Danny weakens; not likely to become a hurricane

By: Dr. Jeff Masters , 7:39 PM GMT on August 27, 2009

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Tropical Storm Danny has weakened. Data from the Hurricane Hunters between 2 - 3 pm EDT showed top winds of just 40 - 45 mph at the surface. Satellite intensity estimates of Danny's strength have also declined since this morning. Danny's satellite appearance is pretty unconventional, and the storm doesn't look much like a tropical cyclone. The low level circulation center is exposed to view, with the heaviest thunderstorms lying several hundred miles east of the center. The center has remained nearly stationary the past four hours, and has grown less distinct. It is possible that a new center will form up to 100 miles to the east, in the region with the heaviest thunderstorm activity. Danny has already undergone several center relocations over the past 12 hours.


Figure 1. Afternoon satellite image at 3:17 pm EDT of Danny, showing the exposed swirl of clouds where Danny's center is, well displaced from the heaviest thunderstorm activity to the east.

The forecast for Danny
There's not much new to report from the latest set of 12Z model runs for Danny. The models have pretty much maintained their previous forecast, calling for Danny to intensify to a Category 1 hurricane by Saturday morning, and pass close to both Cape Hatteras, NC, and Cape Cod, MA. Given that the models did not correctly forecast Danny's current struggles, I believe it is unlikely that Danny will attain hurricane strength. Dry air from the upper-level low that has been keeping Danny disorganized continues to be a problem for the storm, despite the presence of moderate wind shear of 10 - 15 knots. Danny only has about 24 hours of relatively favorable wind shear left, and that is probably not enough time to intensify into a hurricane. By Friday night, a trough of low pressure will approach the U.S. East Coast and bring high wind shear of 20 - 35 knots. Danny will be close enough to this trough that the trough may be able to feed energy to Danny as the trough converts Danny to an extratropical storm. As a result, Danny may not weaken only slowly. A landfall in Cape Cod, eastern Maine, or Nova Scotia as a tropical storm with 45 - 55 mph winds is a reasonable forecast.


Figure 3. Tropical wave 94L off the coast of Africa.

Invest 94L off the coast of Africa
A well-organized tropical wave (94L) lies a few hundred miles southwest of the Cape Verdes Islands, near the coast of Africa. This disturbance continues to look more organized on satellite imagery. Shear is low, about 10 knots, and waters are warm enough to support continued development. The dry Saharan Air Layer is relatively limited in extent and intensity, so dry air may have only a small inhibiting effect on the wave. Expect continued development of this wave as it moves westward over the next few days. NHC is giving this system a medium (30 - 50% chance) of developing into a tropical depression by Saturday. This system is moving rather slowly, 10 - 15 mph. The GFDL and HWRF models both predict 94L will be a Category 1 hurricane five days from now. These models also predict that 94L will take a significant northward jog 3 - 5 days from now, in response to a strong trough of low pressure passing to the north (this is the same trough of low pressure that will be recurving Danny out to sea).

I'll have an update Friday morning.

Jeff Masters

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1195. hydrus
Quoting TexasHurricane:


So, is that bad or means that it won't form or something?
It means at this time of year that the farther south it goes- it can increase the threat to the Lesser Antilles. It can also be to far south were the conservation of angular momentum is not sufficient enough to give the system the spin it needs to become a tropical cyclone. But 10 degrees is enough to get her going. Water temperatures are usually warmer down there too.
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1194. K8eCane
Quoting TexasHurricane:


ok, well I guess none of us on the Gulf coast have anything to worry about....

I don't know, with it that far south I would say it is a possibility for it to go into the Carribean and possibly the GOM. Anyone else?


that far out its a possibility for it to go to nova scotia as well lol
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Strongly agree with you TexasHurricane
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Quoting KerryInNOLA:
Anyoe who thinks 94L Is going to be a GOM storm is either seriously deluded or smoking wishcasters grass. With the pattern of repeating troughs it has ZERO chance to make it to GOM and 25% chance for East Coast. Sorry to let you down.


ok, well I guess none of us on the Gulf coast have anything to worry about....

I don't know, with it that far south I would say it is a possibility for it to go into the Carribean and possibly the GOM. Anyone else?
Member Since: July 2, 2009 Posts: 0 Comments: 2811
1189. JLPR
tropical wave emerging off the coast seems to be holding together nicely

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Quoting mkmand:
94L is at 10N. That is very low for a tropical wave. And it is still moving south of due west.


So, is that bad or means that it won't form or something?
Member Since: July 2, 2009 Posts: 0 Comments: 2811
1186. hydrus
Quoting GatorWX:


What's a gale center?
gale center--A non-tropical area of low pressure associated with winds of gale force. 34 to 47 knots.
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1183. JLPR
the models seem confused and some think west other north =P
lets wait till a TD forms to think were it will go


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1182. hydrus
Quoting reedzone:
Tropical Storm Danny is getting it's act together with some deep convection at the center.

Are you sure that,s the center Reed?
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1180. hydrus
Quoting uhsigep96:
Been reading this blog for awhile now and this is my first post. I know it is early, but is that big mess of red coming behind invest 94 have a chance to form into something?
You bet, This is the time of year were almost anything can happen in the tropics. You would not think so looking at Danny though....lol.
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Tropical Storm Danny is getting it's act together with some deep convection at the center.

Member Since: July 1, 2008 Posts: 13 Comments: 7439
1177. mkmand
94L is at 10N. That is very low for a tropical wave. And it is still moving south of due west.
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Quoting uhsigep96:
Been reading this blog for awhile now and this is my first post. I know it is early, but is that big mess of red coming behind invest 94 have a chance to form into something?


that 2nd wave that is behid 94L is too far N so if it dos do some in it will go out too sea right a way
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Quoting LillySue:
I've been a lurker on this blog since 2002. There have been some unusual storms since then, but I don't think I've ever seen one as weird as Danny.


He will be even weirder if he redevelops into something. Which I don't think we can yet rule out, although he is looking pretty grim at the moment.
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Can anyone explain gfs 00z run, why fall apart the storm that quik in 24 hr by 168 hrs time frame.
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Been reading this blog for awhile now and this is my first post. I know it is early, but is that big mess of red coming behind invest 94 have a chance to form into something?
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1170. xoverau
Adding a happy birthday for Storm. The hard work you and others put into educating the visitors to this site has helped save lives--I can say that with authority, because some of those lives belonged to friends. Thank you.
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at this point in the game anything is possible. The minute you let your guard down is when you get hit. Mother Nature is female as am I (not intended to offend women by no means); with a tendency of doing just the opposite of what is expected/anticipated
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Good night all.. play nice

Blog Update
Reflector site for those at work, which includes Weather456, daily update.
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Quoting StormW:
Thank you all for the Birthday wishes!


If I may add mine please. I really appreciate everything you do here, and read all of your Tropical Updates.

God Bless, StormW
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Quoting Buhdog:
blog freeze


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1163. hydrus
Quoting hydrus:
That is pretty eerie. I never called her.I called the Psychic Friends Network.....I am really,really kidding on that one.
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1162. Buhdog
blog freeze
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CMC lates run places 94L in the Heber box few days from now. and has another system forming of a wave off the coast of Africa.
Member Since: August 1, 2007 Posts: 0 Comments: 206
00Z gfs decrease foward speed by day 4 and 5 and moves 94L Erica on a more west motion can't wait for the finish of that run.
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1159. hydrus
Quoting GatorWX:


They're sea people!! Ahhhhhh, lol. I think they're just referring to storms that recurve early, rather than go into the gulf or make a strike on the east coast of the US. Canada doesn't count, they don't have souls, j/k Keeper!!!
I will settle this. The true definition of a fish storm is........Any, And I mean any , kind of storm with fish in it.
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Friday night Danny should be close to NC/Va. My area is suppose to get rain, wind ect.... The NHC said if Danny moves west, it will bring this storm more inland. 1 day is not enough time to be better prepared. But then storms are hard to predict at times.Tommorow holds the fate of Danny & the EC.
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1157. hydrus
Quoting stillwaiting:
I'm getting a feeling that 94L w/be the TC everyone remembers of this years atlantic TC season....a major headed into the GOM from the SW carib....september w/be active for the SE coastline and the east GOM,IMO
Yep,I know the one you mean.And it usually makes its appearance around Labor Day. Not always,but often.
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1156. GatorWX
Quoting SavannahStorm:


That's almost a haiku. You'd make a great poet.


lol, syllables are tricky!
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Quoting Skyepony:
Taz~94E was 93L. I just got done updating my blog with all the blobs of the world. They have a bunch of floaters on too. All of a sudden we have 10 tropical somethings.. 90W just became 12W too.



thanks

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"erica"....this one w/be the one to watch as the peak of the season approaches.....
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1153. GatorWX
Quoting AussieStorm:

I had someone in here try to correct the definition I gave for a fish storm, they disagreed with my definition and practically gave the same definition.


They're sea people!! Ahhhhhh, lol. I think they're just referring to storms that recurve early, rather than go into the gulf or make a strike on the east coast of the US. Canada doesn't count, they don't have souls, j/k Keeper!!!
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1152. hydrus
Quoting popartpete:
Thanks! Catch this...I called Miss Cleo, bombed one night, years ago, and asked for my free readin'....Guess when it was...September 11, 2001 at 3 a.m....EERIE...but she didn't know anything!
That is pretty eerie! I never called her.I called the Psychic Friends Network.....I am really,really kidding on that one.
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I'm getting a feeling that 94L w/be the TC everyone remembers of this years atlantic TC season....a major headed into the GOM from the SW carib....september w/be active for the SE coastline and the east GOM,IMO
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Thanks homeless, for your answer. I am sending you an email. I am not trying to break the rules by telling you that in the blog, I just don't know how else to let you know because I don't know if it works like regular email or what.

Also, the reason we all like StormW is because he is patient with questions and seems to care about people. There is no need to be ugly; his birthday only comes once a year.
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1149. Skyepony (Mod)
Quoting hydrus:
28 nautical miles sounds alright, the rest suck. like the NOGAPS model, that means in 72 hours NOGAPS would be off it mark by 432 nautical miles. It would be kind of tough to put up watches and warnings,evacuation orders ect, when you have to shift them a couple hundred miles every day and a half. That,s way to big of a GAP.



Most of the time man beats the models & the OFCL track wins. NOGAPS was off by 122nm yesterday, total back of the pack with Bill too.
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Sorry TexNowNM I got that wrong. Quote button decided not to work tonight.
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1147. GatorWX
Quoting hydrus:
Everybody has there opinion about Danny. Well here is mine.Ever since it was declared an invest(. IT. ) has looked like nothing more then a big huge batch of slimy under cooked scrambled eggs and almost every attempt to forecast this mess has been wrong.. And I am sure they found 60 or 70 mph gusts, so what, we get rather frequently during our rainy season thunderstorms. Danny has barely resembled a gale center, let alone a tropical cyclone.I am almost cant believe they sent a recon flight out there. Just a waste of time and fuel.


What's a gale center?
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1146. Skyepony (Mod)
Taz~94E was 93L. I just got done updating my blog with all the blobs of the world. They have a bunch of floaters on too. All of a sudden we have 10 tropical somethings.. 90W just became 12W too.
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Dr. Masters co-founded wunderground in 1995. He flew with the NOAA Hurricane Hunters from 1986-1990. Co-blogging with him: Bob Henson, @bhensonweather

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