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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Station 41097
Meteo France
Location: 14.54N 61.09W
Conditions as of:
Sun, 19 Jul 2009 12:46:00 UTC
Water Temperature: 85.6 F
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SLU, I have become accustom to ppl forgeting about the islands, but over the years I don't see it as much.

The worst ever was Hurricane Emily, Hurricane Dean and Hurricane Felix. Some did not give those the storm much attention (all cat 5) compared to barely cat 1 Humberto.
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Quoting Weather456:
Looking at visible imagery, it is clear to see a low level feature forming at the focal point of the thunderstorms. one thing I would like to see is thunderstorm coverage. That's why i think a TD is likely on Monday if it survives the next DMIN and DMAX.


Yeah, I was wondering. It is so small, I think it needs to get bigger. And, it maybe doing that as it continues to fire thunderstorms. And, what a difference 24 hours makes. Yesterday, people were RIPing it to death, and today it is a totally different story.
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The wave is entering an area of 5kt shear/it was under 10kt.This i think is more than enough for development.Link
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1945. IKE
Quoting Drakoen:
The main problem in it's immediate future is that big upper level trough over the Lesser Antilles.


GFS has that lifting. Moving 23 mph, the trough needs to lift out by tomorrow.
Member Since: June 9, 2005 Posts: 23 Comments: 37858
Quoting Drakoen:


Yes and if it develops a well defined LLC.


not sure if that would help or worsen the blog further, but at least the wait for tracking something *may* be over. *may*

are those banding features im seeing on the north, south, and east sides? im not seeing much on the west tho.
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Quoting Drakoen:
The main problem in it's immediate future is that big upper level trough over the Lesser Antilles.


Yeah I noticed that. Looks to be starting to lift out but not sure if its going fast enough.
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1942. surfmom
Quoting CaneWarning:


I don't like that orange line showing to so close to the west coast of Florida...but then again if its weak and we get a TS Warning then I do get off of work...


MEEEEEE TOO!.... and maybe a taste of groundswell --been a long time.
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Looking at visible imagery, it is clear to see a low level feature forming at the focal point of the thunderstorms. one thing I would like to see is thunderstorm coverage. That's why i think a TD is likely on Monday if it survives the next DMIN and DMAX.

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Quoting CaneWarning:


I don't like that orange line showing to so close to the west coast of Florida...but then again if its weak and we get a TS Warning then I do get off of work...


Don't worry. The track of this system is very uncertain, thus the model guidance is very spread out. One model takes it straight west and into central america, and there is the one you mentioned, which takes it over Hispaniola, Cuba, and up towards Florida.
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1939. Drakoen
The main problem in it's immediate future is that big upper level trough over the Lesser Antilles.
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Anyone know which imagery site will be the first to have rapid scan images? GHCC?
Member Since: August 17, 2005 Posts: 26 Comments: 15678
Quoting SLU:


lol i agree .... i've lost all faith in the TWC since Ivan in 2004. They're only concerned about stuff close to the US. While Ivan was approaching the Caribbean, Frances was heading to Florida and absolutely no mention was made of category 3/4 Ivan at the time. Many people in the Caribbean depend on TWC for weather updates. That was soooo disappointing. Thumbs down TWC.


I agree. They ONLY care about the u.s. ivan was a cat 3 hitting the islands and a 4/5 hitting jamaica and the caymans and they only cared about it once it got into the gulf pretty much.

I dont think they covered paloma or omar at all, but i cant remember. They knew it wasn't going to affect the united states so apparently it didnt matter if a cat 4 hits cuba or the windward islands. (actually i think omar made a direct hit on the u.s. virgin islands but im not sure)
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is it more likely to shoot straight into mexico or take the nw path more up towards cuba?
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This is what makes the tropicals so interesting to watch, it is very unpredictable

and yes I said tropicals lol
Quoting SLU:


lol i agree .... i've lost all faith in the TWC since Ivan in 2004. They're only concerned about stuff close to the US. While Ivan was approaching the Caribbean, Frances was heading to Florida and absolutely no mention was made of category 3/4 Ivan at the time. Many people in the Caribbean depend on TWC for weather updates. That was soooo disappointing. Thumbs down TWC.
Amen.
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Quoting Weather456:
Typhoon Molave; Carlos's Hot Towers; Tropical Update


Nice update.
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1932. Drakoen
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AL, 97, 2009071912, , BEST, 0, 124N, 502W, 20, 1013,
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1930. Drakoen
Quoting HurricaneSwirl:


LOL.

drak you think this could be our next depression if it escapes the shear?


Yes and if it develops a well defined LLC.
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Quoting BenBIogger:
Stu Ostro his response on Bill Gates plan to control hurricane

Can Bill Gates control hurricanes?



interesting.
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1928. SLU
Quoting Weather456:
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.


lol i agree .... i've lost all faith in the TWC since Ivan in 2004. They're only concerned about stuff close to the US. While Ivan was approaching the Caribbean, Frances was heading to Florida and absolutely no mention was made of category 3/4 Ivan at the time. Many people in the Caribbean depend on TWC for weather updates. That was soooo disappointing. Thumbs down TWC.
Member Since: July 13, 2006 Posts: 12 Comments: 4878
Stu Ostro his response on Bill Gates plan to control hurricane

Can Bill Gates control hurricanes?

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Good Morning.

I see 97L has made a comeback. And, IMO it looks better than it ever has during it's time as "97L".
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Quoting CaneWarning:


They have to say that because people will cancel their cruises if they don't. A cat 5 could be coming to Tampa and they'd be saying, "If your cruise is leaving from Tampa you should be safe. The seas may be a little choppy so take some SeasickON. Just apply to the stomach."


LOL.

drak you think this could be our next depression if it escapes the shear?
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The "JeffMasters does not have any blog entries" happenes on a blackberry, too. Apparently not specific to any OS or browser.

And I will take this opportunity to remind y'all that Steve Lyons is a former Aggie prof. (As if anyone here could have forgotten)
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1922. Drakoen
Quoting STORMMASTERG:
Dr.Steve Lyons said the further the wave moves west/winds are not conductive in the caribbean.He must not be looking at the computer models showing favorable shear there.


He could be correct depending on how fast shear moves out. Shear looks less favorable on the GFS than it did yesterday.
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1921. IKE
Quoting STORMMASTERG:
Dr.Steve Lyons said the further the wave moves west/winds are not conductive in the caribbean.He must not be looking at the computer models showing favorable shear there.


It's not in the Caribbean Dr. Lyons...there are islands between where it's at now and the Caribbean Sea.

What about those folks?
Member Since: June 9, 2005 Posts: 23 Comments: 37858
1920. blh65
to early to much shear
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Quoting moonlightcowboy:
Well, good morning, all. I don't guess there's any point in blasting all those that had RIP 97L - it's weather, anything can happen.

97L, for the most part, had a solid mid-level circulation all along. Development was hindered with some dry air initially and its forward speed. It has held a moisture lifeline to the ITCZ as it has continued to move west with no shear to speak of really. My concern was its timing as it approached the Windward islands where the TUTT was located with substantial shear. Now, it look as if the TUTT is lifting out, dissipating and 97L may cross over into the Carribbean unabated by that shear now. If it continues to power up through today and this evening, finally, I think we've got bonified system on our hands.


It is interesting MLC how conditions change in 24 hours it seems when it was deactivated yesterday 97L was dealing with dry air and now that it is gone it can re-form .
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most recent Microwave imagery...



10:15 UTC



10:45 UTC

Member Since: August 17, 2005 Posts: 26 Comments: 15678
1917. dearmas
Quoting CaneWarning:


They have to say that because people will cancel their cruises if they don't. A cat 5 could be coming to Tampa and they'd be saying, "If your cruise is leaving from Tampa you should be safe. The seas may be a little choppy so take some SeasickON. Just apply to the stomach."


Yeah we have a cruise from here in Tampa that leaves on Aug 1st to Mexico nd Cayman Islands
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Dr.Steve Lyons said the further the wave moves west/winds are not conductive in the caribbean.He must not be looking at the computer models showing favorable shear there.
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1915. IKE
NHC still doesn't have a floater up on 97L.
Member Since: June 9, 2005 Posts: 23 Comments: 37858
1914. Drakoen
Nice microwave pass:
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Quoting IKE:
I watched another tropical weather update the other day on TWC where the hot female met said...it's safe to take that cruise.

What is he looking at that we're not? Or vice versa.

I don't see unfavorable because of shear.


They have to say that because people will cancel their cruises if they don't. A cat 5 could be coming to Tampa and they'd be saying, "If your cruise is leaving from Tampa you should be safe. The seas may be a little choppy so take some SeasickON. Just apply to the stomach."
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1912. Drakoen
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Well, good morning, all. I don't guess there's any point in blasting all those that had RIP 97L - it's weather, anything can happen.

97L, for the most part, had a solid mid-level circulation all along. Development was hindered with some dry air initially and its forward speed. It has held a moisture lifeline to the ITCZ as it has continued to move west with no shear to speak of really. My concern was its timing as it approached the Windward islands where the TUTT was located with substantial shear. Now, it looks as if the TUTT is lifting out, dissipating and 97L may cross over into the Carribbean unabated by that shear now. If it continues to power up through today and this evening, finally, I think we've got a bonified system on our hands.
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Although, now that I look at the orange line again, it would have to survive over land for a while and that probably wouldn't happen.
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1909. IKE
Quoting STORMMASTERG:
I said yesterday night this invest was cooling tstms tops and thats what has happened all night.The only thing i don't get is dr.steve lyons just coming out a min ago and saying upper winds are not favorable for it to develop.5 to 10kts is good right now,but twc is not the best resource as you know.


What is he looking at that we're not? Or vice versa.

I don't see unfavorable because of shear.
Member Since: June 9, 2005 Posts: 23 Comments: 37858
Quoting Drakoen:
It has been retagged:


I don't like that orange line showing to so close to the west coast of Florida...but then again if its weak and we get a TS Warning then I do get off of work...
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Blog Update
Reflector site for those at work, which includes Weather456, daily update.


AOI

AOI

AOI
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I said yesterday night this invest was cooling tstms tops and thats what has happened all night.The only thing i don't get is dr.steve lyons just coming out a min ago and saying upper winds are not favorable for it to develop.5 to 10kts is good right now,but twc is not the best resource as you know.
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1904. Drakoen
It has been retagged:
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Quoting extreme236:
What happened to 97L RIP? lol


It was dead, but now it is UNDEAD...
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1902. Drakoen
97L getting interesting. Satellite imagery shows the structure has improved. The mid level circulation is more defined. As long as it remains at it's latitude it should not have a problem with shear and shear is forecasted to decrease in the Caribbean. The system is nearing the "sweet spot" off the northeastern coast of South America the divergence in this area usually can help a system get going.
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Quoting CaneWarning:


It did RIP and then it went unRIP.


lol that is a good way of putting it
Quoting extreme236:
What happened to 97L RIP? lol


It did RIP and then it went unRIP.
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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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