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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I have a meteorology degree so I stay above the fray of it all...
2005: 4 HURRICANES 5 TROPICAL STORMS
2006: 0 HURRICANE 4 TROPICAL STORMS
2007: 1 HURRICANES 3 TROPICAL STORMS
2008: 2 HURRICANES 3 TROPICAL STORMS
2009: 0 HURRICANE 1 TROPICAL STORM
2010: 1 HURRICANE 2 TROPICAL STORMS
2011: 0 HURRICANE 5 TROPICAL STORMS
IF WE SEE UP TO THIS DAY IN THE HURRICANE SEASON:
2005: 9 STORMS
2008: 5 STORMS
2011: 5 STORMS
2007: 4 STORMS
2006: 4 STORMS
2010: 3 STORMS
2009: 1 STORM
IF WE SEE I'M PREDICTING WE ARE GOING TO HAVE A SEASON SIMILAR AS THE 2008 SEASON WHERE THEY HAD 16 STORMS 8 HURRICANES AND 5 MAJOR HURRICANES AND IT WAS A VERY ACTIVE HURRICANE SEASON. So you guys understand this what do you guys think about this search i made. SO IT LOOK LIKES 2011 HAS JUST WOKE UP WE SHALL SEE.
What does the 18Z GFS show? now I am curious....
I guess the blob to the NW of the center then is some mid-level rotation, that NW blob looks really good.
It says we are all DOOM.
That is not far from the truth, as it shows Florida, the SE US, and the eastern GOM getting hit by two strong hurricanes doing the Fujiwara.
Models have shifted west.. Sorry but you cannot have a storm go out to sea in a BLOCKING PATTERN
P451, here is a better one.
Link
That was refreshing Dennis, thank you. It's good to have another professional in-house. Where did study meteorology?
all i can say is WHAT?!?! i mean really? i have seen some loop de loops in my time but that was just rediculous...i watched it like 5 times, slowed it down, etc...thought my eyes were playing tricks on me
Almost two weeks away from the CONUS.
Wouldn't pat yourself on the back yet.
Things change.
how evere the nhc could move the center too the S
Wasn't gonna.. just proving my point from this morning. The "fish" people were out in full force.
It is wild! But...also very far away and we all know how that changes things lol!
So fish people in the mornings and drama queens in the evenings?
that had to be a blurb...i mean...had to...one storm comes in, skirts the coast going ne...slams on the brakes, while the second one puts on the brakes too, so the first one can put it in reverse, go back to the south, and the second one continues as if nothing happened...i mean the chances of that seems as remote as a cat 5 hurricane hitting at the same time as a tsunami during a lunar high tide...
I thought it was really odd with mine this morning too; I actually got a response from Angela Fritz on my comment then my post got removed......Will just stick to the weather from now on.......
2008 was a really bad year and anything similar to that could be devastating.
The first storm seemed to stall, and as the second approached they did the Fujiwara. Those motions look correct in that setup.
That's what happens when someone like Jason gets 20+ handles.
I'm amazed non of the admins have caught on.
in fac they have
look at this
Link
Did you set up your wunderblog?
not what i saw...i put it in super slow motion...the first one got to about the SC/NC boarder, stalled the second, the first hit reverse and went back to the south and across FL into the GOM then the second one started back in...
Link
2004 sets an even better example.
True, sometimes I forget how non-military think.
Link
I didn't respond to an WU mail of his the other day. First time I've ever had a comment removed, lol. That could get annoying real fast.
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