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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146. IKE
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I wish it would just develope then we could deal with what comes after that the waiting game is whats killing me
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There is a minor bit of shear, mainly between 600-300 mb.


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Quoting Skyepony:


Been looking at the CMC this morning??? This morning aka ..solutions where nature will clean up your mess.


what does that mean?? There is a little yellow blob right over my house!
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Quoting Skyepony:


Been looking at the CMC this morning??? This morning aka ..solutions where nature will clean up your mess.


Is that possible? 2 hurricanes converging? Sounds like a movie "The Perfect Storm Part 2"
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TOLD you guys RIP 93 L. Hurricane center already lowers probability of development. Again lets talk about the Pacific. Atlantic has nothing going on till August
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Climo favors the Western and Central Caribbean,..and the organization will likely occur after the next 30 hours or so.
Member Since: July 3, 2005 Posts: 427 Comments: 129457
Bangladesh, 150,000 trapped by floods

* From: AFP
* June 22, 2010 6:04PM

OVER 150,000 people were left marooned after weeks of heavy rain in northeastern Bangladesh.

Five weeks of heavy rain caused rivers to burst their banks and flood large areas of countryside and villages, as well as causing thousands of acres of crops to be ruined, said Sylhet district chief Sazzad Hossain , reported Agence France Presse.

"At least 36,000 families - around 150,000 people - have been marooned by the floods in my district," he said.

The water level was still rising, causing major damage to crops and cutting off communication with many areas, Hossain added.

"We have opened 31 makeshift relief centers, where 2,000 people have taken shelter," he said, adding there were currently no reports of casualties.
Last week, at least 55 people were killed after the worst rains in decades triggered landslides and flash floods in the country's southeastern hill regions, with at least 12,000 people left homeless.
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136. IKE
Quoting Drakoen:


Look at the time stamp on that


I see what you mean.

I'll delete it.
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Quoting Skyepony:


Been looking at the CMC this morning??? This morning aka ..solutions where nature will clean up your mess.


Ew, the CMC shows a strong system going up the west coast of FL. Not good!
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Quoting Patrap:
Wake up in the morning feeling like 93L
(Hey, what up Invest?)
Put my glasses on, Im on the GFS - Im gonna hit this Run(Lets go)
Before I log on, brush my teeth with a bottle of Capri Sun
Cause when I post for the night, I aim to be Number one
Im talking - mjo on our, toes, Blows
Trying on all our GOES,GOES
Post's blowing up our phones, phones
Drop-toping, playing our favorite cds
Pulling up to the Blog-sies
Trying to get a little bit tipsy..


Lol a second version of tick-tock.
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Quoting Stormchaser2007:
I see 93L has been bumped down to 40% with little model support from the global models. Interesting.


Most likely because the GFS doesn't seem interested. It is usually always quick to jump on. It is seeing something that just isn't right down there. Maybe too much energy in the region to consolidate. It just seems strange.
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Quoting IKE:
Heading toward DMIN....



Old image.
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I think 93L's best chance of becoming a TD is on Thursday. Needs to get its act together quite a bit.
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128. Skyepony (Mod)
Quoting Chicklit:
Fan-tastic. Thanks Skye :)


Your welcome...Many times that site seems to update before the other too.
Member Since: Posts: Comments:
Wake up in the morning feeling like 93L
(Hey, what up Invest?)
Put my glasses on, Im on the GFS - Im gonna hit this Run(Lets go)
Before I log on, brush my teeth with a bottle of Capri Sun
Cause when I post for the night, I aim to be Number one
Im talking - mjo on our, toes, Blows
Trying on all our GOES,GOES
Post's blowing up our phones, phones
Drop-toping, playing our favorite cds
Pulling up to the Blog-sies
Trying to get a little bit tipsy..
Member Since: July 3, 2005 Posts: 427 Comments: 129457
NOAA WindSat solution:


Member Since: September 23, 2005 Posts: 14 Comments: 11307
Quoting btwntx08:
anyting negitive saying on the two?
. A STRONG TROPICAL WAVE OVER THE CENTRAL CARIBBEAN SEA IS PRODUCING A
LARGE AREA OF DISORGANIZED SHOWERS AND THUNDERSTORMS OVER PORTIONS
OF THE CENTRAL CARIBBEAN AND THE ADJACENT LAND AREAS. UPPER-LEVEL
WINDS APPEAR TO BE CONDUCIVE FOR GRADUAL DEVELOPMENT AND A TROPICAL
DEPRESSION COULD FORM DURING THE NEXT COUPLE OF DAYS. REGARDLESS
OF DEVELOPMENT...LOCALLY HEAVY RAINFALL AND GUSTY WINDS ARE
POSSIBLE OVER PORTIONS OF PUERTO RICO...THE DOMINICAN REPUBLIC...
HAITI...AND JAMAICA DURING THE NEXT DAY OR SO AS IT MOVES
WEST-NORTHWESTWARD AT ABOUT 10 MPH. THERE IS A MEDIUM CHANCE...40
PERCENT...OF THIS SYSTEM BECOMING A TROPICAL CYCLONE DURING THE
NEXT 48 HOURS.


not sure if you noticed but the NHCs language can give you an indication of of things; they lowered the chances by 10% and now they say the upper winds APPEAR to be conducive for development.

Tells me they arent as sure about the shear as they were yesterday, there is a chance this thing may just never come together; which is something I hinted at last night.
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Quoting GreenMe2225:


93l is something like this right now



Don't rip it.
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I dont even know what i am looking it this mess in the carribean is so confusing i dont know what is what
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Fan-tastic. Thanks Skye :)
Member Since: July 11, 2006 Posts: 14 Comments: 11410
Quoting IKE:
Heading toward DMIN....



Look at the time stamp on that
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Quoting sammywammybamy:



Its Still a Gaint Mess , even though it has alot of mostiure and convection it has yet to consalidate.


I saw a lot of people scream this was going to be a TD today, the more experienced people here stayed realistic

I think most of us knew this would take a few days to develop, if it does at all
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116. IKE
Looks like it's a wait til the western Caribbean for 93L....

12Z NAM @ 84hrs.....

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12z Early Cycle NHC model tracks
Invest93
Statistical/Simple Models (CLIPER,BAMs,LBAR,other Statistical Models)




Dynamic Models (More sophisticated models)




Member Since: July 3, 2005 Posts: 427 Comments: 129457
Quoting twhcracker:
OMG WE'RE ALL GONNA DIE!!

haha



yea from not knowing what is going to do and where its going ROFLMAO
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112. Skyepony (Mod)
Quoting twhcracker:
OMG WE'RE ALL GONNA DIE!!

haha


Been looking at the CMC this morning??? This morning aka ..solutions where nature will clean up your mess.
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111. IKE
...
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Quoting bappit:


Those high wind speeds look like problems with the algorithm that interprets the data. Don't see how you get 50 knot winds at those angles among all the 10 knot (or less) barbs.
I thought something looked unusual with those odd vector points. I wonder if its really blowin 50 out there.
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When do the next model runs come out?
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105. Skyepony (Mod)
Quoting Chicklit:
The Navy site won't let you load 93L, Grothar?
Me neither.


Use FNMOC navy site
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Backup Navy Site (you will most likely get a security certificate warning)
Member Since: September 23, 2005 Posts: 14 Comments: 11307
I see 93L has been bumped down to 40% with little model support from the global models. Interesting.
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Statement from the Harrison Cnty EMS

"The NWS has issued a Special Weather Statement for the MS Coastal Counties. A mass of Tropical Air is producing Thunderstorms off shore and we could see WATER SPOUTS over the open waters through the morning hours until noon. Brief periods of heavy rain.

Please continue to monitor the weather for changing conditions."


It's gonna be a nasty day here.
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Good morning folks, so what do we have going on with 93L

I noticed they dropped the percentages to 40%, but what is the real story?
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The Navy site won't let you load 93L, Grothar?
Me neither.
Member Since: July 11, 2006 Posts: 14 Comments: 11410
97. 7544
btw look at the gfs 850 its exactly where it has it now check it out and follow where it goes it by skims cuba too

Link
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Quoting 7544:
i dont see anymovement west at this hour looks to be heading nnw imo
You're focusing on the convective band. The movement of this band doesn't represent the actual movement of the system's mid-level circulation. It's actually moving WNW
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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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