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 Grothar:


Upper level divergence is enhancing the convection on the wave over the Antilles, but not much chance for development.
..GRO if this should move to the gulf what then
Member Since: August 6, 2011 Posts: 4 Comments: 36667
Quoting LargoFl:
HHjoe..you got another warning out there.........................BULLETIN - EAS ACTIVATION REQUESTED
FLASH FLOOD WARNING
NATIONAL WEATHER SERVICE SAN DIEGO CA
254 PM PDT MON JUL 30 2012

THE NATIONAL WEATHER SERVICE IN SAN DIEGO HAS ISSUED A

* FLASH FLOOD WARNING FOR...
CENTRAL SAN DIEGO COUNTY IN SOUTHWEST CALIFORNIA...

* UNTIL 445 PM PDT

* AT 248 PM PDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED
FLASH FLOODING FROM A STORM OVER THE WARNED AREA. RADAR ESTIMATED
RAINFALL RATES RANGE FROM 1 TO 1.50 INCHES OVER THE PAST HOUR.

* LOCATIONS IN THE WARNING INCLUDE BUT ARE NOT LIMITED TO JULIAN

PRECAUTIONARY/PREPAREDNESS ACTIONS...

DO NOT DRIVE YOUR VEHICLE INTO AREAS WHERE THE WATER COVERS THE
ROADWAY. THE WATER DEPTH MAY BE TOO GREAT TO ALLOW YOUR CAR TO CROSS
SAFELY. MOVE TO HIGHER GROUND.


Yup Thanks,Im a spotter for the NWS office in San Diego.Those Flash Flood warnings are south of me and the storms heading away.The NWS is sending the warnings to my cell phone. This is opposite of usual. Most time on Monsoonal Moisture,it comes from the south and the storms go from SE TO NW. This time we have a ULL coming up from the south around that strong high over texas, and it is imparting it's counterclockwise flow upon us,hence the storms going south.
Member Since: September 18, 2010 Posts: 0 Comments: 4962
Quoting Hurricanes101:


No, we are not talking about wind shear, we are talking about trade winds, huge difference

Well ok, but either way you slice it the effects are the same, still quite sometime out to for a certainity!
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Quoting JLPR2:


Here you go:
Link
thanks you are the best.
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865. HadesGodWyvern (Mod)

Japan Meteorological Agency
Tropical Cyclone Advisory #32
SEVERE TROPICAL STORM SAOLA (1209)
6:00 AM JST July 31 2012
=============================================

SUBJECT: Category Two Typhoon South Of Okinawa

At 21:00 PM UTC, Severe Tropical Storm Saola (980 hPa) located at 21.0N 123.7E has 10 minute sustained winds of 55 knots with gusts of 80 knots. The cyclone is reported as moving northwest slowly.

Dvorak Intensity: T3.5

Storm Force Winds
=================
40 NM from the center

Gale Force Winds
================
270 NM from the center

Forecast and Intensity
==========================

24 HRS: 22.8N 123.2E - 75 knots (CAT 3/Strong Typhoon) - south southwest of Ishigaki Island
45 HRS: 24.6N 122.7E - 80 knots (CAT 3/Strong Typhoon) - Ishigaki Island
69 HRS: 26.8N 121.1E - 70 knots (CAT 3/Strong Typhoon) - East China Sea

Tropical Cyclone Advisory #32
SEVERE TROPICAL STORM DAMREY (1210)
6:00 AM JST July 31 2012
=============================================

SUBJECT: Category Two Typhoon Near Ogasawara Waters

At 21:00 PM UTC, Severe Tropical Storm Damrey (975 hPa) located at 28.2N 141.7E has 10 minute sustained winds of 55 knots with gusts of 80 knots. The cyclone is reported as moving northwest at 17 knots.

Dvorak Intensity: T3.5

Storm Force Winds
==================
40 NM from the center

Gale Force Winds
=================
300 NM from the center in northeast quadrant
180 NM from the center in southwest quadrant

Forecast and Intensity
==========================

24 HRS: 30.5N 134.6E - 55 knots (CAT 2/Severe Tropical Storm) - South of Japan
45 HRS: 32.1N 128.8E - 50 knots (CAT 2/Severe Tropical Storm) - south of Fukue Island
69 HRS: 34.5N 122.5E - 45 knots (CAT 1/Tropical Storm) - Yellow Sea
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Quoting Hurricanes101:


Nothing is ever simple in the tropics, but yeah trade winds are way too strong right now
True...
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Member Since: July 15, 2006 Posts: 168 Comments: 53285
Okay another thing to consider is the dry air or subsidence caused by the strengthening A/B High may also contribute to killing 99L off. Still like I said I wouldn't be surprised this gains enough latitude to affect the Greater Antilles and that this Ernesto might follow the same track as the last Ernesto.
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Quoting LargoFl:
...now come on..LOOK at the system by the islands..now compare that to the supposed 99L..there isnt even a true storm in 99L..its just an area of rain they are watching possibly to develop..now that wave by the Islands..THAT is looking Much better..dont know why the models arent picking up on it right now


Upper level divergence is enhancing the convection on the wave over the Antilles, but not much chance for development.
Member Since: July 17, 2009 Posts: 68 Comments: 25087
Quoting caribbeantracker01:
according to levi WE SHALL SEE however if u ask me based on strength it should get up to a tropical depression atleast dont forget that the atmosphere can and will change this tlk about trade winds is non sense because the first wave should have been destroyed.once the system is not goin north look out for something strong
..boy that wave by the islands is looking better and better
Member Since: August 6, 2011 Posts: 4 Comments: 36667
858. DDR
Looks to me like we in the islands will get some much needed rainfall.
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Quoting stormpetrol:
According to GFS model TWC channel shows, shear will be favorable in the Western Caribbean by the time 99L gets there, I think most are going by what they see now in the W/Caribbean, things can change 7-8 days out! The model they show is the shear further north so if it goes north it will even less chance of surviving, just saying....


No, we are not talking about wind shear, we are talking about trade winds, huge difference
Member Since: March 10, 2010 Posts: 1 Comments: 7337
Quoting flsky:


I wish! Seems like at least 75% of CFL storms either go to the north or south of those of us in Ponce Inlet.
yes it sure is strange alright,southern florida in some area's can really use more rain, but august and sept are coming and you know these african storms like to trek over south florida before going into the gulf..we'll see as the weeks go by
Member Since: August 6, 2011 Posts: 4 Comments: 36667
according to levi WE SHALL SEE however if u ask me based on strength it should get up to a tropical depression atleast dont forget that the atmosphere can and will change this tlk about trade winds is non sense because the first wave should have been destroyed.once the system is not goin north look out for something strong
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Quoting Bluestorm5:
Got to love uneducated people trying to predicts things without facts. It's simple. Trade winds will rip anything apart when it enters the islands.


Nothing is ever simple in the tropics, but yeah trade winds are way too strong right now
Member Since: March 10, 2010 Posts: 1 Comments: 7337
According to GFS model TWC channel shows, shear will be favorable in the Western Caribbean by the time 99L gets there, I think most are going by what they see now in the W/Caribbean, things can change 7-8 days out! The model they show is the shear further north so if it goes north it will even have less chance of surviving, just saying....
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132 hours
Member Since: March 16, 2012 Posts: 127 Comments: 7927
I just finished up a new blog on 99L.
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850. JLPR2
Quoting allancalderini:
Can anyone please tell me or give me a link where I can find the advisories for storms form 1997 backwards in the Pacific and the Atlantic that I can just find from 1998 onward in the Nhc page.please I would really appreciate it.


Here you go:
Link
Member Since: September 4, 2007 Posts: 7 Comments: 8483

Storm Relative 16km Geostationary Water Vapor Imagery

Member Since: July 3, 2005 Posts: 419 Comments: 127374
Quoting GTcooliebai:
So you are saying speed shear as a result of fast trade winds that kill it off?


yes
Member Since: March 10, 2010 Posts: 1 Comments: 7337
Quoting Hurricanes101:


As has been said 25 times in here today, its not shear, but the fast trade winds that would rip anything apart in the Caribbean. Things like that tend to stay that way for longer periods of time than shear generally does
So you are saying speed shear as a result of fast trade winds that kill it off?
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Got to love uneducated people trying to predicts things without facts. It's simple. Trade winds will rip anything apart when it enters the islands.
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lets all welcome MAINE to our storm party this evening...................BULLETIN - EAS ACTIVATION REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE GRAY ME
600 PM EDT MON JUL 30 2012

THE NATIONAL WEATHER SERVICE IN GRAY MAINE HAS ISSUED A

* SEVERE THUNDERSTORM WARNING FOR...
CENTRAL SOMERSET COUNTY IN WEST CENTRAL MAINE...

* UNTIL 645 PM EDT...

* AT 600 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
SEVERE THUNDERSTORM CAPABLE OF PRODUCING QUARTER SIZE HAIL...AND
DAMAGING WINDS IN EXCESS OF 60 MPH. THIS STORM WAS LOCATED NEAR
BINGHAM...OR 24 MILES NORTHWEST OF SKOWHEGAN...AND MOVING EAST AT 5
MPH.

* SOME LOCATIONS IN THE WARNING INCLUDE BUT ARE NOT LIMITED TO
BINGHAM.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

PLEASE REPORT HAIL OR STRONG WINDS TO THE NATIONAL WEATHER SERVICE BY
CALLING TOLL FREE...1-877-633-6772...WHEN YOU CAN DO SO SAFELY.
Member Since: August 6, 2011 Posts: 4 Comments: 36667
Quoting ilovehurricanes13:
what is that tropical storm next to the northeast i see add this storm to the map its was not on here before!!

It's a non tropical low, may provide some rain to Cape Cod.
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Quoting stormpetrol:
I wouldn't be surprised to see a 10% circle on the Lesser Antilles wave and 40% on the CATL low at 8pm est.
I kind of agree and do the NC blob still looks healthy or it already frizzle?
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842. flsky
Quoting LargoFl:
..just imagine..after 3-4 days of this HEAVY rainfall..getting a slow moving Tropical storm here in the southeast, and there is a wave coming Before that tropical something gets here


I wish! Seems like at least 75% of CFL storms either go to the north or south of those of us in Ponce Inlet.
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Quoting LargoFl:
are you folks in a drought over there also?


Early stages,we had a dry winter with about 66% of normal rainfall and San Diego only gets like 10" a year.
Out in the mountains where I live we get double that due mostly to orographic lifting.
Member Since: September 18, 2010 Posts: 0 Comments: 4962
Quoting GTcooliebai:
How confident are you in that though? I mean aren't shear forecasts this far out tough to forecast?


As has been said 25 times in here today, its not shear, but the fast trade winds that would rip anything apart in the Caribbean. Things like that tend to stay that way for longer periods of time than shear generally does
Member Since: March 10, 2010 Posts: 1 Comments: 7337
126 hours
Member Since: March 16, 2012 Posts: 127 Comments: 7927
GFS Come one. Move that thing NORTH!
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Quoting GTcooliebai:
How confident are you in that though? I mean aren't shear forecasts this far out tough to forecast?

Trade winds =/= Wind shear

Wind shear is low but trade winds are racing. Nothing will survive in the Caribbean.
Member Since: July 6, 2010 Posts: 112 Comments: 31336
HHjoe..you got another warning out there.........................BULLETIN - EAS ACTIVATION REQUESTED
FLASH FLOOD WARNING
NATIONAL WEATHER SERVICE SAN DIEGO CA
254 PM PDT MON JUL 30 2012

THE NATIONAL WEATHER SERVICE IN SAN DIEGO HAS ISSUED A

* FLASH FLOOD WARNING FOR...
CENTRAL SAN DIEGO COUNTY IN SOUTHWEST CALIFORNIA...

* UNTIL 445 PM PDT

* AT 248 PM PDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED
FLASH FLOODING FROM A STORM OVER THE WARNED AREA. RADAR ESTIMATED
RAINFALL RATES RANGE FROM 1 TO 1.50 INCHES OVER THE PAST HOUR.

* LOCATIONS IN THE WARNING INCLUDE BUT ARE NOT LIMITED TO JULIAN

PRECAUTIONARY/PREPAREDNESS ACTIONS...

DO NOT DRIVE YOUR VEHICLE INTO AREAS WHERE THE WATER COVERS THE
ROADWAY. THE WATER DEPTH MAY BE TOO GREAT TO ALLOW YOUR CAR TO CROSS
SAFELY. MOVE TO HIGHER GROUND.
Member Since: August 6, 2011 Posts: 4 Comments: 36667
Can anyone please tell me or give me a link where I can find the advisories for storms form 1997 backwards in the Pacific and the Atlantic that I can just find from 1998 onward in the Nhc page.please I would really appreciate it.
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Quoting TropicalAnalystwx13:

That's the thing though. Nothing going into the Caribbean is going to survive.
How confident are you in that though? I mean aren't shear forecasts this far out tough to forecast?
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Quoting TropicalAnalystwx13:
The GFS kills it before it even reaches the Caribbean.
..whew..ty you GFS
Member Since: August 6, 2011 Posts: 4 Comments: 36667
The gfs has been very consistent with having 99L go west into the Caribbean and then have it ripped apart by the strong trade winds.
120 hours, already dissipating.
Member Since: March 16, 2012 Posts: 127 Comments: 7927
The GFS kills it before it even reaches the Caribbean.
Member Since: July 6, 2010 Posts: 112 Comments: 31336
Quoting TropicalAnalystwx13:

It keeps it west.
after what we will be going thru these next few days with rainfall totals..florida does not need this to come anywhere near us..well we shall see,hydus might be right...its florida's turn this year,gonna turn back into swampland geez
Member Since: August 6, 2011 Posts: 4 Comments: 36667
Quoting LargoFl:
..yes we have to stay tuned to the warnings alright,some bad storms out today
Looks like a line developing in the UP.
Member Since: March 16, 2012 Posts: 127 Comments: 7927
I wouldn't be surprised to see a 10% circle on the Lesser Antilles wave and 40% on the CATL low at 8pm est.
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Quoting HurricaneHunterJoe:


Yup,Just south of me,Icaught the back end of the thunderstorm...prob picked up .20. I'll take it though!
are you folks in a drought over there also?
Member Since: August 6, 2011 Posts: 4 Comments: 36667
Quoting StormTracker2K:



A Caribbean tracker that recurves is my worst fear for us in the US this year and this just may do it.


That's the thing though. Nothing going into the Caribbean is going to survive.
Member Since: July 6, 2010 Posts: 112 Comments: 31336
108 hours
Member Since: March 16, 2012 Posts: 127 Comments: 7927
Quoting wxchaser97:

You got me excited when I saw that until I saw it was Marquette area. Late tonight/ tomorrow I join that party here in SE MI.
..yes we have to stay tuned to the warnings alright,some bad storms out today
Member Since: August 6, 2011 Posts: 4 Comments: 36667
Quoting stoormfury:
in other words it is an area of low pressure trying to organise without a surface circulation. the centre is located where sat pics show an area of increase vorticity. hence the reason the models are baving a dusty time in a forecast track fo 99L


um the surface maps of the last 3 days would disagree with you

99L has a surface low
Member Since: March 10, 2010 Posts: 1 Comments: 7337
Quoting TropicalAnalystwx13:

I wonder if any of those analogues had this Bermuda high to deal with.
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Quoting LargoFl:
..had a warning or two over there also


Yup,Just south of me,Icaught the back end of the thunderstorm...prob picked up .20. I'll take it though!
Member Since: September 18, 2010 Posts: 0 Comments: 4962

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About

Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.