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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although the ULL to the northwest of FRED is shoing signs of weakening the ridge i still do not believe that the ridge will be so weakened asto pull the storm so sharply to the north
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Hmmm? Reading about Allison. I knew she was bad but I didn't know some of these things.

Pre-Rita and pre-Ike.


June 6-12, 2001. Southeast Texas. The remnants of Tropical Storm Allison produced the worst natural disaster in Houston's history when 25 to 45 inches of rain fell as the storm meandered across southeast Texas. Damage was especially severe in the downtown area. The costliest storm in Texas history with $5 billion of the $6 billion in damage occurring in Texas. 23 deaths.

And a NO-NAME Storm...

June 29-July 5 2002. Central Texas. A weak tropical disturbance moved in from the Gulf of Mexico on June 29 and became stationary over the Edwards plateau for a week. Heavy rains of 35-45 inches ocurred within an area bordered by Boerne to Kerrville to Medina to Bandera back to Boerne. San Antonio set a record July rainfall of 16.92 inches for its second wettest month ever and the wettest July ever with 9.52 inches falling on July 1 alone. The highest flood stages ever for the upper Guadeloupe River and for the first time in Canyon Dam's history since it was constructed in 1958, water went over the spillway. Water nearly went over the spillway of Medina Dam with flood heights on the Medina River which exceeded those of October 1998. 12 deaths. $2 billion in damage. 36 counties in Central Texas were declared a Federal disaster area.

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1684. amd
Fred could briefly become a hurricane. However, looking at the latest cimss steering maps, and the 200 mb vorticity maps, I see why Fred will turn so sharply.

There is a strong ULL located near 28 N 40 W that has actually moved to the east in the last few hours (look at the CIMSS vorticity page). Also, the 970mb-989mb cimss steering page already shows the weakness developing quite well.

Link

Link
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Quoting homelesswanderer:
I found it. The flood was compliments of Rosa.

October 24-28, 1994. Southeast and east Texas. The remnants of Pacific Hurricane Rosa dropped between 20 and 40 inches of rain. Hardest hit was Liberty County and northeast Harris County. 10 deaths and $750 million in damage.

It was a doozy. :)


Ill bet that was a mess. The flooding from hurricanes concern me more than the wind. The tidal surge is what gets us here on the island more than the rain. Hurricane Alex back in 2004 caught the local emergency planners and I think the NWS by surprise then. There was no evacuation and there was lots of stranded tourists here with flooded cars and no way to leave the island. My house also got flooded. Since then I have had the house elevated.
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Actually by looking at the steering maps, if it gets stronger, it may not pull north... According the the steering layer maps.
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1681. Relix

Link
Middle Layer steering supports the WSW movement of the Ensembles after it gets pulled north.
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1680. Relix


Still bothers me to no end =P.
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Quoting P451:


Indeed.



The GFS is forecasting another "Humberto" like storm in 170 - 180 hours from now.
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Fred appears to be developing an outflow channel to the north and south, evident by a curved band trying to develop on the north side and one is already evident on the southern and eastern sides. A CDO is quite uniform although still a little small. Microwave imagery indicates that an eye and eyewall is trying to form and once this does he could strengthen a little more quickly, but rapid intensification is not likely due to the SSTs around 28C just below the 29C threshold for RI.
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I found it. The flood was compliments of Rosa.

October 24-28, 1994. Southeast and east Texas. The remnants of Pacific Hurricane Rosa dropped between 20 and 40 inches of rain. Hardest hit was Liberty County and northeast Harris County. 10 deaths and $750 million in damage.

It was a doozy. :)
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blob hunting in the BOC is good today
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My guess is that Fred will turn north while still well east of the islands. A trough to the NW of Fred can be seen dipping down and is already in the subtropical latitudes between 45W and 50W longitude. At this time of the year, troughs become stronger. Fred should soon feel the effects of the trough and begin to turn towards it.

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1670. IKE
TROPICAL WEATHER OUTLOOK
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
800 AM EDT TUE SEP 8 2009

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

THE NATIONAL HURRICANE CENTER IS ISSUING ADVISORIES ON TROPICAL
STORM FRED...LOCATED ABOUT 285 MILES SOUTHWEST OF THE SOUTHERNMOST
CAPE VERDE ISLANDS.

A NON-TROPICAL AREA OF LOW PRESSURE ASSOCIATED WITH A MID- TO
UPPER-LEVEL TROUGH IS LOCATED NEAR THE OUTER BANKS OF 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 LOW WILL PRODUCE LOCALLY HEAVY RAINFALL AND
GUSTY WINDS ALONG THE COAST OF EASTERN NORTH CAROLINA AND
SOUTHEASTERN VIRGINIA TODAY AS IT MOVES SLOWLY NORTH-NORTHEASTWARD.
ADDITIONAL INFORMATION ON THIS SYSTEM CAN BE FOUND IN PRODUCTS
ISSUED BY LOCAL NATIONAL WEATHER SERVICE FORECAST OFFICES.

ELSEWHERE...TROPICAL CYCLONE FORMATION IS NOT EXPECTED DURING THE
NEXT 48 HOURS.

PUBLIC ADVISORIES ON TROPICAL STORM FRED ARE ISSUED UNDER WMO
HEADER WTNT32 KNHC AND UNDER AWIPS HEADER MIATCPAT2.
FORECAST/ADVISORIES ON TROPICAL STORM FRED ARE ISSUED UNDER
WMO HEADER WTNT22 KNHC AND UNDER AWIPS HEADER MIATCMAT2.

$$
FORECASTER BLAKE
Member Since: June 9, 2005 Posts: 23 Comments: 37858
1669. RJT185
Why does the tropical map still show 96 & Fred separately??
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Quoting OcracokeISL:


That's not alot of rain compared to what we had with hurricane Dennis back in 1999. During the 5 days it remained nearly stationary off of the NC coast, I recorded 19.13 inches of rain. Most of that rain 13.17 inches fell in less than 24 hours between the 30th. and 31st of August.


Oh wow! That's when these storms are at their worst. When they are slow moving or stall. Allison is one that comes to mind. Erin as well. While we escaped the worst of Allison being to the east of Houston, we weren't so lucky in 1994. I'm not sure how many inches fell but it flooded areas not usually flooded, even by Ike. It was a real mess and it went on for days. I just recently found out that was caused by a stalled Pacific storm. But I can't remember which.
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Quoting StormW:


And mine! LOL!

Back in abit.


And your forecast :)
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Wouldn't be surprised if Fred is a hurricane by 11pm tonight.

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Quoting homelesswanderer:


I'm glad the rain's tapering off. :)


That's not alot of rain compared to what we had with hurricane Dennis back in 1999. During the 5 days it remained nearly stationary off of the NC coast, I recorded 19.13 inches of rain. Most of that rain 13.17 inches fell in less than 24 hours between the 30th and 31st of August.
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Remember with Erika, there were models that verified like the LBAR so there was some indications to her motion. With Fred, almost all models forecast her to turn north. if yu dont believe the models, look at the water vapor imagery.
Member Since: July 24, 2005 Posts: 407 Comments: 19076
Quoting AllStar17:
Ensembles continue to dip Fred back sharply to the southwest.


1 question Does any1 know why is will turn sharply?

----------------------------------------------
My thinking is the ensemble members show a much weaker system than the operational GFS, so they are less affected by the trough and steared more by the low level flow.

End of each ensemble member, last value is strength in knots:

AL 07 2009090800 03 AP01 132 146N 415W 12
AL 07 2009090800 03 AP02 126 165N 430W 17
AL 07 2009090800 03 AP03 144 138N 442W 13
AL 07 2009090800 03 AP04 144 179N 411W 12
AL 07 2009090800 03 AP05 132 179N 392W 15
AL 07 2009090800 03 AP06 126 203N 383W 14
AL 07 2009090800 03 AP07 144 140N 448W 12
AL 07 2009090800 03 AP08 132 142N 410W 12
AL 07 2009090800 03 AP09 150 177N 432W 10
AL 07 2009090800 03 AP10 108 164N 371W 15
AL 07 2009090800 03 AP11 138 138N 437W 10
AL 07 2009090800 03 AP12 132 161N 420W 13
AL 07 2009090800 03 AP13 144 138N 451W 10
AL 07 2009090800 03 AP14 120 158N 391W 15
AL 07 2009090800 03 AP15 138 134N 426W 10
AL 07 2009090800 03 AP16 120 184N 374W 13
AL 07 2009090800 03 AP17 108 167N 377W 16
AL 07 2009090800 03 AP18 84 177N 383W 21
AL 07 2009090800 03 AP19 132 145N 450W 15
AL 07 2009090800 03 AP20 126 167N 403W 12


End of operational GFS:

AL 07 2009090800 03 AVNO 180 272N 432W 42
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Quoting reedzone:
Ok here's my two cents, Fred does not follow the models.. I mean come on now lol, there just computer models. They might not be right.


Lol. Reed, if Fred tuns out to be another Erika I won't have any hair left to pull out! She gave the models, forecasters and us fits. Lol. What a weird year!
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Quoting OcracokeISL:


Most of the rain is about over with. The low pressure area should stall just north of the Outer Banks for a few day per the NWS forecast.


I'm glad the rain's tapering off. :)
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Quoting homelesswanderer:


Good morning. And that's a lot of rain. I hope you don't get too much more. :( That thing looks terrible. I hope the rain slows and doesn't flood any homes. If it hasn't already. Thanks for letting us know how things are up there. Try to stay dry. :)


Most of the rain is about over with. The low pressure area should stall just north of the Outer Banks for a few days per the NWS forecast.
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Quoting cyclonekid:
Eyewall of Fred???


convincing
Member Since: July 24, 2005 Posts: 407 Comments: 19076
BBL,

Hybrid System dumps heavy rains across the Eastern United States; Fred is born
Member Since: July 24, 2005 Posts: 407 Comments: 19076
Ok here's my two cents, Fred does not follow the models.. I mean come on now lol, there just computer models. They might not be right.
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Eyewall of Fred???
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Quoting ChrisDcane:

1 question Does any1 know why is will turn sharply?


hope this help

Repost from last night

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.





Member Since: July 24, 2005 Posts: 407 Comments: 19076
1653. kachina
Quoting Weather456:
Holiday beach wx must have been miserable.



And the drive to work this morning must be awful as well.
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Quoting ChrisDcane:

1 question Does any1 know why is will turn sharply?


I don't know the answer to that one. However this model shows it and the position of the high above Fred. The Euro is also calling for a negative NAO for the next few days at least. And that means the Bermuda high is placed farther to the west. Which, to me, this shows also. I am glad there's supposed to be another trough to cause a weakness before he could reach land. Hopefully.

Link
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Holiday beach wx must have been miserable.

Member Since: July 24, 2005 Posts: 407 Comments: 19076
Low level swirl (19.1N 56.8W) TAFB has been forecasting to dissipate for days now. Shear becomes somewhat favorable briefly in that general area in 36 hours, at least GFS shear forecast.




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well I feel better knowing I am not the only one confused lol
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1648. kachina
Quoting IKE:


I was agreeing with your comments in the post I replied to. A non-tropical system affected the NC/SC area(heavy rains) and a tropical storm named Fred will never affect anyone. It is peculiar the way it works out.


A friend was telling me about an unnamed storm that caused a lot of flooding and wind damage to her home in Florida (she thought in 1999). She said it did more damage than any of the named storms that year.

So, yes it's odd how that works out.

(and good morning everyone!)
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Quoting AllStar17:
Ensembles continue to dip Fred back sharply to the southwest.

1 question Does any1 know why is will turn sharply?
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1646. RJT185
Quoting OcracokeISL:
Good Morning. I am a cooperative weather ovserver here on Ocracoke Island on the Outer Banks of NC. We have had 7.30 inches of rain since yesterday morning at 0200 09/07/09 until this morning 0630 09/08/09 associated with the low pressure area near the NC coast.


thanks for the update!
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The only difference between a TD and the Carolina low is a name. Same effects without the name.

A "name" adds power and importance to a system but too much emphasis is placed on "named" systems.
Member Since: July 24, 2005 Posts: 407 Comments: 19076
Quoting OcracokeISL:
Good Morning. I am a cooperative weather ovserver here on Ocracoke Island on the Outer Banks of NC. We have had 7.30 inches of rain since yesterday morning at 0200 09/07/09 until this morning 0630 09/08/09 associated with the low pressure area near the NC coast.


Good morning. And that's a lot of rain. I hope you don't get too much more. :( That thing looks terrible. I hope the rain slows and doesn't flood any homes. If it hasn't already. Thanks for letting us know how things are up there. Try to stay dry. :)
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Quoting BahaHurican:
Since when is being in this blog a waste of time? And if it is a waste of time, what are u doing in here "wasting time"? and finally, Who says "they" don't respect 456's work?

I find comments like the one quoted presumptous, ingratiating in a nauseating way, and just plain irritating.

BTW, 456, I'm sure u understand the level of appreciation for your wx opinions the blog generally has.



that's why i didn't even bother with the comment.
Member Since: July 24, 2005 Posts: 407 Comments: 19076
1642. kachina
Quoting Weather456:


96L and Fred are the same systems.

96L developed into TD 7 and TD 7 developed into Fred. Some websites havnt updated their info as yet.


Thanks for sorting that out for me! I was confused too....now I get it! :)
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Good Morning. I am a cooperative weather ovserver here on Ocracoke Island on the Outer Banks of NC. We have had 7.30 inches of rain since yesterday morning at 0200 09/07/09 until this morning 0630 09/08/09 associated with the low pressure area near the NC coast.
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Quoting hurricaneseason2006:
Yesterday centex pointed out that Weather456 is NHC surrogate because he agreed with the NHC that TD 7 would curve more towards the north.

Weather456 posted this after TD 7 1st advisory yesterday. Here he did not agree with the NHC intensity guidance intially and he was right per the 5am advisory.

If I was W456, I would not waste my time here, they don't obviously respect your work.
Since when is being in this blog a waste of time? And if it is a waste of time, what are u doing in here "wasting time"? and finally, Who says "they" don't respect 456's work?

I find comments like the one quoted presumptous, ingratiating in a nauseating way, and just plain irritating.

BTW, 456, I'm sure u understand the level of appreciation for your wx opinions the blog generally has.

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Impressive

Member Since: July 24, 2005 Posts: 407 Comments: 19076
1637. RJT185
no update on the blog yet?? wow
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Quoting zebralove:
thank you I have been cvonfused since they put up td7.....sigh am i ever gonna figure this out?


Don't feel bad Zebralove. When you asked someone to put up a graphic showing both I looked for one. Lol. The td7 threw me too.
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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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