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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Quoting centex:
I would keep an eye on TD7. No one predicted Erika would enter Caribbean except a few like me, and the few got blasted because most here are model worshipers. We learned shear forecast are totally unreliable and storms can and do go outside the cone, even in just 12 hour periods.


Centex i agree but, only a half of 1 eye open tho....
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785. IKE
18Z NAM...
Member Since: June 9, 2005 Posts: 23 Comments: 37860
Quoting Floodman:


stormno, is that you? Little matter, I won't see anymore of your posts anyway


He's the same idiot that said there wouldn't be anymore storms this season yesterday.
Member Since: July 8, 2005 Posts: 259 Comments: 24576
I would keep an eye on TD7. No one predicted Erika would enter Caribbean except a few like me, and the few got blasted because most here are model worshipers. We learned shear forecast are totally unreliable and storms can and do go outside the cone, even in just 12 hour periods.
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782. IKE
Quoting stormpetrol:

You know I was one the few , even if I have to say so myself" that said Erika would enter the Eastern caribbean and probably move just south of PR, after that I said I wasn't sure from there, I wasn't 100% dead on, but got that track right for the most part, TD 7 well I'm just not sure of where it will track, but I wouldn't make definitive bet of the path.


Maybe you'll be correct with TD7.

Member Since: June 9, 2005 Posts: 23 Comments: 37860
Quoting TheDawnAwakening:
Linda is over SSTs of 30C.


No its not. Its over 28C right now.
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Quoting IKE:


There's one.

You know I was one the few , even if I have to say so myself" that said Erika would enter the Eastern caribbean and probably move just south of PR, after that I said I wasn't sure from there, I wasn't 100% dead on, but got that track right for the most part, TD 7 well I'm just not sure of where it will track, but I wouldn't make definitive bet of the path.
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Quoting Weather456:
The non tropical low has dumped some heavy rains across South and North Carolina



There's a lot of rain in store for the eastern seaboard over the next 3-6 days. The GFS 72-hour surface map shows the long easterly fetch that sets up bringing a ton of moisture right into New Jersey and the surrounding coastline. The low gets trapped by a big surface high over New England and will be sitting near the coast for several days, making this a serious flooding threat with large amounts of moisture coming in from the easterly flow.

The 500mb map shows how the trough to the west digs in with a negative tilt and helps keep the low close to the coast and allow moisture to come piling into the eastern seaboard.



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Linda is over SSTs of 30C.
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Quoting goddessnoel4u:


FRED WILL DIE


stormno, is that you? Little matter, I won't see anymore of your posts anyway
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Quoting Ameister12:

It seems like I was right.


I was talking about the future not right what was occurring right now. I havnt been watching Linda enough to tell you that.

Member Since: July 24, 2005 Posts: 407 Comments: 19076
Quoting Drakoen:


Ensemble members continue to feature the system heading back west or even WSW.


Yes, it will get pulled by this trough but afterwards a strong high will build over the CATL. Right?
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Quoting Weather456:


unlikely

when ever a tropical cyclone moves into a stratocumulus field in signifies it is moving to a stable enviroment

It seems like I was right.
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At least HH may not have to fly 07L
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I posted this on my blog this morning, I do agree with the NHC intensity guidance but I am going bit higher. Given the the current sat presentations, I still think TD 7 could become Hurricane Fred, briefly:

Much of the intensity guidance indicates that 96L will continue to develop and become our next tropical depression sometime this week. Much of the guidance also rapidly develops 96L into a hurricane over 28C waters and low vertical wind shear. In about 96 hrs, the system begins to turn more towards the northwest and north and encounter cooler sea surface temperatures and possibly higher vertical shear and thus intensity levels off and begins a slow decline.
Member Since: July 24, 2005 Posts: 407 Comments: 19076
18 Z TD-7 or the Fish formerly Known as 96L



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Why isn't TD 7 going to be a hurricane?
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Quoting IKE:


Comebacks will be....

(1)You're jumping to conclusions.
(2)Hate the term fish-storm!
(3)What is a fish-storm?
(4)Can't be a fish-storm! There are ships that have to navigate away from it!

You're probably right, this is a fish storm unless it hits the Azores *(highly unlikely)*
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Guess Linda is rapidly intensifying.
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Phish
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I've made a brief update on my blog about the N.C. swirl.
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764. IKE
Quoting stormpetrol:

I really don't know for sure but I wouldn't bet "the farm" on it, jmo.


There's one.
Member Since: June 9, 2005 Posts: 23 Comments: 37860
Quoting Tazmanian:
yes this is are 1st true fish storm

I really don't know for sure but I wouldn't bet "the farm" on it, jmo.
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Is 07L going to become a hurricane, or become a strong TS and then weaken from there.
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759. IKE
Quoting Tazmanian:
yes this is are 1st true fish storm


Comebacks will be....

(1)You're jumping to conclusions.
(2)Hate the term fish-storm!
(3)What is a fish-storm?
(4)Can't be a fish-storm! There are ships that have to navigate away from it!
Member Since: June 9, 2005 Posts: 23 Comments: 37860
Linda has RAPIDLY intensified...top winds 60mph
Member Since: July 14, 2009 Posts: 51 Comments: 1731
Hope everyone had a great Labor day. I see that "fred" will be heading out to the dead zone during peak season.
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NHC has TD 7 taking a hard right real soon.
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Quoting Acorna:


I can attest to that. Back yard is now flooded, rain gauge says we've had 6.7 inches thus far.


Oh, that is your PWS, I was just looking at the rainfall totals and I saw the 6 inches.
Member Since: July 24, 2005 Posts: 407 Comments: 19076
yes this is are 1st true fish storm
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The nontropical low formed from an old stalled out frontal boundary over the warm Gulf stream waters and shear that has been too strong for a tropical storm. Linda is really intensifying quickly in the East Pacific Ocean. Went from a 35mph depression to a 60mph Tropical Storm in 6 hours.
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It up on NHC sight. They have 7 "recurving" NORTH quite soon.
Member Since: March 10, 2006 Posts: 0 Comments: 10796
5-Day Track Forecast Cone
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ZCZC MIATCDAT2 ALL
TTAA00 KNHC DDHHMM
TROPICAL DEPRESSION SEVEN DISCUSSION NUMBER 1
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL072009
500 PM AST MON SEP 07 2009

SATELLITE IMAGES INDICATE THAT THE BROAD LOW PRESSURE AREA LOCATED
SOUTH OF THE CAPE VERDE ISLANDS HAS ACQUIRED ENOUGH ORGANIZATION TO
BE CLASSIFIED AS A TROPICAL DEPRESSION...THE SEVENTH OF THE 2009
ATLANTIC HURRICANE SEASON. THE EXACT CENTER OF THE DEPRESSION IS
SOMEWHAT DIFFICULT TO LOCATE. EARLIER TODAY THE LOW-LEVEL CENTER
APPEARED TO BE NEAR THE EASTERN EDGE OF THE DEEP CONVECTION.
HOWEVER NOW THE THE CENTER APPEARS TO BE UNDER THE DEEP CONVECTION
...BUT DISPLACED EAST OF THE MID-LEVEL CENTER SEEN IN SATELLITE
IMAGERY. DESPITE A LARGE SPREAD IN THE SATELLITE POSITION ESTIMATES
FROM TAFB AND SAB...BOTH CLASSIFICATIONS WERE T2.0...YIELDING AN
INITIAL INTENSITY OF 30 KT.

THE HIGHLY UNCERTAIN INITIAL MOTION ESTIMATE IS 280/14. THE
DEPRESSION IS CURRENTLY LOCATED SOUTH OF A NARROW EAST-TO-WEST
ORIENTED RIDGE. THE RIDGE IS FORECAST TO WEAKEN AS A MID-LEVEL
TROUGH MOVES INTO THE EASTERN ATLANTIC AND AN UPPER-LEVEL LOW
CUTS-OFF NEAR 27N40W DURING THE NEXT DAY OR TWO. THIS IS EXPECTED
TO ALLOW THE CYCLONE TO TURN NORTHWESTWARD IN A COUPLE OF DAYS...
FOLLOWED BY A TURN TO THE NORTH THEREAFTER. THE TRACK GUIDANCE IS IN
REASONABLY GOOD AGREEMENT ON THIS SOLUTION...AND THE OFFICIAL
FORECAST IS NEAR THE MIDDLE OF THE GUIDANCE ENVELOPE.

THE DEPRESSION IS CURRENTLY WITHIN AN AREA OF MODERATE EASTERLY
VERTICAL SHEAR...BUT THE SHEAR IS FORECAST TO ABATE WITHIN THE NEXT
DAY OR SO. SEA SURFACE TEMPERATURES ARE WARM ALONG THE FORECAST
TRACK AND THE DEPRESSION IS EXPECTED TO GRADUALLY STRENGTHEN DURING
THE NEXT COUPLE OF DAYS. THEREAFTER...INCREASING SOUTHERLY TO
SOUTHWESTERLY SHEAR IS FORECAST TO HALT FURTHER INTENSIFICATION.
THE NHC FORECAST IS CLOSEST TO THE LGEM GUIDANCE...WHICH TYPICALLY
ACCOUNTS FOR INCREASING SHEAR IN THE LONGER RANGES MORE ACCURATELY.
THE OFFICIAL FORECAST IS LOWER THAN THE HWRF AND SHIPS GUIDANCE...
WHICH BOTH BRING THE CYCLONE TO NEAR HURRICANE STRENGTH IN 2-3 DAYS.

THE CENTER OF THE DEPRESSION IS FORECAST TO PASS WELL SOUTHWEST OF
THE SOUTHERNMOST CAPE VERDE ISLANDS TONIGHT. OUTER RAIN BANDS ARE
LIKELY TO CONTINUE TO SPREAD ACROSS THE ISLANDS...PRODUCING LOCALLY
HEAVY RAIN AND GUSTY WINDS.

FORECAST POSITIONS AND MAX WINDS

INITIAL 07/2100Z 12.5N 24.5W 30 KT
12HR VT 08/0600Z 12.6N 26.5W 35 KT
24HR VT 08/1800Z 13.0N 28.7W 45 KT
36HR VT 09/0600Z 13.9N 30.5W 50 KT
48HR VT 09/1800Z 15.1N 32.1W 55 KT
72HR VT 10/1800Z 17.6N 33.9W 55 KT
96HR VT 11/1800Z 19.5N 34.5W 50 KT
120HR VT 12/1800Z 21.0N 34.5W 45 KT

$$
FORECASTER BROWN

NNNN
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747. IKE
Member Since: June 9, 2005 Posts: 23 Comments: 37860
I'm glad there isn't any development currently in the Caribbean. All these troughs would signal for a Wilma-esque track to Florida. Lets hope it stays quiet down there
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Quoting LavosPhoenix:
Is the nontropical low off of NC something that just formed or is it the reminant low of Erika?
I think it formed from a cutoff low that came out of the Gulf and mixed with the rems of Erica
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Quoting goddessnoel4u:


FRED WILL DIE
Good afternoon! Excellent observation!! Everything LIVES then it DIES!! YOUR POINT?? We're here to learn and observe!! Don't be a twit!!
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Stormpetrol, Good call on that mess of a storm Erika,
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00
WTPZ35 KNHC 072033
TCPEP5
BULLETIN
TROPICAL STORM LINDA ADVISORY NUMBER 3
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL EP152009
200 PM PDT MON SEP 07 2009

...TWELFTH NAMED STORM OF THE 2009 EAST PACIFIC SEASON FORMS...
INTENSIFYING QUICKLY...

AT 200 PM PDT...2100 UTC...THE CENTER OF TROPICAL STORM LINDA WAS
LOCATED NEAR LATITUDE 15.5 NORTH...LONGITUDE 127.0 WEST OR ABOUT
1225 MILES...1975 KM...WEST-SOUTHWEST OF THE SOUTHERN TIP OF BAJA
CALIFORNIA.

LINDA IS MOVING TOWARD THE WEST NEAR 7 MPH...11 KM/HR. A TURN
TOWARD THE WEST-NORTHWEST AND THEN TOWARD THE NORTHWEST WITH SOME
FURTHER DECREASE IN FORWARD SPEED IS EXPECTED OVER THE NEXT DAY OR
TWO.

MAXIMUM SUSTAINED WINDS ARE NEAR 60 MPH...95 KM/HR...WITH HIGHER
GUSTS. SOME ADDITIONAL STRENGTHENING IS FORECAST DURING THE NEXT 24
TO 36 HOURS...AND LINDA COULD BECOME A HURRICANE ON TUESDAY.

TROPICAL STORM FORCE WINDS EXTEND OUTWARD UP TO 70 MILES...110 KM
FROM THE CENTER.

THE ESTIMATED MINIMUM CENTRAL PRESSURE IS 997 MB...29.44 INCHES.

...SUMMARY OF 200 PM PDT INFORMATION...
LOCATION...15.5N 127.0W
MAXIMUM SUSTAINED WINDS...60 MPH
PRESENT MOVEMENT...WEST OR 280 DEGREES AT 7 MPH
MINIMUM CENTRAL PRESSURE...997 MB

THE NEXT ADVISORY WILL BE ISSUED BY THE NATIONAL HURRICANE CENTER AT
800 PM PDT.
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Is the nontropical low off of NC something that just formed or is it the reminant low of Erika?
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Quoting Weather456:
The non tropical low has dumped some heavy rains across South and North Carolina



I can attest to that. Back yard is now flooded, rain gauge says we've had 6.7 inches thus far.
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Member Since: July 24, 2005 Posts: 407 Comments: 19076
Quoting Weather456:
The non tropical low has dumped some heavy rains across South and North Carolina

Yes i have had about 2 inches today on Emerald Isle about 20 miles south of Morehead City NC. Its slacked off a lil but i see other bands commin
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000
WTNT32 KNHC 072034
TCPAT2
BULLETIN
TROPICAL DEPRESSION SEVEN ADVISORY NUMBER 1
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL072009
500 PM AST MON SEP 07 2009

...NEW TROPICAL DEPRESSION FORMS IN THE FAR EASTERN ATLANTIC...

AT 500 PM AST...2100 UTC...THE CENTER OF TROPICAL DEPRESSION SEVEN
WAS LOCATED NEAR LATITUDE 12.5 NORTH...LONGITUDE 24.5 WEST OR ABOUT
160 MILES...255 KM...SOUTH OF THE SOUTHERNMOST CAPE VERDE ISLANDS.

THE DEPRESSION IS MOVING TOWARD THE WEST NEAR 16 MPH...26 KM/HR. A
TURN TOWARD THE WEST-NORTHWEST AND A SLIGHT DECREASE IN FORWARD
SPEED IS FORECAST DURING THE NEXT DAY OR TWO.

MAXIMUM SUSTAINED WINDS ARE NEAR 35 MPH...55 KM/HR...WITH HIGHER
GUSTS. STRENGTHENING IS FORECAST OVER THE NEXT COUPLE OF DAYS...AND
THE DEPRESSION IS EXPECTED TO BECOME A TROPICAL STORM TONIGHT OR
TUESDAY.

THE ESTIMATED MINIMUM CENTRAL PRESSURE IS 1005 MB...29.68 INCHES.

OUTER RAIN BANDS FROM THE DEPRESSION ARE EXPECTED TO CONTINUE TO
SPREAD ACROSS THE SOUTHERN CAPE VERDE ISLANDS TONIGHT...PRODUCING
LOCALLY HEAVY RAINFALL AND GUSTY WINDS.

...SUMMARY OF 500 PM AST INFORMATION...
LOCATION...12.5N 24.5W
MAXIMUM SUSTAINED WINDS...35 MPH
PRESENT MOVEMENT...WEST OR 280 DEGREES AT 16 MPH
MINIMUM CENTRAL PRESSURE...1005 MB

THE NEXT ADVISORY WILL BE ISSUED BY THE NATIONAL HURRICANE CENTER AT
1100 PM AST.

$$
FORECASTER BROWN
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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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