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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3096. HadesGodWyvern (Mod)
National Hurricane Center
Tropical Cyclone Advisory #17
SEVERE TROPICAL CYCLONE CELIA (EP042010)
9:00 AM UTC June 23 2010
==================================

At 9:00 AM UTC, Hurricane Celia (980 hPa) located at 11.9N 108.0W or 675 NM south of the Southern tip of Baja California, Mexico has sustained winds of 75 knots with gusts of 90 knots. The cyclone is reported as moving west at 9 knots.

Forecast and Intensity
======================
24 HRS: 12.3N 112.2W - 85 knots (SVR Cyclone SSHS-2)
48 HRS: 13.6N 116.8W - 90 knots (SVR Cyclone SSHS-2)
72 HRS: 14.9N 120.8W - 70 knots (SVR Cyclone SSHS-1)
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3095. HadesGodWyvern (Mod)
National Hurricane Center
Tropical Cyclone Advisory #2
TROPICAL CYCLONE DARBY (EP052010)
9:00 AM UTC June 23 2010
==================================

SUBJECT: Tropical Depression Strengthens To Tropical Storm "DARBY" South Of Tehuantepec

At 9:00 AM UTC, Tropical Storm Darby (1005 hPa) located at 11.5N 94.0W or 290 NM south southeast of Salina Cruz, Mexico has sustained winds of 35 knots with gusts of 45 knots. The cyclone is reported as moving northwest at 8 knots.

Forecast and Intensity
======================
24 HRS: 12.4N 96.6W - 45 knots (Tropical Storm)
48 HRS: 13.0N 99.4W - 55 knots (Tropical Storm)
72 HRS: 13.5N 101.0W - 55 knots (Tropical Storm)
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Two areas of explosive deveopment, might we have 93L and a 94L.
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3093. JLPR2
this is an interesting view, we have three blobs, one is related to 93L, the second is a piece that seems to have broken off 93L and the third is a TW


we have a battle of the blobs! LOL!
Well, goodnight to anyone out there or good morning, choose the most appropriate XD
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3092. xcool
bye all.
Member Since: September 26, 2009 Posts: 2 Comments: 15672
Night Rob.
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3090. xcool
bye rob
Member Since: September 26, 2009 Posts: 2 Comments: 15672
Quoting jlp09550:
Here's the latest satellite animation tonight before I head off to bed. Night everyone, and hopefully this system doesn't become too powerful..



GN JLP I hope it doesn't get that strong either. :)
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Here's the latest satellite animation tonight before I head off to bed. Night everyone, and hopefully this system doesn't become too powerful..

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Quoting Levi32:


Let's hope there is some.


I've been looking at my local forecast, and I do believe that they have upped the rain chances a tad, obviously to err on the side of the caution, as they should.

Forecast for Prairieville, LA, Monday through Wednesday:

Monday
Partly cloudy with scattered showers and thunderstorms. Highs in the lower 90s. Chance of precipitation 40 percent.
Monday Night
Partly cloudy with scattered showers and thunderstorms. Lows in the upper 70s. Chance of precipitation 30 percent.
Tuesday
Partly cloudy with scattered showers and thunderstorms. Highs in the lower 90s. Chance of precipitation 40 percent.
Tuesday Night
Partly cloudy with scattered showers and thunderstorms. Chance of precipitation 40 percent.
Wednesday
Partly cloudy with scattered showers and thunderstorms. Chance of precipitation 40 percent.


Also of note is that the high temperature is forecast to be in the mid 90s from today (Thursday) to Sunday. Yet beginning on Monday and continuing into Tuesday, the high temperature is only forecast to be in the lower 90s, which to me is suggestive of cloud cover.

Also note the increased probability of precipitation beginning on Monday night. Typically during the summer months, we only see a 10 to 20% chance of rain at nighttime, not 30 or higher. And for the daytime, we usually see at most 30%, not 40%, as begins on Monday.
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3084. xcool
334

WHXX01 KWBC 230651

CHGHUR

TROPICAL CYCLONE GUIDANCE MESSAGE

NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL

0651 UTC WED JUN 23 2010



DISCLAIMER...NUMERICAL MODELS ARE SUBJECT TO LARGE ERRORS.

PLEASE REFER TO NHC OFFICIAL FORECASTS FOR TROPICAL CYCLONE

AND SUBTROPICAL CYCLONE INFORMATION.



ATLANTIC OBJECTIVE AIDS FOR



DISTURBANCE INVEST (AL932010) 20100623 0600 UTC



...00 HRS... ...12 HRS... ...24 HRS. .. ...36 HRS...

100623 0600 100623 1800 100624 0600 100624 1800



LAT LON LAT LON LAT LON LAT LON

BAMS 15.6N 76.0W 16.4N 78.1W 16.9N 79.9W 17.7N 81.7W

BAMD 15.6N 76.0W 16.0N 77.7W 16.1N 79.2W 16.1N 80.6W

BAMM 15.6N 76.0W 16.2N 78.0W 16.6N 79.5W 17.0N 80.9W

LBAR 15.6N 76.0W 16.0N 77.9W 16.5N 80.0W 17.0N 82.0W

SHIP 25KTS 28KTS 33KTS 41KTS

DSHP 25KTS 28KTS 33KTS 41KTS



...48 HRS... ...72 HRS... ...96 HRS. .. ..120 HRS...

100625 0600 100626 0600 100627 0600 100628 0600



LAT LON LAT LON LAT LON LAT LON

BAMS 18.2N 83.2W 19.6N 86.2W 21.3N 89.0W 23.2N 91.7W

BAMD 16.2N 82.0W 16.8N 85.1W 17.7N 88.2W 18.4N 91.2W

BAMM 17.3N 82.2W 18.5N 85.0W 20.0N 87.8W 21.5N 90.6W

LBAR 17.6N 83.9W 19.5N 87.7W 21.6N 90.5W 23.1N 91.8W

SHIP 51KTS 68KTS 80KTS 86KTS

DSHP 51KTS 68KTS 61KTS 39KTS



...INITIAL CONDITIONS...

LATCUR = 15.6N LONCUR = 76.0W DIRCUR = 275DEG SPDCUR = 10KT

LATM12 = 15.5N LONM12 = 74.4W DIRM12 = 278DEG SPDM12 = 11KT

LATM24 = 15.1N LONM24 = 71.5W

WNDCUR = 25KT RMAXWD = 60NM WNDM12 = 25KT

CENPRS = 1010MB OUTPRS = 1011MB OUTRAD = 120NM SDEPTH = S


RD34NE = 0NM RD34SE = 0NM RD34SW = 0NM RD34NW = 0NM
Member Since: September 26, 2009 Posts: 2 Comments: 15672
3083. xcool





Member Since: September 26, 2009 Posts: 2 Comments: 15672
Quoting Levi32:


Let's hope there is some.

Hi Levi. Can a system stay that strong and sit there for days? That would be awful.
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3081. xcool
AL, 93, 2010062306, , BEST, 0, 156N, 760W, 25, 1010, WV
Member Since: September 26, 2009 Posts: 2 Comments: 15672
3080. xcool
lolol
Member Since: September 26, 2009 Posts: 2 Comments: 15672
3078. Levi32
Quoting KoritheMan:


I'm a realist, and so I realize that you're probably right.

However, there are some indications that some westerly shear could impinge upon the system as it traverses the central Gulf of Mexico. The GFS isn't showing this, though.

We'll see how it pans out.


Let's hope there is some.
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Hey XCOOL. Hey BT. I see the NOGAPS gave you my storm tonight. Lol. Models such a tease.
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Quoting Levi32:


Unfortunately this is nothing like climatology....we're used to sheared systems for a season opener, but this one won't be sheared.


I'm a realist, and so I realize that you're probably right.

However, there are some indications that some westerly shear could impinge upon the system as it traverses the central Gulf of Mexico. The GFS isn't showing this, though.

We'll see how it pans out.
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3071. xcool
3070. homelesswanderer
hey
Member Since: September 26, 2009 Posts: 2 Comments: 15672
Quoting btwntx08:
dam why wont it load for me lol btw i saw it looks like near tx/la or near lake charles


Too close to there for my comfort. Something can't be right. Surely it could not hold that intensity for days that close to land.
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3069. xcool
:0
Member Since: September 26, 2009 Posts: 2 Comments: 15672
3068. Levi32
Quoting KoritheMan:


Ah yeah, that's a bit close then. Hopefully this system ends up being nothing more than a TS if it approaches us. Climatology would favor that, anyway.


Unfortunately this is nothing like climatology....we're used to sheared systems for a season opener, but this one won't be sheared.
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2943 Unfriendly "bad news... friend posted this up - Don't know if it is legit or not, but definitely a concern if it is. Oil Rain"

Unlikely as yet. Looks more like normal street dregs from leaky vehicles, dirty-burning engines, road-repair, roofing tar, etc. See such sheens quite often after first rains.

I'd expect it'd hafta be quite a STORM to pick up that much garbage outta the Gulf then deposit it inland.

On the other hand, BP's offshore burning operation seems to be filthy beyond anything since the CleanAirAct was passed in 70s. So I suppose some really freak weather coulda picked up that pollution, then deposited it on a small localized area.
Seems improbable as heck though.
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Quoting jlp09550:


Abbeville.


^ Where the star next to "Abbeville" is.


Ah yeah, that's a bit close then. Hopefully this system ends up being nothing more than a TS if it approaches us. Climatology would favor that, anyway.
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Quoting KoritheMan:


Where do you live? I'm in Prairieville, near Baton Rouge.


Abbeville.


^ Where the star next to "Abbeville" is.
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3064. xcool
one of models go be right.I guess well find out.
Member Since: September 26, 2009 Posts: 2 Comments: 15672
Quoting Walshy:
Are we seeing 93L organizing any tonight?


I think so. Satellite loops show some vorticity developing in the midst of the deep convection south of Hispaniola. The large convective mass to the east has also been gradually weakening, as well. This should make it easier for 93L to further consolidate.
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3062. xcool
93L DO GOOD NOW.
Member Since: September 26, 2009 Posts: 2 Comments: 15672
3061. xcool
Levi32 yea .just Take Care of My Son that all.
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3060. Walshy
Are we seeing 93L organizing any tonight?
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3058. Levi32
Hey xcool, hope you're doing well.
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3057. JLPR2
Quoting Levi32:
950mb again....told you the ECMWF would jump around. Still can't take any of the intensity forecasts seriously yet.



thats crazy once again

meanwhile...

Not that many amazing waves lately
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3056. xcool
Levi32 WE KNOW .HEY
Member Since: September 26, 2009 Posts: 2 Comments: 15672
3055. Levi32
950mb again....told you the ECMWF would jump around. Still can't take any of the intensity forecasts seriously yet.

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Quoting jlp09550:


That's mighty close to me.. too close for comfort.


Where do you live? I'm in Prairieville, near Baton Rouge.
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3053. xcool
YEP
Member Since: September 26, 2009 Posts: 2 Comments: 15672
Quoting btwntx08:
right over morgan city


That's mighty close to me.. too close for comfort.
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3050. xcool
GOD DAM BIG FOOT
Member Since: September 26, 2009 Posts: 2 Comments: 15672
It almost looks as if there are three different waves on satellite.

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3047. xcool
LAND FALL BY Terrebonne Parish
Member Since: September 26, 2009 Posts: 2 Comments: 15672

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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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