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 stopped caring about blobs after 92L died the first time. I never thought I'd say this about 2010 but my tropical interest has shifted into the E-pac. That only happened in 2006 and 2009
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Quoting kmanislander:


I know, but I don't pay any attention to models trying to work up an amorphous mix of clouds and rain. If it doesn't fire in the NW Caribbean then its back to the drawing board for answers.
It is a little more than clouds and rain. It does have a broad surface low and vorticity is increasing, a sign of a strengthening low.
Member Since: September 2, 2009 Posts: 130 Comments: 21032
Quoting Drakoen:


The majority of the models are developing this.


Yeah, but GFS is not onboard, which gives me doubts, still concerned though.
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Albeit less defined, the vort max just south of Haiti seem to be more vertically stacked. It also has more surface convergence.
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Quoting CyclonicVoyage:
93L is sitting in prime conditions for development.

Massive anti-cyclone directly overhead, Boiling SST's, 0-5 kts of shear. Almost like watching an episode of Sponge Bob and 93L is Patrick. UMM hey Bob, what do I do?


can you tell me how to spot an anticyclone? i don't know what to look for or where to look. i tried google, but nothing helpful came up
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Quoting truecajun:
i do not like those dynamic spaghettis! but still too early, right?


Way, way too early.
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2390. JRRP
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Quoting futuremet:
Both vort maxes seem to be synthesizing.
I noticed that they were combining but it still remains broad.
Member Since: September 2, 2009 Posts: 130 Comments: 21032
Quoting Drakoen:


The majority of the models are developing this.


I know, but I don't pay any attention to models trying to work up an amorphous mix of clouds and rain. If it doesn't fire in the NW Caribbean then its back to the drawing board for answers.
Member Since: Posts: Comments:
93L is sitting in prime conditions for development.

Massive anti-cyclone directly overhead, Boiling SST's, 0-5 kts of shear. Almost like watching an episode of Sponge Bob and 93L is Patrick. UMM hey Bob, what do I do?
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Quoting nash28:
93L is fighting proximity to land. Also remember, this invest is parked in the ECAR and this is typically no mans land. Give it another couple of days. It needs to clear the ECAR and move closer to the YUC Channel before we begin to see any serious formation.

Hi Nash, the music is really nice while blob watching.
Glad your experience and straightforward comments are back on the blog!
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Quoting kmanislander:


Funny how this is the year when all the conditions are supposed to be ripe for above average activity and yet here is a system underneath a ridge of high pressure and sitting over TCHP that is equal to the peak of the season and yet it just drifts along like it was on a lazy river ride.

Is there such a thing as having conditions that are too optimal ??.
Don't get me wrong, I think that 93L will probably be the seasons first TD but I doubt we'll see it before it gets into the western Caribbean. I do find it odd that with the optimal conditions that it is lacking convection but you can attribute that to a few things.
Member Since: September 2, 2009 Posts: 130 Comments: 21032
i do not like those dynamic spaghettis! but still too early, right?
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Both vort maxes seem to be synthesizing.
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Quoting Patrap:
Im gonna add Home House Oil Boom to my Hurricane Prep List.

Maybe a skimmer too.


We have considered Whole House ShrinkWrap. Don't laugh...I really DID consider it. For just one moment! ;)
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Quoting Drakoen:


The majority of the models are developing this.

gfdl 103 knots ,hmrf 45 knots end of both runs. just ridiculous
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2379. Patrap
Quoting kmanislander:


Funny how this is the year when all the conditions are supposed to be ripe for above average activity and yet here is a system underneath a ridge of high pressure and sitting over TCHP that is equal to the peak of the season and yet it just drifts along like it was on a lazy river ride.

Is there such a thing as having conditions that are too optimal ??.



As the Models reflect, the NHC and climo..she dont get ramped up to TS status till the Yucatan Kman,,as Climo and History still run da Big Show.

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Quoting futuremet:
0z 850MB vorticity

Still broad, but getting a bit stronger.
Member Since: September 2, 2009 Posts: 130 Comments: 21032
anyone on anticyclone? all i know is that it helps a storm out. can you tell me how you know one is there? which map do you look at and what to look for?
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Quoting MiamiHurricanes09:
The supposed broad area of low pressure is at 75.2˚W. I doubt we'll see any development until it reaches 82.5˚W. If it continue moving towards the west at 10 miles per hour it should be reaching there in about 48 hours. So honestly I doubt we'll see development in the very short-term.


Funny how this is the year when all the conditions are supposed to be ripe for above average activity and yet here is a system underneath a ridge of high pressure and sitting over TCHP that is equal to the peak of the season and yet it just drifts along like it was on a lazy river ride.

Is there such a thing as having conditions that are too optimal ??.
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2375. Patrap
00z Early Cycle NHC model tracks
Invest93
Statistical/Simple Models (CLIPER,BAMs,LBAR,other Statistical Models)





Dynamic Models (More sophisticated models)



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The area near 9N 39W is continuing to look better.
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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
Member Since: September 2, 2009 Posts: 130 Comments: 21032
0z 850MB vorticity
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Quoting spathy:
This is just gut feeling here folks.
I have lived through the past many years down here in SW Florida.
We have seen quite a few years that have had late and anomalous season fronts recently.
But this year I am seeing an old pattern of what used to be normal flow across the state!
I just dont see the pattern that would cause a Charlie or Wilma thus far.
Never say never!
But I think an old familiar flow is coming home.
Or just wishful thinking!
I wish no one any land falling storms!
But I see a more Texas/Mexico and Caroline Mid Atlantic type season this year.
Or in other words.
Low chance of sharp R turns in the SE /Mid Gulf.
JM(Wish)O


my mom and dad always talk about how it was always texas that got the storms
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Quoting Patrap:


Just like all the intensity Graphs have been forecasting since yesterday Morning.

Its the "Climo" favored area historically.



Arrrrgg tis be da curse of The Black Pearl at work.

I heard Tony Hayward was on his way down to the area to check things out. I also heard his card was declined when he tried to rent a boat so, apparently he is in a row boat? something about Cantorie too, heck I dunno.

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2364. Drakoen
Quoting kmanislander:
Good evening all

So, nothing new with 93L. Glad I didn't rush back here to see what was up. This is looking more and more like a ride into the Central American coast as a rainmaker. Still no sign of any real organization but there sure is some big time rain trailing in the huge complex to the East. Perhaps a low will develop there instead.



The majority of the models are developing this.
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Quoting kmanislander:
Good evening all

So, nothing new with 93L. Glad I didn't rush back here to see what was up. This is looking more and more like a ride into the Central American coast as a rainmaker. Still no sign of any real organization but there sure is some big time rain trailing in the huge complex to the East. Perhaps a low will develop there instead.

The supposed broad area of low pressure is at 75.2˚W. I doubt we'll see any development until it reaches 82.5˚W. If it continue moving towards the west at 10 miles per hour it should be reaching there in about 48 hours. So honestly I doubt we'll see development in the very short-term.
Member Since: September 2, 2009 Posts: 130 Comments: 21032
2362. mobal
<
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Quoting wxmanjarod:


Good to see most of the usual folks on here and welcome to the new folks. So begins another glorious hurricane season.

Let's keep it clean, watch the rabbit punches and kidney punches... in case of a knockout, go the corner we tell you to and await further instructions.

I promise to go to my corner in case of a KO....
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2360. Patrap
Im gonna add Home House Oil Boom to my Hurricane Prep List.

Maybe a skimmer too.
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Quoting ShenValleyFlyFish:


Where are you getting that radar?


I got them from this site. A few of them are out of service. This is probably due to the dismal economic conditions of these countries.
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Quoting wxmanjarod:


Good to see most of the usual folks on here and welcome to the new folks. So begins another glorious hurricane season.

Let's keep it clean, watch the rabbit punches and kidney punches... in case of a knockout, go the corner we tell you to and await further instructions.



LOL!!!
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Hi Nash...nice to see you back.
.
.
As far as our invest goes.....I'm giving it a 90% chance that the HH flights get cancelled tomorrow.
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Quoting nash28:
Goodnight Tom.

Cybr!! How are ya?


Good! Ready for another hurricane season, which already promises to be insane. Did you see these TCHP levels? Holy cow! Its only June!





Member Since: July 8, 2005 Posts: 259 Comments: 23013
Quoting Drakoen:


Hey Nash28 Good to see you


Good to see most of the usual folks on here and welcome to the new folks. So begins another glorious hurricane season.

Let's keep it clean, watch the rabbit punches and kidney punches... in case of a knockout, go the corner we tell you to and await further instructions.

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Hi again everyone!! Hi hanna!! I remember you from last season!! Good to see you!! :) StormW, how are you doing..besides being busy..:)
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Good to see a new familiar face back here again...always has good opinions and observations.
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Good evening all

So, nothing new with 93L. Glad I didn't rush back here to see what was up. This is looking more and more like a ride into the Central American coast as a rainmaker. Still no sign of any real organization but there sure is some big time rain trailing in the huge complex to the East. Perhaps a low will develop there instead.

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Quoting StormW:
Good night all! See yas in the a.m.
Good night Storm!
Member Since: September 2, 2009 Posts: 130 Comments: 21032
night storm
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2348. nash28
Mobal- How have you been?
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Quoting StormW:


Can't hurt however...in simple form...at DMAX, in effect the ELR is a little steeper.
True.
Member Since: September 2, 2009 Posts: 130 Comments: 21032
Quoting nash28:
Listen to the ebbs and flows of this wonderful piece of music.

This will be the hurricane season, and the people and hearts that will encompass the compassion to the human soul should one strike..



nice piece of music. it reminds of the feelings LOST gives me for some reason.
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About JeffMasters

Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.