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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The center is between Haiti and Jamaica at 15.5. There's some popcorn there. The Doc says while there is a little something at mid levels nothing at the surface and until it gets convection going, it's pretty much gonna be in the incubator. Am paraphrasing, not word for word quote. CU L8R
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Quoting weathermanwannabe:


Dr. M just threw that model under the bus on his show on cyclogenisis issues....

He did say it performed the best on track however .... LOL I still think the CMC is nuts
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Quoting reedzone:
A storm will try hard to stay in favorable conditions, away form the wind shear. This is why I feel the LLC will form south around 15-16N, 73-74W. The future path is uncertain until it forms a LLC.
Interesting. Do you think that these organizing storms have those kind of higher-level thought processes? Perhaps mother clouds pass down to baby clouds the ways of survival, like an animal in a jungle.
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Quoting Jeff9641:


nothing there and barely a shower.

It may have moved from there, but my graphic was based on the 18z position from the FTP site.
Member Since: May 16, 2009 Posts: 1 Comments: 1231
.
Member Since: September 2, 2009 Posts: 130 Comments: 21091
Quoting NOLALawyer:


Judge Feldman is beyond reproach. He also is probably the most intelligent judge on the bench in the EDLA. He follows THE LAW and he is usually pro-government. So, do not attempt to taint his ruling with the tinge of self-serving motives.

Mike

Most anyone with a diversified portfolio owns some oil stuff. It's just good business.
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1287. unf97
Quoting washingaway:


More north


If the upper level trough develops as some of the reliable models are trending, then if 93L evolves into a stronger tropical entity, then a turn to the north would ensue. It is simply a matter of timing as always of when this scenario develops. Just have to keep watching, there are still possibilities the trough may not develop as sharp as the models are forecasting, and a more W-NW track would continue should that happen.
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Quoting IKE:
Dr. Masters said the best model for performance in 2009 in the 1-3 day time period was the GFS...according to the NHC.

CMC was by far the best model in the 4-5 day time period in 2009...according to the NHC.


Model performance in 2009 per

this PDF doc from NHC:

- of 144 official forecasts issued in 2009, only 22 verified at 120 hours.

- however, at 24 to 72 hours, the official forecasts set new records for accuracy, close to (the non-corrected) TCON/TVCN consensus models. The official forecasts were beat by GFSI and EXML, and GHMI also performed well. So yes, GFSI was the one to watch in that time frame, with EXML and GHMI. For 2009 :-)

Edit: fixed typos on GHMI

- although not in this doc, at 96 and 120 hours, CMC provided the best track guidance in 2009.

- kissing cousin of the CMC, the LGEM provided the best intensity estimates for the second year in a row (and the third year wasn't bad either).

So, if you only watch a few models, watch GFS out to 72 hours, CMC out to 120 hours. For intensity guidance, look to LGEM. Then introduce the correction factors to make 2010 like 2009 :-)
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Quoting Jeff9641:


What is this near Grenada. There seems to be something the making there.
Look down the blog, KMAN commented on it the most.
Member Since: September 2, 2009 Posts: 130 Comments: 21091
All the arguing can end tomorrow because we will get all the data we need. There is a requirement to fly into 93L tomorrow. After that mission we will have a lot of the answers we need.
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Quoting btwntx08:

yep


LLC should be there by morning.
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Quoting btwntx08:

nice graphic

Thanks!
Member Since: May 16, 2009 Posts: 1 Comments: 1231
Okay kids... let's all play nice. :)

Can someone post the latest model runs? Thanks.
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Quoting StSimonsIslandGAGuy:
Ganked from Auburn

According to the most recently available financial disclosure form for District Court Judge Martin Feldman, he had holdings of up to $15,000 in Transocean in 2008. He has also recently owned stock in offshore drilling or oilfield service providers Halliburton, Prospect Energy, Hercules Offshore, Parker Drilling Co., and ATP Oil & Gas. Feldman was appointed by President Ronald Reagan in 1983.


Judge Feldman is beyond reproach. He also is probably the most intelligent judge on the bench in the EDLA. He follows THE LAW and he is usually pro-government. So, do not attempt to taint his ruling with the tinge of self-serving motives.

Mike
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Quoting Abacosurf:


Disagreed. Crap changes. The new seed is 72W.
That spin that you see is in the mid levels, not at the surface. Just look at 850 millibar vorticity.
Member Since: September 2, 2009 Posts: 130 Comments: 21091
Quoting Drakoen:
The NHC is absolutely correct when they lowered the chances within 48 hours. The system is really not what we have been monitoring south of the DR and Haiti. Probably just a mesoscale convective vortex. The area we need to focus on is between 75W-72W.


Very interesting argument...

Despite if is or not a MCV, if were... it could be a mechanism of shot of deep convection surround its center, maybe.
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TROPICAL DISCUSSION - INTERNATIONAL DESKS

Excerpt:


A TROPICAL WAVE ALONG 74W AND SOUTH OF 19N SUSTAINS A BROAD
CYCLONIC CIRCULATION INTO THE CENTRAL CARIBBEAN. THE NHC CONTINUES
TO MONITOR THIS WAVE FOR POSSIBILITY OF DEVELOPMENT INTO A
TROPICAL CYCLONE... AND THEY WILL ISSUE THE OFFICIAL FORECAST. AT
THIS TIME...THE TUTT TO THE NORTHWEST AND THE BUILDING RIDGE
ACROSS THE BASIN FAVOR SOUTHWESTERLY SHEAR ACROSS THIS AXIS. THE
MODELS ARE TAKING THIS INTO ACCOUNT AND FOR THE MOST PART ARE NOT
AS AGGRESSIVE AS THEY WERE ON PREVIOUS RUNS (IN PARTICULAR THE
ECMWF). ONLY THE NAM FAVORS RAPID DEVELOPMENT.

THE SLOW TO MOVE PERTURBATION WILL SUSTAIN ORGANIZED CONVECTION
ACROSS HISPANIOLA-JAMAICA-EASTERN CUBA...WITH ACCUMULATION OF
15-20MM/DAY AND MAXIMA OF 35-70MM/DAY THROUGH 36 HRS. OVER
JAMAICA/EASTERN CUBA AND THE CAYMAN ISLANDS IT WILL FAVOR
ACCUMULATION OF 15-20MM/DAY AND MAXIMA OF 30-60MM/DAY AT 36-60
HRS. BY 60-84 HRS MAXIMA ACROSS JAMAICA WILL DECREASE TO
25-50MM/DAY...WHILE ACROSS THE CAYMAN ISLANDS-ISLA DE LA
JUVENTUD/EASTERN CUBA THE MAXIMA WILL INCREASE TO 35-70MM BY 60-84
HRS. OVER NORTHEAST HONDURAS/NICARAGUA IT WILL SUSTAIN
ACCUMULATION OF 10-15MM/DAY AND MAXIMA OF 20-35MM/DAY. ACROSS
NORTHERN COLOMBIA IT WILL FAVOR ACCUMULATION OF 05-10MM/DAY AND
MAXIMA OF 15-30MM/DAY THROUGH 36 HRS...WHILE OVER EJE
CAFETERO/DARIEN IN PANAMA IT WILL SUSTAIN ACCUMULATION OF
05-10MM/DAY AND MAXIMA OF 15-20MM/DAY... SIMILARLY OVER WESTERN
PANAMA-COSTA RICA.
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Quoting Jeff9641:


nothing there and barely a shower.
Pay attention to the FTP. I see the circulation at 75.0W 17.5N, but what do I know?
Member Since: September 2, 2009 Posts: 130 Comments: 21091
1271. guygee
Quoting Jeff9641:


Disregard those runs. They are trash no low there. The is near the Haiti DR border. There is though a critter near Grenada that has nice vorticity.hmmmm
I pretty much agree. The mid-level circulation is just south of Hispaniola. There still is no surface circulation, so how can we trust any model runs yet? Those runs are just reflections of different predictions for the strength and position the steering currents based on the position of the high to the north and the predicted strength of a tropical low that hasn't even formed yet.
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1270. IKE
Member Since: June 9, 2005 Posts: 23 Comments: 37858
Quoting MiamiHurricanes09:
It's actually 75W.


Disagreed. Crap changes. The new seed is 72W.
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Quoting frostynugs:
"We didn't stop flying airplanes for six months after 9/11, did we?"

Planes didn't keep crashing into buildings for 2 months after 9/11, did they? They weren't still crashing into buildings every day when they ban on flight was lifted, were they?


I don't see the twin towers standing either for that matter...
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Quoting Abacosurf:


17N and 72W.

The bands have back built behind the 70 and are all tied to the 72W low.

Now building to the south as well.
It's actually 75W.
Member Since: September 2, 2009 Posts: 130 Comments: 21091
Quoting CyclonicVoyage:
CMC on the 20th 12Z


Dr. M just threw that model under the bus on his show on cyclogenisis issues....
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Quoting btwntx08:

nope its 17n and near 75w the other one is the lrftover mlc that is leaving behind


17N and 72W.

The bands have back built behind the 70 and are all tied to the 72W low.

Now building to the south as well.
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Hurricane Hunters are flying into the Invest tomorrow...
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CMC on the 20th 12Z
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My 18z update:


Latitude and longitude found using BEST position from the ftp site.
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Quoting Chicklit:
Dr. Masters mentioned a big Atlantic trough next week steering 93L somewhere, but I was working and cannot remember details.


More north
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Quoting Jeff9641:


Disregard those runs. They are trash no low there. The is near the Haiti DR border. There is though a critter near Grenada that has nice vorticity.hmmmm


Exactly......shift everything north and east IMO.

The seed for the low is now directly south of the border.
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I am starting to see evidence of a spin near 15N. NOt much. just some clouds moving north while others in the area move south on nasa.
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The center is where the vorticity is and the anticyclone.

| /SATPRODUCTS/TC/tc10/ATL/93L.INVEST/vis/geo/1km_zoom
20100622.2015.goes13.x.vis1km_high.93LINVEST.25kts-1010mb-155N-744W.100pc.jpg |

From Navy site.
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wow!!!
IR image of the heart of Africa.
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1251. xcool
center trying to form
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Quoting RobertM320:


And its been two months and I haven't seen any other rigs explode either.


Just because they're not exploding doesn't mean they're not leaking. This one is: http://www.nola.com/news/gulf-oil-spill/index.ssf/2010/06/another_gulf_oil_spill_well_ne.html
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Quoting CaneWarning:


They look good to me. They take it over the Yucatan which would weaken it before it may hit Mexico or possibly some part of Texas.


I don't like them whatsoever!!! I live in Northeastern Mexico so I will closely follow this fella. A more westerly-like path would be taken if the system remains weak?
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Dr. Masters mentioned a big Atlantic trough next week steering 93L somewhere, but I was working and cannot remember details.
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1246. srada
Why do you think that will happen?
If this blows up to be a monster, then the trough will pick up it earlier..its about timing of the trough and the strength of the storm
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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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