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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apparently no one is awake lol...will pop back in after a while...g'nite to those going to bed after a long nite watching and g'mornin to those just getting up...it is gonna be a LONG LONG day...
Member Since: September 16, 2007 Posts: 0 Comments: 3666
Good morning, all. I see TX is getting rain! I don't know that it's enough to make much of a dent, if any, in the drought, but it's needed pyschologically for them just as much.
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morning everyone...at work but popping in to ck n see what is up with 92 and 93...will pop in and out today as i am working a 12hr shift...
Member Since: September 16, 2007 Posts: 0 Comments: 3666
Weather junkies, as I am one, the guys/girls at the NHC are unbelievably dedicated to there jobs. They look at the same models and analog maps as we do. That said, the percentages they putt out do not really matter to the immediate public, other than like a friend to friend "be careful buddy". Everyone on this forum is at the least informative of weather, give the guys at the NHC a tiny bit of credit. Max Mayfield understood and appreciated storms, and he was the first to warn of the troubles Katrina would bring, even though the models went elsewhere. These people know there stuff
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...SPECIAL FEATURES...

A 1011 MB LOW IS CENTERED ABOUT 850 NM W OF THE CAPE VERDE
ISLANDS NEAR 14N37W WITH A TROPICAL WAVE EXTENDING NW FROM THE
LOW TO 21N43W. THE SYSTEM IS MOVING W AT 9-13 KT. SCATTERED
MODERATE TO ISOLATED STRONG CONVECTION IS FROM 15N-18N BETWEEN
39W-43W. THE ASSOCIATED SHOWER/THUNDERSTORM ACTIVITY HAS BECOME
A LITTLE LESS ORGANIZED DURING THE LAST 24 HOURS. HOWEVER...
ENVIRONMENTAL CONDITIONS APPEAR FAVORABLE FOR GRADUAL
DEVELOPMENT OVER THE NEXT SEVERAL DAYS. THIS SYSTEM HAS A MEDIUM
CHANCE OF BECOMING A TROPICAL CYCLONE DURING THE NEXT 48 HOURS.

A 1011 MB LOW IS CENTERED ABOUT 225 NM S OF THE CAPE VERDE
ISLANDS NEAR 11N26W WITH A TROPICAL WAVE EXTENDING N ACROSS THE
CAPE VERDE ISLANDS TO 19N23W. HE SYSTEM IS MOVING W AT 13-17 KT.
WIDELY SCATTERED MODERATE CONVECTION IS NEAR THE LOW CENTER FROM
12N-14N BETWEEN 25W-27W. SCATTERED MODERATE CONVECTION IS ALSO W
OF THE LOW CENTER FROM 9N-14N BETWEEN 28W-31W. ENVIRONMENTAL
CONDITIONS ARE EXPECTED TO GRADUALLY BECOME MORE CONDUCIVE FOR
DEVELOPMENT OVER THE NEXT SEVERAL DAYS. THIS SYSTEM HAS A MEDIUM
CHANCE OF BECOMING A TROPICAL CYCLONE DURING THE NEXT 48 HOURS.
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Quoting AtHomeInTX:


No rain in SE TX. At least around me. But I did see a radar someone posted with rain over West Texas. I'm happy for them. Things are even more desperate out that way. Hope you're right and there's more to come. :)
I hope so! I told u keep the Faith it will come. Itmay not be the amount you really want but trust me you will get it. What city are u in?
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Well, that only took me about two hours... lol

Think I'll go back to bed now...

AtHome.... I hope you get some rain in ECTX today... you guys deserve it!
Member Since: October 25, 2005 Posts: 19 Comments: 22735
Quoting Tropicsweatherpr:


With only a thunderstorm,power went off in parts of Santurce.
Dunno how our grid will hold up. We got several parts of the CAR here that haven't had a serious impact from a hurricane in a while... I'm wondering how power grids will hold up. Seems like Tstorms have been putting a lot of us down recently...

Quoting Stormchaser2007:
Karen is back in the basin it seems.

Quoting Tazmanian:



hey Karen where you been all my life
"Been around the world and I can't find my baby... don't know where and don't know why..." Sorry guys... lol


Quoting hunkerdown:
taken for the grain of salt its worth but this appears it may track just north of Hispaniola and threaten the T&C/Bahamas...if you are around, sorry Baha.
[laconically] Yah, been sending 92 and / or 93 through here every second / third run.... startin' to get kinda blasé about it...

Quoting reedzone:
It doesn't make sense.. This is August, not October.. Trough should be weaker then what the model is showing.
What about the TX high setup.... is that influencing the troughiness in anyway? I keep thinking a typical summer setup in mid-Aug usually has that high further east?

Member Since: October 25, 2005 Posts: 19 Comments: 22735
Quoting bigwes6844:
did you guys get rain today? I heard that it rained in texas today and it was a nice rainstorm that came threw. I told you keep the faith and that it would rain by this month.


No rain in SE TX. At least around me. But I did see a radar someone posted with rain over West Texas. I'm happy for them. Things are even more desperate out that way. Hope you're right and there's more to come. :)
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Did someone say Yellowstone? Sounds familiar........

Hmm.... i heard i can remember things back with this equation,

umm this equation will work: 1÷0 wait NO!
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Quoting AtHomeInTX:
EURO has my attention. Weaker slower storm. Caribbean cruiser into the Yucatan. Be nice if it stayed weaker and hooked a right into Texas. It would have to miss that trough first. Sigh. Next run will have it going out to sea.

did you guys get rain today? I heard that it rained in texas today and it was a nice rainstorm that came threw. I told you keep the faith and that it would rain by this month.
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Quoting MississippiWx:
In 84 hours, the 00z NAM tries to develop the part that split off Emily and headed south around the Eastern periphery of the Bermuda Ridge. Just something to humor you while waiting on the 00z GFS:

Cripes! Not again... [groan]

Member Since: October 25, 2005 Posts: 19 Comments: 22735
Quoting Landfall2004:


Being a S FL native, I can say that we may be a bit cooler than Central & N FL. I am guessing it is b/c of the sea breezes and then PM thundershowers off The Lake that cool things off. You can't pay me to go to Disney June-Sept. Too hot and humid. However, I find the heat in Vegas at the end of May-early June just as stifling--just not suffocating. Dry heat is still heat--106 on June 6th. And the breeze is HOT, too! We will not go to Vegas June-Sept. either!!!!! Contrarily, it is almost too COLD to go to San Fran and/or Yosemite in May!!!! Yellowstone in 2012 in mid-May may even be a mistake for this Florida-girl!
You aren't wrong there.... Spend a couple weeks in WY every other summer... I'm usually the one walking through central and NW WY at the end of July / beg of August with a jacket on.... lol... I keep telling pple, "it's cooler here now than it EVER gets in my country".... lol ..... May in Yellowstone? Temps in the 50s are not unlikely; there may still be some snow up there... the pass over the Rockies near there has had snowfall recorded in mid-July.

Should be fun. And definitely not as humid as we are here.... lol

Quoting twincomanche:
I spent quite of bit of time on the SW corner or PR in the Summer and the locals said you could set your watch by the 3:15 shower just to get the steam up. They were right.
That's what we've been missing here this summer so far... usually in May and June, u can use the pm downpour instead of the schoolbell.... 2:45 - 3:15, it's raining. This summer? Not so much.

Quoting Thrawst:


I Live in Nassau, Bahamas. Beat this haha :P -

Temperature: 82 F
Dew Point: 81 F
Humidity: 94%
Heat Index: 94
Wind: Calm

... THAT is miserable :P
Thank u for holding up the side.... lol.... and this is pretty normal for summer.... lol Actually the daytime humidity I can cope with, because usually there is some kind of summer breeze.... for nights, there's A/C....
Member Since: October 25, 2005 Posts: 19 Comments: 22735
the models will be scrambling again today. it is appARENT THAT 92l wqs the sacrificial lamb for 93L.although disorganised ,93L is still in it's formative stages. which will be a slow prdcess, the next few says.It is now beginning to look that the weak 93L will contnue west with the east to west flow for a few days. At this stage it would not be surprising if the models shift to the left and this disturbance becomes a lesser antilles and western caribbean storm.
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EURO has my attention. Weaker slower storm. Caribbean cruiser into the Yucatan. Be nice if it stayed weaker and hooked a right into Texas. It would have to miss that trough first. Sigh. Next run will have it going out to sea.

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Quoting Grothar:
This was from two years ago.

Hottest temperatures ever recorded in South Florida.

Robert Jones, Miami Weather Examiner
June 22, 2009

A heat advisory is in effect until 7 PM tonight and we could be near the all-time record highs. That means we will be near the hottest temperatures that have ever been recorded in South Florida. The highest ever recorded in Miami and Ft. Lauderdale was 100 degrees back on July 21, 1942 and August 4, 1944 respectively. West Palm Beach's highest recorded temperature was 101 degrees on July 21, 1942 as well. Yesterday records were broke all across South Florida and Ft. Lauderdale shattered their old record by 4 degrees with a high of 98, hottest June temperature ever recorded.



It's even more so out here in the islands. Think our national record high is around 96. I wouldn't complain about our humidity, because I guess I'm used to it, but also because I think we get more air movement e.g. onshore breezes. The most uncomfortable heat I ever experienced was out in Grand Junction, CO... temp was about 98 and 15% humidity. I thought I would expire...

Quoting twincomanche:
I have never been in the Mid East with their outrageous temperatures but have been in the American South West in the one hundred teens and Oklahoma and Texas in the hundreds and been in Florida and Puerto Rico with mid nineties and very high humidity and I think from a comfort level the hot dry is more tolerable than the lower temps with high humidity. Just my personal observations.
I think it's what you're used to. That dry heat just made me feel dehydrated...

Member Since: October 25, 2005 Posts: 19 Comments: 22735
Quoting SouthDadeFish:
The vorticity associated with the 10% feature is impressive. Perhaps it may gain more model support soon.

Link
Thought that was a ULL there...

Member Since: October 25, 2005 Posts: 19 Comments: 22735
Quoting Neapolitan:

Big Timber (beautiful), then Hardin (not so much). ;-)
Been to / through Big Timber a couple times... bus used to have a 15 minute break there once upon a time. Always went through Hardin in the dark.... for some reason I always thought it was just stock yards.... lol

Member Since: October 25, 2005 Posts: 19 Comments: 22735
Quoting robj144:


Linux is free, but it is not for the faint hearted.
I just about died a while back when I saw Levi talking about command-lining it.... thought nobody in here under 25, no, 30 even had a clue anymore... lol

Quoting Neapolitan:

You have to get out more if you want to see the heavy weather. ;-) I do move around a lot: born in California; Iowa; Missouri; Alabama; back to California; Wyoming; Montana; back to Wyoming; Minnesota; Florida; Texas; Ohio; back to Florida; Colorado; back to Florida, back to California; back to Florida; back to California; and, now, back to Florida. Whew... ;-)
Felt like I was watching a tennis match there for a while... lol

Member Since: October 25, 2005 Posts: 19 Comments: 22735
Turning into a bigger storm now headed towards the Yucatan.
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Looks like it's possibly headed for Mexico
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Storms do love to dance around the island of Jamaica
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93L on top of Jamaica...like always take it with a grain of salt.

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The EURO showing at 192hrs 93L taking a Ivan type track around Jamaica.... starting to rev up
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1433. JLPR2
Quoting MoltenIce:
It would be funny if we have Franklin, Gert, Harvey and Irene at the same time.


Funny? That would be nuts! xD
Member Since: September 4, 2007 Posts: 7 Comments: 8747
It would be funny if we have Franklin, Gert, Harvey and Irene at the same time.
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EURO shows 93L as a weak storm and going more S and W on this run.... heading into the S Caribbean
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The longer 93L struggles to develop the more W it goes.
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It will be funny if the only development out of all these areas ends up being that energy which was once part of Emily. LOL
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1427. JLPR2
Quoting CybrTeddy:


Was expecting this disorganization to happen with 93L for over a day. Gradual organization, not rapid. Over the weekend sure.


Good call! But 93L staying weaker is actually bad. :\
Member Since: September 4, 2007 Posts: 7 Comments: 8747
that system northeast of Puerto Rico is a new area of disturbed weather and is not Emily.
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1424. JLPR2
Quoting Hugo7:
Ya Emily is trying to come back.


Emily can't come back she's in the Natl graveyard.
Member Since: September 4, 2007 Posts: 7 Comments: 8747
Quoting CybrTeddy:


Never has with any storms this season.. very poor job so far with cyclongenesis this year IMO.
It did the last run. And to be honest we haven't had any decent tropical storms this year besides Arlene. It did hint at Emily staying weak and in my opinion did a better job than any of the other models with her.
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1420. Hugo7
Ya Emily is trying to come back.
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Quoting JLPR2:
Considering 93L's appearance as of right now I'll say the slow organization the GFS is showing seems plausible.



Was expecting this disorganization to happen with 93L for over a day. Gradual organization, not rapid. Over the weekend sure.
Member Since: July 8, 2005 Posts: 259 Comments: 24578
1417. JLPR2
Quoting SouthDadeFish:
00Z Euro is running and isn't showing much through 48 hours...


Actually it seems to close off the piece of energy Emily left behind.
Member Since: September 4, 2007 Posts: 7 Comments: 8747
Quoting SouthDadeFish:
00Z Euro is running and isn't showing much through 48 hours...


Same with the GGEM.

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Quoting SouthDadeFish:
00Z Euro is running and isn't showing much through 48 hours...


Never has with any storms this season.. very poor job so far with cyclongenesis this year IMO.
Member Since: July 8, 2005 Posts: 259 Comments: 24578
1414. JLPR2
Considering 93L's appearance as of right now I'll say the slow organization the GFS is showing seems plausible.

Member Since: September 4, 2007 Posts: 7 Comments: 8747
1413. Gearsts
Quoting SouthDadeFish:
00Z Euro is running and isn't showing much through 48 hours...
link?
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For those who are interested, I just did a blog on the tropics. Check it out if you want.

I'm out for now, though. Need a break.
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00Z Euro is running and isn't showing much through 48 hours...
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The vorticity associated with the 10% feature is impressive. Perhaps it may gain more model support soon.

Link
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1409. JLPR2
Each circle is to the NW of the other.

Lots of disturbances out there.
Member Since: September 4, 2007 Posts: 7 Comments: 8747

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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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