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 USAFwxguy:


Oh I see. I noticed the Ignore User link. Now I know why that is there, I guess.


Hopefully not on me. ;)

Anyway, you will need to setup your wunderblog first before you can ignore anyone. After you set up your wunderblog clicking on ignore user will take you to your list, and it will have the name of the user you want to ignore already filled out. You just have to click save, or whatever the button is called, and come back to the blog.
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Quoting USAFwxguy:


Oh I see. I noticed the Ignore User link. Now I know why that is there, I guess.
Warning, do not use it on yourself. Can be very difficult to undo.
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Quoting atmoaggie:
Well, sorry, guys. Some youtube, or whatever was in a post I quoted. I didn't edit the quoted text at all, but it apparently had some issues. And, of course, no issue evident to myself. (Or I would have been swifter to go modify it.)

Fixed.


Its not doing it anymore...mine is fine agian ;)
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About to get an outflow boundary from a storm in Mississippi that happened near Jackson 4 to 5 hours ago. Has been persisting and delivering 20 mph gusts for almost 200 miles.

While that, in and of itself, is interesting, also might be interesting when it meets the sea breeze in the next hour.

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The NHC primarily follows the TVCN correct? If I recall correctly, isn't it a blend of the other models?
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Quoting USAFwxguy:
328...

Thanks. A few people have mentioned this blog gets crazy, wild, etc etc....

I don't get it.


You are so blessed to have come in when everything is fairly normal (Grothar excluded). If you had come in when something was happening you may have turned and fled. Good luck in the coming months and use the ignore feature between your ears as you need.
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Thanks Atmo for straightening it out. Back to "normal".
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336 You just wait and see USAFwxguy as soon as we get a named system people will be wishcasting, doomcasting, downcasting, blasting the models (if they are pointing to a place other than their street) accusing the NHC of incompetence accusing each other of incompetence and even praising the NHC as a group of highly trained meteorologists as long as the system is headed in their general direction!!!LOL
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YAY!!!! thanks Atmo...some of us are stuck with IE... appreciate the fix on your end :)
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I know there was lots of talk about the NAO set up last year. If I remember, the Negative NAO leads to less recurves and positives to more recurves?

I thought the big deal with last year was it was mainly negative, thats why Earl and Igor got closer than expected.

Im just trying to learn some here. any explination would be helpful Thanks.
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Quoting USAFwxguy:
328...

Thanks. A few people have mentioned this blog gets crazy, wild, etc etc....

I don't get it.


We have a population of trolls, among other things, and they come out of the woodwork when there is an actual storm. The ones on right now are a bit more of the core of readers, and the trolls aren't interested atm.
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Well, sorry, guys. Some youtube, or whatever was in a post I quoted. I didn't edit the quoted text at all, but it apparently had some issues. And, of course, no issue evident to myself. (Or I would have been swifter to go modify it.)

Fixed.
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ah the refresh button will fix it too
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18z Early Cycle NHC model tracks
Invest92
Statistical/Simple Models (CLIPER,BAMs,LBAR,other Statistical Models)





Dynamic Models (More sophisticated models)




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Quoting USAFwxguy:
328...

Thanks. A few people have mentioned this blog gets crazy, wild, etc etc....

I don't get it.


You will see..its pretty tame today..(knock on wood)..
Member Since: August 19, 2006 Posts: 13 Comments: 14618
336. USAFwxguy 7:18 PM GMT on August 11, 2011 +0
328...

Thanks. A few people have mentioned this blog gets crazy, wild, etc etc....

I don't get it.

the blog does go a little ape every now and then, some of us are miliary (active or inactive/retired), some are mets, some are lurkers and some are trolls...there are a lot of others as well, but if you avoid and don't feed the trolls it is an EXCELLENT place to learn
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Quoting USAFwxguy:
328...

Thanks. A few people have mentioned this blog gets crazy, wild, etc etc....

I don't get it.


You will figure it out quickly once we have a storm threatening land. Just don't let it get to you. It does get pretty crazy. Welcome aboard, and thanks for your inputs.
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problems here no avatars blog stretched out probally a windows issue
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Quoting weatherjr:
Grothar said: "The recurving should start in the next few days"
I say: Are you so sure? People from the caribbean: watch invest 93 carefully!!



He was talking about 92L LOL
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Quoting USAFwxguy:
328...

Thanks. A few people have mentioned this blog gets crazy, wild, etc etc....

I don't get it.

I hope you get a kick out of Nasty Surprises.....
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I think Atmo needs to edit the comment or remove the You tube, or whatever is messing with the blog. I can't even hide or ignore 304.
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Atmo - close the blockquote HTML tag (and/or the em tag as well) in your post #304, and that should fix the issues for the Internet Explorer people.
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Quoting Levi32:
I believe the WU representation of the LBAR run is in error. The ones I'm looking at have no such SSW hook lol.

Shucks!

:):))
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.
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I believe the WU representation of the LBAR run is in error. The ones I'm looking at have no such SSW hook lol.
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it apparently is happening to everyone using IE... it will straighten out when the next page comes up at post 351...
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A mostly positive NAO setup is in the works for the next 10 days:

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Afternoon all.

Quoting USAFwxguy:


Some good advice is simply to make general preperations for evacuation (or shelter in place, as applicable). If a storm does approach your area, local officials will offer guidance. Otherwise, enjoy the nice weather and maintain your own awareness. If it becomes increasingly likely that the storm may threaten directly, then you begin more specific actions as you deem necessary, or follow instruction of local authorities.
This is some really sound advice here... USAF, u look like a newbie to the blog, but I have a feeling u r going to be a great addition... welcome to this wild place...
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Quoting ILwthrfan:
I got the same problem too Tiggeriffic. Don't know what happened but the whole blog's format is out of whack.

No Probs here!
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i have been lurking...not posting...i can't even do a quote...i can barely post a link let alone a video...
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Quoting pottery:
Post 307...
that LBAR line should freak some people out, LOL!


LOL!!
Member Since: August 19, 2006 Posts: 13 Comments: 14618
.
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@ post 317
I think the blog is messed up because you might have posted a YouTube video? Looks like it started at post 304.
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Post 307...
that LBAR line should freak some people out, LOL!
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I got the same problem too Tiggeriffic. Don't know what happened but the whole blog's format is out of whack.
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Quoting tiggeriffic:
was lurking...initially my page was ok...now it is, well, a bit flukey...no avatars, weird looking...anyone else having the problem?


Mine is ok.
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Quoting Levi32:


Isobar.


ARE WE USING RED PENS ON PEOPLES BLOGS NOW?
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Quoting ncstorm:


Do have an idea what causes that weakening shown by the IVCN and GFDL?
interaction with the islands?
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Quoting tiggeriffic:
was lurking...initially my page was ok...now it is, well, a bit flukey...no avatars, weird looking...anyone else having the problem?
No problems, here.
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Quoting TropicalBruce:
I still wonder whether 93L will dominate 92L to such an extent that it either "steals" the energy from 92L and absorbs it or merely keeps it weak enough from developing much, if at all.


Yes, me too. and wether their proximity to each other will hinder both of their developments. What implications this has for the Fujiwara effect, or the possiblity of them providing themselves mutual ventilation, if possible. I don't know.
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was lurking...initially my page was ok...now it is, well, a bit flukey...no avatars, weird looking...anyone else having the problem?
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Member Since: August 19, 2006 Posts: 13 Comments: 14618
I still wonder whether 93L will dominate 92L to such an extent that it either "steals" the energy from 92L and absorbs it or merely keeps it weak enough from developing much, if at all.
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Quoting xtremeweathertracker:
Hello Levi, your thoughts on the latest ECMWF model run???


I agree with the general recurve of 92L out to sea. It also illustrates the potential dangers that 93L could bring to the Caribbean islands and/or the United States down the road if it develops, due to the more zonal flow that is forecasted to develop over southeastern Canada and New England.
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Quoting twincomanche:
I think we should suggest getting certain people together and having a mud wrestling contest.


Nice... but I would suggest something a little classier, like say puddin wrastlin' now that would be a site to see.

Does the ECMWF Twink keeps posting remind anyone else of a rastafarian knit cap you might find for sale with a street vendor in Jamaica? Damn things are hurting my eyes...
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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.