Two African waves worth mentioning

By: Dr. Jeff Masters , 3:51 PM GMT on July 18, 2009

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There are two African tropical waves worth mentioning today, though neither looks particularly threatening. A tropical wave near 12N 45W, about 1200 miles east of the Lesser Antilles Islands (97 L), is moving west at 15 - 20 mph. This wave is now surrounded by an area of very dry air from the Sahara Desert. The dry air has disrupted most of the wave's heavy thunderstorm activity, and will continue to make it difficult for this system to develop over the next 2 - 3 days. Wind shear is a modest 10 knots over the disturbance, and should remain in the moderate 10 - 15 knot range over the next 2 - 3 days. Thereafter, shear is expected to rise to 20 - 30 knots. This morning's QuikSCAT pass showed no evidence of a surface circulation, and only a modest wind shift associated with 97L. The National Hurricane Center is giving this system a low (less than 30% chance) of developing into a tropical depression in the next 48 hours.

A second tropical wave now approaching the northern Lesser Antilles Islands is under 30 knots of wind shear, and has little prospect of development due to the high shear. However, the wave will bring heavy rain to the islands over the next two days.

None of the computer models are forecasting tropical storm development over the next seven days, and I don't expect either of the two African waves mentioned today to develop over at least the next three days.


Figure 1. Current satellite image of African wave 97L, 1200 miles east of the Lesser Antilles Islands.

I'll have an update Sunday afternoon.
Jeff Masters

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Quoting extreme236:
What happened to 97L RIP? lol


It did RIP and then it went unRIP.
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1899. dearmas
Quoting stormwatcherCI:
BTW enjoy the Cayman Islands. It is beautiful although kind of expensive.


Thanks
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Quoting dearmas:
Just a question: If 97 were to make it to the Caribbean, how long would it take to make it there??? We are going on a cruise on Aug 1st to Cayman islands and Mexico.
BTW enjoy the Cayman Islands. It is beautiful although kind of expensive.
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Quoting dearmas:
Just a question: If 97 were to make it to the Caribbean, how long would it take to make it there??? We are going on a cruise on Aug 1st to Cayman islands and Mexico.


August 1 is about 12 days a way, 97L should be out in 6.
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Quoting dearmas:
Just a question: If 97 were to make it to the Caribbean, how long would it take to make it there??? We are going on a cruise on Aug 1st to Cayman islands and Mexico.

Make sure you buy some sick sickness medicine for a bumpy ride...haha j/k. I would like to beleive if it is moving 500 miles a day (will slow a bit if it gets that far) that it should be clearing out by then for your trip. It will be close though.
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Quoting dearmas:
Just a question: If 97 were to make it to the Caribbean, how long would it take to make it there??? We are going on a cruise on Aug 1st to Cayman islands and Mexico.
Long gone by August1 but don't know about anything after that.
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What happened to 97L RIP? lol
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1893. dearmas
Just a question: If 97 were to make it to the Caribbean, how long would it take to make it there??? We are going on a cruise on Aug 1st to Cayman islands and Mexico.
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Morning all

Will be interesting to see how it handles the day time heating. While looking more organized, it is still a pretty compact fragile looking little system.

Member Since: August 17, 2005 Posts: 26 Comments: 16874
Dr. Lyons is a great forecaster and that's why he should leave the TWC. The TWC is influencing his forecasts. Its now become subjective rather than objective forecasting and all becuz of their sponsors.
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Quoting Weather456:
North of where? The entire Caribbean is shear free according to the forecasts.


agreed
lol 97L is a real forecast buster.
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Not too often one wakes up to 70ish F and no dew outside in mid July in SE LA. This is a treat.
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North of where? The entire Caribbean is shear free according to the forecasts.
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1886. IKE
Quoting leftovers:
steve lyons said "no go"? thats good. the invest still has a chance to prove itself


Surprised? No. TWC isn't worth watching anymore, even with Al Roker coming on-board.

I watched a tropical weather update on TWC the other day where the met stood in front of the satellite of 97L for 45 seconds of the 60 second update.

Impressive.
Member Since: June 9, 2005 Posts: 23 Comments: 37860
I'm not forecasting anything. That way no one can argue with me. Have a great day folks!
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Quoting stormwatcherCI:
Don't put too much stock in what you hear on TWC.

Yea but the one you can listen to is Dr. Lyons. He is a darn good tropical forecaster. As for the rest of them I agree with you.
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Good luck all im out........Your going to have fun today......lots of wishcasting both ways im sure!
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I guess we arent allowed to refute TampaSpin either or he gets defensive lol

Like he said, dont engage the trolls lmao, ok I wont engage him them after this


anyway 97L has slowed down it appears, that could be key, it will allow the shear to lessen in the Caribbean.
My guess is that the huge field of dust off Africa will trump the shear and the only thing tropical for this week will be the boat drinks ...slice of pineapple, please.
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Quoting IKE:


A few of the posters on this blog love to test people...get them involved...get banned with them.

I have to bite my tongue on here...lol...

Best to use the ignore feature.
Ok.
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Quoting Weather456:
2 out of 3 models show low shear in the caribbean over the next 3 days. If you inlude the UKMET and ECMWF, 4 out of 5.



If it stays south it has a better chance.....North it will not!
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Quoting InTheConeOIO:
Dr. Steve Lions said on TWC that this system is going to move into unfavor. cond. over the next few days so he dosn't expect all that much development.
Don't put too much stock in what you hear on TWC.
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1875. IKE
Quoting stormwatcherCI:
I wondered how he has the nerve to comment at times.


A few of the posters on this blog love to test people...get them involved...get banned with them.

I have to bite my tongue on here...lol...

Best to use the ignore feature.
Member Since: June 9, 2005 Posts: 23 Comments: 37860
Dr. Steve Lions said on TWC that this system is going to move into unfavor. cond. over the next few days so he dosn't expect all that much development.
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Good luck with the Trolls today folks....remember don't engage...don't need anyone banned....just put them on ignor!
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2 out of 3 models show low shear in the caribbean over the next 3 days. If you inlude the UKMET and ECMWF, 4 out of 5.

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Quoting IKE:


It's not near Jamaica...that's 1,500 miles to it's west.


but the system is moving 552 miles a day. arent some highs supposed to bridge to cause shear to drop?
Member Since: July 7, 2008 Posts: 2 Comments: 3237
Quoting IKE:


That coming from someone that put an extra yellow-circle on a NHC graphical TWO.

I wondered how he has the nerve to comment at times.
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Quoting jasoniscoolman09:
shear conditions in the Caribbean with up to 44-55 kts of shear near Jamaica


There is blind bloggers that can't understand that! Don't use that word!..LOL
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Quoting hurricaneseason2006:


Well with your large forecast error, I'm now certain 97L will form.


LOL!!
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1867. IKE
Quoting jasoniscoolman09:
shear conditions in the Caribbean with up to 44-55 kts of shear near Jamaica


It's not near Jamaica...that's 1,500 miles to it's west.
Member Since: June 9, 2005 Posts: 23 Comments: 37860
1866. SLU
The NOAA buoy located at 14.5N 53.0W is reporting 1-min sustained winds of 29mph and seas to 9.5ft and it is still 100 miles from the leading edge of the tropical wave. Looks like there are some strong winds developing on the north side as it interacts with the surface high.
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Quoting hurricaneseason2006:


Well with your large forecast error, I'm now certain 97L will form.


Whatever.....go read my updates.....Funny!
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1863. IKE
Quoting jasoniscoolman09:
wind Shear will kill 97L IN THE NEXT 48 HOURS...


That coming from someone that put an extra yellow-circle on a NHC graphical TWO.

Member Since: June 9, 2005 Posts: 23 Comments: 37860
I believe an Invest is declared so Model runs occur....so lets see what the next 4-5 runs show.....The track of Invest 97L will be the key! NOrth it dies.......South it could survive maybe!
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Only buoy near 97L

Station 41040
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Proof that a naked swirl of low level clouds does not mean a system is dead. People are quick to write of systems before observing them for long enough. Got to love the suprises in weather!
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1857. IKE
Member Since: June 9, 2005 Posts: 23 Comments: 37860
Lets go Tom Watson today.....WOW what a story! Everyone have a good day...out till late this evening......can't wait to get back to see what the Shear forecast will be like tonite......things could get very interesting.
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Seems to be consolidating convection towards the center.
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1854. aquak9
sporteguy, maybe there's different stats, esp if they are using the big planes or the smaller NOAA ones, concerning fuel consumption.

A small invest probably doesn't warrant the need, as opposed to a Cat3 that is building,
I guess they balance need of data with fuel consumption, throwing everything into the decision to fly recon or not.
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Quoting TampaSpin:
Just because it is an Invest again does not mean development is probably going to happen! Keep that i mind!


Any model support?
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Just because it is an Invest again does not mean development is probably going to happen! Keep that i mind!
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1851. MZV
I'm not totally convinced that 97L will make depression/storm status, especially with the current shear conditions in the Caribbean with up to 40-50 kts of shear near Jamaica.


Shallow and hybrid systems have demonstrated they can "sneak under" shear. If there are enough other favorable variables, shear isn't a show-stopper.
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1850. aquak9
West of 55ºW.

Thank you, nrtiwl!!
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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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