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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I love the RIP'ers and the CAT5'ers...it does make for fine drama.

LOL
Member Since: August 2, 2006 Posts: 10 Comments: 9922
Carribean Cruise anyone! Some really good deals for the next 2 weeks! LOL
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heres a better image.



Banding features are still there but on the eastern side.
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Quoting Jeff9641:


CMC is wrong as always. There can never be 2 storms that close to each other.

There was one set I think last year in the pacific where the outflow of one was feeding right into another.
Very cool...except for Luzon
Member Since: September 1, 2009 Posts: 23 Comments: 1007
I wonder of bp is keeping up with this thing in the carribean
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Just warming up for later:

Member Since: August 2, 2006 Posts: 10 Comments: 9922
Quoting swlavp:
Plus the number of times a day I think dirty thoughts about Jen Carfagno!!! LOL


times the number of times Mike bettes flirts with Stephanie abrams.
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Quoting tropicfreak:


Kind of like cindy except it was barely minimal hurricane strength when it made land fall.



Impacts count..not the Cat Number

Folks were still cleaning up from Cindy when K hit.

7 weeks later.
Member Since: July 3, 2005 Posts: 434 Comments: 133300
Quoting GreenMe2225:


and they also use a formula.

total number of donuts Al Roker consumes multiplied by the number of viewers that watch Cantore Stories (normally a single digit number) divided by nbc executive suicides (annualized)
Plus the number of times a day I think dirty thoughts about Jen Carfagno!!! LOL
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Quoting weatherwatcher12:

So you are telling me that because it didn't form within 24 hours it can't form. You do know that cyclogenesis takes a while.


Why do you even bother? It's just not worth it. lol.
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Quoting BobinTampa:
I think it makes the Gulf as a strong TS. I, of course, base this on a complete lack of knowledge and understanding. If anyone can provide any facts to back up my hypothesis, I'd greatly appreciate it.



Kind of like cindy except it was barely minimal hurricane strength when it made land fall.
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Quoting Jeff9641:


Hey buddy I see you guys on the westside got hammered yesterday for change how much rain did you get?


I don't know how much rain I got at home, but it was pretty heavy for a while. Not far from me on MacDill AFB there was a wind measured at 70 mph from the storms! The lightning was insane at over 1000 strikes every 15 minutes. It was fun.
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Quoting CyclonicVoyage:
Seems like we have a winner in the battle of the COC's.





That is NOT a COC...there is no COC, Center, LLC!!
That is vorticity which is most simply a value for air flow that is not straight over some area. It does not always mean there is a Circulation it means there is a change in Direction!!
The math is here is you want to dig through it
http://www.cimms.ou.edu/~doswell/vorticity/vorticity_primer.html
Member Since: September 1, 2009 Posts: 23 Comments: 1007


93L looks rather disorganized however, the continous flaring of thunderstorms are keeping this thing alive.
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RE 224:

Damn.
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Levee's

Member Since: July 3, 2005 Posts: 434 Comments: 133300
Thanks for the update StormW - As always, very thought out and intelligent post.

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Quoting 757weather:
Anyone else think a center is trying to develop in that blob just south of Hispaniola


that is all in the midlevels by Hispaniola..it will take a few days to work it way down to the surface if at all. By time it gets near Jamaica or west of there.. a circulation may develop. Right now, there isnt 1 even close.
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morning folks,

CNN) -- Officials in Brazil fear the death toll may rise as four days of flooding has punished the northeastern states of Pernambuco and Alagoas, killing 33 people and leaving thousands homeless, officials said. More than 1,000 people are missing in the state of Alagoas. Some 500 people are unaccounted for in the town of Uniao dos Palmares alone, a state spokesman said. According to Brazil's civil defense agency, more than 40,000 are homeless. Brazil's President Luiz Inacio Lula da Silva is meeting in Brasilia with governors of both states and has promised to facilitate emergency funds to help flood victims. Pernambuco Governor Eduardo Campos -- who flew over the affected areas -- described the situation as "heart-breaking. ""What we have seen since Friday is more than a horror-film," Campos said in an official statement. Alagoas Governor Teotonio Vilela Filho traveled through several affected areas an attempted to reassure public.
"I ask you all to remain calm because we are all invested in helping you," he said. Alagoas state weather officials are forecasting more rain on Tuesday. Brazil's Center for Climatic Studies (CPTEC) predicted rain above average in the Northeast for the Autum season, which is now coming to an end. Brazil's winter season officially began on June 21.
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We in east central Florida are right on target with rainfall so far this year. That is already straining Lake Okeechobee's levees so we do not need a tropical system providing ample amounts of water; I'd hate to think what that would do to the levees.
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I think it makes the Gulf as a strong TS. I, of course, base this on a complete lack of knowledge and understanding. If anyone can provide any facts to back up my hypothesis, I'd greatly appreciate it.

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the eye is more visible if u go to the NHC site.
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Quoting Jeff9641:


CMC is wrong as always. There can never be 2 storms that close to each other.


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anything over 200mph would be considered a cat?
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Theres good old cat 2 celia still chugging along, theres a tiny eye, thank god its going to stay away from land, as most storms in the pacific do.
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Quoting DaytonaBeachWatcher:


Most of the time, this site is more for entertainement and drama than for information.


So true. Note all the heavy breathing over 93L yesterday. Then the good Dr. comes on to give some sanity. It will go loopy around here again by noon (MT).

Pretty entertaining.
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Echo Tops to 52K

Member Since: July 3, 2005 Posts: 434 Comments: 133300
http://drought.unl.edu/dm/DM_south.htm
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Quoting CaneWarning:


Speaking of ants...I saw a ton of them today all over a piece of food someone dropped on the sidewalk. Are these ants a sign of things to come??? I guess we'll see!


They are opportunistic. They see food- then horde for the CAT5 that's coming. (lol)
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210. Skyepony (Mod)
Quoting twhcracker:


omg two hitting near me. are you kidding about a natural solution??


Yes, that would be horrible.. Hard not to laugh when watching the over active doom & gloom of the CMC.

The way they follow so close..really only seen that once & it was over the oil fields of Australia, much weaker storms. Odd solution. (not to the oil but just they end up so close without one obviously absorbing the other as they come together).
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Quoting robert88:
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

So you are telling me that because it didn't form within 24 hours it can't form. You do know that cyclogenesis takes a while.
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The Blogs are only a small part of the wunderground..to be sure.
The server only uses 3-4 percent of its RAM on the blogs on a busy Sept day.

Most never even see the blogs as the wunderground is used by millions for its Weather info.
Member Since: July 3, 2005 Posts: 434 Comments: 133300
new surface map are out (12Z)



Member Since: June 13, 2009 Posts: 2 Comments: 13692
Quoting CosmicEvents:
I've used this formula. I find if you divide the result by the number of new ant hills you've seen in the last week, times 2..the end result is deadly accurate. Forget about rarely, you'll NEVER be wrong.


Speaking of ants...I saw a ton of them today all over a piece of food someone dropped on the sidewalk. Are these ants a sign of things to come??? I guess we'll see!
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Apologies if this is a repost:

Area forecast discussion
National Weather Service Houston/Galveston Texas
444 am CDT Tuesday Jun 22 2010

The buzz about what could become our first tropical cyclone of the season is not dying down. NHC has moderately high confidence (50%) that this central Caribbean wave will become a depression within the next couple of days. If/when this does occur...confidence on where it is heading will significantly increase due to much better initiation. Fwiw...06z NAM the most aggressive with a 1000mb storm just offshore of Cancun Friday afternoon. Euro has significantly backed off on its strong Ivan-looking scenario with the Gem still consistent in its Mobile Bay-to-central Florida Panhandle Sunday storm. The very
like-able GFS still has yet to wake up to the hype as there is no discernible low under our gargantuan 593-ish Dam Ridge. 31
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Quoting helove2trac:
This site is a addiction


Most of the time, this site is more for entertainement and drama than for information.
Member Since: June 29, 2007 Posts: 0 Comments: 1136
Quoting Jeff9641:


Pat you guys need that rain as your drought is becoming national news now. I saw a report from northern LA of lakes and rivers drying up about a week or so ago.


No drought in Se La.
Member Since: July 3, 2005 Posts: 434 Comments: 133300
are you teasing me skye? is the cmc a real thing?
Member Since: July 30, 2007 Posts: 6 Comments: 1448
Quoting PensacolaDoug:
Also... The CMC is too funny!



CMC has Pcola doomed
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TWC will now jump the gun and say this is looking very great and it will develop within the next 12 hours since they use the TWO from 6 hrs before.
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I never sit down in front my Screens without a Java Fix in the am.

That would be a serious protocol infraction here
Member Since: July 3, 2005 Posts: 434 Comments: 133300
NHC expecting a low pressure center south of Jamaica tomorrow morning...

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Dr. Masters co-founded wunderground in 1995. He flew with the NOAA Hurricane Hunters from 1986-1990. Co-blogging with him: Bob Henson, @bhensonweather

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