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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that was quite the model run a lil scary and at the same time puzzling as to how that could happen but storns have made loops and come back to bite us Cleo did
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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.

Thanks for the Inclusion on that list.
But you could take me out and include several others.
Koritheman springs to mind.....
There are others too.

In fact, I think the BEST place to learn about Tropical Weather is right here on this Blog.

Real-Time analysis 24/7, with all the trimmings.

It's Fantastic and Wunderful.
Member Since: October 24, 2005 Posts: 0 Comments: 24314
Quoting tropicfreak:


Don't forget about kman and mississippiwx.


I know a left dozens of quality sources out I just went off the top of my head. Yes both Kman and Misswx are also good sources as well. t

They were referring to 360 hrs out so my response was invalid...lol 360 hrs out from where does the GFS come up with the Gulf Storm? I know that around 144 hrs or so it had the trough splitting some energy into the Gulf I thought. Anyone with a link to a model?!?! woooo
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Quoting tropicfreak:


Don't forget about kman and mississippiwx.
And nrtiwlnvragn. And Miamihurricanes09. Many more.

And a number of others, including mets, that only show up when there is something big going on or they are locally threatened.
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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. :)


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
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403. HCW
Quoting ILwthrfan:


KEEPEROFTHEGATE
Pottery
AtmoAggie
Reedzone
Levi32
Hcw
Hyrdrus
Collition
Grothar
Patrap
Neapolitian

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.


No it's from as cold front that will enter the GOM Sunday night into Monday and by Wed we could see a surface low form . It will bring lower dewpoints to the deep south and some relief from the heat along with some elevated hail chances
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Quoting tiggeriffic:
I think the wildest model posted was one i got to see yesterday or the day before...compliments of WU lol... really can't see that it could even happen at this point let alone ever but a model did come up with it...play it in super slow motion to get the full effect of 92 and 93 it is wicked wild...

Link


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. :)
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Quoting LargoFl:
Hi is this what the GFS saw a few days ago, 360 hours away back then, for two storms, one off the east coast and one off the gulf coast, both at the same time??? im a new observer here, excuse me if i make a mistake or two ok


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.
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Quoting angiest:


Looks like it is falling apart...


It did:(
Some back building toward Abilene, but the line itself is sagging southward, looking like not a drop of rain again for most of DFW. A few rumbles of thunder and it least it has cooled into the mid 80's, this still has a chance of ending the 100+ degree streak at 40 days, just 2 shy of the record which would be a shame really to come this far and not get the record if it's not going to rain anyway.
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Quoting xtremeweathertracker:

WOW!!!! Thats insane!!!!


i know right! and what hit me was i live in SC...imma get triple whammied according to that thing lol
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A repost from last night (and not directed at anyone, in particular):
Quoting atmoaggie:
Just FYI: Very soon any and all comments containing any reference to jasons, and jfvs will be getting flagged...and possibly earning bans. (Same applies to all comments about any other poster, really.)

Use the tools as much as you feel you need to, but commenting on it is way, way OT and disruptive when this place gets busy and only encourages further mischief. Not to mention that is absolutely not the reason any of us decided to visit Dr. Jeff Masters' Tropical Weather Wunderblog.
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this maybe an elementary question for many of you but I am trying to learn more about fronts, pressure systems, etc...

As I understand, troughs could recurve storms but could the High pressure also?

I read somewhere that if storms get close enough to the clockwise ciruclation, the storms could go out to sea

also, what does the ridge over Texas have to do with landfalling cyclones on the east coast?

anyone? thanks
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Quoting tiggeriffic:
I think the wildest model posted was one i got to see yesterday or the day before...compliments of WU lol... really can't see that it could even happen at this point let alone ever but a model did come up with it...play it in super slow motion to get the full effect of 92 and 93 it is wicked wild...

Link

WOW!!!! Thats insane!!!!
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Member Since: Posts: Comments:
I think the wildest model posted was one i got to see yesterday or the day before...compliments of WU lol... really can't see that it could even happen at this point let alone ever but a model did come up with it...play it in super slow motion to get the full effect of 92 and 93 it is wicked wild...

Link
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I encourage anyone who wants to learn how statistical, simplified dynamical, dynamical,and concensus models are run and/or used by the NHC to check out this instructional video from the NHC. It is 1 hour long but well worth the info!!!

Link
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Quoting angiest:


Now how do you find out something like that...?
Well, I did it...

But I knew that if I did, I would be banned from my own blog and not be able to get to the iggy list in order to remove. So I had my iggy list open twice so I could ban myself and then reinstate myself.

If one doesn't do it just right, one would have to WUmail WUadmin...with a sheepish, embarrassing plea for help.

;-)
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any newbies out there if you do not know i have a full tropical blog page on wunderground

you can check it out here thanks best view zoomed in 150 percent

Link
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Quoting tiggeriffic:
btw...heya Pottery! how's the island?

Very Nice, Thank you!
Some gentle showers a little while ago, after about 10 days of mostly dry and HOT.
So far, Aug. has been unusually dry in my area.
Strange.
Member Since: October 24, 2005 Posts: 0 Comments: 24314
Quoting ILwthrfan:
92L looks as if it has multiple vortices within its broad circulation?

To me I don't see 92L doing anything but plowing the road for 93L, the stronger 92L gets the less chance 93L also has at strengthening...AND if 92L gets strong "enough" and is more easily influenced poleward it could carve a significant weakness for 93L to follow, but if 93L is too weak it may miss that weakness and travel further west.

I have no idea as to what may happen, but I don't see both of these making BIG noise at the same time. It'll either be one or the other or neither. I can see 93L doing something very similar to what Emily
did.
Hi is this what the GFS saw a few days ago, 360 hours away back then, for two storms, one off the east coast and one off the gulf coast, both at the same time??? im a new observer here, excuse me if i make a mistake or two ok
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Quoting SuperYooper:


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.



Why do I think of ABBA when you post?
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384. txjac
Quoting 69Viking:


It's been raining most of the day here in NW Florida, seems that warm front is stalled just to our North and keeps pumping out storms and pushing them South. This is the 3rd day in a row that it's rained, I can't remember the last time that happened here! Sorry Texas, if I could send some your way I would in a heartbeat!



Yea, we're sorry you cant send it this way too!
Thanks for the thought though
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btw...heya Pottery! how's the island?
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Quoting floodzonenc:
Shhh....  (I didn't want to scare him away.)  :)


:):))
Member Since: October 24, 2005 Posts: 0 Comments: 24314
Quoting KEEPEROFTHEGATE:


not much gray in that graff there Keeper...realize the red is the most important but that is quite a bit of blue ya know...
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Quoting angiest:


Do you feel like an accluded afront?





(don't take out the red pen)

You meant 'Included afront', surely?
Member Since: October 24, 2005 Posts: 0 Comments: 24314
92L looks as if it has multiple vortices within its broad circulation?

To me I don't see 92L doing anything but plowing the road for 93L, the stronger 92L gets the less chance 93L also has at strengthening...AND if 92L gets strong "enough" and is more easily influenced poleward it could carve a significant weakness for 93L to follow, but if 93L is too weak it may miss that weakness and travel further west.

I have no idea as to what may happen, but I don't see both of these making BIG noise at the same time. It'll either be one or the other or neither. I can see 93L doing something very similar to what Emily did.
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Quoting atmoaggie:
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.



It's been raining most of the day here in NW Florida, seems that warm front is stalled just to our North and keeps pumping out storms and pushing them South. This is the 3rd day in a row that it's rained, I can't remember the last time that happened here! Sorry Texas, if I could send some your way I would in a heartbeat!
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USAF...

You will figure out quickly who can be trusted on the blog...the ones that can will either post a graff or a link with their information...trolls (people who try to get a rise out of people on the blog for no other reason than self amusement) post bogus information that cause panic and upheaval but won't back it up...it is easy...use the ignore link and you wont see anything they post from your own personal page, if someone posts something that is extremely offensive, use the ! button across from their name and it will report them to the blog admin... most on here do say hi to each other as we log on etc and most gets let go of...if there is a serious storm pending landfall, most will keep that to email as to not blow up the blog...we are also know to tell a few jokes or rib on someone here and there but 99% of the time it is all good natured, only the trolls take it too far
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A lil off topic but this is a fun place to get real info and even on occasion a good laugh. I laugh at the trolls and the people who get annoyed by them, I have a sick and sometimes twisted sense of humor and only have a few people on my iggy list one of them made it on monday. If I think you all are crazy at times and wish or doom casting I just go read what the NHC has to say and let you all pontificate whatever you think you see that the NHC doesn't. If weather forecasting was easy everyone would do it. I live in south Fla. All summer long I get 50% of my rain predictions right either it rains or it doesn't pretty simple. I leave the hurricane forecasting to the NHC they are pretty good at guessing what they think that last model run was trying to do.
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Quoting pottery:

Left out the AGW Alarmists and Denialists too...

I feel Totally Afronted.

Re Ported.


Do you feel like an accluded afront?





(don't take out the red pen)
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Quoting floodzonenc:
Great post but you left out the NHC conspiracy theorists and those who invented their own unique models...



Indeed i did leave those two out, now that you mention it someone the other day had people in a tizzy over a FLANBAMS model or some such nonsense, people were going to wiki and google trying to verify it only to be directed back to the blog comments !!!LOL
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Quoting floodzonenc:
Great post but you left out the NHC conspiracy theorists and those who invented their own unique models...


Left out the AGW Alarmists and Denialists too...

I feel Totally Afronted.

Re Ported.
Member Since: October 24, 2005 Posts: 0 Comments: 24314
Quoting USAFwxguy:


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

Stationed in Fla?.. I'm out of PAFB
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Quoting atmoaggie:
Warning, do not use it on yourself. Can be very difficult to undo.


Now how do you find out something like that...?
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364. HCW
Latest NHC model runs for 92L and 93L



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Quoting SWLACajun:
Patrap, don't the models you just posted kind of show a more westerly movement of 92L and 93L than the earlier ones posted by others? Seems less recurvature...why?

DITTO

?????
Member Since: October 24, 2005 Posts: 0 Comments: 24314
Neither 92 or 93 looking all that healthy. Dry air has definitely taken its toll.

Link
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Patrap, don't the models you just posted kind of show a more westerly movement of 92L and 93L than the earlier ones posted by others? Seems less recurvature...why?
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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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Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.