Dr. Jeff Masters' WunderBlog

TD 2 nearly dead; African disturbance 90L gathering strength
Posted by: Dr. Jeff Masters, 2:38 PM GMT on August 13, 2009 +4
Tropical Depression Two is near death, but is still worth watching. The dry, Saharan air to the north and west of the depression, combined with moderately high levels of wind shear of 15 - 20 knots, have almost completely destroyed all of TD 2's heavy thunderstorms. Satellite loops of the storm show a well-formed circulation, but almost no heavy thunderstorm activity.

Wind shear over TD 2 is expected to remain in the modereate range, 10 - 20 knots, over the next five days. Sea Surface Temperatures (SSTs) are 27°C, but will warm to 28°C three days from now. There is plenty of dry, stable air from the Saharan Air Layer (SAL) to to TD 2's north and west that will continue to cause the storm problems. The relatively cool SSTs and dry air mean that TD 2 will not be able to intensify quickly, and some of the models indicate the TD 2 may get destroyed in the next day or two. However, several models still predict TD 2 will become a tropical storm. The HWRF model predicts TD 2 will become a hurricane five days from now, but this seems unlikely given the dry air and relatively high wind shear affecting the storm.


Figure 1. Tropical Depression Two (left side of image) and tropical wave 90L (right side of image).

African tropical wave 90L
A strong tropical wave with a large circulation and plenty of heavy thunderstorm activity is a few hundred miles south of the Cape Verdes Islands, off the coast of Africa. NHC dubbed this disturbance 90L this morning. This morning's QuikSCAT pass shows that 90L has a very large circulation, and top winds of about 30 mph. Satellite imagery from the European METEOSAT satellite show that the heavy thunderstorms associated with 90L are in two major bands, to the north and to the south of the center. There is no heavy thunderstorm activity near the center yet, and this would have to happen before 90L can be named Tropical Depression Three. Water vapor imagery shows that since 90L is forming several hundred miles south of the dry air of the Saharan Air Layer (SAL), the storm should not be affected by dry air and dust as much as Tropical Depression Two has been. Wind shear is about 20 knots over 90L, and is forecast to remain in the moderate range, 10 - 20 knots, over the next five days. Sea Surface Temperatures are about 28°C, and will remain in the 27 - 28°C range the next five days, which are high enough above the 26°C threshold for tropical cyclone formation to allow some slow development to occur. The GFS and ECMWF models continue to predict the development of this wave, though they are now less aggressive about intensifying it than they were in earlier runs. The consensus among the reliable HWRF, GFDL, GFS, and ECMWF models is to bring 90L to point near or just north of the northernmost Lesser Antilles Islands 6 - 8 days from now. The storm could be at hurricane strength by then, as forecast by the SHIPS intensity model.

I'll have an update Friday morning.

Jeff Masters
Categories: Hurricane
  Permalink | A A A
Reader Comments
Display: 0, 50, 100, 200 Sort: Newest First - Order Posted
Viewing: 151 - 201

Page: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30 | 31 | 32 | 33 | 34 | 35 | 36 | 37 | 38 | 39 | 40 | 41 | 42 | 43 | 44 | 45 | 46 | 47 | 48 | 49 | 50 | 51 | 52 | 53 | 54 | 55 | 56 | 57 | 58 | 59 | 60 | 61 | 62 | 63 | 64 | 65 | 66 | 67 | 68 | 69 | 70 | 71 | 72Blog Index

151. BenBIogger 3:24 PM GMT on August 13, 2009    
Member Since: March 19, 2009 Posts: 0 Comments: 1419
154. apocalyps 3:25 PM GMT on August 13, 2009    
Quoting Acemmett90:

i know

I dont know.
Member Since: May 10, 2007 Posts: 0 Comments: 960
158. TampaSpin 3:26 PM GMT on August 13, 2009    
So will Bill need a SEx change or not...LOL
Member Since: September 2, 2007 Posts: 175 Comments: 19747
159. Drakoen 3:26 PM GMT on August 13, 2009    
Quoting P451:


Already up.

Link


There's a floater on the SSD site
Member Since: October 28, 2006 Posts: 57 Comments: 29010
160. PSL2007 3:26 PM GMT on August 13, 2009    
Quoting Acemmett90:

i know


So yesterday's predicted Bill will become Ana.
161. 7544 3:27 PM GMT on August 13, 2009    
looks like the strom everyone thought will be called bill will be ana after all which is 90l
Member Since: May 6, 2007 Posts: 0 Comments: 5925
163. nrtiwlnvragn 3:27 PM GMT on August 13, 2009    
Update bouy at 12N 23W as of 10AM EDT

Member Since: September 23, 2005 Posts: 11 Comments: 8938
165. canesrule1 3:28 PM GMT on August 13, 2009    
WOW! i just calculated that 90L is 1081.8 miles in diameter! in comparison Gilbert in 88' was around 800 miles in diameter at peak intensity!
166. CaneWarning 3:28 PM GMT on August 13, 2009    
Quoting nrtiwlnvragn:
Update bouy at 12N 23W as of 10AM EDT



Pressure falling
Member Since: April 26, 2009 Posts: 3 Comments: 3667
167. canesrule1 3:28 PM GMT on August 13, 2009    
Quoting Acemmett90:

crap can you say andrew
ANDREW, lol
168. canesrule1 3:29 PM GMT on August 13, 2009    
Quoting TampaSpin:
So will Bill need a SEx change or not...LOL
i think sex change will be needed, lol.
170. WxLogic 3:29 PM GMT on August 13, 2009    
12Z GFS... running. Initializing TD#2 as a 1012MB Low and 90L as a 1011MB Low.

Let's see how it wants to develop these...
Member Since: August 14, 2008 Posts: 4 Comments: 4667
171. canesrule1 3:29 PM GMT on August 13, 2009    
Quoting CaneWarning:


Pressure falling
very anticipated i think it will be by 1007 millibars before 5PM EST.
173. hurricanejunky 3:30 PM GMT on August 13, 2009    
90L is monstrous! Good Lord. If that circulation stays that size and is able to develop it will rival Ike or Floyd. Pretty ominous looking Cape Verde system.
Member Since: August 28, 2006 Posts: 6 Comments: 2875
174. FloridaTigers 3:30 PM GMT on August 13, 2009    
Why is every CV storm headed in a W or WNW direction the next omg "Andrew"?
Member Since: May 17, 2009 Posts: 0 Comments: 559
175. palmbaywhoo 3:30 PM GMT on August 13, 2009    
what is a floater
Member Since: August 18, 2008 Posts: 0 Comments: 331
178. canesrule1 3:31 PM GMT on August 13, 2009    
Quoting Acemmett90:

it trying to hit the whole east coast at once CRAP
LOL, i think this will be the largest hurricane ever recorded once it reaches peak intensity, i think instead of ANA, it should be called Typhoon TIP senior.
179. Mclem1 3:31 PM GMT on August 13, 2009    
What are the odds we see TD3 today? All that false Ana talk yesterday made my mouth water now I'm very anxious for something to strengthen!
Member Since: August 12, 2009 Posts: 0 Comments: 48
180. sky1989 3:31 PM GMT on August 13, 2009    
There have been many "Ana" storms, (1979, 1985, 1991, 1997, and 2003)and none of them have been bad. This one, if it becomes Ana has the chance to be an exception, but let's hope not.
Member Since: June 4, 2008 Posts: 0 Comments: 88
181. hurricanejunky 3:31 PM GMT on August 13, 2009    
Quoting Acemmett90:

crap can you say andrew


No that's Ana-drew
Member Since: August 28, 2006 Posts: 6 Comments: 2875
182. Cotillion 3:32 PM GMT on August 13, 2009    
That circulation will likely tighten up though as it's still kinda broad.
Member Since: August 23, 2008 Posts: 7 Comments: 5300
183. FloridaTigers 3:32 PM GMT on August 13, 2009    
Quoting hurricanejunky:
90L is monstrous! Good Lord. If that circulation stays that size and is able to develop it will rival Ike or Floyd. Pretty ominous looking Cape Verde system.


Remember, when Ike was in the CATL it was a pretty small, tightly wound system. It wasn't until it hit the Gulf that it exploded in size.
Member Since: May 17, 2009 Posts: 0 Comments: 559
184. canesrule1 3:32 PM GMT on August 13, 2009    
Quoting hurricanejunky:
90L is monstrous! Good Lord. If that circulation stays that size and is able to develop it will rival Ike or Floyd. Pretty ominous looking Cape Verde system.
yeah, i calculated its over 300 miles bigger in diameter than Gilbert 88' at peak intensity!
185. apocalyps 3:33 PM GMT on August 13, 2009    
Quoting canesrule1:
WOW! i just calculated that 90L is 1081.8 miles in diameter! in comparison Gilbert in 88' was around 800 miles in diameter at peak intensity!


Dont panic and stop making people afraid.
TD2 and 90L are both going west and i know this for sure because the NHC has called me.
The men who called me named WESTwood,the brother of Clint EASTwood.
Member Since: May 10, 2007 Posts: 0 Comments: 960
186. StormFreakyisher 3:32 PM GMT on August 13, 2009    
Herbert box alert!But NHC projects it to be a depression by then other models still take it as a TS over the herbert box.
Member Since: May 16, 2009 Posts: 0 Comments: 684
187. ssmate 3:32 PM GMT on August 13, 2009    
Ana went from a cute little thing to a Big Gal. They need lovin too!
Member Since: July 17, 2008 Posts: 0 Comments: 347
189. BenBIogger 3:33 PM GMT on August 13, 2009    
Member Since: March 19, 2009 Posts: 0 Comments: 1419
190. canesrule1 3:33 PM GMT on August 13, 2009    
Quoting Mclem1:
What are the odds we see TD3 today? All that false Ana talk yesterday made my mouth water now I'm very anxious for something to strengthen!
i think TD today is about 40% TD before Saturday 99.99%
193. AllBoardedUp 3:33 PM GMT on August 13, 2009    
Quoting Acemmett90:

yah it would be the end of nola
You people just put a guy on the ignore list for doing the same thing. The only difference that I see is that he was joking. And if he wasn't I can't see how such intelligent people on the site would fall for this. Before you call me a troll I have been on this site for since 2004, I just don't comment very often. I try to learn what I can and I really do enjoy this site. But people, take a chill pill.
Member Since: July 25, 2008 Posts: 0 Comments: 585
195. stormsurge39 3:36 PM GMT on August 13, 2009    
StormW is wind shear the only thing you see from keeping developement in the gulf? Also how many shear runs will you have to see before you give it a higher chance than low? Im trying to stay on top of this so it doesnt catch me off guard here on the gulf coast. Thank you for your reports.
196. canesrule1 3:34 PM GMT on August 13, 2009    
Quoting Acemmett90:

lol
quick tell ws to get off the east coast in all serousness this is bad
yeah, i think the NHC is starting to pee in there pants with the models coming towards us and a huge storm like this.
198. TheDawnAwakening 3:35 PM GMT on August 13, 2009    
90L will have a harder time strengthening quickly then TD2. Reasoning is the sheer difference in their COC size. TD2 needs to defeat the dry air which seems like its trying to do with the sporadic convection and 90L is trying to strengthen, but with no convection around or near its center it will be hard to do so. Something to watch closely for sure.
Member Since: October 21, 2008 Posts: 215 Comments: 3159
199. 7544 3:35 PM GMT on August 13, 2009    
Quoting P451:
TD2 with yet another comeback. Seems to have been the story with this system time and again.



yeap the race is on who will get the name ana first 99l or 90l stay tuned this should be fun
Member Since: May 6, 2007 Posts: 0 Comments: 5925

Viewing: 151 - 201

Page: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30 | 31 | 32 | 33 | 34 | 35 | 36 | 37 | 38 | 39 | 40 | 41 | 42 | 43 | 44 | 45 | 46 | 47 | 48 | 49 | 50 | 51 | 52 | 53 | 54 | 55 | 56 | 57 | 58 | 59 | 60 | 61 | 62 | 63 | 64 | 65 | 66 | 67 | 68 | 69 | 70 | 71 | 72Blog Index

New Comment
Community Standards Policy Comments will take a few seconds to appear.
Post Your Comments
Please sign in to post comments.
Not only will you be able to leave comments on this blog, but you'll also have the ability to upload and share your photos in our Wunder Photos section.
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.

Local Weather
Mostly Cloudy
41 °F
Mostly Cloudy
Community Activity