Tropical Storm Danny likely to be named today

By: Dr. Jeff Masters , 1:25 PM GMT on August 26, 2009

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First-light satellite images of the tropical wave (92L) a few hundred miles northeast of the Bahama Islands show that the system has developed an organized surface circulation, and 92L will likely be named Tropical Storm Danny later today. This morning's QuikSCAT pass confirms the presence of a surface circulation, and the satellite saw top winds of 50 mph in a cluster of thunderstorms well east of the center. Wind shear has dropped to the moderate range, 10 - 15 knots. The upper-level low 92L is moving underneath has plenty of dry air in it, and the upper low is injecting this dry air into 92L's west side, keeping and heavy thunderstorm activity from developing on that side. The Hurricane Hunters are in 92L, and have found surface winds up to 57 mph so far this morning. NHC continues to give 92L a high (greater than 50% chance) of developing into a tropical depression by Thursday afternoon.


Figure 1. Water vapor satellite image from 8:15 am EDT 8/26/09 showing dry air associated with an upper-level low pressure system to the west of 92L's center of circulation. Image credit: NOAA/SSD.

The forecast for 92L
As 92L continues to plow through the upper low, the low will weaken, and wind shear is expected to decline to the low range, 5 - 10 knots, by tonight. However, the upper-level low will continue to dump dry, cold air into 92L through Thursday afternoon, slowing down development. By Thursday night, when 92L should be several hundred miles off the coast of northern Florida, the upper-level low may be weak enough and far enough away that 92L will find itself in a region with light upper level anticyclonic winds, which would favor more rapid development. Most of the intensity models, including the GFDL, HWRF, and SHIPS model, forecast that 92L will become a hurricane by Friday. However, this favorable environment will not last long, since a strong trough of low pressure will be approaching the U.S. East Coast on Friday. This trough will bring high wind shear of 20 - 30 knots by Friday night. This trough should be strong enough to turn 92L to the north. The models have come into better agreement keeping 92L offshore as it passes North Carolina, though the storm is certainly capable of giving the Outer Banks a direct hit. As 92L passes North Carolina, it should start heading north-northeast, with a second landfall likely Saturday night or Sunday morning somewhere between Massachusetts and Nova Scotia. At that time, 92L is likely to be a strong tropical storm or weak Category 1 hurricane, with winds in the 55 - 80 mph range. It currently appears that 92L will not bring tropical storm-force winds to the Bahamas or to Florida.

Elsewhere in the Atlantic
The models have been inconsistently predicting formation of several tropical waves coming off the coast of Africa over the next week, and I am going to stop mentioning these forecasts until we get two models predicting the same thing, several model runs in a row.

I'll have an update later today.

Jeff Masters

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Quoting pearlandaggie:
doesn't CMC stand for "Can't Model Crap"? has this model's performance been better this year?


yeah, its been altered
Member Since: September 6, 2007 Posts: 0 Comments: 6670
Quoting taistelutipu:
I don't quite understand the requests for removing Felix from the records of the last 20 years. Fair enough, the last Felix was a cat 5 in 2007 and was subsequently retired in spring 2008. So no more Felixes for the future. However, we cannot simply delete the storms named Felix from history. If you choose to delete the memory of Felix along with the name from your mind, alright, but if P451 compiles a statistic for the tendencies where F storms hit, he needs to include them.

Or is there some kind of humour I just don't get? Enlighten me please.


Where did you get this information from? Never heard it before. Har du fott min beskjed?
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Quoting IKE:


Based on the latest GFS...slim.


so based off one model run? cmon ike you know how much they change...
Member Since: September 6, 2007 Posts: 0 Comments: 6670
Quoting adjusterx:
Getting some good winds and getting very dark here in PSL,FL. Anybody over on coast area-Jensen,Jupiter,Stuart hows it look over there? I am on wets side by 95 it's just now getting here but looks ominous to the east.


Not too bad here yet. Only a few clouds but I assume its coming.
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doesn't CMC stand for "Can't Model Crap"? has this model's performance been better this year?
Member Since: September 14, 2007 Posts: 3 Comments: 3963
Why such a big difference between the NAM and GFS? Trying to understand.
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Getting some good winds and getting very dark here in PSL,FL. Anybody over on coast area-Jensen,Jupiter,Stuart hows it look over there? I am on wets side by 95 it's just now getting here but looks ominous to the east.
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but the cmc has had this system skirting much closer than all the other models the whole time...cmc was good with bill...wondering what will play out with Danny...besides...with weaker storms they don't usually have enuf stacking to be pulled by the high level troughs as much as a stronger storm with plenty of vertical stacking
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Quoting IKE:


You're right. 12Z NOGAPS.....is off-shore with Dan the man all the way up the east coast. Also shows a system cruising through the EATL.


I noticed that too... coinciding with GFS but a bit slower.
Member Since: August 14, 2008 Posts: 4 Comments: 5030
Quoting IKE:


Link


Thank you
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Quoting obxnagshead:
Living on the OBX - what does everyone think?


You'll be on the left side of the storm - minimal effects if any
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Quoting mikatnight:


Hi 456! I finally replyed to that email. Better late than never, eh?


yea it was helpful thanks much
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555. IKE
Quoting Rgraham:
OK, what are the chances, based on the latest GFS model, that Danny will come ashore at Hatteras Saturday night?


Based on the latest GFS...slim.
Member Since: June 9, 2005 Posts: 23 Comments: 37860
554. IKE
Quoting caneswatch:
Does anybody have the link to the 12Z GFS?


Link
Member Since: June 9, 2005 Posts: 23 Comments: 37860
456 - How come your tracks are not the same as the historical tracks here?
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OK, what are the chances, based on the latest GFS model, that Danny will come ashore at Hatteras Saturday night?
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Quoting Weather456:


yea


Hi 456! I finally replyed to that email. Better late than never, eh?
Member Since: October 18, 2005 Posts: 4 Comments: 3052
Quoting obxnagshead:
Living on the OBX - what does everyone think?


I think you are lucky - beautiful place.
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Dry air and shear affecting Danny

Tropical Update



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Does anybody have the link to the 12Z GFS?
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Living on the OBX - what does everyone think?
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545. IKE
Quoting WxLogic:
12Z NOGAPS... shifted a bit to the Right.
12Z CMC... also shifted a bit further to Right.

With this right shift it sure looks they're starting to lean on GFS backyard.

Looks like points N of Mass... should get some "direct" effect out of this one... more like Bill did.


You're right. 12Z NOGAPS.....is off-shore with Dan the man all the way up the east coast. Also shows a system cruising through the EATL.
Member Since: June 9, 2005 Posts: 23 Comments: 37860
513. NRAamy 4:55 PM GMT on August 26, 2009
Acemett...Please don't say the f word...

I'm outa here before I get banned by Taz...see ya...
Action: Quote | Ignore User


Quoting NRAamy:
KEEPER..I did not say that Taz banned me...he had nothing to do with it...like duh....
duh
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Due to Dr. Masters expert evaluation of TS Danny, and current imagery analysis...the XtremeHurricanes.com team will not intercept this storm.

However, Hurricane Bill was intercepted in Bermuda this past Friday and an "Experience Hurricane Bill" YouTube production will be created and released at the end of this weekend.

CycloneOz---
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Forecasts indicate September is gonna bring the rain.
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I don't quite understand the requests for removing Felix from the records of the last 20 years. Fair enough, the last Felix was a cat 5 in 2007 and was subsequently retired in spring 2008. So no more Felixes for the future. However, we cannot simply delete the storms named Felix from history. If you choose to delete the memory of Felix along with the name from your mind, alright, but if P451 compiles a statistic for the tendencies where F storms hit, he needs to include them.

Or is there some kind of humour I just don't get? Enlighten me please.
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Quoting DestinJeff:
First signs of some higher cloudtops closer in to the COC (NE side, flowing right to left at about 70W,25N. Click to enlarge.


It looks like its actually wrapping in some moisture - and the water vapor loop shows it pinching off that dry air a bit
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538. IKE
12Z CMC.....has trended east.

CMC seems to over-blow Danny. Then again, it's showing the E and F storms in the CATL.
Member Since: June 9, 2005 Posts: 23 Comments: 37860
KEEPER..I did not say that Taz banned me...he had nothing to do with it...like duh....
Member Since: January 24, 2007 Posts: 317 Comments: 31946
12Z NOGAPS... shifted a bit to the Right.
12Z CMC... also shifted a bit further to the Right.

With this right shift it sure looks they're starting to lean on GFS backyard.

Looks like points N of Mass... should get some "direct" effect out of this one... more like Bill did.
Member Since: August 14, 2008 Posts: 4 Comments: 5030
Thanks NOLA
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That thing is a killer ,ain't it!
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530. IKE
Quoting Acemmett90:

ike its a weather blog what do you expect lol


I understand your point. I just don't need to scroll through 100 different charts.

Member Since: June 9, 2005 Posts: 23 Comments: 37860
Shear has slackened to around 5-15 kts around Danny. Should give it room to develop this afternoon. Might actually look tropical by the 11pm update.
Member Since: August 14, 2008 Posts: 0 Comments: 137
this did not deserved to be named a TS. TD, maybe. The winds associated with the center cant be over 20 knots. I mean just look at it. Anwyauy, be back this evening.



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Quoting Patrap:


Hey Patrap, with this last image you posted, according to Dr. Masters & the NHC the ULL is supposed to migrate to the west and weaken. How much of an effect could this have on the current fix of Danny? Could it "possibly" (note the quotes) steer Danny a little further west? It just appears from the Water Vaport loops that there is another strong swirl much lower that where the official position is located.
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WxLogic I appreciate that. Thank you. Book marked it.
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Quoting NRAamy:
Acemett...Please don't say the f word...

I'm outa here before I get banned by Taz...see ya...


TaZ had nothing to do with it
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Quoting DestinJeff:


do you want the Homepage? color me confused.


yea
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Quoting NOLA2005:


I haven't seen him around much this year, probably because I've too busy to do much lurking, but StormJunkie has a page with tons of information - from the basics on up.....
www.stormjunkie.com
and this one

Link
Member Since: August 18, 2009 Posts: 0 Comments: 157
520. MahFL
Danny is moving WEST, we are all doomed !
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Sorry - I checked the coordinates and now I'm clear on which is which. Carry on. Nothing to see here.

D'oh!

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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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