Developments off the U.S East Coast

By: Dr. Jeff Masters , 10:53 PM GMT on July 16, 2006

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A cold front that pushed off the U.S. East Coast this weekend and stalled out has created an interesting situation to watch. An extratropical or subtropical low has developed along the north portion of the front, about 300 miles southeast of Cape Cod, Massachusetts. Water temperatures are right at the borderline for a tropical storm--about 80 Fahrenheit--so this low is unlikely to develop into a tropical storm as it heads northeast out to sea towards colder water. The low has a large area of heavy thunderstorms on the southeast side of the center of circulation, well removed from the center. This is characteristic of a subtropical storm experiencing significant wind shear. This is the expected development I was referring to this morning in my blog.


Figure 1. Current satellite image of the U.S. East Coast.

The departing low has left behind the tail end of the old cold front over the waters off the South Carolina/North Carolina coast. This old front could serve as the focus for some tropical development over the next few days. Already, some tropical-looking thunderstorms have built over the front, in a narrow area of reduced wind shear of 5-10 knots that has developed. The GFS computer model is indicating that the area of reduced shear will remain. Steering currents are weak, so it is difficult to tell where this tropical blob might go. The models seem to lean towards this system heading northeast up the coast, possibly brushing Cape Hatteras and Nova Scotia later in the week.

Wind shear visualized
I've linked a photo of an odd fog formation a wunderphotographer in Alaska took--I've never seen anything like this photo! It shows very graphically what strong wind shear can do to contort a cloud into strange shapes. The wind speed and direction are different at the bottom of this fog bank than at the top, creating a twisting, shearing effect on the cloud that bends it into strange shapes. Now imagine what strong wind shear can do to a developing tropical depression--ouch!

Jeff Masters

Fog bank in the high Arctic (CypressGrove)
After days of west and north-west winds and heavy fog in Prudhoe Bay Alaska, the wind changed to the south -east....and literally pushed the remaining fog into incredible formations such as the one seen here!
Fog bank in the high Arctic

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186. Skyepony (Mod)
1:35 PM GMT on July 17, 2006
I wanna say 6 hrs, don't have time to look it up.

BBL
Member Since: August 10, 2005 Posts: 226 Comments: 39432
185. thelmores
1:25 PM GMT on July 17, 2006
"could anyone tell me what length of time winds in a tropical system have to remaine to be sustained?"

cas, i do not think there is a "set time", in or to gain td designation, there are several factors, not just wind speed.... although "wind" in general would indicate that alot of the other conditions may also be met...

to answer, its kind of a subjective thing....

hope that makes some sense! :)

Member Since: September 8, 2005 Posts: 0 Comments: 3805
184. Skyepony (Mod)
1:22 PM GMT on July 17, 2006
Beautiful landing:)

refill
8:05 discussion

HIGH AMPLITUDE TROPICAL WAVE IS ALONG 59/60W S OF 22N MOVING W
15-20 KT. THE WAVE SHOWS A WELL DEFINED INVERTED-V CLOUD PATTERN
WITH SCATTERED MODERATE CONVECTION ON THE NORTHERN END OF THE
WAVE AXIS FROM 17N-22N BETWEEN 55W-59W. WAVE IS INTERACTING WITH
AN UPPER LEVEL LOW LOCATED NEAR 23N60W. THIS WAVE IS ALREADY
AFFECTING THE WINDWARD ISLANDS WITH SCATTERED SHOWERS AND
ISOLATED TSTMS. MOISTURE FROM THIS WAVE WILL AFFECT PUERTO RICO
AND THE VIRGIN ISLANDS ON TUESDAY...BRINGING MORE ACTIVE WEATHER
TO THESE ISLANDS.

$$
GR
Member Since: August 10, 2005 Posts: 226 Comments: 39432
183. Cavin Rawlins
1:22 PM GMT on July 17, 2006
dr. jeff has a new blog....
Member Since: July 24, 2005 Posts: 407 Comments: 19076
182. ProgressivePulse
1:20 PM GMT on July 17, 2006
Thanks for the link Pony :-)
Member Since: August 19, 2005 Posts: 5 Comments: 5458
181. partlysunny
1:18 PM GMT on July 17, 2006
Thank you, skyepony, for posting the nasa link. Congrats, Discovery!
Member Since: June 13, 2006 Posts: 0 Comments: 5
180. whirlwind
1:18 PM GMT on July 17, 2006
would anyone have shear maps link to what the levels were last year or previous years past?
179. thelmores
1:14 PM GMT on July 17, 2006
CONGRATS NASA!!!

job well done! ;)
Member Since: September 8, 2005 Posts: 0 Comments: 3805
178. Cavin Rawlins
1:14 PM GMT on July 17, 2006

Today’s Question: What would you describe as good weather?
Member Since: July 24, 2005 Posts: 407 Comments: 19076
177. CFLweather
1:13 PM GMT on July 17, 2006
I hope everyone along the coast has their plywood precut and marked for whichever window it is for. Or have your alumnium sheeting ready, and have your tracks installed for it.

I live in Melbourne, FL and I use 1" plywood now (yes it's a little thick), but I had several large dents in the plywood I was previously using.

The water temps are just too warm at this point for some to make claims that this will be a very slow year. July's shear conditions and masses of African dust are high just like last year. Both of these conditions will relax as we move into the next few weeks.

Everyone said an event like 2004's hurricane season would probably never happen again in our lifetime. 2005 easily eclipsed 2004's hurricane season. Moral of the story, two coincidences so extreme (2004 and 2005 hurricane season) are indeed not consequences at all. By the time 2006 is over, I think alot of people will be re-thinking their choice of location near the coast.
176. whirlwind
1:13 PM GMT on July 17, 2006
hi all,

looks like the EAst Pacific is having all the fun. Storm after storm after storm.

(The East Pacific hurricane season runs from May 15 through November 30, with peak activity occurring during July through September)

Well, the Atlantic season is only 1 month in. Peak is yet to come,maybe just maybe if things fall right(shear), we may just see a hurricane this year.
175. thelmores
1:12 PM GMT on July 17, 2006
BOOM IT WAS! LOL
Member Since: September 8, 2005 Posts: 0 Comments: 3805
174. thelmores
1:11 PM GMT on July 17, 2006
wow, even had a heads up display from inside the orbiter....awesome!
Member Since: September 8, 2005 Posts: 0 Comments: 3805
173. Skyepony (Mod)
1:11 PM GMT on July 17, 2006
sonic BOOM
Member Since: August 10, 2005 Posts: 226 Comments: 39432
172. thelmores
1:09 PM GMT on July 17, 2006
wow, really is cloudy in fla. this morning.......
Member Since: September 8, 2005 Posts: 0 Comments: 3805
171. cas23
1:09 PM GMT on July 17, 2006
could anyone tell me what length of time winds in a tropical system have to remaine to be sustained?
170. refill
1:09 PM GMT on July 17, 2006
The wave NE of the Lesser Antilles look interesting. Any chances to directly affect Puerto Rico??
169. thelmores
1:08 PM GMT on July 17, 2006
wow, wish i could traverse florida that fast.

loose switch??? rats!
Member Since: September 8, 2005 Posts: 0 Comments: 3805
168. thelmores
1:06 PM GMT on July 17, 2006
ft myers... look up NOW!!!!

lol
Member Since: September 8, 2005 Posts: 0 Comments: 3805
167. Skyepony (Mod)
1:06 PM GMT on July 17, 2006
looking at the close up of landing path, I don't think I'll be getting any pics of a fly over.
Member Since: August 10, 2005 Posts: 226 Comments: 39432
166. Skyepony (Mod)
1:04 PM GMT on July 17, 2006
Nash~ if ya got clear skies

I've seen it fly over on this landing path before. I don't know with these clouds.

runway 15 is on the north end so it should be clear of the pop up
Member Since: August 10, 2005 Posts: 226 Comments: 39432
165. thelmores
1:03 PM GMT on July 17, 2006
maybe if the sun wasnt blocking your view, and you knew "exactly" where to look...... at what to look for.....

so your answer is maybe... not! :D

jk..... not sure......
Member Since: September 8, 2005 Posts: 0 Comments: 3805
164. ProgressivePulse
1:01 PM GMT on July 17, 2006
I agree with ya about the East Atl thelmores! Interesting to see though.
Member Since: August 19, 2005 Posts: 5 Comments: 5458
163. thelmores
1:01 PM GMT on July 17, 2006
HEY SKYEPONY, YOU SEE ANYTHING????

they did redes. to alt runway..... small blip! LOL
Member Since: September 8, 2005 Posts: 0 Comments: 3805
162. nash28
1:00 PM GMT on July 17, 2006
Hey guys. Will we be able to see the shuttle at all in St. Pete??
Member Since: July 11, 2005 Posts: 190 Comments: 16972
161. thelmores
12:54 PM GMT on July 17, 2006
appears nasa is diverting to their to their secondary runway in florida, appears a small cell has popped up......

that darn weather! LOL
Member Since: September 8, 2005 Posts: 0 Comments: 3805
160. Skyepony (Mod)
12:53 PM GMT on July 17, 2006
they're watching a pop up at KSC
Member Since: August 10, 2005 Posts: 226 Comments: 39432
159. Skyepony (Mod)
12:51 PM GMT on July 17, 2006
Live feed on the shuttle landing

The flight path had the spacecraft coming in from the south, swooping over the Pacific, Yucatan Peninsula, Gulf of Mexico and across Florida to cap a 5.3 million-mile journey that began on the Fourth of July.

I'll have to go out to see if I can see it, really cloudy though:(
Member Since: August 10, 2005 Posts: 226 Comments: 39432
158. IKE
12:51 PM GMT on July 17, 2006
I think the Atlantic is soon to be getting more active. August is getting close.
Member Since: June 9, 2005 Posts: 23 Comments: 37860
157. IKE
12:50 PM GMT on July 17, 2006
That wave at 21N, 58W is marching westward. Somehow this trough is suppose to turn it more NW...then N.

Things can change though.

Member Since: June 9, 2005 Posts: 23 Comments: 37860
156. thelmores
12:49 PM GMT on July 17, 2006
thanks WSI..... wild! :)

would it seem that perhaps the MJO has moved into the atlantic????
Member Since: September 8, 2005 Posts: 0 Comments: 3805
154. thelmores
12:47 PM GMT on July 17, 2006
O.T.

shuttle landing in 30 min...
http://www.nasa.gov/multimedia/nasatv/
Member Since: September 8, 2005 Posts: 0 Comments: 3805
153. WSI
12:41 PM GMT on July 17, 2006
No, its the truth thelmores.

Don't take my word for it though. :)

Wiki article.


Lake Murray Purple Martin writeup.
151. thelmores
12:38 PM GMT on July 17, 2006
hey PP..... you can use "preview comment" to test your link, before you submit it.....

some weather products can't be directly linked.... in that case, you may have to "capture" the image and post the pic (or link! :p)....

i never get excited about waves until after a day or two off the african coast..... seen way too many "impressive" waves just fizzle out.....

but, in this case, the cape verdes time is upon us, so who knows! ;)
Member Since: September 8, 2005 Posts: 0 Comments: 3805
150. thelmores
12:32 PM GMT on July 17, 2006
hey... you guys pullin my leg..... or what? :D

if not, where the heck all them birds goin..... early bird gets the worm? LOL
Member Since: September 8, 2005 Posts: 0 Comments: 3805
149. ProgressivePulse
12:28 PM GMT on July 17, 2006
Sorry Try This
Member Since: August 19, 2005 Posts: 5 Comments: 5458
148. fredwx
12:25 PM GMT on July 17, 2006
The low South of Nova Scotia sure looks like at least at TD this morning.

Member Since: June 8, 2005 Posts: 221 Comments: 261
147. ProgressivePulse
12:25 PM GMT on July 17, 2006
Nifty wave coming off Africa
Member Since: August 19, 2005 Posts: 5 Comments: 5458
146. WSI
12:21 PM GMT on July 17, 2006
Also, the smaller one near the GA/SC border is on the Savannah River. They nest there too.

I asked a met in the Greer office last week about the images, and he was the one that told me what they were.
145. WSI
12:14 PM GMT on July 17, 2006
"This happens around the lake areas"

That particular lake is Lake Murray, just west of Columbia.
144. StormJunkie
11:59 AM GMT on July 17, 2006
ness = nests
Member Since: August 17, 2005 Posts: 26 Comments: 16874
143. StormJunkie
11:57 AM GMT on July 17, 2006
the doughnut is caused by purple martins leaving there ness around sunrise. This happens around the lake areas. Thanks to WSI for this information.
Member Since: August 17, 2005 Posts: 26 Comments: 16874
142. thelmores
11:53 AM GMT on July 17, 2006
hey.... is that "frock" east of cape cod?

outlasted frick and frack! maybe! LOL

looks pretty impressive this morning, but cooler water awaits our friend! :)
Member Since: September 8, 2005 Posts: 0 Comments: 3805
141. IKE
11:50 AM GMT on July 17, 2006
Somehow this trough/wave...wind up in the Bahamas...then a high builds back in. May be something...a wave or greater, making it into the gulf.
Member Since: June 9, 2005 Posts: 23 Comments: 37860
140. bappit
11:48 AM GMT on July 17, 2006
Thelmores: Had those a week ago in SC and GA. There's a smaller one this morning near the GA SC border. Checked the satellites, dry air aloft, no clouds.

I think they are gravity waves traveling through the temperature inversion. Winds are calm. Question is what kicked it off. Would starting up a power plant or something have that effect? Don't know what's located where these originate.
Member Since: May 18, 2006 Posts: 10 Comments: 6158
139. IKE
11:48 AM GMT on July 17, 2006
That's an impressive wave NE of the islands...greater/lesser antilles moving west. It's suppose to get pulled NW then N by the east coast trough.
Member Since: June 9, 2005 Posts: 23 Comments: 37860
138. thelmores
11:20 AM GMT on July 17, 2006
OT:

anybody know what caused the doughnutt on the greer, sc radar? some kind of ??? small tstorm, temp inversion? just looked strange.....

as for the "broad area" off the sc coast..... we'll have to see if anyconvection refires this morning.....

had a big tsorm last night anout 12:30am near jacksonville (in atlantic), but not much left of that convection......

every body have a good week!

ug... monday!!!
Member Since: September 8, 2005 Posts: 0 Comments: 3805
136. IKE
10:35 AM GMT on July 17, 2006
There is a spin to the clouds east of SC...maybe further south then that. Almost looks like it is east of Jacksonville where it's spinning.
Member Since: June 9, 2005 Posts: 23 Comments: 37860

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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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