reaches for valium*


when that's the first thing I see on this blog, do I even wanna read back???
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3338. Crawls
The local Baton Rouge LA weather showed spagetti models this morning. They said there is an area worth watching we may get something early next week and we may not. Sounded like a CYA broadcast.
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3321:

Not only have I seen the satellite's this morning...I watched that MCV/MCC dissipate last night...

The blob that is in that region now is an entirely different low pressure system that formed some 200 miles to the south.


This short wave is even old enough to watch the remnants of old MCV getting blown away.

watch DR at the beginning of the loop. That is what you were claiming was CoC yesterday, and it moves north east and dissipates
Member Since: June 13, 2010 Posts: 0 Comments: 2336
and make one perfect storm? who knows they might merge
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Quoting extreme236:


Dude, we all saw that thing go inland yesterday.


No it didn't! Let me guess this spin came out of no where S of Haiti LOL.
Member Since: November 4, 2009 Posts: 0 Comments: 6577
3334. IKE
*reaches for valium*
Member Since: June 9, 2005 Posts: 23 Comments: 37858
3333. Dakster
3324 - How do we translate the maps into JHST from Zulu.
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Anybody of the theory that the blobs will merge?
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Quoting StormSurgeon:
Lots of action.....



Looks so timy and compact.
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3328. nash28
Morning all.
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Quoting StormW:


How is he wrong? I sat there and watched that feature go inland late yesterday.


Storm it stayed offshore. It moved back WSW later in the evening this is the reason for code orrange this morning with this blob as it is the mid level circulation. Look at the vis animation.
Member Since: November 4, 2009 Posts: 0 Comments: 6577
one at a time please we just can handle 93L
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Quoting Jeff9641:


Wrong! Have you seen the visible this morning? Nice circulation with the relocation of 93L.


Dude, we all saw that thing go inland yesterday.
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3323. 7544
could we get 94l before the days end ?
Member Since: May 6, 2007 Posts: 0 Comments: 6871
Quoting RecordSeason:
3314:

Actually, It did move over land at about 10:00pm central last night, and was eventually destroyed. It's remnants have blown off and moved well north east of Puerto Rico by now.


Wrong! Have you seen the visible this morning? Nice circulation with the relocation of 93L.
Member Since: November 4, 2009 Posts: 0 Comments: 6577
Ok guys I took a chill pill and I am so cold that I can't feel my feet and I also have the A/C going as well
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Lots of action.....

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3314:

Actually, It did move over land at about 10:00pm central last night, and was eventually destroyed. It's remnants have blown off and moved well north east of Puerto Rico by now.
Member Since: June 13, 2010 Posts: 0 Comments: 2336
3316. IKE
Member Since: June 9, 2005 Posts: 23 Comments: 37858
Quoting MarineMeteorologist:
Last nights various computer models remained all over the map - anywhere from the southern Yucatan Penn. to the central Gulf of Mexico with intensities ranging from a strong tropical wave to a minimal hurricane (as seen in the GFDL forecast). The farther east the forecast track the stronger the development which fits climatology.

This mornings satellite photos show two other areas of convection to the ESE of 93L.


The one east of 93L could end up feeding 93L once the center intensifies.
Member Since: November 4, 2009 Posts: 0 Comments: 6577
Quoting MiamiHurricanes09:
That MCV from yesterday went over land into Hispañiola and then dissipated. If you don't believe me just look at long-term satellite imagery.


No it didn't I was watching this all tyhe way till the sun went down yesterday. It actually moved back WSW and remained over water. Never went over land!
Member Since: November 4, 2009 Posts: 0 Comments: 6577
3313. 7544
arent these 3 blobs to close together to really form into alex or the thinking is they will all connect down the road . if not ill take the middle blob for 100 alex

by the way if they are all sep systems truing to form could they all take the same path or can one be deverted hmm lots to watch today tia
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Quoting MiamiHurricanes09:
That MCV from yesterday went over land into Hispañiola and then dissipated. If you don't believe me just look at long-term satellite imagery.


Wrong.

Cmon. Is there no reason here??
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Last nights various computer models remained all over the map - anywhere from the southern Yucatan Penn. to the central Gulf of Mexico with intensities ranging from a strong tropical wave to a minimal hurricane (as seen in the GFDL forecast). The farther east the forecast track the stronger the development which fits climatology.

This mornings satellite photos show two other areas of convection to the ESE of 93L.
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3310. Becca36
Quoting alaina1085:

Morning Becca! Im right there with ya girl. :)

:)
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TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT WED JUN 23 2010

TROPICAL WAVE IS ALONG 42W S OF 17N MOVING W 20-25 KT. THIS WAVE
IS A BROAD HIGH AMPLITUDE WAVE WITH A WELL DEFINED CYCLONIC
CURVATURE ON SATELLITE IMAGERY. WAVE IS TOWARD THE LEADING EDGE
OF DEEP LAYERED MOISTURE MAXIMUM AS DEPICTED ON THE TOTAL
PRECIPITABLE WATER IMAGERY. CLUSTERS OF SCATTERED MODERATE TO
ISOLATED STRONG CONVECTION ARE FROM 8N-14N BETWEEN 38W-45W.
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Quoting Jeff9641:


This is the same spin from yesterday and on the visible this spin is evident. S of Haiti. Remember I said yesterday this was going to happen.
That MCV from yesterday went over land into Hispañiola and then dissipated. If you don't believe me just look at long-term satellite imagery.
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Quoting CybrTeddy:
Calm down wunderkid.. jeez.




yea wunderkid got on me this morning i told him the same thing chill out LOL
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Quoting Becca36:
Good morning everyone! I know I need help when I run to the computer before I even turn the coffee on to "blob" watch. LOL

Morning Becca! Im right there with ya girl. :)
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HPC hasn't benen buying a strong east coast trough since yesterday...

THE DAYS 3-7 SAT-WED FCST STARTS WITH A 70/30 BLEND OF THE 12Z
ECMWF MEAN/00Z GEFS MEAN DUE TO REASONABLE ENSEMBLE AGREEMENT OVER
THE ERN PAC/WRN NOAM AND AN EASILY ADJUSTED EVOLUTION OVER THE
GULF... WHILE ACCOUNTING FOR CURRENT SOLN SPREAD AND RUN TO RUN
CHANGES IN THE MODELS OVER THE ERN HALF OF THE CONUS. ALSO
AFOREMENTIONED TELECONNECTIONS SEEM TO FAVOR GIVING MORE WEIGHT TO
THE LESS AMPLIFIED ERN TROF OF THE 12Z ECMWF MEAN.
INITIAL BASE
MAPS WERE ADJUSTED SLIGHTLY TO ACCOUNT FOR SOME IDEAS OF THE
OPERATIONAL MODELS AS APPROPRIATE.

Link



Todays prelim...
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Later all. Be back at around 4PM.
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Welcome to Blob Fujiwhara Madness.....
Member Since: August 8, 2006 Posts: 0 Comments: 9317
Quoting MiamiHurricanes09:
Please explain to me where you see this "tight mid-level spin"?


This is the same spin from yesterday and on the visible this spin is evident. S of Haiti. Remember I said yesterday this was going to happen.
Member Since: November 4, 2009 Posts: 0 Comments: 6577
Quoting StormW:


Why do you think the NHC has upped that area a little further east to 30%?




your asking your safe a ? lol
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3299. Becca36
Good morning everyone! I know I need help when I run to the computer before I even turn the coffee on to "blob" watch. LOL
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The NHC is just as much confused as we all are, lol.
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Quoting IKE:


Try decaf.

ROFLMAO.... I was starting to wonder if it was Christmas eve.
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Quoting Abacosurf:


Acceptance is a virtue ......
I understand that, but there is nothing to support what he is saying.
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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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