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 KoritheMan:


If it takes until Friday to develop, then the northern Gulf Coast is, fortunately, likely to be spared.


why would you say that?
Member Since: March 10, 2010 Posts: 1 Comments: 7542
2895. docrod
Quoting EricSFL:
Hey kids.


Time to "thin the herd"
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2894. xcool
20% by nhc
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Quoting Hurricanes101:
If this thing takes until Friday or even the weekend to develop, I think 65% of the blog will be bald from pulling their hair out lol



If it takes until Friday to develop, then the northern Gulf Coast is, fortunately, likely to be spared.
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Galveston Hurricane,
I understand that but the previous person may not have.And I am not offended ,sorry if I came across as such, I am on here too, trying to gather information on a wave/imvest that may or may not form.
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Quoting KoritheMan:


Well to be fair, it is the internet -- as such, sometimes it is difficult, nigh impossible even, to distinguish between satire and seriousness.

My apologies.


Thanks for your understanding. Do you think the NHC will up the percentage at the next advisory?
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2890. xcool
lmao
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2889. EricSFL
Was it shear that enhanced 92L's convection during DMAXs? Because I don't see 93L taking advantage of the current environmental conditions...
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Quoting TampaSpin:


YOu all need to read backwards and catch up....LOL....Just kidding! Funny!


This blog moves so fast now, its hard to read back through the comments. lol
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Quoting galvestonhurricane:


As having been affected by Hurricane Ike myself, I don't think you have taken what I have said the right way. Obviously, it was a stupid comment, but at the same time, it should not have been taken so seriously.


Well to be fair, it is the internet -- as such, sometimes it is difficult, nigh impossible even, to distinguish between satire and seriousness.

My apologies.
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If this thing takes until Friday or even the weekend to develop, I think 65% of the blog will be bald from pulling their hair out lol

and I may be underestimating those numbers lol
Member Since: March 10, 2010 Posts: 1 Comments: 7542
Quoting galvestonhurricane:


There was no malicious intent involved when I made that comment. I know many people who lived there and did not like it. By all means, that is not my personal opinion of Beaumont or the surrounding area.


I see. Fair enough.
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Quoting KoritheMan:


Ah. That makes sense.

I personally thought he was being serious, as well. Obviously he needs to work on his humor.


As having been affected by Hurricane Ike myself, I don't think you have taken what I have said the right way. Obviously, it was a stupid comment, but at the same time, it should not have been taken so seriously.
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yea 93L has a ways to go

I wouldnt expect any change on the TWO, and that is ok, development was never really expected before Thursday or Friday

slow process starting to come together, slowly

anyway I am off to bed, night everyone
Member Since: March 10, 2010 Posts: 1 Comments: 7542
Quoting txsweetpea:


Hickville doesnt bother me, trust me. It was the misleading information that "was just a joke".


I am sorry that you were so offended by that comment, but realistically, everywhere from Texas to Florida could be affected.
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Quoting txsweetpea:


Hickville doesnt bother me, trust me. It was the misleading information that "was just a joke".


Ah. That makes sense.

I personally thought he was being serious, as well. Obviously he needs to work on his humor.
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Quoting KoritheMan:


I think she's probably referencing where you labeled Beaumont "hickville".


There was no malicious intent involved when I made that comment. I know many people who lived there and did not like it. By all means, that is not my personal opinion of Beaumont or the surrounding area.
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Quoting KoritheMan:


I think she's probably referencing where you labeled Beaumont "hickville".


Hickville doesnt bother me, trust me. It was the misleading information that "was just a joke".
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2878. xcool


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Quoting Drakoen:
This is the area we need to focus on.


Whoa, when did that get there? I was just off for half an hour. I guess I'm in for a squally morning.
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2875. Drakoen
Here's a nice satellite loop centered on the lower to mid level center west of the convection. You can see the rotation.


Link
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Quoting galvestonhurricane:


I can only speak for myself, but I have not seen anyone making fun of anyone else on this blog.


As I stated before, txsweetpea I have no idea what you are talking about.
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Quoting cchsweatherman:


Given the strongest vorticity and current upper level pattern, I must agree. As pointed out earlier by scott, pressures have been falling slightly in that area as well. I think many are distracted by the action to the east right now.


YOu all need to read backwards and catch up....LOL....Just kidding! Funny!
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Quoting galvestonhurricane:


I can only speak for myself, but I have not seen anyone making fun of anyone else on this blog.


I think she's probably referencing where you labeled Beaumont "hickville".
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Quoting btwntx08:
hmmm why is shear incrasing in extreme western carribean


Thats just due to the strengthening periphery of the upper level ridge over the Caribbean. Not gonna remain that way in the coming days as the upper level ridge continues to advect northward over the entire Caribbean.
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Quoting Drakoen:
This is the area we need to focus on.



I pointed that out an HOUR ago....i agree!
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2866. EricSFL
Hey kids.
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Quoting txsweetpea:
There are ALOT of people that lurk on this blog, SOME are from the area that IKE DEVASTATED(aka...."20-25 min from bmt"...aka"hickville".)SOME have businesses that house patients and THOSE people come on here and TRY to find out information because MOST trust the people on this blog. SO saying all of that ...its not funny to anyone that is only trying to gain information on the POSSIBLE formation of a storm to practically be made fun of..


I can only speak for myself, but I have not seen anyone making fun of anyone else on this blog.
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Quoting Drakoen:
This is the area we need to focus on.



agreed....i still think this newer cluster of convection is where we will get our eventual coc from...especially as it moves west into Jamaica and south of Cuba...just my opinion...we will see tomorrow...
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Quoting btwntx08:
hmmm why is shear incrasing in extreme western carribean

Yeah I was just looking at that and I also noticed the shear has moved out of the Gulf.
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Quoting Drakoen:
This is the area we need to focus on.



Given the strongest vorticity and current upper level pattern, I must agree. As pointed out earlier by scott, pressures have been falling slightly in that area as well. I think many are distracted by the action to the east right now.
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ok i gave zoomiami my zip code the other night so maybe i will be on there in the future. thanks.
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There are ALOT of people that lurk on this blog, SOME are from the area that IKE DEVASTATED(aka...."20-25 min from bmt"...aka"hickville".)SOME have businesses that house patients and THOSE people come on here and TRY to find out information because MOST trust the people on this blog. SO saying all of that ...its not funny to anyone that is only trying to gain information on the POSSIBLE formation of a storm to practically be made fun of..
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gator23 I sent you a private message.
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Quoting cchsweatherman:
Right now, I'm in total agreement with the NHC outlook on Invest 93L for the next 48 hours. Been going over satellite imagery and surface observations for the past hour now and am not impressed at all with this system. Its had and continues to have a difficult time organizing and consolidating as there's not much at the surface and there's no defined circulation with this system right now. Given the expanse the convective mess and tropical wave covers, it will take some time to get together and organize into a tropical cyclone, maybe even until Thursday or Friday at the earliest. Just gotta remain patient and objective since thats something needed in tropical forecasting.


good call
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Quoting btwntx08:

i think u need to go to bed :P


Yes, sir! Because you are the boss of me.
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Quoting firematt255:
Hello Orca how can i get on your map. That is pretty cool. I also don't like the models they come right over me.


I think (and we know how much that hurts my head), that Zoomiami is making up a new one :)
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2853. Drakoen
This is the area we need to focus on.

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Quoting cchsweatherman:
Right now, I'm in total agreement with the NHC outlook on Invest 93L for the next 48 hours. Been going over satellite imagery and surface observations for the past hour now and am not impressed at all with this system. Its had and continues to have a difficult time organizing and consolidating as there's not much at the surface and there's no defined circulation with this system right now. Given the expanse the convective mess and tropical wave covers, it will take some time to get together and organize into a tropical cyclone, maybe even until Thursday or Friday at the earliest. Just gotta remain patient and objective since thats something needed in tropical forecasting.


The process engine i belive is starting and yes the timing see ok that Scott put together...maybe a little slow on the LLC tho.
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2851. gator23
Quoting galvestonhurricane:


Someone is grumpy and needs to go to bed.

yea your right I am a bit sleepy, ok im out, but you didnt have to knock my sense of humor.
Member Since: August 26, 2008 Posts: 0 Comments: 2165
http://www.usatoday.com/news/nation/oil-spill-environment-recreation-map.htm
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2849. docrod
Quoting Drakoen:
93L has a lot of work to do.


Thankfully I agree (FLKeys).
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Quoting gator23:

im sorry your jokes aren't funny.


Someone is grumpy and needs to go to bed.
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goodnight all.
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2846. gator23
Quoting Drakoen:
93L has a lot of work to do.

I agree, I like the timetable the GFDL gives it. TD 36 hours from now TS in 48 hours. That seems most reasonable.
Member Since: August 26, 2008 Posts: 0 Comments: 2165

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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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