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 ncstorm:
a different way of seeing the invest??


Probably becaus the BAMD forecasts a coordinate that is in the eastern hemisphere
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1608. ncstorm
Member Since: August 19, 2006 Posts: 13 Comments: 13481
1607. ncstorm
a different way of seeing the invest??

Member Since: August 19, 2006 Posts: 13 Comments: 13481
1606. angelafritz (Admin)
Quoting BobinTampa:



Aren't you in San Francisco? Are you up really early or up really late??



Really early. Someone has to monitor the tropics!



..??? a Frog storm???
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Last few frames on 92L's floater, I am definetly noticing some cyclonic turning of the system for the first time..
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Quoting ProgressivePulse:
Looks to be a busy weekend & week ahead with 92, 93, 94L so far and, potentially 95L. Tis the season.

You can safely remove the qualifier... ;-)
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1601. HCW
92L 93L 94L and 95L








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95L Radar:
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Morning All.

Looks to be a busy weekend & week ahead with 92, 93, 94L so far and, potentially 95L. Tis the season. A couple more big dogs coming down the pipe over Africa as well.

I am interested to see if 93L takes a path similar to Emily in 05. That was the only Cape Verde storm to effect land. After Emily, most storms were home brew types that formed west of 60W. The ones that did form in the MDR all re-curved. Trending back to a La Nina, I personally don't think things are much different than 05, with the exception of the low shear anomalies.

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1598. ncstorm
I know Dr. Masters is having to rewrite his update each time these Invests have popped up..
Member Since: August 19, 2006 Posts: 13 Comments: 13481
I wonder if 94L might affect 92L, and could that hurt/help 93L. They are all relatively close, and it appear 94L and 92L are on a collision course. 95L I think will probably develop just like Cindy.
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Quoting MahFL:



Nature will recover.


In the meantime, it's having a billion-plus dollar impact on the Texas economy.
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...And, finally, the complete file on 95L:

BEGIN
NHC_ATCF
invest_al952011.invest
FSTDA
R
U
040
010
0000
201108121229
NONE
NOTIFY=ATRP
END
INVEST, AL, L, , , , , 95, 2011, DB, O, 2011081212, 9999999999, , , , , , METWATCH, , AL952011
AL, 95, 2011081112, , BEST, 0, 304N, 740W, 20, 1014, DB, 0, , 0, 0, 0, 0, 1014, 200, 60, 0, 0,
AL, 95, 2011081118, , BEST, 0, 314N, 724W, 25, 1011, DB, 0, , 0, 0, 0, 0, 1014, 200, 60, 0, 0,
AL, 95, 2011081200, , BEST, 0, 325N, 706W, 25, 1011, DB, 0, , 0, 0, 0, 0, 1014, 200, 40, 0, 0,
AL, 95, 2011081206, , BEST, 0, 336N, 688W, 25, 1011, DB, 0, , 0, 0, 0, 0, 1014, 200, 40, 0, 0,
AL, 95, 2011081212, , BEST, 0, 348N, 668W, 25, 1011, DB, 34, NEQ, 0, 0, 0, 0, 1014, 200, 40, 0, 0, L, 0, , 0, 0, INVEST, S,
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invest 94l already gave us some thunderstorms this morning causing pop up showers here
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All these invests at once, too much to watch!!!
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Quoting stormpetrol:
4 invests in the Atl this morning tells me we're approaching mid August!


shocking... ain't it?
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Quoting trHUrrIXC5MMX:


95L?

See post 1577
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Quoting wunderkidcayman:
ACTIVE STORMS
92L
93L
94L
95L


95L?
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1588. MahFL
Quoting uptxcoast:
... it’s going to have myriad consequences for the area...



Nature will recover.
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Plenty of bark but not much bite.
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4 invests in the Atl this morning tells me we're approaching mid August!
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1585. ncstorm
Quoting MahFL:


Don't be stupid, when the storms, if they develop, are near land the NHC will have a very good idea where they are going.


I didnt say the NHC wouldnt have an idea, I said the models..big difference..the models do not have the best track record right now this season
Member Since: August 19, 2006 Posts: 13 Comments: 13481
ACTIVE STORMS
92L
93L
94L
95L
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1583. ncstorm
Quoting Neapolitan:
Hey, look, honey! It's quadruplets!

BEGIN
NHC_ATCF
invest_al952011.invest
FSTDA
R
U
040
010
0000
201108121210
NONE
NOTIFY=ATRP
END
INVEST, AL, L, , , , , 95, 2011, DB, O, 2011081212, 9999999999, , , , , , METWATCH, , AL952011
AL, 95, 2011081212, , BEST, 0, 348N, 668W, 25, 0, DB, 0, , 0, 0, 0, 0,


LOL..OMGosh!!
Member Since: August 19, 2006 Posts: 13 Comments: 13481
1582. MahFL
Quoting ncstorm:


throw the models out ...


Don't be stupid, when the storms, if they develop, are near land the NHC will have a very good idea where they are going.
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Quoting ncstorm:


anyone want to play connect four?


funny!
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Quoting ncstorm:


anyone want to play connect four?

Bingo...
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wow who gave Miss Tropical Atlantic some heavey rum to go crazy
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Hey, look, honey! It's quadruplets!

BEGIN
NHC_ATCF
invest_al952011.invest
FSTDA
R
U
040
010
0000
201108121210
NONE
NOTIFY=ATRP
END
INVEST, AL, L, , , , , 95, 2011, DB, O, 2011081212, 9999999999, , , , , , METWATCH, , AL952011
AL, 95, 2011081212, , BEST, 0, 348N, 668W, 25, 0, DB, 0, , 0, 0, 0, 0,
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Quoting uptxcoast:
As part of an excellent update on the city’s drought, the National Weather Service dug up an incredible statistic: Since Feb. 1 Houston has recorded just 5.81 inches of rain. The next driest comparable period – that is, the 191 days from Feb. 1 through August 10 – occurred in 1917 when there were 10.98 inches of rain.

Here’s another way of looking at it: The city has now gone 198 days without a 1-inch rain event. The last day Houston recorded 1 inch of rain came on Jan. 24. This has broken the record of 192 days set during the fall and winter of 1917-1918.

In other words, this dry spell is simply off the charts and it’s going to have myriad consequences for the area, from our trees and wild creatures to home foundations, not to mention the agricultural effects on a larger scale.

Link


Yup, and y'all have gotten a ton more rain than we have here in San Antonio. We're 18 inches below normal for the year.

A slow, wet tropical storm would be a good start to refilling the reservoirs, but torrential rains would mostly be lost to run-off. It'll take 2 weeks straight of light-moderate rain to get us back to where we should be. *kicks the drought*
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1575. ncstorm
IF 94L develops, you might be looking at another variable in tracking for the other storms..and if none of the models except the NOGAPS is picking up on these smaller disturbances, how can they see the entire atlantic and its possibilities?
Member Since: August 19, 2006 Posts: 13 Comments: 13481
Quoting GeoffreyWPB:
Lol...



That one drives like my wife
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Now, that's an Atlantic parade...
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We had TOMAS last year and now possibly Franklyn soon. St Lucia still recovering with structyral damages from the storm. another hit could compound things
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1571. ncstorm
Member Since: August 19, 2006 Posts: 13 Comments: 13481
Lol...

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Quoting ncstorm:


the storm that wont die..


Really...Reminds me of Fred-Ex and Karen. The NHC forecast % map looks scarier than the actual satellite presentation.
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waiting for a 94L floater......
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1567. Hugo7
should take note and watch the low that is about to come off the east coast from us for developement too.
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i try not to spam but notice some have their ways of doing it anyway
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Quoting stormpetrol:


Good morning, not good if that pans out!
Good morning. No, it's not but still is a big IF.
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1564. ncstorm
Quoting trHUrrIXC5MMX:


TRIO OF INVESTS


anyone want to play connect four?
Member Since: August 19, 2006 Posts: 13 Comments: 13481
Seems NOGAPS with the weaker west crowd too. Link
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As part of an excellent update on the city’s drought, the National Weather Service dug up an incredible statistic: Since Feb. 1 Houston has recorded just 5.81 inches of rain. The next driest comparable period – that is, the 191 days from Feb. 1 through August 10 – occurred in 1917 when there were 10.98 inches of rain.

Here’s another way of looking at it: The city has now gone 198 days without a 1-inch rain event. The last day Houston recorded 1 inch of rain came on Jan. 24. This has broken the record of 192 days set during the fall and winter of 1917-1918.

In other words, this dry spell is simply off the charts and it’s going to have myriad consequences for the area, from our trees and wild creatures to home foundations, not to mention the agricultural effects on a larger scale.

Link
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1561. ncstorm
Quoting GeoffreyWPB:


the storm that wont die..
Member Since: August 19, 2006 Posts: 13 Comments: 13481
Quoting stormwatcherCI:
Good morning. Not liking this at all.


Link


Good morning, not good if that pans out!
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1559. ncstorm
It might just be a little something for everyone with these Invests developing..
Member Since: August 19, 2006 Posts: 13 Comments: 13481

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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.