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 BWDavis:
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


i want to thank you on behalf of the people of louisiana for looking after our safety by coming to the right place.
Member Since: July 30, 2007 Posts: 6 Comments: 1448
Quoting 850Realtor:
Tweet from Jim Cantore: NHC plans recon on 93L Wednesday.


I give it a 75% chance they will cancel for tomorrow
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Circulation is becoming more visible on Infared.


Link
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The stronger the storm is in the GOM,the more it will go N???
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Quoting Patrap:


."I gotta tell ya folks,them wunderbloggers are on top of things"..

Back to you guys in the Studio..


Actually, I think we should start a movement to bring back Dave " my friends" Schwartz. Now there was an entertaining fellow.
Member Since: August 19, 2006 Posts: 0 Comments: 15842
Quoting kmanislander:
The so called core position of 93L is being robbed of the energy it needs to develop by the vigorous upper level rotation that is being generated by the thunderstorm complex just South of Hispaniola. The rotation can be seen here

One of two things will likely happen next. Either the rotation seen in the image will take over as the focal point of the system and go ashore in Hispaniola spelling the end of 93L in the Caribbean OR the demise of that complex when it hits land will clear the way for 93L to develop further South and West near to where it is currently positioned.

I do not think it can develop while there are two separate areas competing for the energy available to the system and for the moment the complex further North seems to be in control.

That "rotation" is the curvature at the top apex of the wave. The winds switch from NE to SE at the top of the wave but notice the bottom side is Open. The focal point is simply the middle of the wave. Right now there is not much convection in the southern half so it appears to be robbing it but not the case. The Low Level wave is still amplified by it. We need pressure drop to get both a COC and a TD and for that we need convection. If a center does form it may simply be more to the north.
The "focal" point given in the models is probably just the center of the wave.. does anyone know how they pick them?
Member Since: September 1, 2009 Posts: 23 Comments: 1007
Quoting bjdsrq:


300 hours. ROFLMAO.


The GFS, when it comes to Cape Verde storms has a history of nailing potential storms. Storms such as Bertha, Dean, and Bill were all ghost storms of the GFS 300 hours out. It's when the GFS is NOT consistent is when it's totally unreliable. At least in my opinion.
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Quoting twhcracker:


drop a cheezit on the ground and wait a minute.

lol
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.."I gotta tell ya folks, them wunderbloggers are on top of things"..

Back to you guys in the Studio..
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336. IKE
...
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Quoting Patrap:


We knew that yesterday from the NHC


Go to a reliable Government site. That Would be just WRONG. Lol
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Quoting trey33:
I am antless in Tampa


drop a cheezit on the ground and wait a minute.
Member Since: July 30, 2007 Posts: 6 Comments: 1448
From Tampa Bay:

MID/UPPER LEVEL RIDGING WILL REMAIN OVER THE SOUTHEAST U.S. AND
FLORIDA INTO EARLY NEXT WEEK WHILE THE SURFACE RIDGE AXIS REMAINS TO
THE NORTH OF THE FORECAST AREA. MODELS STILL HAVING TROUBLE
RESOLVING THE MOVEMENT...STRENGTH AND TIMING OF THE TROPICAL WAVE
MOVING THROUGH THE CARIBBEAN. FOR NOW HAVE GENERALLY GONE WITH A
MUCH WEAKER VERSION OF THE ECMWF AND KEPT THE EASTERLY FLOW ACROSS
THE REGION WITH DEEP MOISTURE MOVING IN SUNDAY AND MONDAY. BASED ON
THIS SCENARIO THE OVERALL FORECAST FOR THE LONG TERM PERIOD WILL
REMAIN UNCHANGED WITH SCATTERED MAINLY AFTERNOON AND EVENING
THUNDERSTORMS DEVELOPING EACH DAY. TEMPERATURES ARE EXPECTED TO
REMAIN NEAR TO SLIGHTLY ABOVE NORMAL THROUGH THE PERIOD WITH HIGHS
IN THE LOWER TO MID 90S AND LOWS MOSTLY IN THE 70S.
Member Since: April 26, 2009 Posts: 3 Comments: 3667
Quoting reedzone:
Yet again the GFS develops a Cape Verde Storm in 300 hours, since it's being pretty consistent, knowing it's history with long range Cape Verde systems, I'd watch it. Shows a consistent track to the Lesser Antilles and if you look at the high, has 2004 written all over it.


300 hours. ROFLMAO.
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They should have let Jim Cantore be the hurricane expert that would have been exciting LOL
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**REPOST**
Hurricane Celia (Category 2)
*NEW* Graphics Update
Time: 8am PDT/11am EDT
Images made by cyclonekid
Click on images to make them larger


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948

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.



II. PACIFIC REQUIREMENTS

1. NEGATIVE RECONNAISSANCE REQUIREMENTS.

2. OUTLOOK FOR SUCCEEDING DAY.....NEGATIVE.

JWP


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Quoting 850Realtor:
Tweet from Jim Cantore: NHC plans recon on 93L Wednesday.


We knew that yesterday from the NHC


Plan of the Day

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.
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Tweet from Jim Cantore: NHC plans recon on 93L Wednesday.
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Quoting Funkadelic:


Umm kind of scary as soon as you posted that I was listening to the classic Led Zeppelin song "When The Levees Break" take it with a grain of salt but it gave me the creepers!

BTW can you post a link of the long range GFS. I find that run so entertaining most of the time. Much appreciated!


http://www.nco.ncep.noaa.gov/pmb/nwprod/analysis/carib/gfs/06/images/gfs_ten_384l.gif
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ok when is this thing forecasted to be in the gulf this week or next week
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Quoting Jeff9641:
The center that is forming is NNE of where the models have this intialized by about 75 to 100 miles moving WNW/NW.


15.5N, 73.5W is my best guess. I've been looking at the visible close up and following the lower level clouds. If you trace the cloud deck in, this is where they appear to meet imo. The area just lacks deep convection at the moment.
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322. 7544
yeap ike thats where a ll the action and is building and expanding to the north of this system and if keeps on the nw track so fla will get drench too they saying wedns or thurs heavy rain and wind there
Member Since: May 6, 2007 Posts: 0 Comments: 6862
If I had to pick out some coordinates where I thought a circulation was forming, I'd have to say 15.5 N, 71 W... just barely south of the Barahona peninsula, DR.
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Quoting BWDavis:
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



The order by which they fall in the cue thats all.

93L..is now,the next invest will be 94L,L for Atlantic.

When we get to 99L..we start over after the next with 90L.

Thats bout it.

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12Z GFS FINALLY jumps on the band wagon..

http://www.nco.ncep.noaa.gov/pmb/nwprod/analysis/carib/gfs/12/images/gfs_ten_066l.gif

Yeah.. I'm too lazy to jump to IE, I'm on google chrome right now.
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Quoting IKE:
Hispaniola is fixing to get drenched from 93L.


I hope they need the rain!
Member Since: April 26, 2009 Posts: 3 Comments: 3667
93L looking better. Sorry been gone for a bit. Was updating my blog.
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315. IKE
Quoting trey33:
I am antless in Tampa


Plenty of ants up here in the Florida panhandle.

Looks like a wider area of 93L is starting to spin.
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Quoting StormW:


Post #285

No. LOL!

Lol, oops I was making it using the model runs that had it going over Jamaica, didn't have a look at the recent ones. Guess I'll have to update it.
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313. IKE
Hispaniola is fixing to get drenched from 93L.
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Quoting trey33:
I am antless in Tampa


Sounds like a movie.
Member Since: April 26, 2009 Posts: 3 Comments: 3667
Yet again the GFS develops a Cape Verde Storm in 300 hours, since it's being pretty consistent, knowing it's history with long range Cape Verde systems, I'd watch it. Shows a consistent track to the Lesser Antilles and if you look at the high, has 2004 written all over it.
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310. 7544
Quoting Jeff9641:


The models are way off of where this system is forming a center. Impressive banding on the north and east side. Haiti is going to see a lot of rain. Also once the center forms later it will pass just north of the island of Jamaica or over Jamaica.


im with you jeff but i might be the only one lol thats how it looks at this end maybe the next model run will see this too
Member Since: May 6, 2007 Posts: 0 Comments: 6862
Quoting BWDavis:
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

Well they name invests from 90L to 99L in order and then start over at 90L again. btw an invest is a tropical disturbance that the NHC thinks could develop into a tropical cyclone
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I am antless in Tampa
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CosmicEvents "In 2005, we had reports from the New Orleans area 10 days prior to Katrina of beaucoup ant mounds on soccer fields..."

Reports generated cuz that's the most excitement anybody has ever seen on any soccer field anywhere.
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Quoting WinterAnalystwx13:


It'll probably come ashore between next Monday and Thursday, with Tuesday/Wednesday being the best chance.


It will really be a benefit concert then. Forget about stepping on a tar ball...look out for washers, dryers and toilets.

Maybe it will just not develop or fizzle out if it does become something. No one needs this anywhere along the Gulf Coast, wherever it decides to go!
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The so called core position of 93L is being robbed of the energy it needs to develop by the vigorous upper level rotation that is being generated by the thunderstorm complex just South of Hispaniola. The rotation can be seen here

One of two things will likely happen next. Either the rotation seen in the image will take over as the focal point of the system and go ashore in Hispaniola spelling the end of 93L in the Caribbean OR the demise of that complex when it hits land will clear the way for 93L to develop further South and West near to where it is currently positioned.

I do not think it can develop while there are two separate areas competing for the energy available to the system and for the moment the complex further North seems to be in control.
Member Since: August 19, 2006 Posts: 0 Comments: 15842
Quoting twhcracker:
i love that about tourists covered in oil HAHHAHA


They were (are) prophetic words.
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For many of us, it won't be today or tomorrow - next week, next month??? The best advice is to be as prepared as possible. Hope for the best, prepare for the worst!
Member Since: August 17, 2007 Posts: 0 Comments: 272
Little change to 93L
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I have been closely watching the visible daylight satellite pics of 93L. I am pretty sure that there is a LLC trying to form at 15.5N and 70.5W. There is convection firing to north and south of this area, and the low level cloud formations, are arching into this area.
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Quoting SavannahStorm:


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.
Not what the cmc is showing...
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i love that about tourists covered in oil HAHHAHA
Member Since: July 30, 2007 Posts: 6 Comments: 1448
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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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.