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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Nasty weather now at the DWH site.

Member Since: Posts: Comments:
Quoting Jeff9641:


This system is getting better organized right now.


I agree, does look better.
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THERE ARE NO EVACS PLANNED FOR ANYWHERE IN THE ATLANTIC BASIN AT THIS TIME

No Active Tropical Warnings in the Atlantic, Caribbean, or Gulf of Mexico

As of Tue 22 Jun 2010 16:30:02Z
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CMC.... 138H.....OUCH !!!!!

http://moe.met.fsu.edu/cgi-bin/cmctc2.cgi?time=2010062200&field=Sea+Level+Pressure&hour=Animation
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BP sub-contracted Storms..?

They may have some seasonal pull seems
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Quoting JFVfromFlorida:
Do i needs to give my ide to prove that i am indeed the reel Jfv?


Yes.
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Is there talk now about it coming to Florida?
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Here in Palm Harbor (Fla.), during the active '04 and '05 hurricane seasons, we had no wasps and lots of ants and anoles. For the past 3 years, we had just the reverse. This year--like '04/'05--haven't seen a single wasp and ant hills and anoles are everywhere.
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93L keeps getting worse and worse. I don't care that conditions are ideal this blob has never shown signs of organizing or developing.
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Quoting unf97:
Good day everyone!

93L is very slowly organizing in the East Central Carribean Sea. I just signed in and I read a post stating motion is now NW. Has this motion been confirmed?


No LLC yet. The whole package is moving WNW with a few embedded circulations, nothing organized though.
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Good day to everyone, the cmc run shows two tropical systems, one passing through the caribbean and the Yucatan Peninsula moving then northward toward the Oil Spill zone. Followed by another system moving through Cuba and Florida curving to the north following a similar route. This would create some serious problems in that area REALLY too early in the season. And a third system hanging around just east of the Bahamas.





Link
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Link

looks like there is a nice circulation trying to form, also some spiral bands around the middle of the loop. jmo
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431. unf97
Good day everyone!

93L is very slowly organizing in the East Central Carribean Sea. I just signed in and I read a post stating motion is now NW. Has this motion been confirmed?
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430. IKE
Quoting nrtiwlnvragn:


New GFS says.... maybe





You're posting the newer GFS...interesting.

The one I'm looking at doesn't show much at 144 hours.
Member Since: June 9, 2005 Posts: 23 Comments: 37858
Quoting IKE:


He isn't. He's someone else looking for responses.

Teh ignore feature may have an added guest.


Yeah...
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Quoting IKE:


Comebacks....

(1)GFS is out to lunch.
(2)It isn't initializing correctly.
(3)Just wait til....
(4)It's June, it's suppose to be hard for development.
(5)At 384 hours it shows...


Thats the general idea Ike. With a really active season forecast, and two good attempts so far in June, some folks would love to see a "bust" in June so they can downplay the remainder of the season and some folks want formation to support the upcoming forecasts (and potential record numbers)....No one is right or wrong (including the models); we just all have to wait and see what happens.
Member Since: August 8, 2006 Posts: 0 Comments: 8712
Quoting StormW:


I was just kidding...that cone coincides right now with the majority of the models

Oh, I had a thought that it was a little north, but it does coincide well with them. I also believe that the models have average error so the cone can also represent that
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I don't believe in the models right now. Until we get a better defined COC to track, models mean nothing...nadda! Oh by the way Good Afternoon everyone. Has anyone taken a look at the shear map, I mean from the lower levels to the upper levels lately?? Has anything changed with that.
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Quoting JFVfromFlorida:
When do you guys think the officials will tell us to evacuate here in in southern florida?


Similar to IKE, evacuations should commence tomorrow 12Z.
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Good morning all.

Tropical Tidbit for Tuesday, June 22nd
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421. IKE
Quoting CaneWarning:


Please tell me this name is a joke. You used capital letters and your spelling looks ok, so you can't be the real thing.


He isn't. He's someone else looking for responses.

Teh ignore feature may have an added guest.
Member Since: June 9, 2005 Posts: 23 Comments: 37858
Quoting nrtiwlnvragn:


New GFS says.... maybe



If the models keep cranking out maps that look like that, the Gulf is going to be the main drag for storms this season.jmo
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418. IKE
414...I will not quote you. You are just begging for responses. It's silly...childish.
Member Since: June 9, 2005 Posts: 23 Comments: 37858
It is quite curious why most of the other models show development and the GFS now continually doesn't. However, there are many times when the GFS shows a storm going north in the mid-lantic right into a well defined high pressure when we know it wont do that, so it does have issues sometimes. I wonder if its right this time or the rest are....
remains to be seen.
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Quoting JFVfromFlorida:
I think 93l might really get going soon and given the steering it may hook towards Florida,I just hope we evacuate in time here.
evac who what why its not at this time warrented until numbered warnings are issued come on now
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Quoting 7544:


and is moving nw
No, the convective mass is moving north-westward. The actual system is holding a relatively steady WNW track, as it has been for the past few days.
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413. IKE
Quoting nrtiwlnvragn:


New GFS says.... maybe





Uh-oh...I'll teach Mr. IKE!
Member Since: June 9, 2005 Posts: 23 Comments: 37858
Quoting IKE:


Comebacks....

(1)GFS is out to lunch.
(2)It isn't initializing correctly.
(3)Just wait til....
(4)It's June, it's suppose to be hard for development.
(5)At 384 hours it shows...


It isn't initializing correctly!!!
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Quoting IKE:
Well.....



New GFS says.... maybe



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408. IKE
Quoting Hurricanes101:


yup GFS stays consistent with no development


Comebacks....

(1)GFS is out to lunch.
(2)It isn't initializing correctly.
(3)Just wait til....
(4)It's June, it's suppose to be hard for development.
(5)At 384 hours it shows...
Member Since: June 9, 2005 Posts: 23 Comments: 37858
407. 7544
Quoting Jeff9641:


This system is getting better organized right now.


and is moving nw
Member Since: May 6, 2007 Posts: 0 Comments: 6676
Quoting Jeff9641:


This system is getting better organized right now.


I never said it wasn't getting better organized, still going to take a few days though I think; unless organization improves at a greater rate

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INV/93/L
MARK
16.4N/72.6W
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Quoting StormW:


Don't tell Mother Nature that!


I think she already knows!
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Quoting IKE:
Well.....



yup GFS stays consistent with no development

be back in a bit
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399. IKE
Well.....

Member Since: June 9, 2005 Posts: 23 Comments: 37858
Oh no.



Member Since: September 2, 2006 Posts: 110 Comments: 6872
Could anyone present me with an equation that would give me the minimum possible central pressure over a given heat content in ideal conditions?
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Quoting Jeff9641:


Hey buddy, 93L looks very good right and LLC is developing right now and it seems to be moving NW.


???

and this pertains to whether the GFS develops it or not how?
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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.