ATL: Ex-Tropical Storm GASTON - Discussion

[cycloneye]

Tropical cyclone formation Alert at NRL

http://www.nrlmry.navy.mil/atcf_web/images/al092010.gif

WTNT01 KNGU 041400
MSGID/GENADMIN/NAVMARFCSTCEN//
SUBJ/TROPICAL CYCLONE FORMATION ALERT//
RMKS/1. FORMATION OF A TROPICAL CYCLONE IS POSSIBLE
WITHIN 100NM EITHER SIDE OF A LINE FROM 16.4N 45.7W
TO 16.4N 49.2W WITHIN THE NEXT 24 HOURS. AVAILABLE
DATA DOES NOT JUSTIFY ISSUANCE OF A NUMBERED TROPICAL
CYCLONE WARNING AT THIS TIME.
2. A LOW PRESSURE CENTER WITH AN ESTIMATED CENTRAL
PRESSURE OF 1008MB IS LOCATED OVER EASTERN ATLANTIC.
MOVEMENT IS WESTWARD AT APPROXIMATELY 8 KNOTS.
THE ENVIRONMENTAL CONDITIONS ARE EXPECTED TO BECOME
MORE FAVORABLE OVER THE NEXT 24 HOURS AS THIS SYSTEM
REMAINS OVER WARM SEA SURFACE TEMPERATURES AND INCREASED
CONVECTION IS APPARENT NEAR THE CENTER OF THIS SYSTEM.
WEAK UPPER LEVEL ANTICYCLONIC FLOW IS EVIDENT OVER THE
SOUTHERN PORTION OF THIS WAVE.
3. THIS ALERT WILL BE REISSUED, ALLOWED TO EXPIRE,
OR CANCELLED BY 051400Z SEP 2010.//

[cycloneye]

2 PM TWO=Up to 80%

SHOWER AND THUNDERSTORM ACTIVITY ASSOCIATED WITH THE REMNANTS OF
GASTON CONTINUE TO SHOW SIGNS OF ORGANIZATION. ENVIRONMENTAL
CONDITIONS ARE CONDUCIVE FOR RE-DEVELOPMENT OF THIS SYSTEM AND A
TROPICAL DEPRESSION COULD RE-FORM IN THIS AREA AT ANY TIME. THERE
IS A HIGH CHANCE...80 PERCENT...OF THIS SYSTEM BECOMING A TROPICAL
CYCLONE AGAIN DURING THE NEXT 48 HOURS AS IT MOVES WESTWARD AT
ABOUT 10 MPH.

[Vortex]

anyone have the 12Z Bams with ships/lgem intensity forecast?

[ColinDelia]

Vortex here is the 12z SHIPS output with LGEM. It used the OFCI track

ftp://ftp.tpc.ncep.noaa.gov/atcf/stext/ ... _ships.txt

[Vortex]

Very impressive numbers there colin

Per ofc track in about 4-5 days

SST's 30.0C
Verical shear 6kts
Intensity forecast 130kts at H120

[Dean4Storms]

50W has been the area we've seen this year where the storms have been igniting development. I think it is a combination of less dry air and warming SST's as they push westward!!

[cycloneye]

A
TROPICAL DEPRESSION COULD RE-FORM IN THIS AREA AT ANY TIME

That means from this afternoon and foward, we can see the upgrade. Lets see what occurs.

[ColinDelia]

Very impressive numbers there colin

Per ofc track in about 4-5 days

SST's 30.0C
Verical shear 6kts
Intensity forecast 130kts at H120

Man, no kidding. The one thing that really concerns me in all this is Haiti. We don't need a beast in the Caribbean heading that way.

[Frank2]

Before everyone starts boarding up their windows (lol) - the WV loop shows a large ULL/TUTT feature ahead of ex-Gaston, and if this feature remains stationary or moves very slowly, would very likely dissipate whatever is there today...

http://www.goes.noaa.gov/HURRLOOPS/huwvloop.html

that explains why TWC has not mentioned very much at all about ex-Gaston this morning, and explains why last night's 500 mb GFS shows only a one-isobar low moving over Cuba by next weekend...

Frank

[Vortex]

or Frank per 12Z gfs the tutt moves into the sw carribean and ventilates gaston improving conditions even that much more...

[Vortex]

per1745 utc convection is on the increase..note how the outflow is expanding and looks superb on the west side...



http://www.ssd.noaa.gov/goes/east/carb/flash-rb.html

[Aric Dunn]

Well it at least it has a well defined Circ. still needs more time to see if convection can maintain for at least 12 hours before I would upgrade given the the stable air it is in. There is some thickening of the low level clouds on the eastern semi circle so we may see a little more convection build over the next few hours but It probably wont be very expansive more likely just enough to keep it alive long enough to make it far enough west to reach a little better environment in about 24 hours to 36 hours.

[Frank2]

...per 12Z gfs the tutt moves into the sw carribean and ventilates gaston improving conditions even that much more...

Perhaps, but on the WV loop the TUTT/ULL feature is being reinforced from the northeast, so my guess is that's why the 00Z solution was to keep it a very weak system as it moves west - probably why the other models were also making it move almost due west, too, and might be one reason the NHC is holding off from writing advisories once again...

P.S. My thinking is that the environment to the west is actually worse than in it's present location...

[cycloneye]

Sab Dvorak.

04/1745 UTC 16.5N 46.6W T1.5/2.0 GASTON -- Atlantic

[Frank2]

Well, so much for the NHC not wanting to start advisories once again (Avila must be on duty - lol)...

[perk]

Very impressive numbers there colin

Per ofc track in about 4-5 days

SST's 30.0C
Verical shear 6kts
Intensity forecast 130kts at H120

Man, no kidding. The one thing that really concerns me in all this is Haiti. We don't need a beast in the Caribbean heading that way.

Yeah that would a disastrous scenario.

[Aric Dunn]

...per 12Z gfs the tutt moves into the sw carribean and ventilates gaston improving conditions even that much more...

Perhaps, but on the WV loop the TUTT/ULL feature is being reinforced from the northeast, so my guess is that's why the 00Z solution was to keep it a very weak system as it moves west - probably why the other models were also making it move almost due west, too, and might be one reason the NHC is holding off from writing advisories once again...

P.S. My thinking is that the environment to the west is actually worse than in it's present location...

well it has at least 48 hours till it reaches far enough west to hit heavy shear (as long as the upper trough does not move but its should) and during that time it will begin to reach an area of better upper divergence which is much more conducive than where it is now. So bringing this back to TS is a good bet once convection is established and even if it hits shear the shear is very divergent which can be beneficial where the placement of the system and the shear axis will be important.

[CourierPR]

...per 12Z gfs the tutt moves into the sw carribean and ventilates gaston improving conditions even that much more...

Perhaps, but on the WV loop the TUTT/ULL feature is being reinforced from the northeast, so my guess is that's why the 00Z solution was to keep it a very weak system as it moves west - probably why the other models were also making it move almost due west, too, and might be one reason the NHC is holding off from writing advisories once again...

P.S. My thinking is that the environment to the west is actually worse than in it's present location...

If that were so, then I don't think the NHC would give it an 80% chance of becoming a TC. Notice it's not stationary but moving west.

[cycloneye]

18z Best Track

AL, 09, 2010090418, , BEST, 0, 166N, 466W, 30, 1007, LO

No TD yet but pressure is down one millibar.

[Frank2]

If that were so, then I don't think the NHC would give it an 80% chance of becoming a TC. Notice it's not stationary but moving west.

True, but the WV loop shows an environment that really isn't very favorable at all, at least at this time - as others said the ULL is forecast to at least move out of the way, but that is a large and formidable TUTT/ULL feature - if were a single and smaller ULL I'd have to agree, but what's out there now is much greater than ex-Gaston...

http://www.goes.noaa.gov/HURRLOOPS/huwvloop.html