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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920. aspectre
10:40 PM GMT on July 30, 2012
Cuz the link was bad and the address was broken by the WUforum-program
507 CaicosRetiredSailor: Human activities caused 70% to 95% of the Arctic sea ice loss
Member Since: August 21, 2007 Posts: 0 Comments: 4860
919. CaribBoy
10:40 PM GMT on July 30, 2012
Quoting Tropicsweatherpr:


THat is good. Let'see if other islands like Antigua,Guadeloupe,St Kitts,Nevis,Dominica got the same.


I watched the tropical wave on the antilles radar all day, and it looks like all the leeward islands from dominica to anguilla got some decent rain :)
Member Since: October 6, 2007 Posts: 0 Comments: 6423
918. wxchaser97
10:39 PM GMT on July 30, 2012
312 hours, re-development

Member Since: March 16, 2012 Posts: 127 Comments: 7958
917. Grothar
10:38 PM GMT on July 30, 2012
Quoting spathy:


Ack!

Thats a whole new ballgame!
Cant you let me get past the opening pitch before you start talking about overtime?

I am paranoid enough as it is,please dont add to it.

Good question,but ACK!


I didn't know you spoke Martian. Ack,ack.
Member Since: July 17, 2009 Posts: 71 Comments: 26825
916. LargoFl
10:37 PM GMT on July 30, 2012
.......good to see rain in this state..they need it badly
Member Since: August 6, 2011 Posts: 4 Comments: 40845
914. wxchaser97
10:37 PM GMT on July 30, 2012
276 hour
Member Since: March 16, 2012 Posts: 127 Comments: 7958
913. CaribBoy
10:37 PM GMT on July 30, 2012
18Z GFS is disappointed
Member Since: October 6, 2007 Posts: 0 Comments: 6423
912. CybrTeddy
10:37 PM GMT on July 30, 2012
Quoting tj175:
Wow the Wishcasters are really out in full force today.


What I see is a good and very educational discussion going on about this potential threat for development in the medium range and a possible long term threat to the islands.

How is that wishcasting? I'm lost here, please elaborate.
Member Since: July 8, 2005 Posts: 259 Comments: 24468
911. Tropicsweatherpr
10:37 PM GMT on July 30, 2012
Quoting CaribBoy:


Yeah, that was a fairy intersting day (weather wise) :) We got a mix of heavy thundershowers, continued rain, gusty winds... It's been a while.. now nature is happy again.


That is good. Let's see if other islands like Antigua,Guadeloupe,St Kitts,Nevis,Dominica got the same.
Member Since: April 29, 2009 Posts: 75 Comments: 14551
910. Grothar
10:36 PM GMT on July 30, 2012
Quoting LargoFl:
..GRO if this should move to the gulf what then


I don't believe it will go into the Gulf. It should on a pretty much WNW movement and be in the perhaps the Southern Bahamas not much chance for development at this time.

As a matter of fact, with the large ULL between the two systems, it could cause a little problem down the road if 99L gains a little latitude before it gains some attitude.


Member Since: July 17, 2009 Posts: 71 Comments: 26825
909. KEEPEROFTHEGATE (Mod)
10:36 PM GMT on July 30, 2012
Member Since: July 15, 2006 Posts: 175 Comments: 54827
908. CaribBoy
10:34 PM GMT on July 30, 2012
Quoting Tropicsweatherpr:


I hope that you have got rain today in St Maarten.


Yeah, that was a fairy intersting day (weather wise) :) We got a mix of heavy thundershowers, continued rain, gusty winds... It's been a while.. now nature is happy again.
Member Since: October 6, 2007 Posts: 0 Comments: 6423
907. stormpetrol
10:34 PM GMT on July 30, 2012
Shear is like knocking the head off and tradewinds knocks your feet from under you and you fall, that is best way I know to compare the 2, either way , you fall!
Member Since: April 29, 2007 Posts: 0 Comments: 8001
906. GTcooliebai
10:33 PM GMT on July 30, 2012
Quoting TropicalAnalystwx13:

I don't see it.
Link use the panels.
Member Since: August 31, 2009 Posts: 0 Comments: 5628
905. Bluestorm5
10:33 PM GMT on July 30, 2012
WRAL people not expecting the blob to become anything tropical.
Member Since: August 1, 2011 Posts: 28 Comments: 8041
904. HurricaneHunterJoe
10:33 PM GMT on July 30, 2012
The Boys and Girls at the San Diego NWS earning their keep today,Usually the forecast is 75-80 and sunny....lol


Severe Thunderstorm Warning
SEVERE THUNDERSTORM WARNING
CAC073-302300-
/O.NEW.KSGX.SV.W.0005.120730T2209Z-120730T2300Z/

BULLETIN - EAS ACTIVATION REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE SAN DIEGO CA
309 PM PDT MON JUL 30 2012

THE NATIONAL WEATHER SERVICE IN SAN DIEGO HAS ISSUED A

* SEVERE THUNDERSTORM WARNING FOR...
EAST CENTRAL SAN DIEGO COUNTY IN SOUTHWEST CALIFORNIA...

* UNTIL 400 PM PDT

* AT 259 PM PDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
SEVERE THUNDERSTORM CAPABLE OF PRODUCING DAMAGING WINDS IN EXCESS
OF 60 MPH. THIS STORM WAS LOCATED NEAR SHELTER VALLEY...OR 15
MILES SOUTHWEST OF BORREGO SPRINGS...AND MOVING EAST AT 10 MPH.

* THE SEVERE THUNDERSTORM WILL BE NEAR...
AGUA CALIENTE SPRINGS BY 400 PM PDT...

&&

LAT...LON 3309 11621 3287 11630 3298 11658 3315 11651
TIME...MOT...LOC 2209Z 290DEG 7KT 3304 11644

$$

PALMER
Member Since: September 18, 2010 Posts: 0 Comments: 5237
903. MAweatherboy1
10:33 PM GMT on July 30, 2012
Quoting GTcooliebai:
This is one of the CMC ensembles and it looks like they are trending south.


Makes sense as it's looking like we'll be dealing with a pretty weak system.
Member Since: February 11, 2012 Posts: 84 Comments: 7928
902. canehater1
10:32 PM GMT on July 30, 2012
If 99-L gains enough latitude trades are not an issue.

According to grid fcst, winds in Carib much lower in

speed along S coast of DR,etc. 20-30 kt in Central and S carib....much less a little farther N. But first
the storm has to develop, lol
Member Since: September 8, 2008 Posts: 1 Comments: 1083
901. Hurricanes101
10:32 PM GMT on July 30, 2012
Quoting Tazmanian:
in EL nino year dont we norml see higher trade winds in the Caribbean ?


usually yes, its in relation to a strong high pressure I think
Member Since: March 10, 2010 Posts: 1 Comments: 7872
BULLETIN - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE GREEN BAY WI
528 PM CDT MON JUL 30 2012

THE NATIONAL WEATHER SERVICE IN GREEN BAY HAS ISSUED A

* SEVERE THUNDERSTORM WARNING FOR...
NORTHWESTERN BROWN COUNTY IN NORTHEAST WISCONSIN...
OCONTO COUNTY IN NORTHEAST WISCONSIN...

* UNTIL 615 PM CDT

* AT 525 PM CDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
LINE OF SEVERE THUNDERSTORMS CAPABLE OF PRODUCING QUARTER SIZE
HAIL. THESE STORMS WERE LOCATED ALONG A LINE EXTENDING FROM 7
MILES WEST OF OCONTO TO PULASKI...AND MOVING EAST AT 30 MPH.

* SEVERE THUNDERSTORMS WILL BE NEAR...
OCONTO AROUND 540 PM CDT.

OTHER LOCATIONS IMPACTED BY THESE SEVERE THUNDERSTORMS INCLUDE
SOBIESKI...BROOKSIDE...SUAMICO...CULLEN...COUNTY LINE...PENSAUKEE AND
LITTLE SUAMICO.

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: 40845
Quoting GTcooliebai:
This is one of the CMC ensembles and it looks like they are trending south.


I don't see it. Maybe post the previous run in addition to the current?
Member Since: Posts: Comments:
Central Africa.


Member Since: July 17, 2009 Posts: 71 Comments: 26825
Quoting Patrap:


GO NORTH PLASE!!!
Member Since: October 6, 2007 Posts: 0 Comments: 6423
Quoting LargoFl:
ok so we have california,utah,nevada and now lets welcome Arizona to our storm party..gee is there any state without a warning today?.........................ULLETIN - EAS ACTIVATION REQUESTED
FLASH FLOOD WARNING
NATIONAL WEATHER SERVICE PHOENIX AZ
312 PM PDT MON JUL 30 2012

THE NATIONAL WEATHER SERVICE IN PHOENIX HAS ISSUED A

* FLASH FLOOD WARNING FOR...
CENTRAL IMPERIAL COUNTY IN SOUTHEAST CALIFORNIA...

* UNTIL 615 PM PDT

* AT 308 PM PDT...NATIONAL WEATHER SERVICE METEOROLOGISTS DETECTED
THUNDERSTORMS WITH VERY HEAVY RAIN FROM EAST OF IMPERIAL...TO
NORTHEAST OF GLAMIS. MOVEMENT WAS SLOWLY SOUTH.

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

PRECAUTIONARY/PREPAREDNESS ACTIONS...

RADAR INDICATES THAT UP TO 2 INCHES OF RAIN HAS FALLEN IN THE AREA
FROM EAST OF IMPERIAL TO SOUTHEAST OF GLAMIS. RUNOFF FROM THE HEAVY
RAIN WILL CAUSE FLOODING IN THE AREA.

MOST FLOOD DEATHS OCCUR IN MOTORIZED VEHICLES. WHEN ENCOUNTERING
FLOODED ROADS...MAKE THE SMART CHOICE...TURN AROUND...DONT DROWN.



This is the county east of San Diego County and is all low desert,it runs all the way to the Colorado River/Arizona border. For some reason they give this area to Phoenix NWS, maybe because they are the experts on desert weather?
Member Since: September 18, 2010 Posts: 0 Comments: 5237
That monsoon trof is really lighting up this evening for 99L. Nice increase in convection.

Might help generate enough convection to tighten up the surface low in the next 18 hours. Could see 30% at 8pm if things continue like this.

Member Since: Posts: Comments:
Quoting spathy:


Ack!

Thats a whole new ballgame!
Cant you let me get past the opening pitch before you start talking about overtime?

I am paranoid enough as it is,please dont add to it.

Good question,but ACK!


i don't want to scare ya but there could be some type of dev in gom south of la offshore 3 or 4 days from now and maybe another area off east coast off sc and all the while a building 99l

remember sometimes things can pick up so fast we will not even be able to keep up
Member Since: July 15, 2006 Posts: 175 Comments: 54827
Quoting ncstorm:
18z Nogaps takes a 1008mb system into Florida..
..NC in what timeframe?
Member Since: August 6, 2011 Posts: 4 Comments: 40845
This is one of the CMC ensembles and it looks like they are trending south.

Member Since: August 31, 2009 Posts: 0 Comments: 5628
Quoting CaribBoy:


Obviously lol and I'm out too! I got rain today from the antilles wave BUT that's not enough. SO I would like 99L to bring the Leewards some more!.. with of bit of FUN (a well organized 55Kt TS for instance!!) And, no i'm not crazy :)


I hope that you have got rain today in St Maarten.
Member Since: April 29, 2009 Posts: 75 Comments: 14551
Quoting spathy:


Those flash flood warnings are very important out there.

Kids play in those drainage areas and the valleys are subject too.
It could be sunny and dry where you are and BAM!
A wall of disaster come out of nowhere!
yes they are dangerous alright
Member Since: August 6, 2011 Posts: 4 Comments: 40845
18z Nogaps takes a 1008mb system into Florida..
Member Since: Posts: Comments:
Quoting tj175:
Wow the Wishcasters are really out in full force today.


So are the people looking to make drama.

Wishcasters? Really?
Member Since: March 10, 2010 Posts: 1 Comments: 7872
Quoting tj175:
Wow the Wishcasters are really out in full force today.


Obviously lol and I'm out too! I got rain today from the antilles wave BUT that's not enough. SO I would like 99L to bring the Leewards some more!.. with of bit of FUN (a well organized 55Kt TS for instance!!) And, no i'm not crazy :)
Member Since: October 6, 2007 Posts: 0 Comments: 6423
Member Since: August 6, 2011 Posts: 4 Comments: 40845
Quoting Patrap:
..ok you got me hypnotized with that one pat lol
Member Since: August 6, 2011 Posts: 4 Comments: 40845
Quoting caribbeantracker01:


yes that is the point and imagine it was not any significant system i would believe trade winds are accompanied by high wind shear? so we may have 2 systems to watch soon
..yes my local met said the same thing
Member Since: August 6, 2011 Posts: 4 Comments: 40845
Member Since: July 3, 2005 Posts: 426 Comments: 129089
Quoting LargoFl:
ok so we have california,utah,nevada and now lets welcome Arizona to our storm party..gee is there any state without a warning today?.........................ULLETIN - EAS ACTIVATION REQUESTED
FLASH FLOOD WARNING
NATIONAL WEATHER SERVICE PHOENIX AZ
312 PM PDT MON JUL 30 2012

THE NATIONAL WEATHER SERVICE IN PHOENIX HAS ISSUED A

* FLASH FLOOD WARNING FOR...
CENTRAL IMPERIAL COUNTY IN SOUTHEAST CALIFORNIA...

* UNTIL 615 PM PDT

* AT 308 PM PDT...NATIONAL WEATHER SERVICE METEOROLOGISTS DETECTED
THUNDERSTORMS WITH VERY HEAVY RAIN FROM EAST OF IMPERIAL...TO
NORTHEAST OF GLAMIS. MOVEMENT WAS SLOWLY SOUTH.

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

PRECAUTIONARY/PREPAREDNESS ACTIONS...

RADAR INDICATES THAT UP TO 2 INCHES OF RAIN HAS FALLEN IN THE AREA
FROM EAST OF IMPERIAL TO SOUTHEAST OF GLAMIS. RUNOFF FROM THE HEAVY
RAIN WILL CAUSE FLOODING IN THE AREA.

MOST FLOOD DEATHS OCCUR IN MOTORIZED VEHICLES. WHEN ENCOUNTERING
FLOODED ROADS...MAKE THE SMART CHOICE...TURN AROUND...DONT DROWN.



State of confusion? oh wait that always comes with a warning lol
Member Since: March 10, 2010 Posts: 1 Comments: 7872
Quoting tj175:
Wow the Wishcasters are really out in full force today.
well everyone is having fun posting today..its been awhile since the weather provided a storm to talk about, and we just may hit 1000 posts before the sun goes down..dont know another blog out there that is as good as this one
Member Since: August 6, 2011 Posts: 4 Comments: 40845
162 hours:


Member Since: February 11, 2012 Posts: 84 Comments: 7928
Quoting ilovehurricanes13:
here the map!!


the vort max for both systems looks interesting something to look at is the movement of the first wave and the high pressure relative to the second wave and the high pressure
Member Since: Posts: Comments:
Quoting GTcooliebai:
Aren't trade winds measured at the surface? If so it really wouldn't effect a deep system like depicted on the CMC.

It would disrupt the surface circulation which is crucial to be called a tropical cyclone.
Member Since: Posts: Comments:
874. tj175
Wow the Wishcasters are really out in full force today.
Member Since: Posts: Comments:
ok so we have california,utah,nevada and now lets welcome Arizona to our storm party..gee is there any state without a warning today?.........................ULLETIN - EAS ACTIVATION REQUESTED
FLASH FLOOD WARNING
NATIONAL WEATHER SERVICE PHOENIX AZ
312 PM PDT MON JUL 30 2012

THE NATIONAL WEATHER SERVICE IN PHOENIX HAS ISSUED A

* FLASH FLOOD WARNING FOR...
CENTRAL IMPERIAL COUNTY IN SOUTHEAST CALIFORNIA...

* UNTIL 615 PM PDT

* AT 308 PM PDT...NATIONAL WEATHER SERVICE METEOROLOGISTS DETECTED
THUNDERSTORMS WITH VERY HEAVY RAIN FROM EAST OF IMPERIAL...TO
NORTHEAST OF GLAMIS. MOVEMENT WAS SLOWLY SOUTH.

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

PRECAUTIONARY/PREPAREDNESS ACTIONS...

RADAR INDICATES THAT UP TO 2 INCHES OF RAIN HAS FALLEN IN THE AREA
FROM EAST OF IMPERIAL TO SOUTHEAST OF GLAMIS. RUNOFF FROM THE HEAVY
RAIN WILL CAUSE FLOODING IN THE AREA.

MOST FLOOD DEATHS OCCUR IN MOTORIZED VEHICLES. WHEN ENCOUNTERING
FLOODED ROADS...MAKE THE SMART CHOICE...TURN AROUND...DONT DROWN.

Member Since: August 6, 2011 Posts: 4 Comments: 40845
Quoting LargoFl:
..boy that wave by the islands is looking better and better


yes that is the point and imagine it was not any significant system i would believe trade winds are accompanied by high wind shear? so we may have 2 systems to watch soon
Member Since: Posts: Comments:
Aren't trade winds measured at the surface? If so it really wouldn't affect a deep system like depicted on the CMC.
Member Since: August 31, 2009 Posts: 0 Comments: 5628

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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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