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 still like the NHC tune on 93L. Notice they said 20% chance over then next 48 hours. It's reasonable because this has still yet to find a surface closed low level low. So 20% seems right, over the next 48 hours. After that, they said conditions are likely to get conductive for development in a few days. So they're not RIPing it, just saying development, if any, will be slow. Good call :)
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Reminds me of trying to find a center to Hunberto in 2007...with all of that convection and motion there has to be a center developing somewhere. Maybe it is finally manifesting near 15.5 67.5...?
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Quoting Patrap:
Floater - Visible Loop


Circulation definitely noticeable
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Quoting IKE:
12Z HWRF @ 126 hours...



Bad 12Z HWRF..@ 126 hours...

Sit..

Go Lay down..

Dats a good model

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Looks as though it is weakening significantly...
Quoting Patrap:
Floater - Rainbow Color Infrared Loop
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Looks pretty good to me....maybe I need to get my eyes checked too.



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788. IKE
12Z HWRF @ 126 hours...

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um TN the GFDL still has mainly the same forecast today as it did last night
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Quoting Jeff9641:
1/4 mile visibility here right now with this storm. VERY INTENSE storm!!!


Where is here?
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Quoting Skyepony:
After the 1st day the race for who has the least Average Position Error (nm) out of the core models on 93L..We find LBAR in the lead with an error of only 7.5nm. Impressive lead over the rest of the pack BAMD 66.9, MM5B 67.4, HWRF 84.3, MM5E 102.6, GFDL 325.4nm.

GFDL does lead the intensity bit with 7kts error, followed by MM5B 20 & MM5E 25kts.


I WAS THINKING ABOUT THIS TODAY, THE MODELS ARE A COMPLETE JOKE!!!

LAST NIGHT AT 0Z THE GFDL HAD 93L TURNING INTO ALEX AND BLOWING
IT UP TO 99 KTS AND TAKING IT INTO THE CENTRAL GULF
CAUSING MISCHIEF.


TODAY- WELL SURPRIZE! AFTER CREATING MASS HYSTERIA- A COMPLETELY DIFFERENT
SCENARIO. I HAVE NOW BECOME ONE OF THOSE PEOPLE WHO BELIEVE THAT
THE MODELS ARE GARBAGE UNTIL THE SCENARIO IS COMPLETELY OBVIOUS.


CMC = POSSIBLY ON CRACK
GFS = A TROPICAL JOKE
GFDL = IM CONVINCED THIS MODEL IS WORKING
FOR LOWES/CNN/HOME DEPOT.
HWRF = PROABLY THE ONLY DECENT MODEL AVAILABLE
NOGAPS= BORING AND USUALLY WAITS TILL IT OBVIOUS
MAKING IT COMPLETELY USELESS.

LBAR = JUST DRAW A STRAIGHT LINE AND CALL IT A FORECAST
WOW ..BRILLIANT! [LOL]
Member Since: July 3, 2007 Posts: 0 Comments: 524
Floater - Rainbow Color Infrared Loop
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Personally I Think 93L is organizing slowly and looks more compact and organized than it did this time yesterday, I think the NHC probably coded it wrong when they gave it an orange circle yesterday, but thats just my personal take.
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Quoting Drakoen:
I think I need to get my eyes checked...


LOL xD
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Scottvsb, show me anywhere I said LLvs. If I didn't say it then don't quote me as saying it please.
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778. xcool
Drakoen LOL
Member Since: September 26, 2009 Posts: 2 Comments: 15671
Quoting StormW:


The area showing the vorticity though is in an almost stable environment.

I have $5 on it though...
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Quoting StormW:


Ture...in fact, 3 hours prep time.


Exactly... So many fail to realize this. I think that many on here believe that the discussion is produced 10 minutes before post time by one person. Hours of prep go into that statement. By the time its posted, the TEAM is already compiling data for the next discussion, hence the lag, sometimes, in the content of the discussion and what we are seeing real time. So many smart indivuals on here yet so many fail to recognize this process.
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NHC probably realized how slow this thing is developing, so 20% in a 48hour window seems reasonable.

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774. IKE
Quoting Hurricanes101:
Also dont forget, ECMWF never really developed this system until Friday anyway

neither do most of the models, not really sure where this development by Wednesday came from. Could be due to the scheduled recon for tomorrow, but that may just be canceled now


I agree with the 20%, but "less organized"???
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I think I need to get my eyes checked...
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Also dont forget, ECMWF never really developed this system until Friday anyway

neither do most of the models, not really sure where this development by Wednesday came from. Could be due to the scheduled recon for tomorrow, but that may just be canceled now
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Quoting scottsvb:


WOW calm down kid.. just restated the obvious.


HOW DARE YOU HAVE AN OPINION!!!

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Quoting Baltimorebirds:
Guys guess what I found out from another blogger.You wanna know how jfv continues to come back??.Becuase he changes his email address to make it look like a new person.Just thought I tell you guys.
an ip ban would take care of that
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766. IKE
12Z HWRF on 93L.


12Z CMC.
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Quoting WINDSMURF:

Come on JFV don't start with that. It is too early to start predicting major hurricane for Florida.


The more you quote the worse it's gonna get.
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Quoting WINDSMURF:

Come on JFV don't start with that. It is too early to start predicting major hurricane for Florida.


Please Don't quote him.

He is just another wannabe (JFV) craving for attention.
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Quoting Hurricanes101:


yea some of us felt that was a bit premature
Ditto, with no LLC.
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Quoting washingaway:
Dr. Masters gives it less than 20%.

Actually he said that he gave it less than 20% chance to be a hurricane, "I give the storm a low (less than 20% chance) of becoming a hurricane in the Caribbean"
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Quoting 69Viking:


I didn't say LLvs either you putz so don't try to put words into my mouth. I said you can see rotation on the visible satellite with no mention of whether it was mid level or low level. It's visible on the visible satellite in my opinion so back off and quit attacking anyone who mentions rotation. Has it become your job to attack everyone who does?


WOW calm down kid.. just restated the obvious.
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I think some tend to forget the TWO is for a 48 hour period ONLY

I have seen a few times where if the percentages in the TWO go down, people start to write off a system.

It dropped to 20%, only means that over the next 2 days development is less likely than it was yesterday. It has absolutely no bearing on the chances 93L has to become a TD or TS over its entire lifetime
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756. xcool
Member Since: September 26, 2009 Posts: 2 Comments: 15671
744. Put him on ignore and everyone stop quoting him please.
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Floater - Visible Loop
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Looks to me like there is some spin showing up in the last few frames of the RGB sat view of 93L. Latest 12Z GFDL shows Cat 2 in the gulf in 5 days south of LA. Just what the oil spill needs is a strong SE then S then SW wind - great!
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Quoting StormW:
It's just funny how this has become "less organized", but we'll named a naked swirl up by the Azores a ST storm.


Don't mock Grace she had a developing eye at one point!!!!

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Quoting kmanislander:
While 93L is taking its own sweet time deciding what to do here is another interesting area to keep an eye on and follow.

Strong vorticity is showing up here both at 850 mb level and on visible loop imagery. There are tell tale inflow streamers from the SE towards convection that is just starting to show up.



Yeah I was stating this yesterday.. though it will also have the same problem 93L had..but this 1 is better organized @ the LLvs
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Quoting scottsvb:


Midlevel circulation.. he didnt say LLvs :)


I didn't say LLvs either you putz so don't try to put words into my mouth. I said you can see rotation on the visible satellite with no mention of whether it was mid level or low level. It's visible on the visible satellite in my opinion so back off and quit attacking anyone who mentions rotation. Has it become your job to attack everyone who does?
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742. Hurricanes101 1:53 PM EDT on June 22, 2010
Hey StormW, check out the area at 40W

nice vorticity, convergence, divergence, shear looks pretty good too
Action: Quote | Ignore User

a lil far south but it really bears watching for sure
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Quoting IKE:
NHC=Experts.

Me=Amateur.

Looks better this afternoon then it did this morning at the earlier TWO. Maybe I am going blind.


Its no different actually then 24hrs ago. ESE winds @ the surface and a midlevel disturbance being enhanced by the midlevel trough over Jamaica NE thru Cuba into the Bahamas. There is nothing close to the surface right now.. been stating that along with Txmet all day. :))
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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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