Dr. Jeff Masters' WunderBlog

African tropical wave 99L slowly organizing
Posted by: Dr. Jeff Masters, 01:26 PM GMT del 31 Luglio 2012 +38
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
Categories: Hurricane
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2351. washingtonian115 01:57 PM GMT del 01 Agosto 2012    
A storm has to be at least 600 miles in the area of the Cape verde islands to be considered one.
Member Since: Agosto 14, 2010 Posts: 5 Comments: 10664
2352. Patrap 01:57 PM GMT del 01 Agosto 2012    
Member Since: Luglio 3, 2005 Posts: 372 Comments: 111605
2353. LargoFl 01:57 PM GMT del 01 Agosto 2012    
Quoting jascott1967:
As a Kemah, Texas resident I am a bit less concerned about 99L today than I was on Monday. Wind shear appears to be effecting 99L and hopefully will rip it apart before it gets a real chance to develope.
..I am with you on that..we dont need any hurricane this year doing alot of damage to any area
Member Since: Agosto 6, 2011 Posts: 0 Comments: 22426
2354. Patrap 01:58 PM GMT del 01 Agosto 2012    
Member Since: Luglio 3, 2005 Posts: 372 Comments: 111605
2356. floridaboy14 01:58 PM GMT del 01 Agosto 2012    
Quoting TropicalAnalystwx13:

99L's too far from Cape Verde and the East Atlantic to be considered a Cape Verde tropical cyclone.
well not exactly... it would need to be declared a depression pretty soon and has to develop at LEAST 100 miles east of the islands but it has cape verde roots
Member Since: Luglio 25, 2011 Posts: 0 Comments: 978
2357. Stormchaser2007 01:59 PM GMT del 01 Agosto 2012    
*12z SHIPS could be unreliable.

It was run off of the BAMM track due to the Camp Springs, MD computer issues. Last cycle was off the OPFI which was much further south and faster.

Might get an official track later.
Member Since: Giugno 9, 2007 Posts: 4 Comments: 15248
2358. unknowncomic 01:59 PM GMT del 01 Agosto 2012    
Quoting Patrap:
Wave coming off africa looks massive.
Member Since: Agosto 2, 2011 Posts: 0 Comments: 466
2359. washingtonian115 02:00 PM GMT del 01 Agosto 2012    
Quoting muddertracker:


You're right! Let's go back to that global warming discussion! Sarcasam Flag: RI

Now that you mentioned it duck here they come!!.Lol.
Member Since: Agosto 14, 2010 Posts: 5 Comments: 10664
2360. Patrap 02:01 PM GMT del 01 Agosto 2012    
A closed mind sees no Light.

But bulbs are cheap.
Member Since: Luglio 3, 2005 Posts: 372 Comments: 111605
2362. TropicalAnalystwx13 02:01 PM GMT del 01 Agosto 2012    
Quoting floridaboy14:
well not exactly... it would need to be declared a depression pretty soon and has to develop at LEAST 100 miles east of the islands but it has cape verde roots

Most tropical cyclones that develop in the Atlantic do. That doesn't make them a Cape Verde system.

Cape Verde hurricane:



Not a Cape Verde hurricane:

Member Since: Luglio 6, 2010 Posts: 89 Comments: 25330
2363. WunderAlertBot (Admin) 02:02 PM GMT del 01 Agosto 2012    
JeffMasters has created a new entry.
2364. Patrap 02:02 PM GMT del 01 Agosto 2012    
..O the sweet smell of success,

handle me with care..
Member Since: Luglio 3, 2005 Posts: 372 Comments: 111605
2365. LargoFl 02:02 PM GMT del 01 Agosto 2012    
one GOOD thing about 99L....its getting people to THINK..about preparing etc...its been slow for storms so far..and people are relaxed huh....time to prepare..just in case..August is here now
Member Since: Agosto 6, 2011 Posts: 0 Comments: 22426
2366. MississippiWx 02:04 PM GMT del 01 Agosto 2012    
I believe 99L is good enough to be classified a TD. The NHC, however, may not be impressed with the convection-less northern quadrant.

Member Since: Luglio 15, 2006 Posts: 13 Comments: 8621
2367. HurricaneHunterJoe 02:06 PM GMT del 01 Agosto 2012    
Quoting muddertracker:


This is an excellent product! On the shortwave loop you can see it, too.


Link Please
Member Since: Settembre 18, 2010 Posts: 0 Comments: 2690
2368. hurricanejunky 02:09 PM GMT del 01 Agosto 2012    
Quoting TropicalAnalystwx13:

99L's too far from Cape Verde and the East Atlantic to be considered a Cape Verde tropical cyclone.


Oh quit being such a stickler, I'm working on my dramatization skills! LOL
Member Since: Agosto 28, 2006 Posts: 6 Comments: 2875
2369. PensacolaDoug 02:10 PM GMT del 01 Agosto 2012    
Quoting hurricanejunky:
Will Ernesto be the next great Cape Verde storm?
The Gulf temps off the Southwest Florida Coast (Fort Myers area)are running at or above 90 degrees right now so let's hope we don't see another Charley scenario or it could get UGLY!




Caribe will be hard on this system,
Member Since: Luglio 25, 2006 Posts: 0 Comments: 4828
2370. PensacolaDoug 02:19 PM GMT del 01 Agosto 2012    
Quoting Patrap:
A closed mind sees no Light.

But bulbs are cheap.





So are words.
Member Since: Luglio 25, 2006 Posts: 0 Comments: 4828
2371. HurricaneHunterJoe 02:26 PM GMT del 01 Agosto 2012    
Quoting Patrap:


Is bearing 340 degrees on that the actual heading now? 340 is NNW?
Member Since: Settembre 18, 2010 Posts: 0 Comments: 2690

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About JeffMasters
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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