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 Hurricanes12:


To be honest, I don't think they take a look at models or figures unless it becomes an imminent threat to land. Sadly, Vivian is only on during the weekends, haha.
Lol.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
Quoting MiamiHurricanes09:
It should explode after it passes 80˚W or so I reckon.


To be honest, I don't think they take a look at models or figures unless it becomes an imminent threat to land. Sadly, Vivian is only on during the weekends, haha.
Member Since: Posts: Comments:
Quoting nash28:
I'll be on this year. Unless I get banned:-)

Just kidding. I've cleaned up so to speak, but I still have the one liners!


Excellent. It should be a very interesting season.
Member Since: Posts: Comments:
2493. nash28
I'll be on this year. Unless I get banned:-)

Just kidding. I've cleaned up so to speak, but I still have the one liners!
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Quoting nash28:
Actually, land if affecting it marginally. There is no shear issue. But the lack of LLC is the main issue.
Exactly.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
Quoting GTcooliebai:


He's not the only one writing off this system, local met here in Tampa Bay for Bay News 9 pretty says this thing won't develop because it's moving into an area of shear. Man why can't I have their job.
Lol. They just don't see maps.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
2489. nash28
Actually, land if affecting it marginally. There is no shear issue. But the lack of LLC is the main issue.
Member Since: Posts: Comments:
Quoting weatherwatcher12:

I was using them, but I'm not sure if I should use a LOW sign or a tropical wave axis because I'm not too sure whether we have a low or not.
For now use a wave axis symbol instead of a "L".
Member Since: September 2, 2009 Posts: 130 Comments: 21194
Quoting nash28:
Kman-

Please pardon my lack of manners:-)

How are you my friend??


Hi Nash, it is actually me that owes you an apology. I saw you when I came on but got involved in one salvo after another.

It's great to see you back. Did you bring any of those special one liners you became famous for LOL.

All has been well. Seems like a decade since we blogged with you. Hopefully you will hang around for the season.
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Quoting Hurricanes12:


I think Phil Ferro is taking a well deserved vacation. I only trust him with truthful forecasts.

Quoting MiamiHurricanes09:
I have just laughed my butt off, do these people at WSVN 7 know what they are talking about? Brett Cameron (meteorologist) just said that wind shear is preventing 93L in check, and will probably prohibit development. Looks like he doesn't know about the word "a-n-t-i-c-y-c-l-o-n-e".

He's not the only one writing off this system, local met here in Tampa Bay for Bay News 9 pretty says this thing won't develop because it's moving into an area of shear. Man why can't I have their job.
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Even the BAMMS have come around. Rhut Rho.

Member Since: January 30, 2010 Posts: 0 Comments: 3259
Quoting WinterAnalystwx13:


There is an LLC


There isnt a LLC

AL, 93, 2010062300, , BEST, 0, 156N, 752W, 25, 1010, WV,

Still just a wave.
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Quoting MiamiHurricanes09:
Just use the coordinates on the FTP site.

AL, 93, 2010062300, , BEST, 0, 156N, 752W, 25, 1010, WV,

I was using them, but I'm not sure if I should use a LOW sign or a tropical wave axis because I'm not too sure whether we have a low or not.
Member Since: May 16, 2009 Posts: 1 Comments: 1231
Quoting ElConando:
Well its past 75 west.
It should explode after it passes 80˚W or so I reckon.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
Shear isn't effecting 93L, nor is land.

Lack of a well organized LLC is..
Its the return of Dolly folks.
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Quoting Hurricanes12:


I think Phil Ferro is taking a well deserved vacation. I only trust him with truthful forecasts.
Hey! Good to see you on here. Me too, I don't really listen to anyone except for Phil and Vivian but just thought it was pretty funny.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
Well its past 75 west.
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IKE I know what that is whats causing 93L to be 99.5% rather than 100% it is because there is too much downcasting and 93L is crying
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wish one is 93L

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2475. nash28
Kman-

Please pardon my lack of manners:-)

How are you my friend??
Member Since: Posts: Comments:
2474. IKE
Member Since: June 9, 2005 Posts: 23 Comments: 37858
2473. trey33
Quoting Patrap:
93L Floater - JSL Color Infrared Loop



Wake up in the morning feeling like 93L
(Hey, what up Invest?)
Put my glasses on, Im on the GFS - Im gonna hit this Run(Lets go)
Before I log on, brush my teeth with a bottle of Capri Sun
Cause when I post for the night, I aim to be Number one
Im talking - mjo on our, toes, Blows
Trying on all our GOES,GOES
Post's blowing up our phones, phones
Drop-toping, playing our favorite cds
Pulling up to the Blog-sies
Trying to get a little bit tipsy..


Word! That's awesome.
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Quoting ATL:

Isn't 1012 about average? Could you explain how this could help 93L? Thanks
Normal pressure is 1014 mb, just below right now.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
Quoting MiamiHurricanes09:
I have just laughed my butt off, do these people at WSVN 7 know what they are talking about? Brett Cameron (meteorologist) just said that wind shear is preventing 93L in check, and will probably prohibit development. Looks like he doesn't know about the word "a-n-t-i-c-y-c-l-o-n-e".


I think Phil Ferro is taking a well deserved vacation. I only trust him with truthful forecasts.
Member Since: Posts: Comments:
Quoting HurricaneFCast:


They have recent Ship observations the general public is not privy to. Most likely something within those observations--be it the lowest pressure reading, wind data, etc--has given them the knowledge to center the system properly. As for 93L's ability for sustenance, well, as you know, the lack of a circulation doesn't necessarily kill the disturbance, as it is essentially crude convection, however, it does inhibit its ability to develop and therefore allow for a decrease in the probability of genesis as the NHC has suggested.
I learn something new everyday, thank you.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
Quoting IKE:
There has to be some current condition or conditions that is keeping 93L from forming.

From the latest TWO..."ENVIRONMENTAL CONDITIONS ARE FORECAST TO BECOME MORE FAVORABLE FOR
SLOW DEVELOPMENT"


I honestly think it has something to do with the large thunderstorm complex to the east.
Member Since: Posts: Comments:
Quoting spathy:
Kman
I am not sure.
It is June!
Does anyone have the heat depths in that area?
We know the water is abnormally hot.
But to what depth in June?


Here you go, the depth of the 26 degree isotherm

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2467. nash28
Give this another two days to determine whether or not this survives.
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Quoting WinterAnalystwx13:


There is an LLC


I don't have the FTP link at home but post 2443

It's still an open wave. WV stands for tropical wave. When that reads DB you'll have an LLC.
Member Since: January 30, 2010 Posts: 0 Comments: 3259
I have just laughed my butt off, do these people at WSVN 7 know what they are talking about? Brett Cameron (meteorologist) just said that wind shear is preventing 93L in check, and will probably prohibit development. Looks like he doesn't know about the word "a-n-t-i-c-y-c-l-o-n-e".
Member Since: September 2, 2009 Posts: 130 Comments: 21194
Is another system that's behind 93L forecasted to grow and hit somewhere near the islands/Florida? How many models are agreeing with this, if there are any?
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2463. ATL
Quoting MiamiHurricanes09:
Pressures across the Caribbean are around 1012 millibars, that's one factor that will help 93L develop a more organized surface circulation.

18z surface analysis.

Isn't 1012 about average? Could you explain how this could help 93L? Thanks
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Ok what day is this?

Tuesday right?

If I remember right, not one of the models said 93L would get a surface circulation before Wednesday and most did not close that low before Friday

Again I think the tagging of the invest Sunday and the recon scheduled for tomorrow threw off everyones' timing. 93L is likely developing as it was initially scheduled by the models.
Member Since: Posts: Comments:
2460. IKE
There has to be some current condition or conditions that is keeping 93L from forming.

From the latest TWO..."ENVIRONMENTAL CONDITIONS ARE FORECAST TO BECOME MORE FAVORABLE FOR
SLOW DEVELOPMENT"
Member Since: June 9, 2005 Posts: 23 Comments: 37858
Upwelling usually occurs when either systems move slowly over an area or are stationary, or when multiple systems move over the same area. This isn't always the case, but often times it is.
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Quoting MiamiHurricanes09:
Lol. I have no clue why the NHC put the location of the circulation so south. Looking at shortwave I would put the COC at 75.2˚W 17.5˚N.



They have recent Ship observations the general public is not privy to. Most likely something within those observations--be it the lowest pressure reading, wind data, etc--has given them the knowledge to center the system properly. As for 93L's ability for sustenance, well, as you know, the lack of a circulation doesn't necessarily kill the disturbance, as it is essentially crude convection, however, it does inhibit its ability to develop and therefore allow for a decrease in the probability of genesis as the NHC has suggested.
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Ok folks, leaving for Jamaica Thursday morning, your thoughts on where this 93L will be and do you think it will affect travel?
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2455. nash28
Quoting spathy:
Nash
Are you hinting that 92 could have stirred the waters and lets just get this thing outa the same area and watch?
What are the heat depths?
There at the moment.
You may be on to something!


Not deep enough to upwell and cool. Only on the surface. Honestly, this is a bit of a buggerboo of an invest. The conditions are all in line for formation. The only thing that I "believe" is inhibiting this is its close proximity to land mass. I know, the circ. is not over land, but I believe the mass is disrupting the the flow.
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Pressures across the Caribbean are around 1012 millibars, that's one factor that will help 93L develop a more organized surface circulation.

18z surface analysis.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
Quoting spathy:
Nash
Are you hinting that 92 could have stirred the waters and lets just get this thing outa the same area and watch?
What are the heat depths?
There at the moment.
You may be on to something!


93L's winds might blow out a candle but would not stir up anything. I think Nash was speaking generally.
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Quoting MiamiHurricanes09:
Could be.Like Drak said, without a center of circulation 93L can't sustain convection. And when you think about it, the lack of a circulation kills a system.


I know there isn't an LLC, why hasn't it been able to make one is my question.
Member Since: January 30, 2010 Posts: 0 Comments: 3259
According to the MJO chart there is downward motion right over where Celia and 95E is, but yet that's not really effecting much. Clearly, MJO isn't a deal-breaker, or in this case (93L), overly helpful.
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Quoting kmanislander:


Neutral MJO in the Western caribbean but just exiting a positive phase in the Eastern. Certainly not negative today but just around the corner.

Agreed.
Quoting wunderkidcayman:
MiamiHurricanes09 maybe the reason why they put it far south is because they don't want to scare the Jamaicans LOL ps I heard news out of Jamaica They have captured the nortourous Dudus Coke
Like Chicklit said, they could of just put the COC directly below the center of the anticyclone aloft.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
I think the low is forming to the left of the biggest area of storms right off the coast of DR/Haiti which may inhibit development. Until it moves west or reforms away there's not going to be much action going on.

Latest models are a concern as it would put the storm to the left of the oil spill and it would surely bring fresh oil instead of tarballs onto the shores. This is going to be a disaster of epic proportions if that pans out.
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Quoting Patrap:
93L Floater - JSL Color Infrared Loop



Wake up in the morning feeling like 93L
(Hey, what up Invest?)
Put my glasses on, Im on the GFS - Im gonna hit this Run(Lets go)
Before I log on, brush my teeth with a bottle of Capri Sun
Cause when I post for the night, I aim to be Number one
Im talking - mjo on our, toes, Blows
Trying on all our GOES,GOES
Post's blowing up our phones, phones
Drop-toping, playing our favorite cds
Pulling up to the Blog-sies
Trying to get a little bit tipsy..


ROFLMAO! OMG Paltrap! I barely comment all I do is lurk and read but I just had to comment. This cracked me up. Thanks for making weather fun. And the parody is just like that during hurricane season.

Don't stop 93L
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MiamiHurricanes09 maybe the reason why they put it far south is because they don't want to scare the Jamaicans LOL ps I heard news out of Jamaica They have captured the nortourous Dudus Coke
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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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