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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2946. xcool
ATTENTION...NATIONAL HURRICANE CENTER

NCEP COUPLED GFDL HURRICANE MODEL FORECAST MADE FOR

TROPICAL DEPRESSION INVEST 93L

INITIAL TIME 0Z JUN 23

DISCLAIMER ... THIS INFORMATION IS PROVIDED AS GUIDANCE. IT
REQUIRES INTERPRETATION BY HURRICANE SPECIALISTS AND SHOULD
NOT BE CONSIDERED AS A FINAL PRODUCT. PLEASE SEE THE TPC/NHC
OFFICIAL FORECAST.


FORECAST STORM POSITION

HOUR LATITUDE LONGITUDE HEADING/SPEED(KT)

0 15.4 75.2 280./12.0
6 15.8 76.5 288./13.0
12 16.0 77.2 282./ 6.7
18 16.5 78.1 302./10.4
24 16.8 78.8 292./ 7.1
30 17.4 79.5 305./ 9.4
36 17.9 80.6 293./11.1
42 18.5 81.5 308./10.8
48 18.6 82.3 275./ 7.8
54 19.4 83.6 302./14.6
60 19.9 84.5 300./ 9.9
66 20.7 85.7 304./13.7
72 21.0 87.0 282./12.7
78 21.4 88.3 285./12.2
84 21.9 89.2 302./10.3
90 22.2 89.6 303./ 4.9
96 22.6 90.0 321./ 5.2
102 23.4 90.5 326./ 9.7
108 24.9 90.6 356./14.5
114 26.3 90.6 1./14.0
120 27.5 90.3 13./12.7
126 28.9 90.0 12./13.9

Member Since: September 26, 2009 Posts: 2 Comments: 15620
I'm gonna say orange 40 at 2am.....nite all...i am out!
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bad news... friend posted this up - Don't know if it is legit or not, but definately a concern if it is.

Oil Rain

(I'm assuming that it is caused by evaporation of light volatiles and an onshore breeze?)

http://www.youtube.com/watch?v=un8co1d4zb4
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2942. xcool
wow RIGTH BY ME WT----
Member Since: September 26, 2009 Posts: 2 Comments: 15620
2941. xcool
wow
Member Since: September 26, 2009 Posts: 2 Comments: 15620
2940. Drakoen
HWRF 00Z:

Member Since: October 28, 2006 Posts: 57 Comments: 29888
2939. xcool
lmao
Member Since: September 26, 2009 Posts: 2 Comments: 15620
2938. JLPR2
Quoting tornadodude:


Whats up man!?

how you been???


All's good, sighing every time I see the calendar since my university starts the 5th, got to finish my second semester. :S
But besides taking classes in the middle of summer, yeah, all's good LOL!

How about over there?
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My apologies to the blog and galveston Hurricane if I offended any of you. I truly did not mean to, I am generally concerned about the many people(lurkers) that value all of the people on this blog and their input, and perhaps maybe I should not be, and it is truly hard to know shen someone is joking or not.Ya'll are great and very informative. Now back to the "supposed 93L" or whatever is out there.
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2934. JLPR2
Quoting xcool:
poor rob.


*scratches head* yeah...
that sort of didn't end good, didn't it? :P
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2933. sdswwwe
Does anyone know where I can find raw data for the various computer models and NHC official tracks?
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Quoting JLPR2:


Yo Matt! XD


Whats up man!?

how you been???
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2931. EricSFL
Sorry, I did not mean to take the blog in a different direction (discussing Mexican regions) lol
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2929. Drakoen
Member Since: October 28, 2006 Posts: 57 Comments: 29888
2928. JLPR2
Quoting tornadodude:


Lol it is southern mexico :P


Yo Matt! XD
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2927. xcool
poor rob.
Member Since: September 26, 2009 Posts: 2 Comments: 15620
2925. JLPR2
Quoting btwntx08:
lol i just call it the yucatan and that is it


that works too, but its a part of Mexico, so I guess everyone is right, just saying it differently haha! XD
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Quoting btwntx08:
lol i just call it the yucatan and that is it


Lol so does that mean that Brownsville is not southern Texas, just Brownsville?
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2922. Drakoen
Quoting btwntx08:

lol u cslled the yucatan southern mx lol


LOL. So what else would it be?
Member Since: October 28, 2006 Posts: 57 Comments: 29888
Quoting btwntx08:

lol u cslled the yucatan southern mx lol


Lol it is southern mexico :P
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2920. EricSFL
Quoting btwntx08:

lol u cslled the yucatan southern mx lol


Well, it ain't northern Mexico for sure! lol
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2918. JLPR2
Quoting btwntx08:

lol u cslled the yucatan southern mx lol


yes it is southern Mexico XD its farther to the south than the rest of it LOL! XD
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2917. xcool
lol
Member Since: September 26, 2009 Posts: 2 Comments: 15620
2915. EricSFL
Quoting btwntx08:
i think the tx/mx is a good bet and why would it go in southern mx lol


Because if it does not develop it would be propelled by the low level steering flow into the Yucatan (southern Mexico).
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2914. Drakoen
HWRF 00z

Member Since: October 28, 2006 Posts: 57 Comments: 29888
Just an overall statement to everyone. Theres no need for panic or excitement right now with this system. Nothing defined has yet to develop and it will continue to take some time to get together. Even then, there will be much time to watch the system and be prepared as well as much time for the environmental conditions to change as well. Just remain vigilant in watching the system for now.
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Last two or three frames seem to be showing forming banding features to the southwest of the area that we are watching (sse of Jamaica) in 93L.

Link
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157. TampaSpin 3:03 PM GMT on June 22, 2010
Quoting Hurricanes101:


I saw a lot of people scream this was going to be a TD today, the more experienced people here stayed realistic

I think most of us knew this would take a few days to develop, if it does at all


Glad your back and i am sorry about yesterday! But, with that i hope you can now understand why i posted it was not well organized Structurlly as was said. Again Sorry!


I apoligized to you earlier really for no reason and never even got a word...since i really did nothing wrong but, to point out your faulty words of choice! NICE REPLY KID!
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Quoting Hurricanes101:


Yes but development on Friday does not guarantee the rate of intensification after that and therefore the path in which it goes

Friday is when most of the models develop 93L and the consensus still takes it toward the northern Gulf Coast


Alright well if it doesn't develop on Friday, then it follows the low-level into the Yucatan.
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2908. EricSFL
Quoting btwntx08:
then where would it go if it takes that long lol


I believe into southern Mexico if it takes that long to develop.
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how strong is that trough expected to be now?
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anyway I am out this time, night everyone
Member Since: March 10, 2010 Posts: 1 Comments: 7367
I think if this thing is strong enough and the trough is strong enough, it could maybe be a Florida storm like Charley or Wilma. However, for now it looks like the Central Gulf Coast is at risk.
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Quoting galvestonhurricane:
Good night everyone!


Good night!
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Quoting KoritheMan:


The weaker it stays, the more it follows the low-level flow. This is the solution provided by the NOGAPS and GFS.


Yes but development on Friday does not guarantee the rate of intensification after that and therefore the path in which it goes

Friday is when most of the models develop 93L and the consensus still takes it toward the northern Gulf Coast
Member Since: March 10, 2010 Posts: 1 Comments: 7367
Good night everyone!
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Quoting Hurricanes101:


why would you say that?


The weaker it stays, the more it follows the low-level flow. This is the solution provided by the NOGAPS and GFS.
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Quoting txsweetpea:
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.


Fair enough
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Quoting galvestonhurricane:


Thanks for your understanding. Do you think the NHC will up the percentage at the next advisory?


No, they will keep it at 20%.
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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: 7367

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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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