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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296. 900MB
Quoting Jeff9641:
93L is organizing as we speak.


Yep, looks like a little better spin factor. Let's see if it can become more symmetrical.
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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)


hilarious!
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I work for the Louisiana Department of Public Safety in IT and watch these storms to know if I will have to man our Emergency Operations Center. Please forgive my ignorance, but I have been wondering about how a low pressure system is named. I notice that it is usually 92L, 93L, etc. What determines the numeric part of the name?

Thank you for any assistance, Brian
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Do you guys think that this projected path is plausible.


*Made by me*
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Quoting robert88:

That wasn't me. I messed up with the quotes and it is fixed now. Go back to the last page and see post 158 :)

Oh, lol sorry.
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Quoting ssmate:
Not today. Today is the BP summer company picnic. Food, face painting, clowns and heavy alcohol consumption.


Isn't that every day at BP?

Well, at least the clowns and heavy alcohol consumption.
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I am going to see a new movie next week called "OIL VS CAIN playing in the gulf of mexico near you
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Quoting FLWeatherFreak91:
The CMC is out to lunch on that last run... yes, there can be two storms relatively close to one another, but not nearly as close and rotating around each other as the CMC suggests.


Fujiwhara effect- When the cyclones approach each other, their centers will begin orbiting cyclonically about a point between the two systems. The two vortices will be attracted to each other, and eventually spiral into the center point and merge. When the two vortices are of unequal size, the larger vortex will tend to dominate the interaction, and the smaller vortex will orbit around it.
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Quoting Hurricanes101:


Yea, we did get a nasty storm last night

lightning, thunder, high winds, big time rains for about 90 minutes


I didn't realize you were in St. Pete.
Member Since: April 26, 2009 Posts: 3 Comments: 3667
12z Early Cycle NHC model tracks
Invest93
Statistical/Simple Models (CLIPER,BAMs,LBAR,other Statistical Models)




Dynamic Models (More sophisticated models)




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Quoting helove2trac:
I wonder of bp is keeping up with this thing in the carribean
Not today. Today is the BP summer company picnic. Food, face painting, clowns and heavy alcohol consumption.
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Quoting FLWeatherFreak91:
Well, blame the seabreeze for keeping the coast too dry. Just north of Tampa I'm well above average for this month and the year.


Yea, we did get a nasty storm last night

lightning, thunder, high winds, big time rains for about 90 minutes
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Quoting Capeskies:

They know something we don't.
then a storm is comming to my yard, and a cat 5.
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I have $5 on this guy in 96 hours.. The low level trough will suck enough moisture out of the south and give the wave the rotational energy it needs to develop.
"TROPICAL WAVE IS ALONG 30W/31W S OF 14N MOVING W NEAR 20 KT. A
DRY LOW LEVEL VORTICITY CENTER IS TO THE W OF THE WAVE ANALYZED
AS A SURFACE TROUGH EXTENDING FROM 14N36W TO 10N38W WITH A WELL
DEFINED CYCLONIC CURVATURE ALONG TROUGH AXIS. TOTAL PRECIPITABLE
WATER IMAGERY ALSO INDICATES A DRY CIRCULATION TO THE E OF THE
WAVE AXIS AND A DEEP LAYERED MOISTURE MAXIMUM ALONG THE WAVE
AXIS S OF 12N. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS
EMBEDDED WITHIN THE ITCZ FROM 3N-7N BETWEEN 28W-31W. "
Member Since: September 1, 2009 Posts: 23 Comments: 1007
278. srada
I really think this storm will be an ernesto event..if this storm ramps up and with that trough dipping from the north along with the bermuda high sitting over the atlantic..it will get pulled before getting into the gulf of mexico
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StormW you hit the nail on the head

kudos to the GFS shear forecast for nailing the anticyclone moving eastward for a short time

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Quoting twhcracker:


yes thank god this blog was beginning to make my brains whirl


It's the gherkins, hon
Member Since: August 2, 2006 Posts: 10 Comments: 9922
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Quoting 757weather:

Some people on this site are too funny


Patience...the tropics are about patience and boredom interspersed with several days of frantic panic stricken activity...
Member Since: August 2, 2006 Posts: 10 Comments: 9922
Quoting Dakster:
Thanks for the update StormW - As always, very thought out and intelligent post.



yes thank god this blog was beginning to make my brains whirl
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June 22, 2010

An update on that vigorous tropical wave

The strong tropical wave in the Caribbean (dubbed 93L) has changed little in organization overnight as it moves south of Hispaniola. The National Hurricane Center gives it a 40 percent chance of becoming a tropical storm during the next 48 hours.

To guess whether this wave will become the season's first named storm, or whither it will go, would be rank speculation. There has been little consistency among the computer models.

As of this morning most of the intensity models eventually develop the wave into a tropical storm and some into a hurricane after four or five days:


Colo. State
Model predictions of storm intensity over time.
As for where it might go if it develops, the possibility remains from anywhere in Mexico to the Florida Panhandle. There really is no way of telling as the track models, especially after about four days, are widely variable.

Joe Bastardi, a senior meteorologist with Accuweather told me last night he expects the system will eventually move over Texas or Louisiana. That's probably as good a guess as any.

He also mentioned the following, which is interesting and a tad concerning.

"The monster seasons of 1995 and 2005 began with Gulf storms that formed out of deep tropical waves rather than the normal systems this time of year that come down from the westerlies," Bastardi said. "That we are seeing this kind of development threat early is just as big a deal as whether it actually develops."

In other words, the fact that we're seeing African waves develop into very vigorous tropical waves in June does not bode well for hopes of an inactive season this year.


Link
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271. 7544
Quoting Jeff9641:
93L is organizing as we speak.


looking better lets see if in can get conv on ythe south side so far its been all to the north
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Quoting Hurricanes101:


not in St Pete we arent lol
Well, blame the seabreeze for keeping the coast too dry. Just north of Tampa I'm well above average for this month and the year.
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Yea i remember just before katrina i saw a lot of black birds in a group together and i saw the same thing about 2weeks ago and i said to myself please not another katrina
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The CMC is out to lunch on that last run... yes, there can be two storms relatively close to one another, but not nearly as close and rotating around each other as the CMC suggests.
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Quoting Floodman:
I love the RIP'ers and the CAT5'ers...it does make for fine drama.

LOL

Some people on this site are too funny
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Quoting Jeff9641:
93L is organizing as we speak.


in the process anyway.
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Quoting FLWeatherFreak91:
We're above avg rainfall on the other side of the peninsula...


not in St Pete we arent lol
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Quoting CosmicEvents:

Back in 2005 we first learned of a possible connection between ants and approaching cyclones. In order to fit the criteria what you see must be:
NEW ANT HILLS.large, IN NEW SPOTS.
.
.
In 2005, we had reports from the New Orleans area 10 days prior to Katrina of beaucoup ant mounds on soccer fields, and other areas that normally didn't have large ant mounds.


Guess I should't have spent so much on high dollar ant poison. Kills for up to 9 months. If they show up know, could be real trouble.
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Quoting helove2trac:
I wonder of bp is keeping up with this thing in the carribean


You can bet your ass they are. lol
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Quoting reedzone:
Ughh you all should know you just can't RIP a storm when it's in favorable conditions for a few days.


Believe me reedzone, some people just don't listen and take time to look at the maps.
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Ughh you all should know you just can't RIP a storm when it's in favorable conditions for a few days.
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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.

That wasn't me. I messed up with the quotes and it is fixed now. Go back to the last page and see post 158 :)
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Quoting Jeff9641:


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



Of course there can...
Member Since: August 2, 2006 Posts: 10 Comments: 9922
Quoting rmbjoe1954:
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.
We're above avg rainfall on the other side of the peninsula...
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catman neither is impossible LOL
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Quoting extreme236:


Old image...


oops didn't see that.
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What's the latest timing with this system...if it becomes a system?

All I can say is if this storm is offshore on June 30/July 1st, it will just have to sit offshore and wait! I am going to the FREE Jimmy Buffett concert, storm or no storm! :) Who knew his song lyrics "All of those tourists covered with oil" would have such a meaning.
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robert88 says 93L's RIP.. now we can be assured that this could be a threat down the road. I'll have my own update shortly.
Member Since: July 8, 2005 Posts: 259 Comments: 24016
Quoting CosmicEvents:

Back in 2005 we first learned of a possible connection between ants and approaching cyclones. In order to fit the criteria what you see must be:
NEW ANT HILLS.large, IN NEW SPOTS.
.
.
In 2005, we had reports from the New Orleans area 10 days prior to Katrina of beaucoup ant mounds on soccer fields, and other areas that normally didn't have large ant mounds.

They know something we don't.
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Quoting tropicfreak:
heres a better image.



Banding features are still there.


Old image...
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Quoting Floodman:
I love the RIP'ers and the CAT5'ers...it does make for fine drama.

LOL


Lame yet epic arguements.
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Quoting StadiumEffect:


Why do you even bother? It's just not worth it. lol.

lol
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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!

Back in 2005 we first learned of a possible connection between ants and approaching cyclones. In order to fit the criteria what you see must be:
NEW ANT HILLS.large, IN NEW SPOTS.
.
.
In 2005, we had reports from the New Orleans area 10 days prior to Katrina of beaucoup ant mounds on soccer fields, and other areas that normally didn't have large ant mounds.
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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

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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.