93L slow to develop, but bringing heavy rains to Haiti
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
Reader Comments
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I know there isn't an LLC, why hasn't it been able to make one is my question.
93L's winds might blow out a candle but would not stir up anything. I think Nash was speaking generally.
18z surface analysis.
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.
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.
From the latest TWO..."ENVIRONMENTAL CONDITIONS ARE FORECAST TO BECOME MORE FAVORABLE FOR
SLOW DEVELOPMENT"
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?
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.
Isn't 1012 about average? Could you explain how this could help 93L? Thanks
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.
Here you go, the depth of the 26 degree isotherm
I honestly think it has something to do with the large thunderstorm complex to the east.
I think Phil Ferro is taking a well deserved vacation. I only trust him with truthful forecasts.
Word! That's awesome.
Please pardon my lack of manners:-)
How are you my friend??
Lack of a well organized LLC is..
Its the return of Dolly folks.
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.
There isnt a LLC
AL, 93, 2010062300, , BEST, 0, 156N, 752W, 25, 1010, WV,
Still just a wave.
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.
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.
Was that low enough winds to stir up things?
I am curious.
Or is the East West flow pushing the layers faster than ????
I O Words
It needs to catch up to its self.
Or find its groove.
Just kidding. I've cleaned up so to speak, but I still have the one liners!
Excellent. It should be a very interesting season.
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.
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?
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