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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We'll just have to wait and see how it unfolds
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A series of trough will help pull 96L north. But becuz these are alternating between ridge and trough, a NW motion isnt going to be consistent.

From my blog

My thinking is that the storm will continue west and take a gradually turn towards the northwest through days 4-5. Afterwhich, the storm may fluctuate between west-northwest and north-northwest through days 5-7 due to successive trough and ridge flows.
Member Since: July 24, 2005 Posts: 407 Comments: 19076
Quoting futuremet:
It is still more likely that TD7 will recurve out to sea, as a series of trough will create weaknesses along the A/B high.

I just don't see how it can bypass such a weakness.



It can bypass it if the Azores high strengthens back in time, which is why the CMC and other models stalls it and moves it back west. One thing is for sure, the chance of a U.S. impact is low, for the model ensemble shows another prolonged troughing pattern.
good post
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Quoting weatherblog:


Do you think that scenario is possible or are you thinking otherwise?


It is possible and while the GFS loses the system's vortex it is showing that possibility as well. The ECMWF, however, continues to take this system out to sea early. That certainly cannot be ignored considering it is one of the best performing models this year.
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It is still more likely that TD7 will recurve out to sea, as a series of trough will create weaknesses along the A/B high.

I just don't see how it can bypass such a weakness.



It can bypass it if the Azores high strengthens back in time, which is why the CMC and other models stalls it and moves it back west. One thing is for sure, the chance of a U.S. impact is low, for the model ensemble shows another prolonged troughing pattern.
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Quoting TheDawnAwakening:
The Central Atlantic Ocean infrared imagery is beginning to show 96L's western circulation. I believe by tomorrow the full circulation will be on the satellite imagery. Also there is no active floaters on the SSD site for 96L or 07L.


They can't put up a GOES-12 floater until the system comes at least mostly into the satellite's view, as you mentioned it's starting to do.
Member Since: November 24, 2005 Posts: 635 Comments: 26548
Quoting NARCHER:
don't waist your time on this one. in a normal season yeas but this is going to the north in 72hr will need your talent later maybe in oct when the us may get a threat.


I put forth the same effort with every system since I care about all people out there, not just my local interests. Given the current GFS ensembles, I wouldn't be so quick to definitively say that this will go north.
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Quoting Drakoen:


That is true and the ensemble GFS usually performs better than the operational GFS. The system would have to increase it's diameter at 500mb to get caught under the ridge earlier.


The circulation at 500mb is pretty strong right now. It is a pretty stacked system.
Member Since: October 21, 2008 Posts: 243 Comments: 3673
Yay! We have something for all the xxxxCasters to talk about.
Member Since: March 10, 2006 Posts: 0 Comments: 10034
My linited knowledge tells me area in SW GOMEX
bears watching too see if a surface low develops along this inverted trough..anyoone have any thoughts?
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The Central Atlantic Ocean infrared imagery is beginning to show 96L's western circulation. I believe by tomorrow the full circulation will be on the satellite imagery. Also there is no active floaters on the SSD site for 96L or 07L.
Member Since: October 21, 2008 Posts: 243 Comments: 3673
Quoting Weather456:


unlikely

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


I suppose so.
But what is with the eye like feature.
Member Since: August 9, 2009 Posts: 10 Comments: 4898
Quoting presslord:
Ameister...we're all weather weenies...extreme nature of most any sort is pretty much fair game...especially when the tropics are kinda quiet...
Not quite anymore TD7 is born.
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Quoting TheDawnAwakening:
Drak, the ensembles could be on to something. With a potentially stronger system it could continue west without any effects felt from the upper level low to the north. Since 07L is developing Spiral banding it has the conditions favorable for possible a little more rapid intensification as well as the lowering of the minimum central pressure. Erika never had spiral banding.


That is true and the ensemble GFS usually performs better than the operational GFS. The system would have to increase it's diameter at 500mb to get caught under the ridge earlier.
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07L has the potential to pull an Ike. I believe the models see a high pressure system building swward.
Member Since: October 21, 2008 Posts: 243 Comments: 3673
Quoting Weather456:
Hello Levi!


Hey there 456 :)
Member Since: November 24, 2005 Posts: 635 Comments: 26548
Quoting cchsweatherman:
TROPICAL DEPRESSION SEVEN
18Z Statistical Model Runs


18Z Early Dynamical Model Runs
don't waist your time on this one. in a normal season yeas but this is going to the north in 72hr will need your talent later maybe in oct when the us may get a threat.
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From the NRL website...96L has become TD 7 and TD 15E is now TS Linda.

IT IS OFFICIAL!!!! *clapping*
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Welcome back Levi!
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Quoting ElConando:
Ike you got mail you understand when you read it.
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Quoting Drakoen:


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


The GFS ensembles have continued to be persistent in showing this trend. In my experience, the ensembles usually do rather well in showing future general trends, so this is quite interesting.
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Quoting Drakoen:


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


Do you think that scenario is possible or are you thinking otherwise?
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Drak, the ensembles could be on to something. With a potentially stronger system it could continue west without any effects felt from the upper level low to the north. Since 07L is developing Spiral banding it has the conditions favorable for possible a little more rapid intensification as well as the lowering of the minimum central pressure. Erika never had spiral banding.
Member Since: October 21, 2008 Posts: 243 Comments: 3673
Hello Levi!
Member Since: July 24, 2005 Posts: 407 Comments: 19076
Quoting Ameister12:
I think 15E might be going under rapid intensification.

There seems to be an eye like feature.


unlikely

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

Member Since: July 24, 2005 Posts: 407 Comments: 19076
what is this a wather blog or guss on WS blog??
Member Since: May 21, 2006 Posts: 5091 Comments: 114728
Quoting TheDawnAwakening:
Where is the blog? I mean there should be a lot of activity during the peak of hurricane season with a newly developing tropical cyclone now.


I agree, but the reason there isn't is because apparently 96L looks to be going out to sea. That's why there's more talk of a sheared disturbance in the GOM that'll probably never form than TD 7.
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If future Fred can develop into a strong cyclone and a large cyclone and the low to the north is weak enough, then Fred could continue to move westward and not be influenced by the low.
Member Since: October 21, 2008 Posts: 243 Comments: 3673


Ensemble members continue to feature the system heading back west or even WSW.
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Quoting Ameister12:
I think 15E might be going under rapid intensification.

There seems to be an eye like feature.


An eye-like feature like that is more likely caused by dry air messing with its inner structure. Notice the stratocumulus field to the NW on that image. That's indicating a dry and stable airmass associated with cool SSTs. Strengthening of 15E is unlikely.
Member Since: November 24, 2005 Posts: 635 Comments: 26548
Ike you got mail you understand when you read it.
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Im so confused..is it 96L,0L7, 007,or TD-7..and should I sauce the Chicken again or start the wienies?

The Shrimps are beginning to Burl too.

Smells like a Holiday here.

Member Since: July 3, 2005 Posts: 421 Comments: 127566
Hey ya'll, please don't get WeatherStudent banned? I like to click on his avatar every once in a while for a good laugh.
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Quoting Ameister12:
I think 15E might be going under rapid intensification.

There seems to be an eye like feature.


unlikely

when ever a tropical cyclone moves into a stratocumulus field in signifies it is moving to a stable enviroment
Member Since: July 24, 2005 Posts: 407 Comments: 19076
Wow, WS is Drakoen? I hope not! Drakoen's one of my favorite bloggers.
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Where is the blog? I mean there should be a lot of activity during the peak of hurricane season with a newly developing tropical cyclone now.
Member Since: October 21, 2008 Posts: 243 Comments: 3673
Is there any chance TD7 could get strong enough (hurricane status) that when it interacts with the low from the north it will push it more to the east than the north? It looks like he's got potential to grow rapidly before the low starts moving down.
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645. IKE
Quoting sammywammybamy:


Whats he Doing.. ive had him ignore since the beginneing


Being himself.
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futuremet: you got mail
Member Since: May 21, 2006 Posts: 5091 Comments: 114728
Quoting nrtiwlnvragn:
Taz?





yup there TD 7
Member Since: May 21, 2006 Posts: 5091 Comments: 114728
Quoting WeatherStudent:
Let him be, Ice. He's asking for a ban. 456, why were you comparing me to Drakoen on here, a short while ago, my friend? :(


you just let your yourself out...I never said you were Drakoen, read my post again.

I said of an existing member.

The truth is out of the bag.
Member Since: July 24, 2005 Posts: 407 Comments: 19076
Futuremet - Bonswa!

Komon ou ye?

Bon travay on youtube.
Member Since: March 10, 2006 Posts: 0 Comments: 10034
I see 96L has continued to improve in organization to become 07L with microwave images showing multiple low level spiral bands.
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I think 15E might be going under rapid intensification.

There seems to be an eye like feature.
Member Since: August 9, 2009 Posts: 10 Comments: 4898

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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.