Two African waves, 92L and 93L, worth watching

By: Dr. Jeff Masters , 2:59 PM GMT on August 11, 2011

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An African wave is near 13°N 35°W, about 700 miles west-southwest of the Cape Verde Islands. This system, (Invest 92L), 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 has less heavy thunderstorm activity near where it is trying to develop its circulation center than yesterday. Water vapor satellite loops that a large area of dry air lies just to the west of 92L, but the atmosphere in the immediate vicinity of 92L is moist. Even so, the decline of heavy thunderstorm activity since yesterday implies that dry air is probably working its way into 92L. The SHIPS model and University of Wisconsin CIMSS wind shear analysis are showing moderate wind shear of 10 - 15 knots 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. Morning satellite photo of Invest 92L and Invest 93L.

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 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 weak development or no development of 92L, and NHC gave 92L a 30% chance of developing into a tropical depression by Saturday morning in their 8am outlook. 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 is likely to pass north of the Lesser Antilles, though may pass close enough to give heavy rains to the northernmost islands. 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.

93L
An African wave that emerged off the coast of Africa is near 10°N 22°W, a few hundred miles south of the Cape Verde Islands. This system, (Invest 93L), is also moving west 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 near the middle of next week. Recent visible satellite loops show that 93L has a decent amount of heavy thunderstorms, but this activity is not well organized. There is not much spin associated with 93L yet. 93L is fairly well-protected from dry air to its north and west. The SHIPS model and University of Wisconsin CIMSS wind shear analysis are showing moderate wind shear of 10 - 20 knots affecting 93L. Sea surface temperatures are 27.5°C, which is one degree above the 26.5°C threshold usually needed to support a tropical storm.

Forecast for 93L
Moderate wind shear below 20 knots is predicted along 93L's path over the coming five days, which should allow the storm to steadily organize. 93L is about 600 miles east of 92L, which is close enough that the two systems may interfere with each others' organization. The latest 00Z and 06Z model runs of the four best models for predicting tropical storm formation (GFS, ECMWF, NOGAPS, and UKMET), have only one model, the GFS, that is indicating significant development of 93L. This model brings 93L near the northern Lesser Antilles Islands by Wednesday. NHC gave 93L a 20% chance of developing into a tropical depression by Saturday morning in their 8am outlook. Due to moister air, the potential for less wind shear, and a more southerly track, 93L is probably a greater threat to the Lesser Antilles than 92L.

Jeff Masters

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Quoting Levi32:


The video run you were asking about, I see Levi posted it so he may have already made it recordable.. I tried this in mozillafirefox and it seemed to work. Right clip on image, click on view image info, click on save image.
File type listed as .jpg, but to view it, it needs to be changed to .gif. It saved for me and works
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Quoting Levi32:




"Gert, move over! Go somewhere else." Gert "Ok that's not a nice way to treat a female hurricane, but I guess I'll hit FL since there are no other choices, GA is too boring to hit."
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Quoting tsowen:

Interesting. But what does it mean? What did cause this swell?
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92 and 93L are really beginning to get their acts together, IMO I think 93L will be named Franklin and 92L Gert.
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Here's some pretty big news for those of you who, like me, enjoy looking at patterns from the past. ESRL NCEP Reanalysis is changing the long-term climatology period from 1968-1996 to 1981-2010. This will make maps look different, sometimes quite a bit different, than they were before. I just figured this out when looking at the ridge orientation in one of my hurricane analog maps.
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Thats the scariest Run on 92l, 93L ive ever seen!
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501. MTWX
Tornado watch up in SD...

Link
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What's so bad about saying, "Don't forget about kman or misswx"?
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Quoting ILwthrfan:


KEEPEROFTHEGATE
Pottery
AtmoAggie
Reedzone
Levi32
Hyrdrus
Collition
Grothar
Patrap
Neapolitian

These guys are great sources of INFO and do a great job breaking down things and know far more than I ever will. But To answer your question I believe that the gulf coast storm your referring to in the GFS output was from the tail end of a trough laying across Florida. The other was 92L I believe riding up the East coast, but I know the Gulf storm wasn't 93L. Any storm right now coming off Africa would have a VERY LOW chance making it all they west into the Gulf Of Mexico.


/left out :( LOL Jk.

Aternoon all. Looks like 93L is beginning to work up a surface circulation but it needs to detach from the ITCZ. It might be a race between 92L and 93L to TD6/Franklin, but I suspect 93L is going to win. Very active off Africa though today.
Member Since: July 8, 2005 Posts: 259 Comments: 24580
Quoting CaicosRetiredSailor:


I approve of models coming here...
but NOT hurricanes!
thank you.
These models don't seem to do much except attend ribbon-cutting sessions for hurricane superhighways down the backbone of the archipelago...


Quoting rv1pop:
us.
Hey, rv1.... I enjoyed the conversation about alt. energy sources in the context of hurricane prep....
Member Since: October 25, 2005 Posts: 19 Comments: 22736
This is a new CPR technique which is much simpler. This is a very important video regarding the latest CPR procedure. Please watch and forward to your friends and family if you haven't already done so. You never know, a life may be saved utilizing this new procedure.

http://tinyurl.com/2fx8r59
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Quoting seasntrees:


I keep hearing about this model (and the link) but I can't find it. Does anyone still have access to it. I would love to see it!


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Am I on anyone's ignore list? Post 402 didn't deserve to be removed.
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Clear Center....
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Quoting CaicosRetiredSailor:


...well I guess the only time I was "stationed" somewhere was when I was the Park Warden for the Bahamas National Trust in the Exuma Cays Land and Sea park. I did my sailing on various sailing vessels, and retired in 2004 here on Providenciales.
CRS
Yeah, never mind that Caicos bit.... we nabbed him first.... lol

Quoting tiggeriffic:


LOL CRS has a diff meaning where i come from lol...i was navy...thought that was what you were referring to...
Nah.... just means I type too slow to type out the whole name every time.... lol

Quoting TropicalAnalystwx13:
Good afternoon all.



Seriously, enough with all the New Orleans talk.
At least "hit NOLA" can be construed as a joke.... If I put "hit Bahamas" that's prolly actually got 13% probability next to it :o(....
Member Since: October 25, 2005 Posts: 19 Comments: 22736
402. tropicfreak
This comment has been removed for violating the Community Standards.


What did I say wrong?
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Since you are all concerned about safety, I thought you might enjoy this. Link
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Does anyone think that one of those AOI's will cancel out the other? They are pretty close in proximity and might just be fighting for position and moisture. TIA
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POSS TWINS

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Hi all. If you look to the development of those waves 92L and 93L, they both don't look very concerning at the moment in respect to their spin. Earlier it was much better.

http://cimss.ssec.wisc.edu/tropic/real-time/tpw2/ natl/main.html
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Quoting tiggeriffic:


email me how to do it...i have it saved just like this in my favorites...i have a second tab open with it running now...tell me how to archive it and i will save it on my puter for later reference
I do not have the program to do it, but if it is a javascript, there is a way to capture the stream. you start the capture program, it captures in a .ts stream then you save the stream and edit it with VideoReDo. Thatmay be the program that capture it, but my computer is not fast enough to do any of it. Information was on satelliteguys dot us.
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Quoting BahaHurican:
Geez.... I fixed it as quick as I could!!!!! lol

Hey,CRS. I hope u r noticing all these models paving ahurricane superhighway across r islands.......


I approve of models coming here...
but NOT hurricanes!
thank you.
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Quoting seasntrees:


I keep hearing about this model (and the link) but I can't find it. Does anyone still have access to it. I would love to see it!


Link

here ya go, play in slow mo
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Quoting CaicosRetiredSailor:


uh
yep...

Hi Baha :})
Geez.... I fixed it as quick as I could!!!!! lol

Hey,CRS. I hope u r noticing all these models paving ahurricane superhighway across r islands.......
Member Since: October 25, 2005 Posts: 19 Comments: 22736
480. MTWX
Quoting tiggeriffic:


LOL CRS has a diff meaning where i come from lol...i was navy...thought that was what you were referring to...

AF here...
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Good afternoon all.

Quoting CorneliaMarie:
473. CaneHunter031472 5:00 PM EDT on August 11, 2011 +0
Poll time:

So, are these two systems off the coast of Africa going to be:

A= Fish

B= Hit

C= Too early to decide




B = Hit New Orleans


Seriously, enough with all the New Orleans talk.
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...and CRS also does apply to my memory ability for sure!
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Quoting CaicosRetiredSailor:


...well I guess the only time I was "stationed" somewhere was when I was the Park Warden for the Bahamas National Trust in the Exuma Cays Land and Sea park. I did my sailing on various sailing vessels, and retired in 2004 here on Providenciales.
CRS


LOL CRS has a diff meaning where i come from lol...i was navy...thought that was what you were referring to...
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Quoting BahaHurican:
Think levi said he would do it.


I keep hearing about this model (and the link) but I can't find it. Does anyone still have access to it. I would love to see it!
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XX/INV/93L
MARK
12.35N/28.00W


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Poll time:

So, are these two systems off the coast of Africa going to be:

A= Fish

B= Hit

C= Too early to decide
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Quoting tiggeriffic:


hey ya Caicos...where were you stationed and when did you retire?


...well I guess the only time I was "stationed" somewhere was when I was the Park Warden for the Bahamas National Trust in the Exuma Cays Land and Sea park. I did my sailing on various sailing vessels, and retired in 2004 here on Providenciales.
CRS
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Quoting MiamiHurricanes09:
Interesting that the TWO mentioned that 93L has a well-defined circulation. Could mean that the system is closer to becoming a tropical depression that we actually believe. Let's see how the convection and circulation progresses throughout the night.


A "well-defined low pressure system" does not necessarily imply a well-defined circulation. The same phrase could be applied to a consolidated low pressure area on the equator with say an 8mb gradient between it and the surrounding environment, but is there any coriolis force at the equator to make it spin? No, therefore there is no circulation.
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Quoting angiest:


That link will cease to work later this evening when the new 18Z run comes out. If someone has a means of archiving it, it would be worthwhile to do so. :)
Think levi said he would do it.
Member Since: October 25, 2005 Posts: 19 Comments: 22736
Interesting that the TWO mentioned that 93L has a well-defined circulation. Could mean that the system is closer to becoming a tropical depression that we actually believe. Let's see how the convection and circulation progresses throughout the night before making any calls though.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
Quoting CaicosRetiredSailor:


uh
yep...

Hi Baha :})


hey ya Caicos...where were you stationed and when did you retire?
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monsters are starting to lurk

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Quoting BahaHurican:
Yeah. ... And as others have said, we have some bloogers on here.......


uh
yep...

Hi Baha :})
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Quoting flsky:
Coral reefs: winners and losers

Link

Thanks for that.
Will study it later.
Looks like the Caribbean Islands are generally "green" except for (apparently) Trinidad&Tobago.
Trinidad has very little coral except on the NW point (effects of the Orinoco River and water temps) but Tobago has plenty which is in pretty bad shape, and getting worse. Due to water temps, sediment run-off, effluent from resorts etc etc.

Same story as other places.....
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Quoting JLPR2:
ASCAT last pass missed 92L, but Oceanscat caught it.



Any kind of circulation that 93L has looks like it would be on the eastern side of the convection, but as I noted this morning, I don't really see a circulation there on satellite imagery - just linearly converging winds into the monsoon trough for now.
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Quoting PaulinJax:



There are a couple different ways to reporduce into a movie but all include copying each image seperately ..

Painful process , I will try when I get home tonight if it is still there. It does stimulate conversation.


even if you did the last half from the bahamas on...would save a bunch of time....
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462. flsky
Coral reefs: winners and losers

Link
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Quoting angiest:


Unfortunately, the only way I know of is to save every image in that run as a separate file. The loop is a java applet that takes all of the images for a given run of GFS and loops them together.

Unfortunately, he seems to have permissions set up such that wget can't go grab them all.



There are a couple different ways to reporduce into a movie but all include copying each image seperately ..

Painful process , I will try when I get home tonight if it is still there. It does stimulate conversation.
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460. JLPR2
ASCAT last pass missed 92L, but Oceanscat caught it.

Member Since: September 4, 2007 Posts: 7 Comments: 8747
Quoting EYEStoSEA:


You're so right....ya get a little rain and then you pay for with the sultry steam....but glad you did get a little reprive...:)
me too, hoping this reprieve equates to that evil high pressure going on vacation somewhere else for a while.
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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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