Dr. Jeff Masters' WunderBlog

Danny still weak

Posted by: Dr. Jeff Masters, 7:32 PM GMT on August 28, 2009

Tropical Storm Danny continues to look unhealthy, with an exposed low-level center and the main heavy thunderstorms well to the east. The center is oval instead of circular, which may portend that this center will dissipate and a new center will form under the heaviest thunderstorm activity. Danny has more of the appearance of a subtropical storm than a tropical storm on satellite imagery, and this structure will slow down any potential intensification. The amount of heavy thunderstorm activity has increased in the past few hours, though no thunderstorms have formed near the center. The latest Hurricane Hunter mission found one small spot of 45 mph surface winds between 1 - 3 pm EDT today, so Danny may barely qualify as a tropical storm. Danny's center may have begun moving to the north over the past hour, giving confidence that the storm's strongest winds and rain will stay offshore of North Carolina tonight and Saturday morning.

Figure 1. Afternoon satellite image at 3:03 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 center is oval-shaped and not circular, the sign of a weak circulation.

The forecast for Danny
With wind shear at 15 knots this afternoon, and forecast to increase to 20 knots tonight and 30 knots Saturday morning, it is unlikely Danny will be able to strengthen to more than a 50 mph tropical storm. Dry air from the upper-level low that has been keeping Danny disorganized continues to be a problem for the storm, as well. Most of the intensity forecast models continue to insist Danny will strengthen, but they have been doing a very poor job forecasting the intensity of Danny. With Danny's heavy thunderstorms all on the east side of the storm, it is unlikely that North Carolina or New England will feel tropical storm force winds from Danny when it scoots past on Saturday. Large swells from Danny creating high surf along the beaches of New England will be the primary hazard from the storm.

Massachusetts hurricane history
Two tropical storms have affected Massachusetts in the past decade, though neither of these storms brought sustained winds of tropical storm force (39 mph) to the state. Tropical Storm Beryl of 2006 just missed Cape Cod as a weak tropical storm with 45 mph winds. Beryl brought wind gusts to tropical storm force to Nantucket Island, and a 1 foot storm surge. Tropical Storm Hermine hit southeast Massachusetts on August 31, 2004, as a minimum-strength tropical storm with 40 mph winds. No land stations in Massachusetts reported tropical storm force winds during Beryl. The last time Massachusetts measured tropical storm force winds was in 1997 during that year's version of Tropical Storm Danny. Chatham recorded sustained winds of 44 mph, and Nantucket had 43 mph winds. The last time Massachusetts had hurricane force winds was in 1991 during Hurricane Bob, which hit Rhode Island as a Category 2 hurricane. Provincetown, Massachusetts measured sustained winds of 98 mph, gusting to 115 mph, and Buzzard's Bay received a 15 foot storm surge.

Invest 94L
The well-organized tropical wave (94L) mid-way between Africa and the Lesser Antilles Islands continues to be a threat to develop into a tropical depression in the next day or two. Water vapor satellite loops show that 94L has moistened the region surrounding it considerably today, and the storm is not ingesting as much dry air as this morning. However, visible satellite loops show only a small amount of heavy thunderstorm activity near the circulation center, which is broad and elongated from east to west. Shear is low, about 10 knots, and is expected to remain low, 5 - 10 knots, over the next five days. The waters are warm enough to support development, 27°C, and are expected to remain in the 27 - 28°C range over the next five days. It appears that 94L needs another 1 - 3 days to develop a well-formed circulation and become a tropical depression, given the favorable environment. NHC is giving 94L a medium (30 - 50% chance) of developing into a tropical depression by Sunday. Most of the models predict 94L will Be affected by two troughs of low pressure over the next week, which will pull the storm far enough north so that it will miss the Lesser Antilles Islands. It is then probable that 94L will be forced to the west again as the high pressure ridge steering the storm builds back in. The possible long-term threat to the U.S. East Coast is impossible to evaluate at this time.

I'm in New York City this weekend for my cousin's wedding, so will not be blogging again until Monday morning. In my absence, wundergound's severe storms expert, Dr. Rob Carver, will be posting in my blog Saturday and Sunday.

Jeff Masters

Categories: Hurricane

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303. futuremet 10:48 PM GMT on August 28, 2009
Quoting Dakster: Ouch. I don't think anything is going to push through that ridge! Within two days, we will know if this pattern will establish or not. Member Since: July 19, 2008 Posts: 43 Comments: 4049

305. JLPR 10:49 PM GMT on August 28, 2009
Quoting kmanislander: Actually it looks like 11N 35 W !! See QS pass just downloaded QS wow =O I wasn't expecting such a good looking circulation so all it really needs is some convection to get going Member Since: September 4, 2007 Posts: 36 Comments: 5223

306. futuremet 10:50 PM GMT on August 28, 2009
Quoting JLPR: wow =O I wasn't expecting such a good looking circulation so all it really needs is some convection to get going Beauty is only convection deep... Member Since: July 19, 2008 Posts: 43 Comments: 4049

307. jurakantaino 10:50 PM GMT on August 28, 2009
Quoting IKE: KMAN...have you gotten any rain lately...this summer? I'm serious...I haven't seen much in the NW Caribbean all summer! Here in Puerto Rico in the north east caribbean we been having an above average rain fall season this summer. Member Since: July 31, 2008 Posts: 0 Comments: 730

308. JLPR 10:50 PM GMT on August 28, 2009
Quoting serialteg: you downcaster lol ;D xD after looking at that quickscat I think 94L is close to TD status Member Since: September 4, 2007 Posts: 36 Comments: 5223

309. BenBIogger 10:51 PM GMT on August 28, 2009
Quoting iceman55: El Nino.very weak Soon to be moderate El Nino. Member Since: March 19, 2009 Posts: 0 Comments: 1419

310. Patrap 10:51 PM GMT on August 28, 2009
Member Since: July 3, 2005 Posts: 372 Comments: 111605

311. kmanislander 10:51 PM GMT on August 28, 2009
Quoting JLPR: wow =O I wasn't expecting such a good looking circulation so all it really needs is some convection to get going The convection is there, just not over the center LOL. Easterly shear at work Member Since: August 19, 2006 Posts: 0 Comments: 14939

312. mobilegirl81 10:51 PM GMT on August 28, 2009
Quoting iceman55: El Nino.very weak Trade winds getting ready to relax in correlation with a negative NAO. Member Since: August 31, 2008 Posts: 0 Comments: 833

313. Cavin Rawlins 10:52 PM GMT on August 28, 2009
Earliet today Member Since: July 24, 2005 Posts: 407 Comments: 19076

314. IKE 10:52 PM GMT on August 28, 2009
Quoting jurakantaino: Here in Puerto Rico in the north east caribbean we been having an above average rain fall season this summer. Same here. I just don't recall seeing many clouds in the NW Caribbean this entire tropical season. Member Since: June 9, 2005 Posts: 23 Comments: 37044

315. JLPR 10:52 PM GMT on August 28, 2009
Quoting kmanislander: The convection is there, just not over the center LOL. lol true Member Since: September 4, 2007 Posts: 36 Comments: 5223

316. Drakoen 10:52 PM GMT on August 28, 2009
The quickscat pass indicates the system is acquiring a well defined circulation Member Since: October 28, 2006 Posts: 57 Comments: 29010

317. KEHCharleston 10:53 PM GMT on August 28, 2009
Regarding position of 94l As fast as 94l is moving, by the time you post the coordinates, they have changed LOL ; ) Member Since: August 19, 2008 Posts: 6 Comments: 2490

318. kmanislander 10:53 PM GMT on August 28, 2009
Taking a break for a while. Member Since: August 19, 2006 Posts: 0 Comments: 14939

319. Patrap 10:53 PM GMT on August 28, 2009
Member Since: July 3, 2005 Posts: 372 Comments: 111605

322. mobilegirl81 10:53 PM GMT on August 28, 2009
Quoting BenBIogger: Soon to be moderate El Nino. Next 3 weeks may get interesting very fast. Keep guards up. Member Since: August 31, 2008 Posts: 0 Comments: 833

324. KEHCharleston 10:54 PM GMT on August 28, 2009
Quoting futuremet: Beauty is only convection deep... You are on a roll, tonight! LOL Member Since: August 19, 2008 Posts: 6 Comments: 2490

325. Cavin Rawlins 10:56 PM GMT on August 28, 2009
Member Since: July 24, 2005 Posts: 407 Comments: 19076

326. bajelayman2 10:56 PM GMT on August 28, 2009
Quoting P451: 94L: Strong convection that too many are focusing on as the actual wave is at 39-44W -- Low center is at 10.5N 36W with the wave axis stretching northward to 19N. The Low is put on the final frame of the loop. 2PM TROPICAL WAVE WAS ADJUSTED TO ALONG 36W BASED ON THE 1011 MB SURFACE LOW POSITION. THE LOW IS CENTERED NEAR 10.5N36W. THE SYSTEM IS MOVING W NEAR 20 KT OVER THE PAST 24 HOURS. THIS WAVE/LOW COINCIDES WITH A BROAD AREA OF LOW LEVEL CYCLONIC CURVATURE FOCUSED AROUND THE SURFACE LOW AND IS EMBEDDED IN AN AREA OF DEEP LAYERED MOISTURE AS INDICATED BY PRECIPITABLE WATER IMAGERY. ENVIRONMENTAL CONDITIONS APPEAR CONDUCIVE FOR FURTHER DEVELOPMENT OF THIS SYSTEM OVER THE NEXT COUPLE OF DAYS. SCATTERED MODERATE/STRONG CONVECTION IS W OF TE WAVE FROM 8N-12N BETWEEN 39W-42W. SMALL CLUSTERS OF SCATTERED MODERATE/ISOLATED STRONG CONVECTION ARE FROM 11N-15N BETWEEN 34W-39W. Looks like the convection is trying to build around the low, some circulation seen to this. Member Since: August 13, 2007 Posts: 0 Comments: 468

328. JLPR 10:56 PM GMT on August 28, 2009
soo the center is at 11N 35W lol xD if it weren't for the quickscat I wouldn't believe it =P Member Since: September 4, 2007 Posts: 36 Comments: 5223

329. KEHCharleston 10:58 PM GMT on August 28, 2009
Futuremet How about: Beauty is in the "EYE" of the beholden. Member Since: August 19, 2008 Posts: 6 Comments: 2490

330. HurricaneSwirl 10:58 PM GMT on August 28, 2009
Quoting Patrap: could any of you experienced weather ppls out there tell me what that spin is over my house in GA? if that trough was longer that could have pulled a cluadette, i think Member Since: July 7, 2008 Posts: 2 Comments: 3237

333. Cavin Rawlins 10:59 PM GMT on August 28, 2009
Kitty Hawk, North Carolina Member Since: July 24, 2005 Posts: 407 Comments: 19076

334. futuremet 11:00 PM GMT on August 28, 2009
Quoting KEHCharleston: Futuremet How about: Beauty is in the "EYE" of the beholden. Don't get it lol? I am not good at humor....I don't how I came up with that. Member Since: July 19, 2008 Posts: 43 Comments: 4049

336. Patrap 11:01 PM GMT on August 28, 2009
A well formed ULL Exiting to the Ne.. Member Since: July 3, 2005 Posts: 372 Comments: 111605

338. futuremet 11:02 PM GMT on August 28, 2009
Quoting Patrap: A well formed ULL Exiting to the Ne.. A "blackhole" warning should be posted. Member Since: July 19, 2008 Posts: 43 Comments: 4049

339. JLPR 11:02 PM GMT on August 28, 2009
The TAFB people are trying to scare us lol Member Since: September 4, 2007 Posts: 36 Comments: 5223

340. popartpete 11:03 PM GMT on August 28, 2009
Quoting Weather456: A CDO???? Member Since: July 10, 2007 Posts: 0 Comments: 415

341. JLPR 11:05 PM GMT on August 28, 2009
Quoting P451: Relax lol. I compensated for time difference by moving the low further west in the image. I probably should have put it a degree further west though. You can see the circulation for yourself. I have lost track of time today I thought it was earlier. don't worry, not agitated, you might have noticed it with the all the( =P ) and don't worry I tend to loose track of time too , a lot lol Member Since: September 4, 2007 Posts: 36 Comments: 5223

343. flibinite 11:05 PM GMT on August 28, 2009
Bizarre... on the last few visual sat's of Danny, the COC is jumping ENE, like something just exploded it that way, or what convection there is out there is sucking it over and under. Going from stationary to that big move was pretty amazing to watch (unless the satellite messed up the framing, somehow). Jo Member Since: April 14, 2007 Posts: 0 Comments: 256

344. Dakster 11:08 PM GMT on August 28, 2009
Quoting canesrule1: I still go, i have season tickets in the student section :-) SO Iguess there will be a Hurricane in Miami on Sept. 25th! Member Since: March 10, 2006 Posts: 0 Comments: 4938

345. canesrule1 11:09 PM GMT on August 28, 2009
Quoting Dakster: :-) SO Iguess there will be a Hurricane in Miami on Sept. 25th! lol

346. Tazmanian 11:09 PM GMT on August 28, 2009
we may all so have 13E and 14E soon in the E PAC Member Since: May 21, 2006 Posts: 5088 Comments: 111357

347. stormpetrol 11:09 PM GMT on August 28, 2009
If 94L keeps going as it is , it will go into SA Member Since: April 29, 2007 Posts: 0 Comments: 6400

348. Relix 11:11 PM GMT on August 28, 2009
Well that puts 94L in a more favorable position for a N turn. It isn't as southerly as I expected. Go up! Go up! Go uuup!!! Member Since: August 3, 2006 Posts: 0 Comments: 2358

349. PcolaDan 11:13 PM GMT on August 28, 2009
Quoting Patrap: A well formed ULL Exiting to the Ne.. That's the guy that dumped all the rain here yesterday and dropped pressures a fair amount. Member Since: August 22, 2008 Posts: 12 Comments: 6008

350. Dakster 11:15 PM GMT on August 28, 2009
Quoting Relix: Well that puts 94L in a more favorable position for a N turn. It isn't as southerly as I expected. Go up! Go up! Go uuup!!! The 8pm EST model runs will be interesting. Member Since: March 10, 2006 Posts: 0 Comments: 4938

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