African tropical wave 99L has potential to develop

By: Dr. Jeff Masters , 3:10 PM GMT on July 30, 2012

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The first African tropical wave of 2012 with a potential to develop is Invest 99L, located in the Eastern Atlantic near 9°N 36°W, midway between the Lesser Antilles Islands and the coast of Africa. Visible satellite loops show a large area of the surrounding atmosphere has a pronounced counter-clockwise spin, though there is no surface circulation. The disturbance's heavy thunderstorm activity is pretty sparse, but appears to be slowly increasing. Water vapor satellite loops show that 99L has a reasonably moist environment, and the latest Saharan air layer analysis shows that the dry air from the Sahara lies well to the north of 99L. WInd shear over the disturbance is a light 5 - 10 knots, and ocean temperatures are 28°C, (82°F) which is well above the 26.5°C (80°F) threshold typically needed to allow formation of a tropical depression.


Figure 1. Morning satellite image of Invest 99L.

Forecast for 99L
Wind shear is expected to remain light for the next five days, and ocean temperatures will remain near 28°C, according to the 8 am EDT run of the SHIPS model. The disturbance is at 9°N, which is close enough to the Equator that the storm will have some difficultly getting spinning. Most of the models are showing some slow development of 99L, with the storm reaching the Lesser Antilles Islands on Saturday, August 3. NHC gave 99L a 20% chance of developing into a tropical depression by Wednesday morning. I expect the storm will have trouble with dry air at times this week as it crosses the Atlantic, but I give 99L a 50% chance of eventually developing into Tropical Storm Ernesto sometime in the next ten days. Residents and visitors to the Lesser Antilles Islands should anticipate heavy rains and strong winds from 99L beginning to affect the islands as early as Friday night. The long-range fate of 99L is uncertain, but a trough of low pressure is expected to be present over the Eastern U.S. early next week, which would be capable of turning 99L more to the northwest.

Hot in the Central U.S.
The heat in America's heartland continued on Sunday, with Wichita, KS hitting 111°F, just 3° short of their all-time hottest temperature of 114° set on 8/12/1936. Other notable highs on Sunday:

111° Coffeyville, KS
111° Winfield, KS
110° Chanute, KS
110° Parsons, KS
109° Joplin, MO (all-time record is 115° on July 14, 1954)

The low temperature in Tulsa, Oklahoma this Monday morning dropped to only 88°F. This is the all-time warmest low temperature in the city since record keeping began in 1905. The previous record warmest minimum temperature was 87°F set on August 2, 2011 and July 16, 1980. The high in Tulsa Monday - Wednesday is expected to reach 110° - 111°, close to the city's all-time hottest temperature of 115° set on August 10, 1936.

Jeff Masters

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Quoting nigel20:

Yeah, it's mostly sunny at the moment, but maybe we'll get some rain later as a result of day time heating.
Our only entrant in swimming is in a swimming final today, so I'm very happy...medal or no medal. I'm also anxiously awaiting the start of track and field on Friday.


Will be on alert hearing the TV while blogging....
Member Since: August 2, 2010 Posts: 21 Comments: 9882
Quoting WeatherNerdPR:

Flash Flood Watch issued for PR and USVI.

Hopefully if there is flooding it will be limited!
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266. JLPR2
Quoting WeatherNerdPR:

Flash Flood Watch issued for PR and USVI.


Culebra is under some heavy stuff.
Member Since: September 4, 2007 Posts: 7 Comments: 8747
Here are two latest sample runs for 99L. CMC takes it North of PR towards the Bahamas and GFS takes it South of PR into the Northern Caribbean.

GFS

Link

CMC

Link

CMC currently has a stronger storm thus the difference in a higher trajectory while GFS has a weaker system further to the West.
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Quoting sunlinepr:


What about in Jamaica? Is it dry today?

And what about the games?
You talking about Cricket? The next test match starts on the 2nd. West Indies vs. New Zealand.
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Quoting CaribBoy:
We are getting much needed rain in the Leeward Islands right now thanks to the strong TWave. An interesting thing to note is the VERY STRONG wind gusts ahead of a squall earlier this morning.. probably around 60MPH. Leaves were flying, and some stuffs outside were broken as well. Right now there are still thunder and lightnings..

That's good to know.
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News Release

Department of Communication (DCOMM), Ennia Bldg., Longwall Rd., Philipsburg, Sint Maarten D.W.I. Tel. +1 721 543-1162, 542-4119, Fax: 543-1169; Email: gis at sintmaarten.net; Website: www.sintmaartengov.org

For Immediate Release: Monday, July 30, 2012/N184-1.20am RADIO ANNOUNCEMENT

Country under Heavy Rainfall Advisory; Drivers cautioned about: possible flooding in low lying areas; and rock falls due to forecasted rainfall – drive with caution

GREAT BAY, Sint Maarten (DCOMM) – The Department of Disaster Management has been updated by the Meteorological Department of Curacao that the country is now under a code Orange and a heavy rainfall advisory (is when heavy rains about to occur or occurring already, but not strong enough to require a warning) is now in effect until late Monday afternoon.

Motorists are advised to exercise caution while driving in low lying areas which could flood – street flooding - due to forecasted heavy and persistent rainfall, and/or avoid driving in flooded streets until heavy rains taper off or has ended.

Motorists driving near hillsides are also asked to exercise caution with respect to possible rock falls.

Drivers and individuals who do not need to be on the road should remain at home until weather conditions improve.

Lightning strikes are also forecasted, and therefore residents should switch off and disconnect sensitive electronic equipment; and disconnect your phone line from your computer.
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Quoting BVI:
We have been getting some very heavy rain here in Tortola, British Virgin Islands for last hour or so, looks like we have a wet night ahead. Also closely watching what is happening further east, with our yearly carnival festival underway and most of the big events happening next weekend we would rather not have any interuptions!!

Flash Flood Watch issued for PR and USVI.
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Quoting sunlinepr:


What about in Jamaica? Is it dry today?

And what about the games?

Yeah, it's mostly sunny at the moment, but maybe we'll get some rain later as a result of day time heating.
Our only entrant in swimming is in a swimming final today, so I'm very happy...medal or no medal. I'm also anxiously awaiting the start of track and field on Friday.
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259. Skyepony (Mod)
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Quoting CaribBoy:
We are getting much needed rain in the Leeward Islands right now thanks to the strong TWave. An interesting thing to note is the VERY STRONG wind gusts ahead of a squall earlier this morning.. probably around 60MPH. Leaves were flying, and some stuffs outside were broken as well. Right now there are still thunder and lightnings..


So looks like that will be our scenario for tonight...
Member Since: August 2, 2010 Posts: 21 Comments: 9882
meanwhile...


LinkSELoop
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Quoting BVI:
We have been getting some very heavy rain here in Tortola, British Virgin Islands for last hour or so, looks like we have a wet night ahead. Also closely watching what is happening further east, with our yearly carnival festival underway and most of the big events happening next weekend we would rather not have any interuptions!!


We all around will have to watch the situation... Models are still uncertain about the path, the development of 99L.... Still time to go and do some Hurricane season groceries at the supermarket...
Member Since: August 2, 2010 Posts: 21 Comments: 9882
This is a good link about the upcoming winter season and what El-Nino and the PDO are doing.Link
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Quoting BVI:
We have been getting some very heavy rain here in Tortola, British Virgin Islands for last hour or so, looks like we have a wet night ahead. Also closely watching what is happening further east, with our yearly carnival festival underway and most of the big events happening next weekend we would rather not have any interuptions!!

Hopefully you'll have little or no interruptions!

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Quoting sunlinepr:
......for being JUST a tropical wave, this sure looks impressive huh
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We are getting much needed rain in the Leeward Islands right now thanks to the strong TWave. An interesting thing to note is the VERY STRONG wind gusts ahead of a squall earlier this morning.. probably around 60MPH. Leaves were flying, and some stuffs outside were broken as well. Right now there are still thunder and lightnings..
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Quoting nigel20:

It seems as if will get some rain later today into tomorrow.


What about in Jamaica? Is it dry today?

And what about the games?
Member Since: August 2, 2010 Posts: 21 Comments: 9882
250. BVI
We have been getting some very heavy rain here in Tortola, British Virgin Islands for last hour or so, looks like we have a wet night ahead. Also closely watching what is happening further east, with our yearly carnival festival underway and most of the big events happening next weekend we would rather not have any interuptions!!
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Yoboi, Andrea did a blog entry yesterday where she addressed the study of climate scientists "cherry picking" data. That notion has been studied and found not to be lacking, but has been fully debunked when talking about credited climate scientists. I don't know if you read her entry yesterday, but she addressed a lot of things you've said over the last month. Not trying to start up the debate when we've got an invest that has high probability of being a lanfaller. Just wanted you to know she specifically addressed "cherry picking." If this is going to be the likely track area of storms this year then we're in for a long season. Jeff's only giving it 50/50 to develop in the next ten, so maybe we'll luck out with this first wave invest.
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Quoting sunlinepr:
Almost no movement since last night..


It seems as if will get some rain later today into tomorrow.
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Rutgers animations have not been updated since yesterday morning.... Last week they were more than 4 days off....

OLD YESTERDAY MORNING ANIMATION

Member Since: August 2, 2010 Posts: 21 Comments: 9882
Quoting TAMPASHIELD:


It's going to hit your house!

na if it does get this far it will pass between Grand Cayman and Central America LOL
Member Since: June 13, 2009 Posts: 2 Comments: 12717
Quoting Skyepony:
Chicklit ~ Looking at the 850vort you posted, I think that ASCAT pass of the Leeward Islands was a complete miss. It's taking some shear.


Not sure looks embedded still in the monsoon trough and between 30 and 40 just south of 10 from the vorticity map. Lotta junk in the trunk. Wouldn't be surprised to see it catch up with itself.
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199 Waltanater: Get ready to pay more for your steak!

Who cares when "...last year...peanut butter surged a whopping 42%"
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Quoting wunderkidcayman:
anyway I say orange circle with either 30% or 40% for 99L

also I think maybe the trades may calm down abit


It's going to hit your house!
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anyway I say orange circle with either 30% or 40% for 99L

also I think maybe the trades may calm down abit
Member Since: June 13, 2009 Posts: 2 Comments: 12717
Almost no movement since last night..

Member Since: August 2, 2010 Posts: 21 Comments: 9882
237. Skyepony (Mod)
Chicklit ~ Looking at the 850vort you posted, I think that ASCAT pass of the Leeward Islands was a complete miss. It's taking some shear.
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Link WV Loop

The Atlantic high is huge. I think this is also properly called the Azores or Bermuda High.

Link Wiki on the Azores HIgh
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Quoting stormchaser19:
CMC





The Lesser Antilles will have to watch this one quite keenly.
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Member Since: August 2, 2010 Posts: 21 Comments: 9882
This ones going to be a long haul...Long time before we have any really solid idea of exactly how strong it may get or where it may end up...Watch and wait mode as usual with long trackers.
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Thanks Dr Masters...I see that we now have 99L. We will have to watch 99L very closely.
Good afternoon everyone!
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CMC




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229. yoboi
Quoting ilovehurricanes13:
very big t.storm off the east coast this morning!! wow


are you going to do a youtube video about any storms??
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Quoting HurricaneDean07:

Currently, only 2 models out of the 7 support movement north of the islands.


That is 3 models.:) Mine also supports movement North of the Islands.
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Quoting Skyepony:
Fresh partial OSCAT of 99L ~9N 37W.


Partial surface circulation, it appears... Open on the Southwest side.
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.
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A lot of dry air to the North of 99L.

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Quoting rmbjoe1954:
Too much attention is being placed on tracks considering there is no discernable center of circulation on 99L on which to base possible tracks.

I would assign a low confidence level on any track at this stage of 99L's development.


Amen and the same goes for predictions of 99-L's

demise in the trades....wait and watch...
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222. Skyepony (Mod)
Fresh partial OSCAT of 99L ~9N 37W.

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Quoting ncstorm:
Interesting to note but the Nogaps looks like it may want to form something off the SE coast





And of course, the NOGAPS has a tropical cyclone near Nicaragua..:)
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Quoting TropicalAnalystwx13:

Wind shear is not an issue, trade winds are.
And if 99L goes into the Caribbean the trade winds rip it apart.
Member Since: March 16, 2012 Posts: 127 Comments: 7972

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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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