African tropical wave 99L slowly organizing

By: Dr. Jeff Masters , 1:26 PM GMT on July 31, 2012

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A tropical wave (Invest 99L) near 9°N 41°W, halfway between the Lesser Antilles Islands and the coast of Africa, has the potential to develop into a tropical depression later this week as it moves westward at 10 - 15 mph. Visible satellite loops show that the disturbance now has a moderate amount of poorly-organized heavy thunderstorms that continue to slowly increase in intensity and areal coverage. There is no surface circulation, but some counter-clockwise rotation of the large-scale cloud pattern is evident. Water vapor satellite loops show that 99L has a reasonably moist environment. The latest Saharan air layer analysis shows that the dry air from the Sahara lies to the north of 99L and is currently not affecting the storm. 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 through Friday, and ocean temperatures will remain near 28°C, according to the 8 am EDT run of the SHIPS model. However, a band of high wind shear of 20 - 40 knots associated with the subtropical jet stream lies just to the north of 99L, and it would not be a surprise to see 99L experience some higher shear conditions than are currently forecast. The farther north 99L gets, the higher the shear it will experience, and the SHIPS model is predicting shear in the moderate range, 10 - 20 knots, for Saturday - Sunday, as the storm works its way to 15°N. 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. There are some major differences in the predicted forward speed of 99L, with the ECMWF and UKMET models predicting the storm will reach the Lesser Antilles on Friday, and the GFS predicting a later arrival, on Saturday. At 8 am Tuesday, NHC gave 99L a 20% chance of developing into a tropical depression by Thursday morning. I expect the storm will begin having trouble with tendrils of dry air reaching down from the north at times this week, but 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 morning. The long-range fate of 99L next week is uncertain. A track west to west-northwest through the Caribbean, or to the northwest towards the U.S. East Coast are both possible. The storm is less likely to survive if it heads northwest towards the U.S.

Extreme heat in the Central U.S.
The withering heat in America's heartland continued on Monday, with high temperatures of 112° recorded in Winfield, Kansas and Searcy, Arkansas. Little Rock, Arkansas hit 111°, their 3rd hottest temperature ever record, behind the all time record of 114° set just last year on August 3, and the 112° reading of 7/31/1986. Wichita and Coffeyville in Kansas both hit 111° Monday, and in Oklahoma, Enid, Tulsa Jones Airport, and Chandler all topped out at 111°. Carr Creek, Missouri hit 110°, the hottest temperature measured in the state so far this year. Highs temperatures Tuesday and Wednesday in this region could reach 110° again, as the most extreme heat this week will stay focused over Oklahoma and surrounding states.

Jeff Masters

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1521. Patrap
A Hammer will not get you out of a Submerged car,thats why we carry a center punch in our Pockets whenever we cross the 24 Mile Causeway across Lake Pontchartrain.

Spring Loaded Center Punch w/ FETT lanyard Attachment
[FE103]
Price: $38.00




you dont get a second chance most times.
Member Since: July 3, 2005 Posts: 426 Comments: 128667
Looks like 99L is poise to be Ernesto could be near hurricane status when it nears the windward islands btw do the Gfs still develop the storm near NC?
Member Since: October 15, 2011 Posts: 0 Comments: 4401
TROPICAL WEATHER OUTLOOK
NWS NATIONAL HURRICANE CENTER MIAMI FL
800 PM EDT TUE JUL 31 2012

FOR THE NORTH ATLANTIC...CARIBBEAN SEA AND THE GULF OF MEXICO...

1. SHOWERS AND THUNDERSTORMS HAVE BECOME A LITTLE MORE CONCENTRATED
NEAR THE CENTER OF A LOW PRESSURE SYSTEM LOCATED ABOUT 1150 MILES
EAST-SOUTHEAST OF THE WINDWARD ISLANDS. ENVIRONMENTAL CONDITIONS
ARE AT LEAST MARGINALLY CONDUCIVE FOR SOME GRADUAL DEVELOPMENT OF
THIS DISTURBANCE OVER THE NEXT FEW DAYS AS IT MOVES WESTWARD AT
15 TO 20 MPH. THIS SYSTEM HAS A MEDIUM CHANCE...50 PERCENT...OF
BECOMING A TROPICAL CYCLONE DURING THE NEXT 48 HOURS


I KNOW IT'S LATE, but why did he said that?
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What to do to get the blog active again...
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1517. etxwx
Quoting CaicosRetiredSailor:



re Flood.... trapped in a car... electric windows... must break window to escape

True. A hammer just seemed like an odd item to purchase online. Hope they have fast shipping...
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One of the 00Z GFS members
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Winds out of the SW near Kingston, Ja.
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Quoting weathermanwannabe:


That lingering Tutt cell at around 55W would have created developmental problems in a few days; at this rate, it becomes a non-issue for the moment.


Yeah,as happened with debby
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1513. help4u
Love Rush!
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Quoting Saltydogbwi1:
img src="">

Nice burst of convection south of DR


Continuing to flare....hard to believe it's till at 0%.
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Quoting TropicalAnalystwx13:

Hey hey hey. You can't rush perfection.

Lol, jk.


XD

Riiiight.
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Quoting Articuno:

Should be a 30 - 35 mph TD soon, there is a ring of convection around it, and it is also fairly organized.

It just needs to disconnect from ITCZ
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Quoting KoritheMan:
Your turn, Cody. Get that blog up and running.

Hey hey hey. You can't rush perfection.

Lol, jk.
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Quoting bluenosedave:


That's headed my way here in Nova Scotia. Looks like we'll get a nice soaker out of it. Then clear off for the weekend 'cause I'm going camping!
It was suppose to be a few showers off the cape, but a few heavy bands are setting up over Eastern MA, and more breazy than they said, it looks to be heading further west than they though, or its just stronger, im hoping the former.
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Quoting washingtonian115:
99L is developing a anti-cyclone.Could help a little with the conditions in the caribbean.Ya'll along the Gulf coast better hope shear stays in place and keep it in check.
I like you she called us Ya'll!!!
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Quoting KoritheMan:


Agreed. And that will be the make it or break it point as far as potential for a strong system.


That lingering Tutt cell at around 55W would have created developmental problems in a few days; at this rate, it becomes a non-issue for the moment.
Member Since: August 8, 2006 Posts: 0 Comments: 9231
Quoting Grothar:


When 99L gain strength, the models will take track more to the west-north west to jamaica. Write it
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Your turn, Cody. Get that blog up and running.
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img src="">

Nice burst of convection south of DR
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Quoting washingtonian115:
99L is developing a anti-cyclone.Could help a little with the conditions in the caribbean.Ya'll along the Gulf coast better hope shear stays in place and keep it in check.


Well, it's about that time of year again.
Time to get my SIP-GO kit ready...
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Quoting TropicalAnalystwx13:
99L should be fully separated from the ITCZ by tomorrow afternoon.


Agreed. And that will be the make it or break it point as far as potential for a strong system.
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Quoting Methurricanes:
Mini-Noreaster is kicking into gear the entire South Shore, down Cape Cod has greater than 20mph winds, 30 mph Winds moving onshore now, according to NECN wind map


That's headed my way here in Nova Scotia. Looks like we'll get a nice soaker out of it. Then clear off for the weekend 'cause I'm going camping!
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Quoting MAweatherboy1:

This has to be post of the year, I'm still laughing right now.
That is GOOD!!!!
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This is what can happen when there is no Tutt in the way, in the short term, and sheer is favorable that can allow a wave to organize fairly quickly. I was not expecting the 50% until the am.
Member Since: August 8, 2006 Posts: 0 Comments: 9231
99L should be fully separated from the ITCZ by tomorrow afternoon.
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Should be a 30 - 35 mph TD soon, there is a ring of convection around it, and it is also fairly organized.
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Mini-Noreaster is kicking into gear the entire South Shore, down Cape Cod has greater than 20mph winds, 30 mph Winds moving onshore now, according to NECN wind map
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Quoting MAweatherboy1:
Generally Caribbean shear isn't that bad... The only questionable area is around Jamaica as I said... That 40 doesn't look too friendly:

When it get there that shear could be lower! If you look on sat. loops the shear is not that bad!
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Just did a blog on 99L.
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.
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1491. EricSFL
Saola, WPAC.
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Quoting Clearwater1:


Yep, you're right. I think in order to gain lat., it has to build intensity (high cloud towers) to get pulled towards the low. We shall see soon enough.

Trinidad may want to take cover. lol
Remember one of the strongest hurricanes (Allen)started around 9 degrees lattitude.
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1489. KEEPEROFTHEGATE (Mod)
Member Since: July 15, 2006 Posts: 174 Comments: 54398
Quoting EricSFL:

Consolidating right around the center.
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1487. EricSFL
99L
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Blog just died, LOL.
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Blog Update!!
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1484. DeValk
Quoting KoritheMan:


I was down in Gulfport not too long ago. There was still plenty of oil in the sand. Hate to see the subsurface.



Really??
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1483. Grothar
Member Since: July 17, 2009 Posts: 71 Comments: 26499
1482. ncstorm
CMC Ensembles 12z--takes it north of the islands, through the bahamas




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Quoting stormchaser19:
i don't know what thing is seeing the HWRF at 96 hour, that develops the system, i think the HWRF is seeing the same thing of us, remember HWRF is one of the best models predicting intensity


Respectfully disagree..HWRF is the worst by far. It over does intensity about as bad as the CMC.
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new from ATCF
00Z fix
AL, 99, 2012080100, , BEST, 0, 97N, 430W, 25, 1009, LO

lower pressure and tagged as LO not DB anymore
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1479. Grothar
first 00z Dynamic models for 08/01




Member Since: July 17, 2009 Posts: 71 Comments: 26499
1478. SLU
31/2345 UTC 9.2N 43.0W T1.0/1.0 99L -- Atlantic
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Quoting VAbeachhurricanes:


REally? I thought the main run was the average of the ensembles?


No, the main run is at full resolution (for the GFS T574 ~27KM for the first 192 hours). The ensembles are run at a lower resolution (for the GEFS T254 ~55km for the first 192 hours).
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1476. Grothar
Quoting stormpetrol:


LMAO!! Tell Romney to take out his money from here, it might get wet , J/K, personally this looks more like an Emily 05 or Felix 07 track to me!


Bad little storms, those!
Member Since: July 17, 2009 Posts: 71 Comments: 26499
Quoting ryang:


Where can I find the link to this info?


Link
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Quoting Bluestorm5:
No problems! I wasn't the one starting the idea anyway :) Beside, I encourages others to do it as well :)

Just making sure that it doesn't look like I am copying anyone.
Member Since: March 16, 2012 Posts: 127 Comments: 7948
1473. KEEPEROFTHEGATE (Mod)
126

WHXX01 KWBC 010041

CHGHUR

TROPICAL CYCLONE GUIDANCE MESSAGE

NWS NATIONAL HURRICANE CENTER MIAMI FL

0041 UTC WED AUG 1 2012



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 (AL992012) 20120801 0000 UTC



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

120801 0000 120801 1200 120802 0000 120802 1200



LAT LON LAT LON LAT LON LAT LON

BAMS 9.7N 43.0W 10.5N 46.4W 11.0N 49.7W 11.2N 53.2W

BAMD 9.7N 43.0W 10.2N 45.1W 10.6N 47.0W 10.8N 48.8W

BAMM 9.7N 43.0W 10.3N 45.4W 10.8N 47.6W 11.2N 49.7W

LBAR 9.7N 43.0W 10.2N 45.9W 10.8N 48.9W 11.2N 52.1W

SHIP 25KTS 32KTS 39KTS 45KTS

DSHP 25KTS 32KTS 39KTS 45KTS



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

120803 0000 120804 0000 120805 0000 120806 0000



LAT LON LAT LON LAT LON LAT LON

BAMS 11.1N 56.5W 10.7N 63.0W 11.5N 68.1W 13.6N 72.8W

BAMD 11.0N 50.6W 12.1N 54.6W 13.8N 58.7W 15.4N 62.0W

BAMM 11.7N 51.9W 13.3N 57.0W 15.5N 62.7W 17.4N 68.8W

LBAR 11.5N 55.2W 11.8N 61.4W 12.4N 66.5W .0N .0W

SHIP 50KTS 56KTS 55KTS 53KTS

DSHP 50KTS 56KTS 55KTS 53KTS



...INITIAL CONDITIONS...

LATCUR = 9.7N LONCUR = 43.0W DIRCUR = 280DEG SPDCUR = 17KT

LATM12 = 9.3N LONM12 = 39.6W DIRM12 = 277DEG SPDM12 = 16KT

LATM24 = 8.9N LONM24 = 36.6W

WNDCUR = 25KT RMAXWD = 50NM WNDM12 = 20KT

CENPRS = 1009MB OUTPRS = 1012MB OUTRAD = 150NM SDEPTH = M

RD34NE = 0NM RD34SE = 0NM RD34SW = 0NM RD34NW = 0NM



$$

NNNN
Member Since: July 15, 2006 Posts: 174 Comments: 54398
Quoting Grothar:


Geoff, that looks like it wants to go straight for the Cayman Islands. What do you think?


LMAO!! Tell Romney to take out his money from here, it might get wet , J/K, personally this looks more like an Emily 05 or Felix 07 track to me!
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i don't know what thing is seeing the HWRF at 96 hour, that develops the system, i think the HWRF is seeing the same thing of us, remember HWRF is one of the best models predicting intensity
Member Since: Posts: Comments:

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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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