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 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!
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Quoting TropicalAnalystwx13:

It keeps it west.



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

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Quoting JLPR2:





Take a close look at this loop and tell me just how organized you think the wave is.

RAMSDIS Floater


Nice one!
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Quoting LargoFl:
looks like Michigan is joining the severe weather party we are throwing today.............................
BULLETIN - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE MARQUETTE MI
538 PM EDT MON JUL 30 2012

THE NATIONAL WEATHER SERVICE IN MARQUETTE HAS ISSUED A

* SEVERE THUNDERSTORM WARNING FOR...
NORTHERN DELTA COUNTY IN SOUTH CENTRAL UPPER MICHIGAN...
EXTREME SOUTHEASTERN MARQUETTE COUNTY IN NORTH CENTRAL UPPER
MICHIGAN...

* UNTIL 645 PM EDT

* AT 532 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 5 MILES
EAST OF WATSON...OR 23 MILES NORTHWEST OF ESCANABA...AND MOVING
EAST AT 30 MPH.

* LOCATIONS IMPACTED INCLUDE...
ROCK...ST. NICHOLAS...PERKINS...MAPLEWOOD...NAHMA JUNCTION AND
CHICAGO LAKE.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

SEVERE THUNDERSTORMS PRODUCE DAMAGING WIND IN EXCESS OF 60 MILES PER
HOUR...DESTRUCTIVE HAIL...DEADLY LIGHTNING...AND VERY HEAVY RAIN. FOR
YOUR PROTECTION MOVE TO AN INTERIOR ROOM ON THE LOWEST FLOOR OF YOUR
HOME OR BUSINESS. HEAVY RAINS FLOOD ROADS QUICKLY SO DO NOT DRIVE
INTO AREAS WHERE WATER COVERS THE ROAD.

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.
Member Since: March 16, 2012 Posts: 127 Comments: 7928
Quoting StormTracker2K:
Very bad news for the US down the road if this pans out.


It keeps it west.
Member Since: July 6, 2010 Posts: 113 Comments: 31577
Quoting Tazmanian:
this is not good this is all most a Andrew set up


here what i think 99L will do it gets too 85mph hurricane hits a wall of shear that knocks it down too 55mph but when it finds the 5 too to 10 kt of shear it will really take off


worse.kind.of.yr..new.el.nino
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Very bad news for the US down the road if this pans out.

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Quoting CybrTeddy:
I'd be somewhat surprised if they went anything above 30% for 8pm.
So would I, I've been thinking 30% until it breaks from the ITCZ and convection really increases. So tomorrow or Wednesday it's chances should increase.
Member Since: March 16, 2012 Posts: 127 Comments: 7928
GFS has 99L looking stronger this run. Expect the percentages to up to 40% at 8pm.

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looks like Michigan is joining the severe weather party we are throwing today.............................
BULLETIN - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE MARQUETTE MI
538 PM EDT MON JUL 30 2012

THE NATIONAL WEATHER SERVICE IN MARQUETTE HAS ISSUED A

* SEVERE THUNDERSTORM WARNING FOR...
NORTHERN DELTA COUNTY IN SOUTH CENTRAL UPPER MICHIGAN...
EXTREME SOUTHEASTERN MARQUETTE COUNTY IN NORTH CENTRAL UPPER
MICHIGAN...

* UNTIL 645 PM EDT

* AT 532 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 5 MILES
EAST OF WATSON...OR 23 MILES NORTHWEST OF ESCANABA...AND MOVING
EAST AT 30 MPH.

* LOCATIONS IMPACTED INCLUDE...
ROCK...ST. NICHOLAS...PERKINS...MAPLEWOOD...NAHMA JUNCTION AND
CHICAGO LAKE.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

SEVERE THUNDERSTORMS PRODUCE DAMAGING WIND IN EXCESS OF 60 MILES PER
HOUR...DESTRUCTIVE HAIL...DEADLY LIGHTNING...AND VERY HEAVY RAIN. FOR
YOUR PROTECTION MOVE TO AN INTERIOR ROOM ON THE LOWEST FLOOR OF YOUR
HOME OR BUSINESS. HEAVY RAINS FLOOD ROADS QUICKLY SO DO NOT DRIVE
INTO AREAS WHERE WATER COVERS THE ROAD.
Member Since: August 6, 2011 Posts: 4 Comments: 37121

Flash Flood Warning
FLASH FLOOD STATEMENT
NATIONAL WEATHER SERVICE SAN DIEGO CA
234 PM PDT MON JUL 30 2012

CAC073-302215-
/O.CON.KSGX.FF.W.0005.000000T0000Z-120730T2215Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000 Z.OO/
SAN DIEGO CA-
234 PM PDT MON JUL 30 2012

...A FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 315 PM PDT FOR SOUTH
CENTRAL SAN DIEGO COUNTY...

AT 218 PM PDT...TRAINED WEATHER SPOTTERS REPORTED CONTINUOUS HEAVY
RAIN AT CAMPO. VERY HEAVY RAIN WAS IMPACTING INTERSTATE 8 NEAR
CAMERON. FLASH FLOODING IS LIKELY ON INTERSTATE 8...OLD HIGHWAY 80
AND KITCHEN CREEK ROAD THROUGH 315 PM.

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.

&&

LAT...LON 3278 11655 3279 11634 3264 11633 3262 11650

$$

MOEDE
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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
one.model.was.just.north.of.hispanola..twc
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Quoting HurricaneHunterJoe:
Good Lord.......it actually rained today for the first time since April. Rained for 40 minutes 20 minutes moderate to heavy. Thank you Lord,May I have another tomorrow?
..had a warning or two over there also
Member Since: August 6, 2011 Posts: 4 Comments: 37121
Quoting CybrTeddy:
I'd be somewhat surprised if they went anything above 30% for 8pm.

It looks like 1.5x better then it did at 2
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18Z GFS out to 78 hours:

Member Since: July 6, 2010 Posts: 113 Comments: 31577
Quoting CybrTeddy:
I'd be somewhat surprised if they went anything above 30% for 8pm.
me too teddy,i just dont see it happening, now maybe tomorrow things could change one way or the other..me right now im concentrating on the Severe USA weather thats happening right now
Member Since: August 6, 2011 Posts: 4 Comments: 37121
this is not good this is all most a Andrew set up


here what i think 99L will do it gets too 85mph hurricane hits a wall of shear that knocks it down too 55mph but when it finds the 5 too to 10 kt of shear it will really take off


Member Since: May 21, 2006 Posts: 5091 Comments: 114785
Quoting TropicalAnalystwx13:

Because it's heading west and will be ripped apart by trade winds, whereas 99L has a nice surface circulation and is moving west/west-northwest across very favorable conditions.
yes but there isnt anything there,a wide area of rain showers,until it does develop and right now there is only a low 20% chance of that happening, its just an area to be watched right?
Member Since: August 6, 2011 Posts: 4 Comments: 37121
I'd be somewhat surprised if they went anything above 30% for 8pm.
Member Since: Posts: Comments:
799. JLPR2

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




Take a close look at this loop and tell me just how organized you think the wave is.

RAMSDIS Floater
Member Since: September 4, 2007 Posts: 7 Comments: 8526
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
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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

Because it's heading west and will be ripped apart by trade winds, whereas 99L has a nice surface circulation and is moving west/west-northwest across very favorable conditions.
Member Since: July 6, 2010 Posts: 113 Comments: 31577
Good Lord.......it actually rained today for the first time since April. Rained for 40 minutes 20 minutes moderate to heavy. Thank you Lord,May I have another tomorrow?
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Member Since: July 6, 2010 Posts: 113 Comments: 31577
...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
Member Since: August 6, 2011 Posts: 4 Comments: 37121
I believe StormJunkie and presslord will be live on a link in a few.
Member Since: July 3, 2005 Posts: 421 Comments: 127702
778: The trade winds is correct but it doesnt mean it ends the western gulfs season! Remember homegrown storms can form too but it wont be as strong though!
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BULLETIN - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE GREEN BAY WI
436 PM CDT MON JUL 30 2012

THE NATIONAL WEATHER SERVICE IN GREEN BAY HAS ISSUED A

* SEVERE THUNDERSTORM WARNING FOR...
NORTH CENTRAL MARINETTE COUNTY IN NORTHEAST WISCONSIN...

* UNTIL 500 PM CDT

* AT 433 PM CDT...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 5 MILES
NORTHEAST OF PEMBINE...OR 12 MILES SOUTHEAST OF IRON MOUNTAIN...AND
MOVING EAST AT 30 MPH.

* THE SEVERE THUNDERSTORM WILL AFFECT MAINLY RURAL AREAS OF NORTH
CENTRAL MARINETTE COUNTY...INCLUDING THE FOLLOWING LOCATIONS
KREMLIN.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

SEVERE THUNDERSTORMS PRODUCE DAMAGING WINDS...LARGE HAIL...AND DEADLY
LIGHTNING. FOR YOUR PROTECTION...MOVE TO AN INTERIOR ROOM ON THE
LOWEST FLOOR OF YOUR HOME OR BUSINESS.

Member Since: August 6, 2011 Posts: 4 Comments: 37121
Quoting stoormfury:
a whole lot of conjecture about track of 99L. the system is weak ,not even with a surface reflection. such weak disturbances in the organising stage tend to track with the 700_850mb steering currents which will take it west or north of west. at the moment the system is moving along the periphery of the strong A/B to it's north.

Not sure where you're getting there is no surface circulation.
Member Since: July 6, 2010 Posts: 113 Comments: 31577
Quoting Articuno:

B. 40%

Actually I will go out on a limb,
I say C 50%
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Quoting Neapolitan:
This looks like fun:

hot

So does this...

hot

and most of all this:

hot


I would take those temps with those dew points all day every day over the upper 90s temps with mid-upper 70s dew points we've been having in NC lately .... 115 heat index the other day, finally cooled down today with more clouds/rain from whatever the hell is off the NC/SC coast
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Quoting Doppler22:
Heres a poll for everybody (howevr if Patrap doesnt poll on a monday he doesnt have too ;)

At 8pm what will the % b on 99L?

A. 10-20% (Low)
B.30-40% (Medium)
C. 50% or greater(High)

B
Member Since: March 16, 2012 Posts: 127 Comments: 7928
Member Since: August 6, 2011 Posts: 4 Comments: 37121
Quoting PalmBeachWeather:
So you based your forecast on "Someone said?"


of course..
someone said to
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Quoting Stormchaser121:

Well the reason i said that was because someone said that there are strong trade winds over the carribean, therefore they will all be torn up if they go there, also they said that all the homegrown development occured earlier in the year, so the cape verde season storms will all re-curve into the Atlantic or the eastern seaboard. But idk if its all true or not.
So you based your forecast on "Someone said?"
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Member Since: August 6, 2011 Posts: 4 Comments: 37121
i dont poll on the weekends its not good for you
Member Since: May 21, 2006 Posts: 5091 Comments: 114785
a whole lot of conjecture about track of 99L. the system is weak ,not even with a surface reflection. such weak disturbances in the organising stage tend to track with the 700_850mb steering currents which will take it west or north of west. at the moment the system is moving along the periphery of the strong A/B to it's north.
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Member Since: July 21, 2011 Posts: 83 Comments: 7167
07/30/12 12UTC Peak Wave Direction and Period animated.

Link
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Quoting STXHurricanes2012:

Not even close yet lol

Well the reason i said that was because someone said that there are strong trade winds over the carribean, therefore they will all be torn up if they go there, also they said that all the homegrown development occured earlier in the year, so the cape verde season storms will all re-curve into the Atlantic or the eastern seaboard. But idk if its all true or not.
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BULLETIN - EAS ACTIVATION REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE MIAMI FL
535 PM EDT MON JUL 30 2012

THE NATIONAL WEATHER SERVICE IN MIAMI HAS ISSUED A

* SEVERE THUNDERSTORM WARNING FOR...
NORTH CENTRAL PALM BEACH COUNTY IN SOUTH FLORIDA.

* UNTIL 600 PM EDT

* AT 534 PM EDT...NATIONAL WEATHER SERVICE METEOROLOGISTS DETECTED A
SEVERE THUNDERSTORM CAPABLE OF PRODUCING DAMAGING WINDS IN EXCESS
OF 60 MPH. THIS STORM WAS LOCATED NEAR CALOOSA. THIS STORM WAS
NEARLY STATIONARY.

* THE STORM WILL AFFECT...
RURAL NORTHERN PALM BEACH COUNTY
AND SURROUNDING COMMUNITIES.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

SEVERE THUNDERSTORMS PRODUCE DAMAGING WINDS IN EXCESS OF 58 MPH AND
OR LARGE HAIL. FREQUENT TO EXCESSIVE LIGHTNING AND HEAVY RAINFALL IS
ALSO POSSIBLE. IF THE STORM APPROACHES YOUR LOCATION, SEEK SHELTER IN
AN ENCLOSED BUILDING ON THE LOWEST FLOOR AND STAY AWAY FROM WINDOWS.
Member Since: August 6, 2011 Posts: 4 Comments: 37121
Quoting Doppler22:
Heres a poll for everybody (howevr if Patrap doesnt poll on a monday he doesnt have too ;)

At 8pm what will the % b on 99L?

A. 10-20% (Low)
B.30-40% (Medium)
C. 50% or greater(High)
C. and I poll any day.
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Quoting Doppler22:
Heres a poll for everybody (howevr if Patrap doesnt poll on a monday he doesnt have too ;)

At 8pm what will the % b on 99L?

A. 10-20% (Low)
B.30-40% (Medium)
C. 50% or greater(High)


B.
Member Since: July 21, 2011 Posts: 83 Comments: 7167
Quoting Stormchaser121:
Looks like the Western Gulf and TX might escape yet another hurricane season!
"You have to be kidding"
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anyone remember Debby?..this could very well happen all over again in the days to come........................................Debby, the minimal tropical storm which has sat and spun over the northeast Gulf of Mexico for several days, has produced rainfall totals in north Florida not to be believed, exceeding 20” in spots. Additional heavy rain is forecast, likely worsening ongoing flooding in the region.
Member Since: August 6, 2011 Posts: 4 Comments: 37121
Quoting Doppler22:
Heres a poll for everybody (howevr if Patrap doesnt poll on a monday he doesnt have too ;)

At 8pm what will the % b on 99L?

A. 10-20% (Low)
B.30-40% (Medium)
C. 50% or greater(High)

B.
Member Since: July 6, 2010 Posts: 113 Comments: 31577

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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.