Two African waves that may develop
Hello everyone, it's Jeff Masters back with you again after a long stretch of vacation. Now that the peak part of hurricane season is upon us, I'll be with you every day for the next few months, in what promises to be an unusually active Atlantic hurricane season. We've got several threats to talk about today, most notably a strong African wave near 12.5°N 30.5°W, about 400 miles west-southwest of the Cape Verde Islands. This system, dubbed Invest 92L by NHC, is moving west to west-northwest at 10 - 15 mph, and has the potential to develop into a tropical depression or tropical storm before arriving near the northern Lesser Antilles Islands early next week. Recent visible satellite loops show that 92L is beginning to develop a surface circulation, and heavy thunderstorms are slowly building along the western edge of the center. However, a separate area of heavy thunderstorms lies 400 miles to the east, just south of the Cape Verde Islands, and this blob is interfering with consolidation of the center near the blob of heavy thunderstorms at 30.5°W. Water vapor satellite loops show that a large area of dry air from Africa lies just to the west of 92L, but the atmosphere in the immediate vicinity of 92L is moist, so dry air is currently not a problem for the storm. The SHIPS model is diagnosing low shear, 5 - 10 knots, over 92L, but the University of Wisconsin CIMSS analysis shows that moderate shear of 10 - 20 knots is affecting 92L. Sea surface temperatures are 26.5° - 27°C, which is very close to the 26.5°C threshold usually needed to support a tropical storm.
Figure 1. Noon satellite photo of Invest 92L.
Forecast for 92L
Low to moderate wind shear of 5 - 15 knots is predicted along 92L's path over the coming three days, which should allow the storm to steadily organize, assuming it can shut out any incursions of dry air that might intrude. The latest 00Z and 06Z model runs of the four best models for predicting tropical storm formation (GFS, ECMWF, NOGAPS, and UKMET) show little or no development of 92L, and NHC gave 92L just a 20% chance of developing into a tropical depression by Friday morning in their 8am outlook. Given the recent improvement in the satellite appearance of 92L, I would put these odds at 30%. A steady west to west-northwest motion for 92L is predicted by all of the models, which would put the storm in the vicinity of the northern Lesser Antilles Islands by Sunday. On Saturday and Sunday, 92L is expected to enter a region where an upper-level low pressure system will bring high wind shear of 20 knots to the storm, which should slow development. This upper-level low is also expected to turn 92L more to the northwest, so the storm may pass north of the Lesser Antilles. It is too early to know if 92L will recurve out to sea and potentially threaten Bermuda, or continue to the northwest towards the U.S. East Coast.
Figure 2. NASA MODIS image taken at 10:40am EDT 8/10/11 of the tropical wave emerging from the coast of Africa. The GFS model is predicting this system will develop into a tropical storm early next week. Image credit: NASA.
Tropical wave emerging from the coast of Africa
A strong tropical wave currently emerging from the coast of Africa near 8°N has a modest amount of spin and heavy thunderstorm activity associated with it, and has the potential to develop early next week once it moves past the Cape Verde Islands. The GFS model has been developing this system into a tropical storm in several of its recent runs. A westerly track towards the Lesser Antilles is expected by the GFS model.
Jeff Masters
Reader Comments
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The National Hurricane Center goes by current organization more than anything. From what I see, 92L has become a little better organized this afternoon, thus warranting a 30% chance. However, I won't guarantee that, but I think 30% is a good choice.
Please, tigger, send some Texas way. We need it! Water rationing here.
you dont want this one...so hard it will all be runoff...wow...this is nasty...waiting for the hail
Sorry to tell ya but you're wrong
18z Early Cycle NHC model tracks
Invest92
Statistical/Simple Models (CLIPER,BAMs,LBAR,other Statistical Models)
Dynamic Models (More sophisticated models)
Giving us Tampa residents a crazy amount of weather. Several inches since Tuesday morning.
Ha ha, freshman!!! LOL Hope it went well.
Yes I think so.
You got that right! 2011 is about to break loose it looks like. Take a look at the 4 disturbances on the heels of 93L...
Another user said this some minutes ago:
WEATHER WEATHER WEATHER WEATHER WEATHER WEATHER WEATHER WEATHER WEATHER WEATHER WEATHER WEATHER WEATHER WEATHER WEATHER WEATHER
August 2011
8th-11th. Scattered thunderstorms and muggy. Gusty winds for the Mississippi River Valley.
12th-15th. Continued humid, with more scattered showers and thunderstorms.
16th-19th. Scattered thunderstorms.
20th-23rd. Pleasant, turning unsettled.
24th-27th. Hazy and humid, with scattered thunderstorms.
28th-31st. Hot and steamy. A hurricane threat for the Southeast.
Sea temps show GOM at 93 degrees F
Current:
Current Shear compared to average:
Atlantic
Caribbean
i do all so we most watch 92L has well
Link
I think 93 is the one to watch.
We can almost bank on the GOM SSTs to be high every year. This year, they are about 1-2C above average. However, we can't bank on a system actually making it there. Even if one does, it has to have favorable upper level conditions to take advantage of those warm waters.
I did, and I agree. 93L looks to be like more western-tracker than 92L.
Dunno... something tells me it resembles Ivan from 2004. I just thought I would ask to see if anyone else felt the same way. We'll see what happens, I guess...BTW that was just a "what if". I have no info supporting it going into the GOM.
Where are you located? we have a similar storm getting ready to move into Columbus it the next couple minutes!
is it storming in Goose Greek?
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