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 angiest:


Better Mexican food in Houston and San Antonio, I'd bet. ;)


angiest, I worked on the east side of Houston for 7 years, and I enjoyed the Mexican food, also miss a place called Burger-Tex. Also good Bar-B-Que places.
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Quoting TropicalAnalystwx13:
The Texas ridge is getting soft.


The moment they've been waiting for...is almost here
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907. MTWX
Quoting aislinnpaps:


Neo, you even beat my moves with the military. I just get to add Germany to the list, and some different states. But when you live in different places you do get to see interesting weather, from blizzards to dust storms to lightening that is so nonstop it looks like daylight outside.

I here ya. Being an AF brat/Active Duty AF I've been all over the place and have experienced just about every weather phenomenon first hand.
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Quoting Neapolitan:
Pressure up just a bit:

AL, 92, 2011081200, , BEST, 0, 140N, 373W, 25, 1011, LO, 34, NEQ, 0, 0, 0, 0, 1014, 200, 90, 0, 0, L, 0, , 0, 0, INVEST, S,
She is awesome!

Have you had her Blueberry Muffins?
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Quoting Levi32:


Because from Day 9 onward the GFS has a much lower resolution, and thus only the 1000mb isobar is shown on that product. Some GFS products show the pressure down to 982mb even at the lower grid resolution. The NCEP products don't show the central pressure well.


Still a goofy run, almost as extreme as yesterdays 18 Z. Just can't put much stock in anything yet. I still think only one of these invests are going to survive.
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The Texas ridge is getting soft.

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Quoting aquak9:
hi caneswatch! gee I didn't recognize ya with the new avatar. But, I understand.



Howdy Aqua!

It was time for a new avatar. I thought I'd put up a stormtrooper as one because that was the first thing to pop into my head LOL. What are you thinking of 93L? I personally don't like what it could do in the future.
Member Since: October 8, 2008 Posts: 14 Comments: 4553
Quoting rod2635:


Wouldn't 980mb be in the area of 28.90 barometer...would think we'd need 27.9 or below to get that wind speed



Definitely.
Member Since: June 23, 2010 Posts: 0 Comments: 589
Quoting SLU:
063

WHXX01 KWBC 120105

CHGHUR

TROPICAL CYCLONE GUIDANCE MESSAGE

NWS NATIONAL HURRICANE CENTER MIAMI FL

0105 UTC FRI AUG 12 2011



DISCLAIMER...NUMERICAL MODELS ARE SUBJECT TO LARGE ERRORS.

PLEASE REFER TO NHC OFFICIAL FORECASTS FOR TROPICAL CYCLONE

AND SUBTROPICAL CYCLONE INFORMATION.



ATLANTIC OBJECTIVE AIDS FOR



DISTURBANCE INVEST (AL932011) 20110812 0000 UTC



...00 HRS... ...12 HRS... ...24 HRS. .. ...36 HRS...

110812 0000 110812 1200 110813 0000 110813 1200



LAT LON LAT LON LAT LON LAT LON

BAMS 11.0N 25.6W 11.5N 27.8W 12.2N 29.9W 12.8N 32.7W

BAMD 11.0N 25.6W 11.3N 28.1W 11.7N 30.5W 12.1N 32.9W

BAMM 11.0N 25.6W 11.3N 28.4W 11.5N 31.0W 11.8N 33.7W

LBAR 11.0N 25.6W 11.5N 28.8W 12.0N 32.4W 12.4N 35.8W

SHIP 25KTS 31KTS 39KTS 46KTS

DSHP 25KTS 31KTS 39KTS 46KTS



...48 HRS... ...72 HRS... ...96 HRS. .. ..120 HRS...

110814 0000 110815 0000 110816 0000 110817 0000



LAT LON LAT LON LAT LON LAT LON

BAMS 13.4N 36.0W 14.1N 43.5W 13.8N 50.4W 14.2N 56.2W

BAMD 12.7N 35.2W 14.3N 39.2W 16.9N 42.4W 20.3N 45.1W

BAMM 12.2N 36.3W 13.4N 41.7W 15.3N 46.9W 17.7N 52.9W

LBAR 12.8N 39.2W 13.1N 45.2W 13.4N 48.4W .0N .0W

SHIP 54KTS 70KTS 82KTS 93KTS

DSHP 54KTS 70KTS 82KTS 93KTS



...INITIAL CONDITIONS...

LATCUR = 11.0N LONCUR = 25.6W DIRCUR = 280DEG SPDCUR = 15KT

LATM12 = 10.6N LONM12 = 22.5W DIRM12 = 278DEG SPDM12 = 15KT

LATM24 = 10.2N LONM24 = 19.5W

WNDCUR = 25KT RMAXWD = 60NM WNDM12 = 25KT

CENPRS = 1011MB OUTPRS = 1014MB OUTRAD = 180NM SDEPTH = M

RD34NE = 0NM RD34SE = 0NM RD34SW = 0NM RD34NW = 0NM



$$




DSHP and SHIP takes 93L under a RI
Member Since: May 21, 2006 Posts: 5091 Comments: 115435
Quoting Tazmanian:



i tihnk a 980mb low would mean a 140 too 150mph storm


Wouldn't 980mb be in the area of 28.90 barometer...would think we'd need 27.9 or below to get that wind speed
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So both invests are of equal strength.
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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... ;-)


Neo, you even beat my moves with the military. I just get to add Germany to the list, and some different states. But when you live in different places you do get to see interesting weather, from blizzards to dust storms to lightening that is so nonstop it looks like daylight outside.
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Could 93 over take 92 and suck it in?
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Quoting angiest:


Into the western Gulf? California maybe? Best bet for us to move NE, get us on the southwestern periphery.
Thanks.
Member Since: June 21, 2011 Posts: 0 Comments: 329
Quoting MTWX:

I'll have to try those next time I'm out that way...:)


Clem is out of Temple but has a bunch of locations. Jerry is in Columbus, Mike is in El Campo (I think).
Member Since: August 26, 2006 Posts: 16 Comments: 4766
Quoting Neapolitan:
And here's 93L:

AL, 93, 2011081200, , BEST, 0, 110N, 256W, 25, 1011, LO, 34, NEQ, 0, 0, 0, 0, 1014, 180, 60, 0, 0, L, 0, , 0, 0, INVEST, M,
Thanks.
Member Since: October 9, 2008 Posts: 0 Comments: 8436
Quoting MississippiWx:


Yeah, that's not what it wants. It wants a major hurricane to hit its house in Florida.


If that's what he wants it...... I live a good 10-15 miles inland. If I see a 145 mph hurricane, there's no need to tell me twice to drive north on 441.
Member Since: October 8, 2008 Posts: 14 Comments: 4553
Quoting TropicalAnalystwx13:


No, that is usually Category 1/2 hurricane strength.



Yeah...145mph plus would be closer to 940mb and lower.
Member Since: July 15, 2006 Posts: 17 Comments: 10284
Quoting aquak9:

hiking, sight-seeing, eating awesome mexican food, drinking fancy california wines...it's a rough life.
going to the cold and cloudy beach, having only one weather season, watching all out sports teams fail...yeah, you could say it's a pretty rough life

Quoting TropicalAnalystwx13:
Who wants my weather? Speak now, or forever keep your bad weather.

Thunderstorms? 90 degree weather?

I'll take it
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Quoting MississippiWx:


There is no pressure requirement for TD/TS status.
oh okay i was wondering about that when they have the invest info.
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888. MTWX
Quoting angiest:


Clem, Mike, and Jerry Mikeska throughout Central and the western parts of SE Texas. The Swinging Door in Richmond. Luling City Meat Market in Houston.

I'll have to try those next time I'm out that way...:)
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Quoting Tazmanian:



i tihnk a 980mb low would mean a 140 too 150mph storm


No, that is usually Category 1/2 hurricane strength.

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Quoting Matt74:
How far would the high have to retrograde west to allow something in to the western gulf?


Into the western Gulf? California maybe? Best bet for us to move NE, get us on the southwestern periphery.
Member Since: August 26, 2006 Posts: 16 Comments: 4766
885. SLU
063

WHXX01 KWBC 120105

CHGHUR

TROPICAL CYCLONE GUIDANCE MESSAGE

NWS NATIONAL HURRICANE CENTER MIAMI FL

0105 UTC FRI AUG 12 2011



DISCLAIMER...NUMERICAL MODELS ARE SUBJECT TO LARGE ERRORS.

PLEASE REFER TO NHC OFFICIAL FORECASTS FOR TROPICAL CYCLONE

AND SUBTROPICAL CYCLONE INFORMATION.



ATLANTIC OBJECTIVE AIDS FOR



DISTURBANCE INVEST (AL932011) 20110812 0000 UTC



...00 HRS... ...12 HRS... ...24 HRS. .. ...36 HRS...

110812 0000 110812 1200 110813 0000 110813 1200



LAT LON LAT LON LAT LON LAT LON

BAMS 11.0N 25.6W 11.5N 27.8W 12.2N 29.9W 12.8N 32.7W

BAMD 11.0N 25.6W 11.3N 28.1W 11.7N 30.5W 12.1N 32.9W

BAMM 11.0N 25.6W 11.3N 28.4W 11.5N 31.0W 11.8N 33.7W

LBAR 11.0N 25.6W 11.5N 28.8W 12.0N 32.4W 12.4N 35.8W

SHIP 25KTS 31KTS 39KTS 46KTS

DSHP 25KTS 31KTS 39KTS 46KTS



...48 HRS... ...72 HRS... ...96 HRS. .. ..120 HRS...

110814 0000 110815 0000 110816 0000 110817 0000



LAT LON LAT LON LAT LON LAT LON

BAMS 13.4N 36.0W 14.1N 43.5W 13.8N 50.4W 14.2N 56.2W

BAMD 12.7N 35.2W 14.3N 39.2W 16.9N 42.4W 20.3N 45.1W

BAMM 12.2N 36.3W 13.4N 41.7W 15.3N 46.9W 17.7N 52.9W

LBAR 12.8N 39.2W 13.1N 45.2W 13.4N 48.4W .0N .0W

SHIP 54KTS 70KTS 82KTS 93KTS

DSHP 54KTS 70KTS 82KTS 93KTS



...INITIAL CONDITIONS...

LATCUR = 11.0N LONCUR = 25.6W DIRCUR = 280DEG SPDCUR = 15KT

LATM12 = 10.6N LONM12 = 22.5W DIRM12 = 278DEG SPDM12 = 15KT

LATM24 = 10.2N LONM24 = 19.5W

WNDCUR = 25KT RMAXWD = 60NM WNDM12 = 25KT

CENPRS = 1011MB OUTPRS = 1014MB OUTRAD = 180NM SDEPTH = M

RD34NE = 0NM RD34SE = 0NM RD34SW = 0NM RD34NW = 0NM



$$
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And here's 93L:

AL, 93, 2011081200, , BEST, 0, 110N, 256W, 25, 1011, LO, 34, NEQ, 0, 0, 0, 0, 1014, 180, 60, 0, 0, L, 0, , 0, 0, INVEST, M,
Member Since: November 8, 2009 Posts: 4 Comments: 13725
Quoting TropicalAnalystwx13:


980-985 MB.




i tihnk a 980mb low would mean a 140 too 150mph storm
Member Since: May 21, 2006 Posts: 5091 Comments: 115435
Quoting angiest:


At least as of yesterday, NWS Houston was forecasting the high to back off toward El Paso, which *might* could open the easternmost Gulf, if there were anything there to take advantage of it.
How far would the high have to retrograde west to allow something in to the western gulf?
Member Since: June 21, 2011 Posts: 0 Comments: 329
Quoting JFV2013:



Yup, sadly, trailer trash boy is right, that is indeed what I want, ma'am.


Happy Birthday JFV.

Please don't call him any rude names, he is one of my friends, and definitely not a ma'am, lol.
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Quoting Chucktown:
You know, just glancing at that 18 Z run again, why does the GFS only show a surface pressure of 1000 mb at "landfall". There is a tremendous amount of convective feedback on that.

Link


Because from Day 9 onward the GFS has a much lower resolution, and thus only the 1000mb isobar is shown on that product. Some GFS products show the pressure down to 982mb even at the lower grid resolution. The NCEP products don't show the central pressure well.
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Lesser Antilles, US east coast and even Hawaii at risk



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Quoting Chucktown:
You know, just glancing at that 18 Z run again, why does the GFS only show a surface pressure of 1000 mb at "landfall". There is a tremendous amount of convective feedback on that.

Link


980-985 MB.

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Quoting MTWX:

Rudys in San Antonio!! Hands down!


Clem, Mike, and Jerry Mikeska throughout Central and the western parts of SE Texas. The Swinging Door in Richmond. Luling City Meat Market in Houston.
Member Since: August 26, 2006 Posts: 16 Comments: 4766
Aqua is nice....Xcool, that was funny, and Happy Birthday JFV.....


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Quoting MississippiWx:


Texas is in trouble if we head into even a moderately strong La Nina.


Yes sir.

I hope it doesn't reemerge for their sake (and admittedly also for mine -- I'm quite tired of this overwhelming heat).
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Quoting floodzonenc:
Looks almost identical to mine... LOL. Greenville, here.



100 miles to my north, Rocky Point (just north of Wilmington) here.
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You know, just glancing at that 18 Z run again, why does the GFS only show a surface pressure of 1000 mb at "landfall". There is a tremendous amount of convective feedback on that.

Link
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869. MTWX
Quoting aquak9:
angiest- heck I'm happy at Taco Bell. I ain't picky. But if I'm in Texas, I'm gonna eat Barbeque. :)

Rudys in San Antonio!! Hands down!
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Looks almost identical to mine... LOL.  Greenville, here.
Quoting TropicalAnalystwx13:
Who wants my weather? Speak now, or forever keep your bad weather.


Member Since: June 12, 2006 Posts: 1 Comments: 600
Quoting ncstorm:
Just saw the 18Z GFS run..next run will be bermuda again..



that map looks scary...
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Quoting KoritheMan:


If La Nina returns, that high may never move that much.


Texas is in trouble if we head into even a moderately strong La Nina.
Member Since: July 15, 2006 Posts: 17 Comments: 10284
hi caneswatch! gee I didn't recognize ya with the new avatar. But, I understand.

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Quoting TropicalAnalystwx13:


For now anyways.


If La Nina returns, that high may never move much.
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Absolutely.
Quoting aquak9:


If it would only stay a tropical storm, and go to Texas? that would be the answer to many prayers.

Member Since: June 12, 2006 Posts: 1 Comments: 600
Quoting aquak9:


If it would only stay a tropical storm, and go to Texas? that would be the answer to many prayers.


Yeah, that's not what it wants. It wants a major hurricane to hit its house in Florida.
Member Since: July 15, 2006 Posts: 17 Comments: 10284
Quoting clwstmchasr:
Bad news for Texas with the heatwave continuing, means good news for us in the Eastern GOM. That high will block any storms from getting into the GOM.


At least as of yesterday, NWS Houston was forecasting the high to back off toward El Paso, which *might* could open the easternmost Gulf, if there were anything there to take advantage of it.
Member Since: August 26, 2006 Posts: 16 Comments: 4766
angiest- heck I'm happy at Taco Bell. I ain't picky. But if I'm in Texas, I'm gonna eat Barbeque. :)
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Quoting aquak9:

hiking, sight-seeing, eating awesome mexican food, drinking fancy california wines...it's a rough life.


I'd gladly take the first three of those any day (:
Member Since: October 8, 2008 Posts: 14 Comments: 4553

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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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