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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MiamiHurricanes09 that one is old this is the new one



Member Since: June 13, 2009 Posts: 2 Comments: 12157
2595. IKE
00Z NAM @ 84 hours...

Member Since: June 9, 2005 Posts: 23 Comments: 37858
Quoting Hurricanes101:


not even a possible developing low on that map
I'm fairly convinced that there is a very broad area of low pressure supported by satellite imagery (shortwave), 850mb vorticity, and MIMIC-TPW. But I won't make any guarantees until I hear anything from the NHC or if we can get a clean ASCAT/WindSAT pass.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
2593. BDAwx
I hope the Atlantic doesn't get its act together and start spewing tropical cyclones like the East Pacific is right now...
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Quoting TampaSpin:
It finally appears to me that 93L is trying to wrap itself up tighter now......gotta see if it continues tho..As i posted this loop earlier.....it easily show a COC...not saying it is a Surface LLC yet but, it is certainly wrapping now......Floater - Infrared Channel 2 Loop


Humm.. no sure about that but it will eventually conditions ahead are just perfect.
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2590. Patrap
Quoting AllBoardedUp:
Ouch! Did you randomly pick Ike as an example, or did you remember from past years that I'm from the Galveston area? One heck of a Catagory 2 storm when you consider the storm surge it carried!


Just a Google Image example.


Thats a early Ike track..

And Ike was nuther xample of How Lousy Surge is quantified by the SSS.

K was a CAt 3/4 depending on what Landfall one uses and had a 17-30 ft Surge.

It was Ike,Katrina and Rita and Gustav that made the NHC go with the new Warnings for Surge Package
Member Since: Posts: Comments:
Quoting CyclonicVoyage:


NHC mentions it quite frequently and is usually fairly accurate. I want access to the LGEM though, lol. TCVN is right on with the GFDL at the moment, that's a tough combo to beat, especially with other majors in the same area.
Lol. TVCN verified second to the ECMWF last year so it definitely is a good model.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
I think the west coast of FL might
get 93
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2587. xcool
TampaSpin:good job
Member Since: September 26, 2009 Posts: 2 Comments: 15684
2586. pottery
Those Brazilian flood images are as scary as Hell itself.
Looks like damage from a tsunami/earthquake/war/hurricane all rolled into one.
An example of the deadly power of the river.....
Member Since: Posts: Comments:
Quoting Patrap:
Ouch! Did you randomly pick Ike as an example, or did you remember from past years that I'm from the Galveston area? One heck of a Catagory 2 storm when you consider the storm surge it carried!
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Quoting MiamiHurricanes09:
00z Surface Analysis.



not even a possible developing low on that map
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Quoting TampaSpin:
It finally appears to me that 93L is trying to wrap itself up tighter now......gotta see if it continues tho..As i posted this loop earlier.....it easily show a COC...not saying it is a Surface LLC yet but, it is certainly wrapping now......Floater - Infrared Channel 2 Loop
You might be seeing wrapping around the MCV that was being watched earlier. The dominating circulation is a broad area of low pressure SE of Jamaica.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
Wow guys-Those poor people in Hati & the Dominican Republic. They did not need this on top of everything else that's happened.
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2581. xcool


Member Since: September 26, 2009 Posts: 2 Comments: 15684
Quoting MiamiHurricanes09:
I'm following the TVCN. Looks like it has the best handle on what's going on even though it is a combination of like 7 models.


NHC mentions it quite frequently and is usually fairly accurate. I want access to the LGEM though, lol. TCVN is right on with the GFDL at the moment, that's a tough combo to beat, especially with other majors in the same area.
Member Since: January 30, 2010 Posts: 0 Comments: 3259
Could we see the Fujiwara Effect between Celia and TD5E?
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2578. JRRP
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Hello everyone I usually stay quite but I live in Houma, LA and the cmc and gfdl models are not what I want to see happen. They are coming right at me. LOL
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It finally appears to me that 93L is trying to wrap itself up tighter now......gotta see if it continues tho..As i posted this loop earlier.....it easily show a COC...not saying it is a Surface LLC yet but, it is certainly wrapping now......Floater - Infrared Channel 2 Loop
Member Since: Posts: Comments:
00z Surface Analysis.

Member Since: September 2, 2009 Posts: 130 Comments: 21194
Well at least we don't have to pull out the Jimmy Buffet song I don't know where I'm going to go when the hurricane blows. YET
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2573. Patrap
Quoting AllBoardedUp:
I see what you are talking about, thanks again.


Anytime,,my pleasure.
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Quoting TampaSpin:


OK!!!!!!
Ok?
Member Since: September 2, 2009 Posts: 130 Comments: 21194
Quoting Patrap:



actually,that..and the positions of the Loop eddy,..and the eddies that shed and move west off the Sw and Central Louisiana Coasts come into play as well. Rita tapped the far Western one in 2005..



I see what you are talking about, thanks again.
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2569. Patrap
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Quoting AllStar17:
Keep one eye on the 9N 40W area. Vorticity looks fairly good in that area.


I agree that wave is looking more and more interesting as time pass... In the meanwhile 93L has everething to be clasified as the first TC of the season high SST, Low Shear and climatology in his favoe, a concern the latest models runs that shows it as strong TC in the GOM.
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Quoting CyclonicVoyage:


Although, there is a fairly good consensus among the models now, which is surprising. Even the Bamms came around which hasn't been the case until recently.

I'm following the TVCN. Looks like it has the best handle on what's going on even though it is a combination of like 7 models.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
My graphic for the 8:00 pm TWO update (projected path made by me not the NHC)
*Graphic issued 9:45pm CST*

Based on 00z model runs.
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Quoting MiamiHurricanes09:
You really can't get a good idea of where 93L will go after it enters the GOM because it will greatly vary on how south the trough digs and how strong the upper level ridge by Texas is.


OK!!!!!!
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Quoting MiamiHurricanes09:
You really can't get a good idea of where 93L will go after it enters the GOM because it will greatly vary on how south the trough digs and how strong the upper level ridge by Texas is.


Although, there is a fairly good consensus among the models now, which is surprising. Even the Bamms came around which hasn't been the case until recently.

Member Since: January 30, 2010 Posts: 0 Comments: 3259
,
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2562. Patrap
Quoting AllBoardedUp:
Thanks, Patrap. Am I to understand that the TCHP at the beginning of the season has as much bearing on the intensity of a storm even if follows another one in a short period of time?



actually,that..and the positions of the Loop eddy,..and the eddies that shed and move west off the Sw and Central Louisiana Coasts come into play as well. Rita tapped the far Western one in 2005..



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Quoting Skyepony:
The wave behind 93L, the one lastnight.. I was calling to eventually steal the show from 93L. It crossed over the islands today, improved it's 850vort some. Almost to 65W now & just beginning to tap & take the moisture that 93L has extended out near PR.
Something is going on there. You can see the areas combing on satellite.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
I am off for tonight. Nothing is going to change in the short term. Have a good evening all.
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Quoting Hurricanes12:


The setup that WSVN uses just keeps me coming back. They may be a over-dramatized station, but they do become reliable when something does occur, or so in my opinion. Are any other news stations any better?


Yes channel 10, Max Maxfield joins their crew when things start popping.
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2557. 786
Hello! First time this year I am coming out of lurk mode. I am a bit perplexed with 93L can someone please explain what variable(s)is/are preventing 93L from developing a closed low as I was under the impression it was in a favourable environment (low shear, boiling SSTs, possible anticyclone...)
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Spathy from one rookie to another I was looking at the wv loop for the Atlantic at NHC and the 200mb vorticity. Look at se fl. watch the motion on the WV loop. But me far from competent on satellite analysis, but if we don't post we will never learn even if sometimes it learning the hard way if you know what I mean. WU blog rules dang it.
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Quoting Patrap:




Total heat content of the ocean

As most of you are aware, hurricanes generally require sea surface temperatures (SSTs) of at least 80 F (26.5 C) to exist, and the hotter the water, the better.Hurricanes also like to have these warm ocean waters extend to a depth of several hundred feet, since the winds of a hurricane generate ocean turbulence that stirs up colder water from the depths to the surface. Hurricane that pass over a region of ocean with very deep warm waters can intensify explosively; this happened with Katrina, Rita, and Wilma in 2005. A good way to monitor this total oceanic heat is with the Tropical Cyclone Heat Potential (TCHP) imagery prepared daily by NOAA using satellite measurements of the height of the ocean surface. Hotter water expands, creating a higher water surface that the satellite can measure.

Let's take a look at the TCHP data from July 28 this year, and compare it to last year (Figures 4 and 5). The units of measurement are in kilojoules per square centimeter, and any value greater than 20 kJ/cm**2 (a medium blue color) is high enough to support a Category 1 hurricane. A TCHP greater than 90 kJ/cm**2 (orange color) can lead to rapid intensification of a hurricane. The TCHP image from last year shows a large area of oranges and reds in excess of the 90 kJ/cm**2 threshold for rapid hurricane intensification covering most of the Gulf of Mexico, Caribbean, and tropical Atlantic. A red bullseye in the Gulf of Mexico marks the Loop Current Eddy that broke off in the Gulf last July, and helped fuel Katrina and Rita to record intensities.

In contrast, the TCHP image for this year shows the oranges and reds covering just a portion of the western Caribbean and southern Gulf. There is much less heat energy available to fuel intense hurricanes, and thus we should see fewer of them this year than in 2005 (or 2004, which also had very high TCHP values). However, we again see an ominous looking red bullseye in the central Gulf of Mexico this year, similar to what was there last year.
Thanks, Patrap. Am I to understand that the TCHP at the beginning of the season has as much bearing on the intensity of a storm even if follows another one in a short period of time?
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.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
2553. Skyepony (Mod)
The wave behind 93L, the one lastnight.. I was calling to eventually steal the show from 93L. It crossed over the islands today, improved it's 850vort some. Almost to 65W now & just beginning to tap & take the moisture that 93L has extended out near PR.
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Keep one eye on the 9N 40W area. Vorticity looks fairly good in that area.
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Quoting TampaSpin:
I had 93L organizing and becoming a TD Tomorrow....as this was my Graph i put together as i color code it the yellow, orange, red like NHC....I do believe once 93L does become better organized "IF IT DOES", it will move further North then what the Concensus of Models are showing...

This was my Forecast direction and Intensity....from yesterday at 10am





This loop shows easily a COC may not be a LLC but, its there at ...17.3N 72.8W Speed it up as it is now coming together it appears...
You really can't get a good idea of where 93L will go after it enters the GOM because it will greatly vary on how south the trough digs and how strong the upper level ridge by Texas is.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
Quoting MiamiHurricanes09:
2528. Ameister12 10:32 PM EDT on June 22, 2010

LOL! You can tell it's Avila who wrote it when the head title is:

"...AND YET ANOTHER TROPICAL DEPRESSION FORMS IN THE EASTERN
PACIFIC..."

But I got to say, 5 tropical depressions in like 10 days is pretty crazy.

Yeah. I loved what he had to say about TD 5-e. Lol!
Member Since: Posts: Comments:
I had 93L organizing and becoming a TD Tomorrow....as this was my Graph i put together as i color code it the yellow, orange, red like NHC....I do believe once 93L does become better organized "IF IT DOES", it will move further North then what the Concensus of Models are showing...

This was my Forecast direction and Intensity....from yesterday at 10am





This loop shows easily a COC may not be a LLC but, its there at ...17.3N 72.8W Speed it up as it is now coming together it appears...
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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.

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