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 Jeff9641:


So everybody including JB is wrong. Why don't you think this is going to the Panhandle when a huge trough will be digging across the east this weekend.


Wishcasting is ever-present as we both know.
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Quoting wunderkidcayman:
oh I see what you mean utilaeastwind and you meant 16N 75W either there or at 16N 72W


THANKS FOR THE CORRECTION. TO ME 16N 75W LOOKS THE MOST FAVORABLE.
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3594. Patrap
I just post um..

I dont elaborate on them as to why,..who's in the way or not.

They are used for Guidance,,not Gospel.
Member Since: July 3, 2005 Posts: 426 Comments: 128874
3593. bappit
Quoting sailingallover:

What center???


Why you keep sayin' that?

Must be a center of something, or they wouldn't have co-ordinates with it.


The North Atlantic discussion this morning does not give a center. Re-read the discussion and remember that the model outputs are not forecasts.
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3592. Patrap
Some folks get a tad tizzy over colored Lines seems.

LMAO


Member Since: July 3, 2005 Posts: 426 Comments: 128874
3591. gator23
Quoting FLWeatherFreak91:
Just ignore people like that. You think he knows what he's talking about?

None of us know where this is going really, so we should stop the speculation.

I agree with you. KENTS LAW: Tropical Cyclone landfalls are directly and inversly proporational to the location of the WU Blogger. In laymens terms. It is going to go wherever the blogger lives regardless of climo.
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Quoting IKE:


Recon canceled for today is what I've read. They'll have today's recon mission for tomorrow coming out shortly.

Ref Post 3565:
They may change coordinates, but I would be surprised if they don't go out today, particularly since Dr. Masters has said the HH flights would be a record number this year due to a study on rapid intensification.
With the models all over the place, it's a good time to go.
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3588. IKE
Quoting btwntx08:

yes im sure and if models are indeed correct this is a la storm


Well if you say so.
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There is a naked swirl in the Atlantic at 7N 42W moving WNW.
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Models spreading apart


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Quoting IKE:


Really? You know that huh? There is a panhandle of Florida.


I'm all messed up, I thought the panhandle was in Texas......LOL. Go Gamecocks!
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3583. IKE
Quoting FLWeatherFreak91:
Just ignore people like that. You think he knows what he's talking about?

None of us know where this is going really, so we should stop the speculation.


Amen.
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3581. bappit
Quoting Patrap:
Dynamic Models (More sophisticated models)






Those models assume that there is some sort of defined center to the thing. There ain't.
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Not sure if anyone else has spotted this as yet, but take a look at between 45 and 40. Very interesting.....something to keep an eye on. Link
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3579. IKE
Quoting gator23:

and Keys.


True.
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Quoting IKE:


Really? You know that huh? There is a panhandle of Florida.
Just ignore people like that. You think he knows what he's talking about?

None of us know where this is going really, so we should stop the speculation.
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Still remains rather disorganzied this morning. 12z UK isn't doing much of anything with this disturbance. Keep in mind there are no reliable computer models when it comes to genesis of a tropical cyclone.
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3574. gator23
Quoting IKE:


Really? You know that huh? There is a panhandle of Florida.

and Keys.
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Quoting Floodman:


Well stop it!


Hi Flood, I thought it was funny. Heh heh.
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3572. gator23
Quoting btwntx08:
its not forming at 72w and no its not headed to fl period


SEE KENT'S LAW of Global Fluid Dynamics
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The thing that I don't understand is, according to MIMIC, total precipitable water is actually increasing around 16N, 78W, and yet nothing has been firing there. Maybe it is getting ready to?
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oh I see what you mean utilaeastwind and you meant 16N 75W either there or at 16N 72W
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3568. IKE
Quoting btwntx08:
its not forming at 72w and no its not headed to fl period


Really? You know that huh? There is a panhandle of Florida.
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Quoting ecflweatherfan:
If the storm heads west of the spill, it will pull even more oil into the bayous and beaches of the Gulf Coast. If the storm heads east of the spill... it will help pull massive amounts of oil southward into the Gulf Loop... which could affect the SE CONUS coastline. Either way is not good. We do not need any tropical system in the GOMEX.


You are right on the money. But then again, dispersion would help thin out the oil across the Gulf. But regardless, I would hate oil to be trapped into the Gulf Loop Current.
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Unless there is a source I am not aware of, this is the most up-to-date information RE: recon. All other speculation is just that - speculation....

000
NOUS42 KNHC 221500
WEATHER RECONNAISSANCE FLIGHTS
CARCAH, NATIONAL HURRICANE CENTER, MIAMI, FL.
1100 AM EDT TUE 22 JUNE 2010
SUBJECT: TROPICAL CYCLONE PLAN OF THE DAY (TCPOD)
VALID 23/1100Z TO 24/1100Z JUNE 2010
TCPOD NUMBER.....10-022

I. ATLANTIC REQUIREMENTS
1. SUSPECT AREA (SOUTH OF JAMAICA)
FLIGHT ONE - TEAL 70
A. 23/1800Z
B. AFXXX 01AAA INVEST
C. 23/1330Z
D. 17.0N 77.5W
E. 23/1700Z TO 23/2100Z
F. SFC TO 10,000 FT

FLIGHT TWO - TEAL 71
A. 24/0600Z
B. AFXXX 0201A CYCLONE
C. 24/0100Z
D. 17.5N 79.5W
E. 24/0400Z TO 24/0830Z
F. SFC TO 10,000 FT

2. SUCCEEDING DAY OUTLOOK: CONTINUE 12 HRLY
FIXES IF SYSTEM REMAINS A THREAT.
Member Since: July 20, 2008 Posts: 0 Comments: 152
HH trips. TROPICAL CYCLONE PLAN OF THE DAY (TCPOD)
VALID 23/1100Z TO 24/1100Z JUNE 2010
TCPOD NUMBER.....10-022

ATLANTIC REQUIREMENTS
1. SUSPECT AREA (SOUTH OF JAMAICA)
FLIGHT ONE - TEAL 70
A. 23/1800Z
B. AFXXX 01AAA INVEST
C. 23/1330Z
D. 17.0N 77.5W
E. 23/1700Z TO 23/2100Z
F. SFC TO 10,000 FT

FLIGHT TWO - TEAL 71
A. 24/0600Z
B. AFXXX 0201A CYCLONE
C. 24/0100Z
D. 17.5N 79.5W
E. 24/0400Z TO 24/0830Z
F. SFC TO 10,000 FT

2. SUCCEEDING DAY OUTLOOK: CONTINUE 12 HRLY
FIXES IF SYSTEM REMAINS A THREAT.
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If the storm heads west of the spill, it will pull even more oil into the bayous and beaches of the Gulf Coast. If the storm heads east of the spill... it will help pull massive amounts of oil southward into the Gulf Loop... which could affect the SE CONUS coastline. Either way is not good. We do not need any tropical system in the GOMEX.
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Quoting 34chip:
How does anyone see Key West being effective by this wave or waves. Thanks

weather outlook for key west
weds 30% chance of rain today & tonight
thurs & thurs night 40% RAIN WINDS 15-20 MPH
FRI/SAT/SUN 50% chance rain
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Okay, looking at the MIMIC animation, it would look like the "center" of 93L is actually around 16N, 78W.
http://cimss.ssec.wisc.edu/tropic/real-time/tpw2/natl/main.html
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Quoting sailingallover:

But wouldn't that be better? If a storm washes all the oil into tar way up above the water line it will have way less environmental impact as far as Life goes. You can pave right up to a tree but a snail in the water gets suffocated..



I would hope you're right, but I still think it would be a mess.
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3557. IKE
Quoting Floodman:


Well stop it!


?
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3555. IKE
Quoting Chicklit:

Hi Ike, so that means they're flying today.
Yippee.


Recon canceled for today is what I've read. They'll have today's recon mission for tomorrow coming out shortly.
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What I'm seeing on satellite this morning seems to be very similar to the scenario the CMC was playing out yesterday. It formed two area south of Hispaniola, strengthened the more westerly on (the on currently south of Haiti) and slingshot the other one on the east around north of Hispaniola.

I find this plausible if the area south of Haiti is able to keep developing. Looks as if cloud tops are warming though.
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3552. gator23
Quoting StormSurgeon:
Wow IKE, you're in a typing mood this morning. The last thing we need is a storm of any magnitude rampaging in to the Gulf...the outcome will be horrible at best. I'm sick of this oil mess (as are you), but a T.S. or hurricane will make life miserable for us folks on the coast, as if it's not bad enough already for the shrimpers, crabbers and recreational fishers to boot.

I remember the Doc saying that a TS or small hurricane would help disperse some of the oil. And that the real danger isi if you get a large storm with lots of surge.
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Hi Patrap, with that satellite view, we're lookin down two barrels this morning.
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Quoting IKE:


LOL..I was quoting Bastardi.


Well stop it!
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Quoting weatherman566:


Yes and no. Since a an area of low pressure moves counterclockwise, the winds would blow away from the shore on the storm's west side. In other words, if the system is east of New Orleans, then yes, New Orleans would be spared. However, winds would blow on shore towards Mississippi and Alabama, which could be bad (oil fears). So, it could be a good thing and a bad thing if a tropical system is east of Louisiana.


True, but it'se easier to clean their beaches than our marshes.
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LOOKS TO ME THAT CIRCULATION IS STARTING AGAIN AT 16W 75N on RGB LOOP.

http://www.ssd.noaa.gov/goes/east/tatl/flash-rgb.html
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Quoting IKE:
chicklit...that's yesterday...6-22-10.

Hi Ike, so that means they're flying today.
Yippee.
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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.