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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201. presslord 10:04 PM GMT on August 28, 2009
Quoting Hurricane009: Isabel was a Cat. 2 at landfall you're right Member Since: August 13, 2007 Posts: 0 Comments: 10377

203. JamesSA 10:06 PM GMT on August 28, 2009
Quoting kmanislander: If it maintains the same speed and heading. A couple of big ifs! I would like to see that thing moving a little more north but it hasn't yet. Member Since: August 17, 2009 Posts: 0 Comments: 579

205. Patrap 10:07 PM GMT on August 28, 2009
Once Again I post Dr. Masters Late Sunday afternoon entry from 28 August 2005..it was this post that encouraged many still waffling on staying..to Leave. Without a doubt this entry in itself saved Lives. And for that we and I are forever grateful to Dr. Jeff Masters for it. Katrina stronger than Camille Posted by: JeffMasters, 5:52 PM CDT on August 28, 2005 The 6:30pm EDT NOAA Hurricane Hunter mission found a central pressure of 904 mb, up from the 902 measured at 3:30pm. These pressures make Katrina the fourth strongest hurricane ever, and the strongest hurricane ever observed in the Gulf of Mexico, surpassing Camille. However, the winds of Katrina are 165 mph, far from Camille's 190 mph winds at landfall. Although the pressure has stopped falling, there is no indication that Katrina is about to undergo weakening, like we saw yesterday during her eyewall replacement cycle. When that cycle started, the eye diameter was 9 nm, but the present eye diameter is 28 nm. Eyewall replacement cycles usually begin when the eye shrinks below 10 nm, and there are no indications that Katrina's eye is going to shrink. The list of strongest hurricanes of all time now reads: Hurricane Gilbert (888 mb, 1988) The Great Labor Day Hurricane (892 mb, 1935) Hurricane Allen (899 mb, 1980) Hurricane Katrina (902 mb, 2005) Hurricane Camille (905 mb, 1969) Landfall location and intensity Katrina has continued to expand in size, and now rivals Hurricane Gilbert and Hurricane Allen as the largest hurricanes in size. When hurricanes reach such enormous sizes, they tend to create their own upper-air environment, making them highly resistant to external wind shear. The global computer models are not really hinting at any wind shear that might affect Katrina before landfall, and the only thing that might weaken her is an eyewall replacement cycle. Even if one of these happens in the next 12 hours, the weakest Katrina is likely to get before landfall is a Category 4 hurricane with 145 mph winds. Katrina is so huge and powerful that she will still do incredible damage even at this level. The track forecast has not changed significantly, and the area from New Orleans to the Mississippi-Louisiana border is going to get a catastrophic blow. I put the odds of New Orleans getting its levees breached and the city submerged at about 70%. This scenario, which has been discussed extensively in literature I have read, could result in a death toll in the thousands, since many people will be unable or unwilling to get out of the city. I recommend that if you are trapped in New Orleans tomorrow, that you wear a life jacket and a helmet if you have them. High rise buildings may offer good refuge, but Katrina has the potential to knock down a high-rise building. A 25 foot storm surge and 30 - 40 foot high battering waves on top of that may be able to bring down a steel-reinforced high rise building. I don't believe a high rise building taller than six stories has ever been brought down by a hurricane, so this may not happen Monday, either. We are definitely in unknown waters with Katrina. I have focused on New Orleans in much of my discussions about this storm, but Katrina will do tens of billions in damage all along the coast of Louisiana, Mississippi, Alabama, and Florida. Mobile Bay could well see a 10-foot storm surge. And inland areas will take heavy damage as well; Katrina will still be a hurricane 180 miles inland, and cause widespread flooding throughout the Tennessee Valley. My thoughts and prayers go out to all of you in Katrina's way, and I urge all readers of this blog to do the same. Jeff Masters Member Since: July 3, 2005 Posts: 371 Comments: 111503

206. StormFreakyisher 10:08 PM GMT on August 28, 2009
Those models are from the Storm2k site.By the way does anyone use the Storm2K site? Member Since: May 16, 2009 Posts: 0 Comments: 684

208. kmanislander 10:09 PM GMT on August 28, 2009
Quoting presslord: Dude! You mean...You're not impressed with his broad vocabulary and stunning command of English?!?!?!?!?! No more so than the NHC if anyone from there were ever to read the post LOL Member Since: August 19, 2006 Posts: 0 Comments: 14939

209. Patrap 10:10 PM GMT on August 28, 2009
Atlantic, 2 Sept 2008 Be prepared now as we head into the Heart of the 09 season in the Atlantic.. Member Since: July 3, 2005 Posts: 371 Comments: 111503

210. presslord 10:11 PM GMT on August 28, 2009
Quoting kmanislander: No more so than the NHC if anyone from there were ever to read the post LOL which is a distinct possibility Member Since: August 13, 2007 Posts: 0 Comments: 10377

213. kmanislander 10:12 PM GMT on August 28, 2009
Quoting JamesSA: A couple of big ifs! I would like to see that thing moving a little more north but it hasn't yet. Recent positioning suggests that it is now at 10.2N which would mean a due S of W motion for the last few hours if correct. I am waiting on the QS pass for this evening to see where it actually is. It looks as if the satellite will catch that area. Member Since: August 19, 2006 Posts: 0 Comments: 14939

214. futuremet 10:12 PM GMT on August 28, 2009
Quoting Tazmanian: are you looking for a ban??? You are also looking for one by quoting that post. Please unquote it before it is too late. Member Since: July 19, 2008 Posts: 43 Comments: 4049

217. futuremet 10:13 PM GMT on August 28, 2009
Guess who I saw, folks? :) Your friend Stormtop? Member Since: July 19, 2008 Posts: 43 Comments: 4049

221. presslord 10:15 PM GMT on August 28, 2009
Quoting futuremet: Guess who I saw, folks? :) Your friend Stormtop? Excellent...just outstanding... Member Since: August 13, 2007 Posts: 0 Comments: 10377

222. kmanislander 10:15 PM GMT on August 28, 2009
Quoting WeatherStudent: IDK, Kman, perhaps I guess. Well, I was just wondering why you used the "S" word. It didn't even make sense in the context it was used in so maybe a mistake on your part ?. Perhaps you might want to delete it. Member Since: August 19, 2006 Posts: 0 Comments: 14939

223. violet312s 10:15 PM GMT on August 28, 2009
Even though NC has gotten off lightly of late (with no "majors" hitting) the flooding from Frances (mountains) and Floyd (coast) were extreme and caused much loss of life and property. Some communities never recovered from Floyd. Member Since: June 1, 2007 Posts: 0 Comments: 779

226. serialteg 10:18 PM GMT on August 28, 2009
lol i see the drama has returned Member Since: August 22, 2006 Posts: 2 Comments: 1966

227. kmanislander 10:18 PM GMT on August 28, 2009
Quoting Vortex95: Kman- In America the "S" word in slang can also mean great or amazing. I'll take your word on that, pun intended LOL Member Since: August 19, 2006 Posts: 0 Comments: 14939

229. Snowhaoleboy 10:19 PM GMT on August 28, 2009
Danny will produce very good surf...OH and better surfing form than Bill. With the exception of just a dozen or so spots up and down the east coast, Bill's swell was basically unridable. The long period and large size closed out a lot of breaks (especially sandbars). Unfortunately, not a lot of good point breaks on the east coast. Those that held the Bill swell were crowded. Danny will provide prolific OH surf this weekend for the young and old from FL to ME (although FL has probably already peaked). Hurricane Helene 2006 produced enormous surf north of Cape Cod, and it was not a notably strong storm. Just the right "window." With surfing and hurricanes, bigger is not necessarily better. I'll be out tomorrow AM crack of dwan somewhere in southeast NC. Expect some great fun.

230. adjusterx 10:19 PM GMT on August 28, 2009
Quoting WeatherStudent: Good call there, Pressy. Apparently the golden old saying that would go, ''older and certainly wiser'', those indeed apply to a certain extent, I'd say. Well at least of course, to some and definitely not all. Anyways...G'afternoon Taz and FM. what's up my friends? :) Should went Snoop and put some shazizzle in it. That would of really confused some people.

232. JLPR 10:19 PM GMT on August 28, 2009
not much left of the wave at the coast but the one at 0w is still impressive Member Since: September 4, 2007 Posts: 36 Comments: 5223

233. bingcrosby 10:19 PM GMT on August 28, 2009
If you think about it, he used the "s" word in a context not related to bodily functions, but as a confirmation of the NHC as a great place. Perhaps there is a gap in generational terminology because I hear young people (and future mets) say that phrase every day..... Member Since: August 14, 2008 Posts: 0 Comments: 137

234. futuremet 10:20 PM GMT on August 28, 2009
I am ok WS. It looks like 18Z GFS is diminishing 94L, but might regenerate in 0z as convection builds back. BTW, how was Stormtop? Member Since: July 19, 2008 Posts: 43 Comments: 4049

235. kmanislander 10:21 PM GMT on August 28, 2009
Quoting WeatherStudent: K, I used it as a term of excitement in regards to how my trip went today. I apologies if it offended you, sir. I have mad props and respect for you on here, KMan, you know that, don't you? Unlike certain others. Not really an issue of whether or not I was offended. I have heard much worse but it seems to me that knowing the rules of the road on the blog you would have been more circumspect in your choice of language. Just trying to save you a possible ban, that's all. Member Since: August 19, 2006 Posts: 0 Comments: 14939

237. Chiggy007 10:22 PM GMT on August 28, 2009
I really do NOT see any circulation what so ever above 10N with 94L... I see lots of rotations and swirls at 9N - 38W Anyone agree on here?

238. Tazmanian 10:22 PM GMT on August 28, 2009
doing good SW Member Since: May 21, 2006 Posts: 5088 Comments: 111354

239. kmanislander 10:23 PM GMT on August 28, 2009
Quoting bingcrosby: If you think about it, he used the "s" word in a context not related to bodily functions, but as a confirmation of the NHC as a great place. Perhaps there is a gap in generational terminology because I hear young people (and future mets) say that phrase every day..... I'm off to air brush my avatar. Looking far too old apparently . Member Since: August 19, 2006 Posts: 0 Comments: 14939

240. canesrule1 10:22 PM GMT on August 28, 2009
Quoting kmanislander: Not really an issue of whether or not I was offended. I have heard much worse but it seems to me that knowing the rules of the road on the blog you would have been more circumspect in your choice of language. Just trying to save you a possible ban, that's all. I go to the NHC building all the time, don't know what is so "magical" lol

241. msphar 10:24 PM GMT on August 28, 2009
I don't see a COC in that mass of ITCZ clouds accompanying 94. Is there a center ? I see the movement but not any rotation. Member Since: August 20, 2006 Posts: 0 Comments: 258

242. presslord 10:24 PM GMT on August 28, 2009
At any rate...I think what we're all trying to say here is: No one is interested in your supposed visit to NHC... Member Since: August 13, 2007 Posts: 0 Comments: 10377

244. serialteg 10:25 PM GMT on August 28, 2009
Quoting Chiggy007: I really do NOT see any circulation what so ever above 10N with 94L... I see lots of rotations and swirls at 9N - 38W Anyone agree on here? watch the quickscat, it should reveal the LLC Member Since: August 22, 2006 Posts: 2 Comments: 1966

245. Chiggy007 10:25 PM GMT on August 28, 2009
msphar: Look at 9N - 38W or thereabouts - let me know what you see... :)

246. canesrule1 10:25 PM GMT on August 28, 2009
HAHA! Danny is classified at a tropical wave, lol! 28/1745 UTC 30.1N 75.6W T1.0/2.0 DANNY

247. kmanislander 10:25 PM GMT on August 28, 2009
Quoting Chiggy007: I really do NOT see any circulation what so ever above 10N with 94L... I see lots of rotations and swirls at 9N - 38W Anyone agree on here? Remember that 94L still has a broad circulation. Trying to identify one area of a defined low center will be next to impossible for the time being. There are often many areas of rotation within a broad low where you have a system that has not yet consolidated a center. Member Since: August 19, 2006 Posts: 0 Comments: 14939

249. Orcasystems 10:26 PM GMT on August 28, 2009
Quoting WeatherStudent: Lesson learned, thank you. Why don't you post the whole thing on your blog.. save yourself the bother of repeating it numerous times? Member Since: October 1, 2007 Posts: 77 Comments: 26077

250. will40 10:27 PM GMT on August 28, 2009
Quoting canesrule1: HAHA! Danny is classified at a tropical wave, lol! 28/1745 UTC 30.1N 75.6W T1.0/2.0 DANNY One child already missing in the surf from Danny do you think that is funny? Member Since: September 19, 2005 Posts: 2 Comments: 3439

251. presslord 10:27 PM GMT on August 28, 2009
Quoting Orcasystems: Why don't you post the whole thing on your blog.. save yourself the bother of repeating it numerous times? spoken by yet another wise, bitter old man...spot on Grandpa... Member Since: August 13, 2007 Posts: 0 Comments: 10377

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