Gaston still a threat to redevelop

By: Dr. Jeff Masters , 3:17 PM GMT on September 05, 2010

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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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Thanks...
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Quoting TexasHurricane:


ok, I don't even know what TCHP is. I guess we will need to keep an eye on Gaston if he can make it through the Caribean and into the GOM...


Tropical Cyclone Heat Potential(TCHP), or how much deep warm water is available for a tropical system & there is plenty in the carrib....

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StormW, What do you think of the NAM for 90L?
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427. IKE
Latest ECMWF @ 96 hours...Link
Member Since: June 9, 2005 Posts: 23 Comments: 37860
I'll be back when evening hits. ;)
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Quoting StormW:


TCHP = Tropical Cyclone Heat Potential.

Values at and above 80 kJ/cm2 allow for rapid intensification of hurricanes if everything else is favorable.


oh, thanks storm. :)
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Gusting to near TS strenght here...check out the dewpoint...thought some of you would get a kick out of that. Of course our fire danger is extreme today. :^(

Pocatello, Pocatello Regional Airport
Last Update on 05 Sep 11:53 MDT


Partly Cloudy

65°F
(18°C) Humidity: 23 %
Wind Speed: WSW 24 G 36 MPH

Barometer: 29.94 in (1009.80 mb)
Dewpoint: 26°F (-3°C)
Visibility: 10.00 Miles
More Local Wx: 3 Day History:



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Quoting Cotillion:


Thursday at the Superdome.

Ah!
Thanks.
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Quoting btwntx08:
those maps are wrong its overwater read the twd


I agree. Heading slowly to the NNW or N it seems.
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Quoting shenandoah:
"there are no indications that today's break in the action represents a beginning of an extended quiet period in the Atlantic."

God forbid. How can we go without another crisis in the near future? People might lose their fear of "global warming" and world government might not become a reality!

Not today, Please!!
It's Sunday afternoon.
We are all relaxed.....
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Quoting MiamiHurricanes09:
05/1745 UTC 16.8N 51.1W T1.5/1.5 GASTON


DVORAK T-Numbers are at 1.5, which would equate to around 25 kts.

-Snow
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Quoting InTheCone:


The potential is certainly there with the TCHP in that area. Any developed system with good upper level conditions would have the opportunity to be quite powerful.

I have no idea if Gaston will do that, but it is the first system that could go through there this year.


ok, I don't even know what TCHP is. I guess we will need to keep an eye on Gaston if he can make it through the Caribean and into the GOM...
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05/1745 UTC 16.8N 51.1W T1.5/1.5 GASTON

05/1745 UTC 19.9N 95.5W T1.0/1.0 90L
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Good Afternoon all.
A very peculiar set of nothing much going on in the Atlantic Basin.
Death and Destruction in Guatemala from rainstorms.
All conditions are Favourable, all over the place.(some heavy sheer in the East Atl though).

So, when does The Season start, again?
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Quoting StormW:


Right now, it depends on if the center jogs a little south or not....on current trend, could pass right over PR, or just along the north coast. That's why we have to keep close tabs on it...a slight shift south of the LLC, and it would come south and ride along the south coast of everything.


I know its hard to say but will it make a WNW or NW turn at some point before entering the Golf (maybe another Earl track?)
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410. IKE
72 hour 12Z ECMWF...Link
Member Since: June 9, 2005 Posts: 23 Comments: 37860
Quoting Snowlover123:


The HPC map has the Low Pressure of 90L over land.


Also note the new Low P. coming off of Africa...
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Quoting TexasHurricane:


oh, is it that? I thought he was to referring to where it may go. Who knows maybe it is both....


The potential is certainly there with the TCHP in that area. Any developed system with good upper level conditions would have the opportunity to be quite powerful.

I have no idea if Gaston will do that, but it is the first system that could go through there this year.
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Quoting Bordonaro:

Sorry, I was going by this map below:


The HPC map has the Low Pressure of 90L over land.
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the upper level environment is getting better ahead of ex Gaston. the system which already has the characteritics of a TD will get even more organised and stronge when it passes 55W where there is more moisture closer to the islands ,and where the SST is very much above average. it would not be too surprising if we were to get a TS/ minimal hurricane before land fall on the leeward islands
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Quoting cirrocumulus:


The center is over water as per NHC.
A BROAD AREA OF LOW PRESSURE COVERS THE SW GULF WHERE A SURFACE
TROUGH IS ANALYZED FROM A 1005 MB LOW 35 NM NE OFF THE COAST OF
THE CITY OF VERACRUZ NEAR 19.6N 95.4W.

Sorry, I was going by this map below from 7AM CDT today, posted a bit earlier today:
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Gaston - the little disturbance that could



I check in to see if dry air or a flock of gulls flying through might have killed Gaston but it keeps on coming.
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Quoting StormW:


Think about the implications of something developing mid Gulf or Yucatan area.


and that would be?
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Quoting InTheCone:


Potentially dire to catastrophic given the right conditions.


oh, is it that? I thought he was to referring to where it may go. Who knows maybe it is both....
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Quoting Eugeniopr:


Storm, remember some of us are learning, what that map means?

Thank you


amen.
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Quoting BDADUDE:
From what im reading on the maps gaston will be recurving by day 3 due to a weakness in the ridge.


?????
Member Since: July 8, 2005 Posts: 259 Comments: 24574
Quoting Bordonaro:

Well, the latest cold front from Central Canada dropped dewpoints into the lower 40's yesterday here at the DFW, TX AP.

Dewpoints today are back to normal, in the upper 60's, however, some drier air made it all the way down to the Northern GOM. That needs to mix out and the surface boundary is about dissapated over the NW GOM.

The COC of 90L is also indicated to be over land at the moment. It will move offshore later today. 90L will slowly intensify and may become our "H" TC.

The SAL is having a party with ex-Gaston. After 24 hrs ex-Gaston will be in a moister environment and should ramp up quickly.


The center is over water as per NHC.
A BROAD AREA OF LOW PRESSURE COVERS THE SW GULF WHERE A SURFACE
TROUGH IS ANALYZED FROM A 1005 MB LOW 35 NM NE OFF THE COAST OF
THE CITY OF VERACRUZ NEAR 19.6N 95.4W.
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Quoting MiamiHurricanes09:
White areas indicates <1 knot(s) of vertical wind shear.


thanks
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Quoting StormW:


Think about the implications of something developing mid Gulf or Yucatan area.


Potentially dire to catastrophic given the right conditions.
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392. Vero1
TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT SUN SEP 05 2010

...TROPICAL WAVES...

TROPICAL WAVE REMAINS INLAND OVER WEST AFRICA ALONG 10W MOVING W
NEAR 10 KT. SATELLITE IMAGERY INDICATES CYCLONIC FLOW NEAR THE
WAVE AXIS CONCENTRATED NEAR A 1009 MB LOW ALONG AND THE AXIS
NEAR 9N. THIS SYSTEM IS EXPECTED TO ENTER THE ATLC OVER THE NEXT
24 HRS.
...ITCZ...

A MONSOONAL TROUGH EXTENDS FROM THE COASTAL WATERS OF W AFRICA
NEAR 19N20W ALONG 10N23W TO 6N35W...WHERE THE ITCZ AXIS BEGINS
AND CONTINUES WESTWARD ALONG 10N45W TO 12N60W.
SCATTERED
MODERATE TO STRONG CONVECTION IS E OF THE TROUGH FROM 6N TO 14N
BETWEEN THE COAST OF WEST AFRICA AND 22W. CLUSTERS OF SIMILAR
CONVECTION ARE FROM 4N TO 8N BETWEEN 30W-43W.

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Quoting MiamiHurricanes09:
ULL backing off towards the WNW.


Making room for Gaston, it seems. ;)
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390. xcool
SUNDAY 10 AM
TROPICAL DEPRESSION FORMING IN THE SOUTHWEST GULF.

The data buoy near 22 north and 94 west has had its wind turn from east with gusts to 35 mph to south, though only at around 10 kts but the pressure is down to 1005.7 and is falling against the rise indicating to me a tropical depression is starting to form. Depending on where the center develops, this is something that should concern residents of deep south Texas. Obviously the WRF is wildest about this, but this is contingent on the development being further out over the water, something the global models arent seeing.

And then there is gaston, which my strict interpretation is a depression, but has essentially continued west unchanged It will be in the islands by Tuesday afternoon
BY JOE B
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Quoting PrivateIdaho:


Are the white areas on that map extremely low shear or just no data?
White areas indicates <1 knot(s) of vertical wind shear.
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Quoting Hurricanes101:


you are blind as a bat then

take a look at the forecast model tracks


I think that Greenland will have to worry about Gaston, as a warm cored system. May bring hurricane force conditions there. XD
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Quoting StormW:
Last update on shear...how's that grab you where Gaston might be?



Are the white areas on that map extremely low shear or just no data?
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ULL backing off towards the WNW.
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Quoting StormW:


Think about the implications of something developing mid Gulf or Yucatan area.


um....guessing here. Going to TX?
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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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