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 Jeff9641:
In the upper & mid levels there is a dominate swirl near the Haiti/DR border which is working down to the surface. This feature is moving WNW and will pass north of Jamaica. Watch for intense convection to fire over this tonight and strengthen it further. Disregard all the computer models right now is there will be no low there. If you don't believe it just wait 8 to 12 hours as a dominate low is developing in that area.

I just noticed the same thing
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Quoting Snowlover123:
Why is everyone getting hyped over 93L right now, when the NHC has a 20% chance for it to develop?

-Snowlover123
Nobody is hyped over 93L, and just because the NHC gives it a 20% chance doesn't mean it is never going to develop. You have to remember that the percentage is for the next 48 hours not the systems entire lifespan.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
I say we get our COC by tonight we get our convection by early morn and we get our TD1 by mid day tomorrow at the most tomorrow afternoon when the Hurricane Hunters fly in
Member Since: June 13, 2009 Posts: 2 Comments: 12712
See everyone tommorow.....My brain overloaded listening to Dr. M and watching the Blog at the same time..........WW
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Quoting MrMarcus:
Well, I see the boards are lit up with a bunch of spin about (another) storm with no spin. This is just a repeat of 92L. Gonna be a rainy weekend in Mexico. If this mess does somehow get a name, it will be for no good reason.

I'm waiting for the season to really start, cause this ain't it.
Looks like you haven't been paying any attention.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
Current HPC forecast:

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Quoting Jedkins01:
Man I love weather with a passion, but I find it disturbing how much hype there is over disturbances these days, its not even a depression yet and there's fighting and pride over a silly disturbance in tropics, of which there are thousands of them down there every year.

I'd be pretty excited if one of them was over my ares, providing big time heavy rain squalls, but honestly, this just is not a big deal.



The reason I'm saying this is that it worries me what this blog will become when something impressive actually happens! LOL


I'm just surprised people aren't talking more about their local weather, like about severe weather events that are already occurring and what not.


I don't know about anyone else, but weather when it actually happens is a million times more exciting then talking on and on about what might happen 4 days from now.


It's more exciting to talk about the tropics. If a t-storm pops up it's not that exciting to talk about. I had one yesterday and made a few posts about it. Nobody cared. Why should they? Tropical systems on the other hand can impact many people and are more exciting, especially when they are developing and models show crazy stuff.
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Re: restarting drilling

One of the problems we are facing is getting all the foxes out of the MMS hen-house. When you don't know if your regulators are reliable how do you go about reviewing the regs. Shaking up a gov agency doesn't happen in a day. Till that's done I say put everything on hold.
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Quoting SouthDadeFish:
Vorticity has greatly improved since yesterday.
Last night the anticyclone aloft to 93L moved to the east and allowed shear to penetrate the system for a couple of hours. This probably caused the circulation to be so poor, looks like it has intensified and consolidated since then.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
Quoting cyclonekid:
Hurricane Celia slightly weakens
Graphic Update
Time: 2pm PDT/5pm EDT
Image made by cyclonekid



95E becomes better organized: Could become a tropical depression tonight or tomorrow
Graphic Update
Time: 2pm PDT/5pm EDT
Image made by cyclonekid



Lol, when Celia gains an eye, the NHC weakens it. This is the best eye-like feature on satelite presentation that I've seen from Celia so far.

-Snowlover123
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Quoting StSimonsIslandGAGuy:
I would love to know if there were west winds at that buoy 42058 at 15 N 75W. And what the pressure is.

Out of service since Nov 22, 2009. They should have had that buoy replaced months ago!


NOAA should start a "adopt a Buoy" program.
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Quoting Snowlover123:
Why is everyone getting hyped over 93L right now, when the NHC has a 20% chance for it to develop?

-Snowlover123



hahaha I was just talking about the same thing!
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First time on today... and I see we have a nice mid-level spin down south of Hispanola. Just need some good thunderstorm activity around it to help bring it to the surface. Let's see what Dmax has to offer us tonight!
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Well, I see the boards are lit up with a bunch of spin about (another) storm with no spin. This is just a repeat of 92L. Gonna be a rainy weekend in Mexico. If this mess does somehow get a name, it will be for no good reason.

I'm waiting for the season to really start, cause this ain't it.
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Quoting 900MB:


Was gonna buy Mets tix for tonight, but looks like a thunderstorm in there sometime during game.


Lighter rains are up further north, and heavier rains are further south. There is actually a storm that is confirmed to produce 1.5" hail!
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Quoting Snowlover123:
Why is everyone getting hyped over 93L right now, when the NHC has a 20% chance for it to develop?

-Snowlover123
Because it has great potential. It was 50% yesterday. We shall see. Still disorganized for now.
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1319. 606
Guys the wave at 40w looks interesting
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1317. DEKRE
1202:

It is an unfortunate fact that nobody has any experience with deep-sea wells.

However, have you ever given any thought on HOW people can possibly gain experience?
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"I think part of the 6 month timeline was to give enough time to make some relatively informed decisions as to what safety guidelines are to be put in place; it doesn't take much to be disgusted by the fact that the drilling industry has increased the ability to drill while at the same time doing absolutely NOTHING to improve safety and fall back in the event of a blow out like this. BP's reps were saying really confidence inspring things like "we're trying what we know" and "no one has had a blow out at 5000 feet before". That begs the question: Why were you doing it if you had no idea how to stop it if it got out of hand?"

I don't disagree with any of the points you make. So, when all the retail stores and all the restaurants in South Louisiana shut down, and half the State ends up on unemployment, thats ok? I make over $100K a year running my retail business, I have over $18K a year in mortgage and taxes and insurance on my home. Unemployment for an entire year pays a max of $14,404...you do the math. I guess its easy to say shut it down when its just someone elses life.
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Why is everyone getting hyped over 93L right now, when the NHC has a 20% chance for it to develop?

-Snowlover123
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Vorticity has greatly improved since yesterday.
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Hurricane Celia slightly weakens
Graphic Update
Time: 2pm PDT/5pm EDT
Image made by cyclonekid



95E becomes better organized: Could become a tropical depression tonight or tomorrow
Graphic Update
Time: 2pm PDT/5pm EDT
Image made by cyclonekid

Member Since: Posts: Comments:
Man I love weather with a passion, but I find it disturbing how much hype there is over disturbances these days, its not even a depression yet and there's fighting and pride over a silly disturbance in tropics, of which there are thousands of them down there every year.

I'd be pretty excited if one of them was over my ares, providing big time heavy rain squalls, but honestly, this just is not a big deal.



The reason I'm saying this is that it worries me what this blog will become when something impressive actually happens! LOL


I'm just surprised people aren't talking more about their local weather, like about severe weather events that are already occurring and what not.


I don't know about anyone else, but weather when it actually happens is a million times more exciting then talking on and on about what might happen 4 days from now.
Member Since: Posts: Comments:
1311. 900MB
Quoting Snowlover123:
Nasty storms about to hit me...


-Snowlover123


Was gonna buy Mets tix for tonight, but looks like a thunderstorm in there sometime during game.
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Quoting StSimonsIslandGAGuy:
Miamihurricanes09 glad to see you back :)
Thank you. Like several said, don't take it to heart.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
Quoting StSimonsIslandGAGuy:
Eyeballing it I can see several pseudoswirls but can't tell if they are at mid levels or the surface.

Buoy 42059 located at about 67.5W 15.0N never had a good pressure drop as 93L went by.

Annoyingly, buoy 42058 at 15N 75W is not in service.

The strong swirl by 71.5W 17.5N is in the mid levels.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
1055 Hurricanes101 "atcf has the center of 93L, it is well south of Hispaniola"

True... ifn ya stretch the vertical-to-horizontal by 2to1. Even at the Gulf's northernmost extreme, there is less than a 7to6 vertical-to-horizontal distance-to-degree distortion.
And flatness rapidly gets closer to 1to1 as ya approach the equator. At 16degreesNorth, the distortion is 21to20.

Admittedly many of the hard weather sites distort their maps&charts by up to 7to5 -- though why they'd want to distort symmetries is beyond me -- but what's up with those same maps&charts posted here being distorted by 2to1 or more?
Cuz it ain't using the forum's IMAGE auto-sizing that's putting in the extra distortion.
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Quoting CosmicEvents:
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.


lol.. It's only my opinion. I could be wrong, it's just a big mess out there right now, I need nothing but a broad circulation.
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1305. 900MB
Man! These things are so much easier to evaluate when they are organized!!!
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Looks like the system ejected a mid level vortex to the NW heading to Hispaniola. A lower level vortex looks to be forming north of 15N 75W which is what floaters are centered on.

Link
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Quoting StormW:


DYNAMIC MODELS


STATISTICAL MODELS




Hi StormW! What's the difference between Statisticaal and Dynamic Models? Thanks :)
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Most likely candidate for action is at 40w 11n IMO.
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Quoting Jeff9641:


Could this be our near invest? What do you think?
I haven't done research on it except looking at satellite and 850 millibar vorticity so I couldn't give you an accurate answer. But from what I've heard on the blog, my answer would be no.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
Quoting smmcdavid:
Okay kids... let's all play nice. :)

Can someone post the latest model runs? Thanks.


Good luck with the let's play nice advice, that's why I've just been lurking.
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Thanks StormW! On that note: I'm out. Check back later this evening.
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Nasty storms about to hit me...


-Snowlover123
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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
Member Since: July 11, 2006 Posts: 14 Comments: 11410

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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.