Dr. Jeff Masters' WunderBlog

Gaston still a threat to redevelop
Posted by: Dr. Jeff Masters, 3:17 PM GMT on September 05, 2010 +3
For the first time since August 22, when Danielle became a tropical storm, there are no named storms active in the Atlantic. An extratropical storm absorbed Tropical Storm Earl last night, bringing an end to the 11-day life of the 2010 season's longest-lived storm. While Earl was mostly a non-event for North Carolina and New England, the storm gave Nova Scotia a solid pounding, reminding us of what could have easily happened to New England had the forecast track deviated slightly to the left. Kudos go to the computer models and NHC, who successfully predicted the path of Earl very accurately four days in advance. As we approach the climatological peak of Atlantic hurricane season, which occurs on September 10, there are no indications that today's break in the action represents a beginning of an extended quiet period in the Atlantic. Indeed, we have two systems that could become tropical depressions in the next day, and we also have model predictions of another storm to come late in the week.


Figure 1. Morning satellite image of the remains of Gaston, approaching the Lesser Antilles Islands.

Gaston near tropical depression status again
The remains of Tropical Storm Gaston, located about 700 miles east of the Lesser Antilles Islands and moving west at about 13 mph, are close to reaching tropical depression status again. Recent satellite imagery shows that Gaston's remains have developed a well-organized surface circulation, but not enough heavy thunderstorm activity to be considered a tropical depression. A large amount of dry air surrounds Gaston's remains on all sides, as seen on water vapor satellite loops. This dry air will continue to be a major impediment to development. The latest SHIPS model forecast predicts shear will remain moderate, 10 - 15 knots, for the next three days, then fall to the low range. The winds creating the shear are coming from the east, where a tongue of dry air has intruded. These easterly winds will be able to drive the dry air into Gaston's core, disrupting it, unless the storm can find a moister environment, or moisten its environment on its own by generating enough heavy thunderstorms. Gaston has managed to develop more heavy thunderstorms near its center of circulation late this morning, but the amount of dry air it is battling is formidable. Even if Gaston does manage to become a tropical depression today, development will be slow over the next few days, due to the dry air. When Gaston passes over or just to the northeast of the Lesser Antilles Islands early Tuesday morning, the storm is unlikely to have more than 50 mph winds. More significant development is possible later in the week, as the atmosphere should be moister for Gaston. Gaston may threaten Puerto Rico on Wednesday, the Dominican Republic on Thursday, and Haiti, Jamaica, and/or the Turks and Caicos Islands by Friday, depending upon the storm's interaction with a trough of low pressure expected to move off the U.S. East Coast later this week. The earlier Gaston develops into a tropical storm, the more likely it is to "feel" the upper-level winds of the approaching trough, and curve more to the northwest. The HWRF model predicts Gaston will develop by Monday, and pass just northeast of the Lesser Antilles Islands Tuesday morning. The GFDL model, on the other hand, delays development until Wednesday, keeping Gaston in the Caribbean. The GFDL has Gaston hitting Jamaica as a strong tropical storm on Friday morning. However, the GFDL forecast is dubious, because on Wednesday and Thursday, Gaston may have an encounter with the high mountains of the island shared by the Dominican Republic and Haiti, Hispaniola, which could easily destroy a system as fragile as Gaston. Gaston has a 70% chance of developing into a tropical depression by Tuesday, according to NHC.

Gulf of Mexico disturbance 90L
A concentrated area of heavy thunderstorms (90L) has developed over the extreme southwestern Gulf of Mexico, in the Bay of Campeche. Satellite imagery shows that this disturbance is disorganized, but has some modest spin to it. The disturbance is under a moderate 10 - 15 knots of wind shear, and has a 60% chance of developing into a tropical depression by Tuesday, according to NHC. The disturbance is headed northwest at 5 - 10 mph, and should bring heavy rains to the Texas/Mexico border region on Monday, according to the latest run of the GFS model. The main impediment to development will be the limited time 90L has over water; the storm will be ashore by Tuesday, which doesn't give it much time to develop.

Elsewhere in the tropics
The GFS and NOGAPS models are predicting development on Thursday of a tropical wave that will emerge from the coast of Africa on Tuesday or Wednesday.

Next post
I'll have an update Monday morning.

Jeff Masters
Sunrise Surf was cranking (RIWXPhoto)
Sunrise Surf was cranking
Post Hurricane Earl surf photos at Newport, RI (RIWXPhoto)
Post Hurricane Earl surf photos at Newport, RI
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1152. WeatherNerdPR 12:24 AM GMT on September 06, 2010    
My avatar finally changed to the Hurricane Earl Radar, again, thanks MH09!
Member Since: July 7, 2010 Posts: 0 Comments: 5464
1153. bayeloi 12:25 AM GMT on September 06, 2010    
Quoting Vero1:


It appears NEXRAD is down.. However NWS radars are up.


NEXRAD Radar's are what the National Weather Service uses pretty much exclusively.
Member Since: August 18, 2009 Posts: 0 Comments: 23
1154. MiamiHurricanes09 12:26 AM GMT on September 06, 2010    
Quoting WeatherNerdPR:
My avatar finally changed to the Hurricane Earl Radar, again, thanks MH09!
No problem!
Member Since: September 2, 2009 Posts: 129 Comments: 19976
1156. flightweatherfan 12:26 AM GMT on September 06, 2010    
pretty cool!
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1157. Tropicaldan 12:26 AM GMT on September 06, 2010    
51W on the NHC 8pm discussion is an error

Clearly it has moved westward since the 2pm discussion when it was also given as 51W, as can be clearly seen on the visible loop

There is no excuse for statistical errors like that when dealing with a potential tropical cyclone so close to land

Poor effort

Dan
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1158. Kristina40 12:27 AM GMT on September 06, 2010    
Things are livening up out in the BOC...

Member Since: June 27, 2010 Posts: 0 Comments: 681
1159. InTheCone 12:27 AM GMT on September 06, 2010    
Quoting futuremet:
My post from last night:

We will see a substantial increase in ex-Gaston's convection activity tomorrow. It is moving into an area of moist air with good diffluent flow aloft. The upper level low will provide good ventilation and will trigger quasi-persistent convection. This system will not move too close to the upper level low to get sheared apart.

If this system enters the Caribbean, it will be capable of pumping a lot of heat into the upper air and generate a vigorous upper level high. The GFS also expects the upper level low weaken slowly as it moves across the Caribbean. The upper level low is the only possible factor I see that can hinder ex-Gaston's tropical cyclognesis. However, this upper level low will actually prove to be beneficial tomorrow.

Water vapor imagery shows that Gaston is starting to interact with the ULL.


Excellent analysis, tomorrow should be interesting!
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1160. BDADUDE 12:27 AM GMT on September 06, 2010    
Quoting futuremet:
My post from last night:

We will see a substantial increase in ex-Gaston's convection activity tomorrow. It is moving into an area of moist air with good diffluent flow aloft. The upper level low will provide good ventilation and will trigger quasi-persistent convection. This system will not move too close to the upper level low to get sheared apart.

If this system enters the Caribbean, it will be capable of pumping a lot of heat into the upper air and generate a vigorous upper level high. The GFS also expects the upper level low weaken slowly as it moves across the Caribbean. The upper level low is the only possible factor I see that can hinder ex-Gaston's tropical cyclognesis. However, this upper level low will actually prove to be beneficial tomorrow.

Water vapor imagery shows that Gaston is starting to interact with the ULL.

If Gaston does survive then he will be directed north in 3-4 days. The weakness in the ridge will catch him and send him between Bermuda and The United States of America.
Member Since: September 3, 2008 Posts: 0 Comments: 602
1161. WeatherNerdPR 12:28 AM GMT on September 06, 2010    
Quoting flightweatherfan:
pretty cool!

What is pretty cool?
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1162. MiamiHurricanes09 12:29 AM GMT on September 06, 2010    
Quoting Kristina40:
Things are livening out in the BOC...

That's a pressure of 1005.8mb. Not bad. What are the coordinates to that buoy?
Member Since: September 2, 2009 Posts: 129 Comments: 19976
1163. Kristina40 12:30 AM GMT on September 06, 2010    
Quoting MiamiHurricanes09:
That's a pressure of 1005.8mb. Not bad. What are the coordinates to that buoy?


22.01N 94.04W

Link
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1164. weathermancer 12:32 AM GMT on September 06, 2010    
Post Earl WX Synopsis:
Earls' eastward bias moved its landfall position to the SE shore, rather than the forecast SW shore of NS... following the warm water.
Member Since: August 29, 2009 Posts: 10 Comments: 481
1165. Goldenblack 12:32 AM GMT on September 06, 2010    
LOL, you still trying to sell that?.......good luck with that prediction....

Quoting BDADUDE:

If Gaston does survive then he will be directed north in 3-4 days. The weakness in the ridge will catch him and send him between Bermuda and The United States of America.
Member Since: June 28, 2010 Posts: 0 Comments: 705
1166. Kibkaos 12:32 AM GMT on September 06, 2010    
Okay guys I was looking at the Caribbean Infrared Loop and it LOOKS like there is something starting up. Please let me know if there is anything to this. We already are watching the Invest near South Texas. It is getting very serious right now.
Caribbean Loop
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1167. BobinTampa 12:32 AM GMT on September 06, 2010    
Are we really arguing 60% v. 70%?? Seriously?
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1168. MiamiHurricanes09 12:33 AM GMT on September 06, 2010    
Quoting Kristina40:


22.01N 94.04W

Link
Odd, on RGB the circulation is to the WNW of that location. Looks like we're dealing with a broad area of low pressure.
Member Since: September 2, 2009 Posts: 129 Comments: 19976
1169. Ameister12 12:34 AM GMT on September 06, 2010    
I see the NHC pulled the ol' switcher-a-roo.

This TWO:
90l: 80%
Gaston: 60%

Last TWO:
90l: 60%
Gaston: 80%
Member Since: August 9, 2009 Posts: 9 Comments: 3518
1170. ElConando 12:35 AM GMT on September 06, 2010    
Quoting MiamiHurricanes09:
Odd, the on RGB the circulation is to the WNW of that location. Looks like we're dealing with a broad area of low pressure.


Well that explains that.
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1171. futuremet 12:35 AM GMT on September 06, 2010    
Quoting BDADUDE:

If Gaston does survive then he will be directed north in 3-4 days. The weakness in the ridge will catch him and send him between Bermuda and The United States of America.


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1172. Kristina40 12:35 AM GMT on September 06, 2010    
Tampico is reporting a 1004.9 now.
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1173. JLPR2 12:36 AM GMT on September 06, 2010    
AL, 09, 2010090600, , BEST, 0, 171N, 524W, 30, 1008, LO

yeah, its at 52W
Member Since: September 4, 2007 Posts: 7 Comments: 7487
1174. ElConando 12:37 AM GMT on September 06, 2010    
Quoting JLPR2:
AL, 09, 2010090600, , BEST, 0, 171N, 524W, 30, 1008, LO

yeah, its at 52W


It is back up to 30 kts?
Member Since: September 6, 2009 Posts: 2 Comments: 3703
1176. Goldenblack 12:37 AM GMT on September 06, 2010    
BDADUDE: this is the layer that will steer Gaston, big high pressure.....thanks futuremet for posting. I too at one point did not know which steering layers to look at for the strength of systems..


Quoting futuremet:


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1177. WeatherNerdPR 12:38 AM GMT on September 06, 2010    
Quoting Kristina40:
Tampico is reporting a 1004.9 now.

O_O
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1178. BDADUDE 12:38 AM GMT on September 06, 2010    
Quoting futuremet:



Your not reading the full picture. Why do you keep showing that map? That map does not show the weakness.
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1179. JLPR2 12:38 AM GMT on September 06, 2010    
Quoting ElConando:


It is back up to 30 kts?


yep, apparently for most of today.
AL, 09, 2010090512, , BEST, 0, 169N, 500W, 30, 1008, LO
AL, 09, 2010090518, , BEST, 0, 170N, 512W, 30, 1008, LO
AL, 09, 2010090600, , BEST, 0, 171N, 524W, 30, 1008, LO
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1180. weathermancer 12:38 AM GMT on September 06, 2010    
Quoting futuremet:




Gaston into Gulf, then hooking over Florida ?
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1181. MiamiHurricanes09 12:38 AM GMT on September 06, 2010    
Quoting Kristina40:
Tampico is reporting a 1004.9 now.
Nah, this has to be a larger scale pressure drop. Notice the 1004-1006mb pressures across Mexico and the Gulf of Mexico. The true central pressure then is near <1003mb, I assume.

Member Since: September 2, 2009 Posts: 129 Comments: 19976
1182. MiamiHurricanes09 12:38 AM GMT on September 06, 2010    
LOL, winds up 5mph and the pressure is down 1mb, yet the NHC dropped the percentage by 20%.

AL, 09, 2010090600, , BEST, 0, 171N, 524W, 30, 1008, LO,
Member Since: September 2, 2009 Posts: 129 Comments: 19976
1184. Ameister12 12:39 AM GMT on September 06, 2010    
I noticed something with most of the storms in the Caribbean/GoMEX.

Alex, TD2, and now 90L are huge storms.

Member Since: August 9, 2009 Posts: 9 Comments: 3518
1185. ElConando 12:39 AM GMT on September 06, 2010    
Quoting MiamiHurricanes09:
Nah, this has to be a larger scale pressure drop. Notice the 1004-1006mb pressures across Mexico and the Gulf of Mexico. The true central pressure then is near <1003mb, I assume.



If you are right then the NHC had good reason to put a 80% chance on it.
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1186. Houstonweathergrl 12:40 AM GMT on September 06, 2010    
BDADUDE why don't you show us your map?????
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1187. WeatherNerdPR 12:40 AM GMT on September 06, 2010    
Quoting MiamiHurricanes09:
Nah, this has to be a larger scale pressure drop. Notice the 1004-1006mb pressures across Mexico and the Gulf of Mexico. The true central pressure then is near <1003mb, I assume.

Quoting MiamiHurricanes09:
Nah, this has to be a larger scale pressure drop. Notice the 1004-1006mb pressures across Mexico and the Gulf of Mexico. The true central pressure then is near <1003mb, I assume.


lol Double-Post!
EDIT: Never mind, you fixed it.
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1188. stormwatcherCI 12:40 AM GMT on September 06, 2010    
Quoting BDADUDE:

Your not reading the full picture. Why do you keep showing that map? That map does not show the weakness.
Doesn't show it cause it's not there.
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1189. Goldenblack 12:40 AM GMT on September 06, 2010    
Okay....I am sorry, I apologize, coming on too hard. It is just when I was last on here this afternoon, you were saying the same thing. The problem is, wherever you are getting your information, you are looking at the wrong steering layer, that is why we keep posting the correct level for predicted strength. A MUCH stronger storm might feel the weakness that you are talking about at the DEEP LAYER.

Quoting BDADUDE:

Your not reading the full picture. Why do you keep showing that map? That map does not show the weakness.
Member Since: June 28, 2010 Posts: 0 Comments: 705
1190. JLPR2 12:41 AM GMT on September 06, 2010    
Quoting BDADUDE:

Your not reading the full picture. Why do you keep showing that map? That map does not show the weakness.


If the map doesn't show a weakness then it means there isn't a any, that is the steering layer map, look at the high, it's solid and there is no weakness in sight, maybe in a few days, once Gaston is already in the Caribbean a weakness could show up but as of now, no.
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1191. stormwatcherCI 12:41 AM GMT on September 06, 2010    
Quoting ElConando:


It is back up to 30 kts?
Pressure down too.
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1192. Ameister12 12:41 AM GMT on September 06, 2010    
Quoting WeatherNerdPR:

lol Double-Post!

Double-post caster!
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1193. MiamiHurricanes09 12:41 AM GMT on September 06, 2010    
SAB up to T1.5 for 90L. We may very well have 10L if TAFB comes in at T2.0 (preferably).

05/2345 UTC 20.6N 95.4W T1.5/1.5 90L
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1194. challengerpr 12:42 AM GMT on September 06, 2010    
05/2345 UTC 17.1N 52.2W T2.0/2.0 GASTON -- Atlantic
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1195. Ameister12 12:42 AM GMT on September 06, 2010    
Quoting MiamiHurricanes09:
LOL, winds up 5mph and the pressure is down 1mb, yet the NHC dropped the percentage by 20%.

AL, 09, 2010090600, , BEST, 0, 171N, 524W, 30, 1008, LO,

Gaston?
Member Since: August 9, 2009 Posts: 9 Comments: 3518
1196. MiamiHurricanes09 12:43 AM GMT on September 06, 2010    
Quoting challengerpr:
05/2345 UTC 17.1N 52.2W T2.0/2.0 GASTON -- Atlantic
Wow, that equates to a 35mph TD. TAFB will probably come in at the same estimate. Ex-Gaston should get re-classified tonight based on those estimates...although I doubt that the NHC actually will.
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1197. JLPR2 12:43 AM GMT on September 06, 2010    
Quoting challengerpr:
05/2345 UTC 17.1N 52.2W T2.0/2.0 GASTON -- Atlantic


eh... *scratches head* now what? XD
Member Since: September 4, 2007 Posts: 7 Comments: 7487
1198. NOSinger 12:43 AM GMT on September 06, 2010    
Quoting BDADUDE:

If Gaston does survive then he will be directed north in 3-4 days. The weakness in the ridge will catch him and States of America.
send him between Bermuda and The United

????
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1199. WeatherNerdPR 12:43 AM GMT on September 06, 2010    
Quoting Ameister12:

Double-post caster!

I just notice them that they double post so they can fix it fast. No harm done. lol
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1200. Skyepony (Mod) 12:43 AM GMT on September 06, 2010    
Water temp up to 86ºF under 90L today..
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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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