New African disturbance 96L likely to develop

By: Dr. Jeff Masters , 2:55 PM GMT on September 07, 2009

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A tropical wave (96L) that emerged off the coast of Africa yesterday has organized rather quickly, and will likely become a tropical depression by Tuesday night. Satellite imagery from the European satellite shows a well-organized circulation, but not enough heavy thunderstorm activity near the center of circulation to be considered a tropical depression. The storm is far enough south that the dry air of the Saharan Air Layer is not a major impediment to development. Wind shear is moderate, 10 - 15 knots, and ocean temperatures are 1 - 2°C above the threshold needed for tropical cyclone formation.


Figure 1. Morning satellite image of 96L, off the coast of Africa. The remains of disturbance 95L, which are under 30 - 40 knots of wind shear, can be seen at upper left.

The forecast for 96L
Most of the models develop 96L, and the chances are that this disturbance will become Tropical Storm Fred later this week. The system will initially move west-northwest, but by Thursday, a strong trough of low pressure passing to 96L's north will pull the storm to the northwest, and may be capable of fully recurving the storm to the northeast. However, most of the models foresee that 96L will not move far enough north for this to happen, and that the storm will have to wait for the next trough of low pressure. With the steering pattern for this year continuing to feature plenty of deep troughs of low pressure moving off the U.S. East Coast, the odds of 96L making it all the way across the Atlantic to threaten land areas appear low. Still, much that is unexpected can and does happen in the world of tropical meteorology, and 96L bears watching.

North Carolina low
An area of concentrated thunderstorms has developed off the North Carolina coast in association with the remains of an old cold front. This system is under about 20 - 30 knots of shear, and is not tropical. However, it will bring heavy rain to eastern North Carolina today and Tuesday, as the storm slides north-northeastward along the coast.

I'll have an update Tuesday.

Jeff Masters

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looking for too the E PAC posts season,
Member Since: May 21, 2006 Posts: 5091 Comments: 114720
1035. amd
Quoting Dakster:
Hurricane Warnings just posted for Tallahassee...



just been downgraded to a tropical storm watch...
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Quoting laflastormtracker:
No, it is cool I was just thinking more of a scientific view point while you may be deducing some form of pattern or trend? Is that right? No worries..lol!


Lol. Sorry. I've not the most scientific of minds. No problem. :)
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Carolina system getting close to weak TS strength:Link

rapidly falling pressures and 40 kt gusts...
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1032. Seastep
ty 456
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Quoting P451:
I really have a feeling this is going to be one good winter for the mid-atlantic and north east.




Approx 17 hour loop.


do you mean heavy snow? Oh, and this is definitely tropical, just too heavily sheared to be declared. If i can survive passage through NC and then stalls it might have a chance.

(repost image)
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Quoting Levi32:


I really think that system is more tropical than it's getting credit for. Consistent thunderstorm activity has warmed all layers of the atmosphere, and surface obs indicate a tight closed circulation, which is evident on radar as well. SW winds aloft are keeping the center just on the SW side of the CDO, but that's expected with hybrid systems like this. Looks like a TD to me to be honest.


I would like to see QS, but as I indicated before - Cyclone phase diagrams show a shallow warm-core system due to the injection of tropical air. But that was also the case with 98L.
Member Since: July 24, 2005 Posts: 407 Comments: 19076
Lol. I like this one. Quick concise ad to the point.

SYNOPSIS FOR THE GULF OF MEXICO
430 PM CDT MON SEP 07 2009

.SYNOPSIS...WEAK PRESSURE PATTERN THROUGH THURSDAY. WEAK TROUGH
OVER THE WESTERN PART FRIDAY AND SATURDAY.
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1027. Dakster
Hurricane Warnings just posted for Tallahassee...

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Quoting Seastep:


Would love a link to that ecmwf if possible, 456.


LINK
Member Since: July 24, 2005 Posts: 407 Comments: 19076
1025. Levi32
Quoting Weather456:
This is rather identical to 98L and Danny but the difference with this 1 is that blocking high over Nova Scotia Island will stall the feature near 35N-40N (look at frame # 2 in post 1007)



I really think that system is more tropical than it's getting credit for. Consistent thunderstorm activity has warmed all layers of the atmosphere, and surface obs indicate a tight closed circulation with good pressure falls, which is evident on radar as well. SW winds aloft are keeping the center just on the SW side of the CDO, but that's expected with hybrid systems like this. Looks like a TD to me to be honest.
Member Since: November 24, 2005 Posts: 635 Comments: 26547
1024. Seastep
Quoting Weather456:
TD through a similar track to 95L.

Initial the cyclone is moving westward, maybe south thereof due to the Azores High.

However, it eventually turns more northward as a trough breaks down the high and create a weakness.

After that trough passes, high pressure rebuilds and TD 7 resumes wnw (that is if it does not re-curve the 1st time)

Last, at the end of the forecast cycle, another weakness develops and TD moves toward it, they meet near 50-60W. The question is, will this recurve it becuz if it misses this 1, it brings it closer to Bermuda as the TD 7 meet the 3rd and final trough near 70W.













Would love a link to that ecmwf if possible, 456.
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No, it is cool I was just thinking more of a scientific view point while you may be deducing some form of pattern or trend? Is that right? No worries..lol!
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This is rather identical to 98L and Danny but the difference with this 1 is that blocking high over Nova Scotia Island will stall the feature near 35N-40N (look at frame # 2 in post 1007)

Member Since: July 24, 2005 Posts: 407 Comments: 19076
While fairly good guidance, models are overblown imo, too much faith in them, what ever happen to good old fashion forecasting, man has become to dependent on the very thing they invented, some may say yes, but the computer can do this 1000s of time faster than man, but the final question is the true answer who made the computers? or did they just evolve, just my thought for tonight.
Member Since: April 29, 2007 Posts: 0 Comments: 7669
Could TD7 track more southerly and not move towards weakness when it occurs.
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Quoting laflastormtracker:


I don't like the 13th either. Just believe it is coincidence no matter how many times something may come in on a certain date. I am from Abbeville (in Vermilion Parish) and most of my family lives there. I was living in Abbeville when Humberto hit in 2007. We lost power and I drove to Lafayette (north) that morning for work dealing with westerly winds maneuvering my car and flooding of urban and side streets was not fun. Then Ike was a very bad storm for many in SW LA and SE TX last year.


Yeah. I was here for those too. It was said in jest. Geesh! I forgot not everyone has the same sense of humor. My bad. I apologize! I'm sorry! Never do it again! Hope that's ok now. You're correct its all coincidence. We'll move on now.
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1015. JLPR


looking nice
and is the wave behind TD7 the one the GFS says could develop into a weak system?
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Quoting Weather456:


it dont think so. Its actually a shallow warm-core system but it does not appear to be a true hybrid system and most of the models take it to a cold core system as slides N.
Darn! Thank you though.
Member Since: July 14, 2009 Posts: 51 Comments: 1721
Quoting homelesswanderer:


Well yeah. I'm not crazy about the 24th at all. That pretty much sucked! But other than the last 2 years on the 13th, our area has been hit more on that day of the year than any other. If your area was hit on the same day of the year a couple of years in a row you might think that too. But for some reason when I say it people get upset so I'll stop. Sigh.


I don't like the 13th either. Just believe it is coincidence no matter how many times something may come in on a certain date. I am from Abbeville (in Vermilion Parish) and most of my family lives there. I was living in Abbeville when Humberto hit in 2007. We lost power and I drove to Lafayette (north) that morning for work dealing with westerly winds maneuvering my car and flooding of urban and side streets was not fun. Then Ike was a very bad storm for many in SW LA and SE TX last year.
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At the very least this weekend will be a wash out. Whatever day that may be. :)

MARINE WEATHER DISCUSSION FOR THE GULF OF MEXICO...CARIBBEAN SEA
AND SOUTHWEST NORTH ATLC S OF 31N W OF 55W.

GULF OF MEXICO...
A WEAK E-W TROUGH OVER THE NW COASTAL PLAINS WILL DISSIPATE
TONIGHT. A WEAK RIDGE EXTENDS NNE TO SSW ACROSS THE CENTRAL
WATERS. THE RESULT IS LIGHT WINDS ACROSS ALL ZONES. A WEAK
INVERTED TROUGH OVER THE WESTERN BAHAMAS IS EXPECTED TO DRIFT W
THROUGH THE FLORIDA STRAITS TONIGHT THROUGH WED NIGHT...THEN
CONTINUE NW REACHING THE CENTRAL GULF WATERS FRI. EXPECT THE
LATE AFTERNOON INTO EARLY EVENING INCREASE IN WINDS ALONG THE NW
YUCATAN COAST. INTENSE CONVECTION ENHANCED OVER THE SW GULF HAS
INDUCED A WEAK INVERTED TROUGH AND ITS EXPECTED TO CONTINUE FOR
A FEW DAYS WITH THE POSSIBILITY OF A WEAK LOW PRES DEVELOPING
ALONG THE TROUGH.
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The hernia should be repaired in the Azores High and TD7 should truck westward :) j/k!
Member Since: April 29, 2007 Posts: 0 Comments: 7669
Quoting WPBHurricane05:
Flood warnings have been issued for portions N. Carolina near Morehead City. Flood watches have been issued for portions of the Virginia Coast.

Looks like a big rain maker since it ain't moving much.


Link

Morehead is about 15-20 miles from me. It has been raining all day, non stop.
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Quoting laflastormtracker:
It is merely a date. I am from LA, and I'd venture to say you'd feel the same about the 14th if a system would make landfall on that date this year...


Well yeah. I'm not crazy about the 24th at all. That pretty much sucked! But other than the last 2 years on the 13th, our area has been hit more on that day of the year than any other. If your area was hit on the same day of the year a couple of years in a row you might think that too. But for some reason when I say it people get upset so I'll stop. Sigh.
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TD 7 may take a similar track to 95L.

Initially the cyclone is moving westward, maybe south thereof due to the Azores High.

However, it eventually turns more northward as a trough breaks down the high and create a weakness.

After that trough passes, high pressure rebuilds and TD 7 resumes wnw (that is if it does not re-curve the 1st time)

Last, at the end of the forecast cycle, another weakness develops and TD moves toward it, they meet near 50-60W. The question is, will this recurve it becuz if it misses this 2nd weakness, it brings it closer to Bermuda as TD 7 meet the 3rd and final trough near 70W (not shown)





Member Since: July 24, 2005 Posts: 407 Comments: 19076
Flood warnings have been issued for portions N. Carolina near Morehead City. Flood watches have been issued for portions of the Virginia Coast.

Looks like a big rain maker since it ain't moving much.
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It is merely a date. I am from LA, and I'd venture to say you'd feel the same about the 14th if a system would make landfall on (the 14th) this year...
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Good evening all. Just trying to catch up on things. Still watching the gulf. One local says it'll track by us. Another said towards us. One says it will or it won't develop the other maybe. Lol. At least one of them did say the same thing I said this morning...September 13th is not lucky for us. :)
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AOI

AOI

AOI

AOI
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Quoting cyclonekid:
Hey 456, is there any chance for subtropical development for the NC low or if anything were to develop, would it be tropical.


it dont think so. Its actually a shallow warm-core system but it does not appear to be a true hybrid system and most of the models take it to a cold core system as slides N.
Member Since: July 24, 2005 Posts: 407 Comments: 19076
Hello StormW-

Did you notice 24N94W ?
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good evening everyone

Im still new at this but is there still a chance of Erika reforming?
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Quoting btwntx08:

u just made urself into an empty space goodbye # 40


What took you so long :)
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Gulf of Mexico
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TROPICAL WEATHER OUTLOOK
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
800 PM EDT MON SEP 7 2009

FOR THE NORTH ATLANTIC...CARIBBEAN SEA AND THE GULF OF MEXICO...


A NON-TROPICAL AREA OF LOW PRESSURE ASSOCIATED WITH A MID- TO
UPPER-LEVEL TROUGH IS LOCATED JUST EAST OF WILMINGTON NORTH
CAROLINA. WHILE THIS LOW IS PRODUCING SHOWER AND THUNDERSTORM
ACTIVITY...UPPER-LEVEL WINDS ARE EXPECTED TO REMAIN UNFAVORABLE FOR
TROPICAL CYCLONE FORMATION. THERE IS A LOW CHANCE...LESS THAN 30
PERCENT...OF THIS SYSTEM BECOMING A TROPICAL CYCLONE DURING THE
NEXT 48 HOURS. THIS SYSTEM WILL PRODUCE LOCALLY HEAVY RAINFALL AND
GUSTY WINDS ALONG THE COAST OF SOUTHERN AND CENTRAL NORTH CAROLINA
TONIGHT AS IT MOVES SLOWLY NORTH-NORTHEASTWARD. ADDITIONAL
INFORMATION ON THIS SYSTEM CAN BE FOUND IN PRODUCTS ISSUED BY
LOCAL NATIONAL WEATHER SERVICE FORECAST OFFICES.
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TD 7 just dipped south
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hi StormW
can you please tell me what is gonna happen in GOM?? Thanks!!
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Hey 456, is there any chance for subtropical development for the NC low or if anything were to develop, would it be tropical.
Member Since: July 14, 2009 Posts: 51 Comments: 1721
989. amd
Seems to me that TD7 continues to organize as far south as it possibly can.

Just for today, winds have shifted from the west to SSE with buoy 13001 located south of the cape Verde islands.

Since buoy 13001 is located at roughly 11.8 N 23.0W, I'm thinking the center of TD7 and soon to be Fred will organize between 11 and 11.5 degrees North.

Link
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Quoting Weather456:
One thing I've learn is that Tropical Forecasting is very difficult becuz you are trying to forecast the state of an atmosphere that is uniform in structure or composition throughout. As compared to mid-latitude weather where the atmosphere is contrasting.


Very true.
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One thing I've learn is that Tropical Forecasting is very difficult becuz you are trying to forecast the state of an atmosphere that is uniform in structure or composition throughout. As compared to mid-latitude weather where the atmosphere is contrasting.
Member Since: July 24, 2005 Posts: 407 Comments: 19076

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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.