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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2846. gator23
Quoting Drakoen:
93L has a lot of work to do.

I agree, I like the timetable the GFDL gives it. TD 36 hours from now TS in 48 hours. That seems most reasonable.
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2845. JLPR2
Quoting Relix:
Suck a rainy summer here in PR. =/


ah yes, :(
Cant go to the beach with cloudy skies T_T
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2844. xcool
hey rob
Member Since: September 26, 2009 Posts: 2 Comments: 15684
2843. JLPR2
TW in the Eastern Caribbean looks happy



And it seems to be connecting with the convection between PR and the DR
O_o
Man, the Caribbean is a mess of convection
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2842. Relix
Suck a rainy summer here in PR. =/
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2841. Drakoen
93L has a lot of work to do.
Member Since: October 28, 2006 Posts: 57 Comments: 30813
2839. gator23
Quoting galvestonhurricane:


It was a joke. I'm sorry that you don't have a sense of humor.

im sorry your jokes aren't funny.
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2838. JLPR2
Quoting Drakoen:
All of the convection associated with 93L is east of the 700mb-850mb center



93L is a mess XD it has a blob between PR and DR, another forming south of Haiti and nothing over it LOL!
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2837. xcool
Drakoen ?
Member Since: September 26, 2009 Posts: 2 Comments: 15684
Quoting gator23:

oh thank god, you were able to pinpoint something no one else could, whew


It was a joke. I'm sorry that you don't have a sense of humor.
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Quoting TampaSpin:


speed this loop up fast as it will go...
http://www.ssd.noaa.gov/goes/flt/t1/flash-ir2.html


i see where your looking but i think your a little far west imo...my tired eyes are seeing what your seeing, but i think the eventual main center will be further to the ne...coming from the area of 73.5/ 17 ish....

but once again....my tired eyes...lol...how you doing tonight tampa btw...:P
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Hello Orca how can i get on your map. That is pretty cool. I also don't like the models they come right over me.
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2833. xcool
wunderkidcayman /guess we 'll find out
Member Since: September 26, 2009 Posts: 2 Comments: 15684
2832. gator23
Quoting galvestonhurricane:


Don't worry it is headed for Texas.

oh thank god, you were able to pinpoint something no one else could, whew
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2831. leo305
Quoting wunderkidcayman:
I would not be suprised if the energy from the wave SE of 93L goes into 93L and help through out the rest of the night and morning maybe by mid morn we get a llc S or SSE of Jamaica


doubt it, the SE wave has a stronger vortocity and it's far from 93L's strongest surface spin
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2830. Drakoen
All of the convection associated with 93L is east of the 700mb-850mb center

Member Since: October 28, 2006 Posts: 57 Comments: 30813
Quoting KEEPEROFTHEGATE:
no doom casters but there was an oilcaster here a while ago



Only you can prevent oil casters.
Member Since: September 6, 2009 Posts: 2 Comments: 3784
Is that 93L just south of Haiti?

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Nice general lesson on tropical waves for the noobs such as myself:

http://www.accuweather.com/video/90494793001/bilo-breakdown-tropical-waves.asp
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Quoting wunderkidcayman:
I would not be suprised if the energy from the wave SE of 93L goes into 93L and help through out the rest of the night and morning maybe by mid morn we get a llc S or SSE of Jamaica

I hope you aren't offended by this, but... how old are you?
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I would not be suprised if the energy from the wave SE of 93L goes into 93L and help through out the rest of the night and morning maybe by mid morn we get a llc S or SSE of Jamaica
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Quoting galvestonhurricane:


Where are you from? Beaumont, aka Hickville?


orange area, about 20-25 minutes from Beaumont.
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Quoting TexasHurricane:


It is? hmmmmm


Where are you from? Beaumont, aka Hickville?
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Quoting galvestonhurricane:


Don't worry it is headed for Texas.


It is? hmmmmm
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Right now, I'm in total agreement with the NHC outlook on Invest 93L for the next 48 hours. Been going over satellite imagery and surface observations for the past hour now and am not impressed at all with this system. Its had and continues to have a difficult time organizing and consolidating as there's not much at the surface and there's no defined circulation with this system right now. Given the expanse the convective mess and tropical wave covers, it will take some time to get together and organize into a tropical cyclone, maybe even until Thursday or Friday at the earliest. Just gotta remain patient and objective since thats something needed in tropical forecasting.
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Where is the center of 93L for real?
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Quoting MScasinojunkie:
oh my - I really do not like the latest model run - I am SO unprepared for a storm taking the Katrina route - especially with the oil in its path!! And look at the SST's in the Gulf - I am definitely gonna be on pins and needles for the next week.


Don't worry it is headed for Texas.
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2818. xcool
galvestonhurricane huh.
Member Since: September 26, 2009 Posts: 2 Comments: 15684
oh my - I really do not like the latest model run - I am SO unprepared for a storm taking the Katrina route - especially with the oil in its path!! And look at the SST's in the Gulf - I am definitely gonna be on pins and needles for the next week.
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2816. docrod
Quoting pottery:

GOOD!!
He was still in the same area?


BBC link
http://news.bbc.co.uk/2/hi/world/latin_america/10386028.stm
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2815. leo305
Quoting JLPR2:
I'm wondering if that area of convection that was left behind by 93L will try to do something with the TW at the Eastern Caribbean, maybe it will be enough to spark something



I think it will, the area in the Eastern Carribean is already sparking up and has a mighty strong vortocity, it will merge with that moisture over puerto rico/DR
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Quoting xcool:




When should Katy evacuate?
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2813. JLPR2
I'm wondering if that area of convection that was left behind by 93L will try to do something with the TW at the Eastern Caribbean, maybe it will be enough to spark something

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2812. Drakoen
Quoting leo305:


CMC develops it


Out in the middle of the Atlantic north of the Greater Antilles similar to what the GFS 18z showed. Something to watch but nothing imminent at this time.
Member Since: October 28, 2006 Posts: 57 Comments: 30813
Quoting KEEPEROFTHEGATE:
no doom casters but there was an oilcaster here a while ago


I don't even want to think about it... its all bad.

KOG, you should drive around here sometime... Drove from Victoria all the way up to Salmon Arm today... spectacular.
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2810. xcool


Member Since: September 26, 2009 Posts: 2 Comments: 15684
Someone needs to give 93L this recipe:

Hurricane on the rocks:

1 oz vodka
1/4 oz grenadine syrup
1 oz gin
1 oz light rum
1/2 oz Bacardi® 151 rum
1 oz amaretto almond liqueur
1 oz triple sec
grapefruit juice
pineapple juice

Pour all but the juices, in order listed, into a hurricane glass three-quarters filled with ice. Fill with equal parts of grapefruit and pineapple juice, and serve.
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2808. leo305
Quoting Drakoen:


Not much. No model support.


CMC develops it
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2807. KEEPEROFTHEGATE (Mod)
Quoting Orcasystems:
I figured the doomcasters would be going nuts tonight.... I am impressed with the calm :)



AOI

AOI

AOI

AOI

TS BUSTED FORECAST ALIBI
no doom casters but there was an oilcaster here a while ago
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2806. leo305
Don't ignore the low to the South east of 93L, as it is firing up convection.. The LOW in the CATL is merging with ITCZ moisture, so it will likely develop from here on out, since it already had a large somewhat closed circulation.
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2805. Drakoen
Quoting Hurricanes101:


what do you think of the wave in the CATL?


Not much. No model support.
Member Since: October 28, 2006 Posts: 57 Comments: 30813
2804. xcool
wow..
Member Since: September 26, 2009 Posts: 2 Comments: 15684
I figured the doomcasters would be going nuts tonight.... I am impressed with the calm :)



AOI

AOI

AOI

AOI

TS BUSTED FORECAST ALIBI
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Quoting scottsvb:
93L is actually having some slight pressure drops now SSE of Jamaica near 15.8N and 76W. There is no LLC there yet.. but during the next 24-36hrs as the pressures start to fall, A LLC has a decent chance to develop south of the cayman islands on Thurs as pressure in the NW carribean start falling below the 1010 line to 1008-1009mbs.
It's too early to tell if this will develop into a Tropical Storm cause its not even a TD yet. We will go step by step with this each day. Long range outlook for path is always skeptical after 3 days..but by early next week, a decent trough will dig down east of 90W pushing anything N or NE. Question will be, will there be a TS or more? If so where? Central GOM or Eastern or will it be weak and decouple pushing midlevel rains NE towards Florida while the LLC weakens and moves WSW thru drier air. Too early to speculate on what will pan out. Right now, its take it day by day. Tomorrow we might see a broad low get better organized..and by Thurs we have a 50-50chance of development.


I really respect this approach and your reasoned forecasting. You've got a supporter in me.
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Floater - Dvorak Color Infrared Loop

Very Clear here on Dvorak
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2800. KEEPEROFTHEGATE (Mod)
INV/93/L
MARK
17.1N/73.9W
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Quoting galvestonhurricane:
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2798. centex
Anyone notice how the DR blob sucked in wave in SE caribean. the blob will be gone by morning.
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Does anyone have the coordinates on 93L?
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Quoting galvestonhurricane:
When do the next model runs come out?
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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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