Dr. Jeff Masters' WunderBlog

Tropical Storm Danny likely to be named today
Posted by: Dr. Jeff Masters, 1:25 PM GMT on August 26, 2009 +3
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
Categories: Hurricane
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901. tropicfreak 7:26 PM GMT on August 26, 2009    
Danny



Wave off Africa

Member Since: September 2, 2006 Posts: 110 Comments: 6566
902. AllStar17 7:27 PM GMT on August 26, 2009    
Quoting extreme236:
Once the ULL gets out of the picture we should see a better looking system. I agree it looks rather ugly right now.


Yep. I'll have a complete graphics and blog update later on Danny, Hilda, and Ignacio. Be back in a few minutes.
Member Since: June 29, 2009 Posts: 13 Comments: 5135
903. tropicfreak 7:27 PM GMT on August 26, 2009    
Quoting justalurker:
you guys are scaring me..i think its time for me to drive up to NC..


Where do you live.
Member Since: September 2, 2006 Posts: 110 Comments: 6566
905. hahaguy 7:28 PM GMT on August 26, 2009    
The wave off Africa is looking good.
Member Since: August 12, 2007 Posts: 2 Comments: 2838
906. mikatnight 7:29 PM GMT on August 26, 2009    
new blog!
Member Since: October 18, 2005 Posts: 0 Comments: 1971
907. AllStar17 7:29 PM GMT on August 26, 2009    
I am predicting an orange circle for the AOI (soon to be 93L) off the coast of Africa at 8 pm. Looking good. Be back in a few.
Member Since: June 29, 2009 Posts: 13 Comments: 5135
908. WxLogic 7:30 PM GMT on August 26, 2009    
Quoting AllStar17:
I am predicting an orange circle for the AOI (soon to be 93L) off the coast of Africa at 8 pm. Looking good. Be back in a few.


Correctin... 94L. We already had 93L... :)
Member Since: August 14, 2008 Posts: 4 Comments: 4667
909. cajunmoma 7:30 PM GMT on August 26, 2009    
Quoting K8eCane:
i,m not buying any extra supplies until i hear of a warning...NOT a watch


having been through several hurricanes, may I offer advice...Get your supplies now, if you wait until the panic starts there will be nothing left. It is no fun when there is no gas, water, canned foods, plywood if you need it, generators, etc. Just a suggestion.
910. justalurker 7:30 PM GMT on August 26, 2009    
Quoting tropicfreak:


Where do you live.


sfla.
Member Since: August 18, 2009 Posts: 0 Comments: 157
911. StormSurgeon 7:32 PM GMT on August 26, 2009    
Danny is in trouble! Low level circulation is distended f4om the absolute LOW. No Low, No breeze.
Member Since: September 1, 2007 Posts: 0 Comments: 1792
912. K8eCane 7:34 PM GMT on August 26, 2009    
Quoting cajunmoma:


having been through several hurricanes, may I offer advice...Get your supplies now, if you wait until the panic starts there will be nothing left. It is no fun when there is no gas, water, canned foods, plywood if you need it, generators, etc. Just a suggestion.


i know what ya mean...been thru a few myself
i'm not exactly doing great in the recession so i dont have money to spare for extra plywood or expensive items and my point is i dont think i will need all that for this storm
Member Since: April 26, 2006 Posts: 5 Comments: 2371
913. extreme236 7:37 PM GMT on August 26, 2009    
Quoting StormSurgeon:
Danny is in trouble! Low level circulation is distended f4om the absolute LOW. No Low, No breeze.


Give Danny time. Its not going to look good for a little while.
Member Since: August 2, 2007 Posts: 19 Comments: 19234
914. K8eCane 7:37 PM GMT on August 26, 2009    
Quoting K8eCane:


i know what ya mean...been thru a few myself
i'm not exactly doing great in the recession so i dont have money to spare for extra plywood or expensive items and my point is i dont think i will need all that for this storm


but on second thought anybody reading this that isnt familiar with the drill, its not a bad idea to go ahead
better safe than sorry
Member Since: April 26, 2006 Posts: 5 Comments: 2371
915. Cavin Rawlins 9:19 PM GMT on August 26, 2009    


Member Since: July 24, 2005 Posts: 407 Comments: 19076
916. klaatuborada 10:10 PM GMT on August 26, 2009    
trough does look like it's flattening, but there's a high pressure system to the West of Danny right now. Is it going to scoot over his north and then steer him up East coast? Depending on speed, I think the High pressure could loop him away. What am I not seeing?
Member Since: August 15, 2004 Posts: 23 Comments: 380
917. Orcasystems 10:54 PM GMT on August 26, 2009    
Member Since: October 1, 2007 Posts: 77 Comments: 26077

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About JeffMasters
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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