ATL: GABRIELLE - Remnants - Discussion

[NDG]

Dare I say remember it is in the East Caribbean.

And the Trade Winds west of 97L have really slow down today.

[gatorcane]

NHC 2pm EST TWO snippet for this area:

SHOWERS AND THUNDERSTORMS CONTINUE IN ASSOCIATION WITH AN AREA OF
LOW PRESSURE CENTERED ABOUT 100 MILES WEST OF DOMINICA. UPPER-LEVEL
WINDS ARE EXPECTED TO REMAIN FAVORABLE FOR DEVELOPMENT OVER THE
NEXT FEW DAYS...BUT INTERACTION WITH THE LAND MASSES OF THE GREATER
ANTILLES COULD INHIBIT TROPICAL CYCLONE FORMATION AS THE SYSTEM
MOVES GENERALLY WEST-NORTHWESTWARD AT AROUND 10 MPH. THIS SYSTEM
HAS A MEDIUM CHANCE...30 PERCENT...OF BECOMING A TROPICAL CYCLONE
DURING THE NEXT 48 HOURS...AND A MEDIUM CHANCE...50 PERCENT...OF
BECOMING A TROPICAL CYCLONE DURING THE NEXT 5 DAYS. LOCALLY HEAVY
RAINFALL AND GUSTY WINDS ARE EXPECTED TO AFFECT PORTIONS OF THE
NORTHERN LESSER ANTILLES OVER THE NEXT DAY OR SO...AND SPREAD OVER
PUERTO RICO BY THURSDAY.

http://www.nhc.noaa.gov/text/refresh/MI ... WOAT.shtml

[tailgater]

I think I would have gone up to 50% possibly, really starting to get it's act together today, after almost 30 hrs. of pretty much nothing to speak of. Still a little broad but definetly tightening up.

[Florida1118]

NHC 2pm EST TWO snippet for this area:

SHOWERS AND THUNDERSTORMS CONTINUE IN ASSOCIATION WITH AN AREA OF
LOW PRESSURE CENTERED ABOUT 100 MILES WEST OF DOMINICA. UPPER-LEVEL
WINDS ARE EXPECTED TO REMAIN FAVORABLE FOR DEVELOPMENT OVER THE
NEXT FEW DAYS...BUT INTERACTION WITH THE LAND MASSES OF THE GREATER
ANTILLES COULD INHIBIT TROPICAL CYCLONE FORMATION AS THE SYSTEM
MOVES GENERALLY WEST-NORTHWESTWARD AT AROUND 10 MPH. THIS SYSTEM
HAS A MEDIUM CHANCE...30 PERCENT...OF BECOMING A TROPICAL CYCLONE
DURING THE NEXT 48 HOURS...AND A MEDIUM CHANCE...50 PERCENT...OF
BECOMING A TROPICAL CYCLONE DURING THE NEXT 5 DAYS. LOCALLY HEAVY
RAINFALL AND GUSTY WINDS ARE EXPECTED TO AFFECT PORTIONS OF THE
NORTHERN LESSER ANTILLES OVER THE NEXT DAY OR SO...AND SPREAD OVER
PUERTO RICO BY THURSDAY.

http://www.nhc.noaa.gov/text/refresh/MI ... WOAT.shtml

NHC must be having difficulties or something, since it wasnt written by the NHC:

TROPICAL WEATHER OUTLOOK
NWS NATIONAL HURRICANE CENTER MIAMI FL
ISSUED BY THE NWS WEATHER PREDICTION CENTER COLLEGE PARK MD

[NDG]

This is proof of how weaker than average the trade winds have become west of 97L, in the famous "death zone" of the Caribbean.
The buoy is several hundred miles west of 97L, in the heart of where most times the trade winds are ripping across between Hispaniola and S.A. in the 15-25 knot range.


Conditions at 42058 as of
(12:50 pm EST)
1750 GMT on 09/03/2013:
Unit of Measure: Time Zone:
Click on the graph icon in the table below to see a time series plot of the last five days of that observation.

Wind Direction (WDIR): E ( 100 deg true )
Wind Speed (WSPD): 11.7 kts
Wind Gust (GST): 11.7 kts
Wave Height (WVHT): 4.6 ft
Dominant Wave Period (DPD): 7 sec
Average Period (APD): 5.3 sec
Mean Wave Direction (MWD): E ( 97 deg true )
Atmospheric Pressure (PRES): 29.86 in
Pressure Tendency (PTDY): -0.04 in ( Falling )
Air Temperature (ATMP): 84.0 °F
Water Temperature (WTMP): 84.2 °F
Dew Point (DEWP): 77.7 °F
Heat Index (HEAT): 94.6 °F
Wind Speed at 10 meters (WSPD10M): 11.7 kts
Wind Speed at 20 meters (WSPD20M): 11.7 kts
Combined plot of Wind Speed, Gust, and Air Pressure

http://www.ndbc.noaa.gov/station_page.php?station=42058

[cycloneye]

18z Best Track.

AL, 97, 2013090318, , BEST, 0, 150N, 621W, 30, 1007, LO

[Alyono]

maybe the aircraft should have flown after all. How things have changed during the past several hours

[floridasun78]

18z Best Track.

AL, 97, 2013090318, , BEST, 0, 150N, 621W, 30, 1007, LO

did pressure drop?

[tolakram]

Is that an anti-cyclone sitting right on top of it? Looks like < 10 kts shear at the moment.

[caneman]

Yes, it did drop and wind speed is now up to 30 kt. so looks like we are getting close to a TD.

In my amateur opinion.

[ROCK]

yes that is an anticyclone.

[Hammy]

18z Best Track.

AL, 97, 2013090318, , BEST, 0, 150N, 621W, 30, 1007, LO

did pressure drop?

Position seems a tad too far northeast as the winds all seem to be out of the south there. Either way its not going anywhere in a hurry which is certainly a change from earlier systems.

[thetruesms]

Dare I say remember it is in the East Caribbean.

While the Caribbean low level jet can increase low level divergence and cut down on genesis, it's really more of a feature of the early season. Once you get to September, the Eastern Caribbean sees formation on par with the rest of the basin, and in the late season, is even proportionally a little higher.

So, like many things on the board, this is something that has some truth to it, but gets overused and beaten into the ground.

This paper is technical, but since it's in BAMS, is written to be a little more accessible: http://journals.ametsoc.org/doi/pdf/10. ... BAMS2822.1

[cycloneye]

Moving slowly WNW at 295 degrees.

LATCUR = 15.0N LONCUR = 62.1W DIRCUR = 295DEG SPDCUR = 5KT

[Sanibel]

Dare I say remember it is in the East Caribbean.

While the Caribbean low level jet can increase low level divergence and cut down on genesis, it's really more of a feature of the early season. Once you get to September, the Eastern Caribbean sees formation on par with the rest of the basin, and in the late season, is even proportionally a little higher.

So, like many things on the board, this is something that has some truth to it, but gets overused and beaten into the ground.

This paper is technical, but since it's in BAMS, is written to be a little more accessible: http://journals.ametsoc.org/doi/pdf/10. ... BAMS2822.1

I'm not disputing that however I saw a formation chart for early September on TWC last night that shows the opposite. Also, don't forget that each individual year affects the process and this year has been unquestionably unfavorable.

I'd even add that yesterday's low level cloud formation in the east Caribbean showed a streaky, striated appearance with higher speed while the low level clouds above the Antilles showed a more even, slower pattern. This itself is a visual clue of the effect.

[tolakram]

Latest. More visible evidence of an tighter LLC IMO. Near 63.5w 14N

[gatorcane]

Moving slowly WNW at 295 degrees.

LATCUR = 15.0N LONCUR = 62.1W DIRCUR = 295DEG SPDCUR = 5KT

I don't see anything at this location when I look at the vis loops. I am guessing an adjustment will be necessary to reflect where the true center is consolidating.

Looks more like 14.5N 63.0W.

[wxman57]

Moving slowly WNW at 295 degrees.

LATCUR = 15.0N LONCUR = 62.1W DIRCUR = 295DEG SPDCUR = 5KT

I don't see anything at this location when I look at the vis loops. I am guessing an adjustment will be necessary to reflect where the true center is consolidating.

Looks more like 14.5N 63.0W.

Appears to be a degree or more farther west (of 62.1W) and farther south, to me.

[cycloneye]

Moving slowly WNW at 295 degrees.

LATCUR = 15.0N LONCUR = 62.1W DIRCUR = 295DEG SPDCUR = 5KT

I don't see anything at this location when I look at the vis loops. I am guessing an adjustment will be necessary to reflect where the true center is consolidating.

Looks more like 14.5N 63.0W.

They did an update.

AL, 97, 2013090318, , BEST, 0, 150N, 630W, 30, 1007, LO

LATCUR = 15.0N LONCUR = 63.0W DIRCUR = 290DEG SPDCUR = 8KT

[Gustywind]

Increasing T Numbers...


03/1745 UTC 14.4N 63.2W T1.0/1.0 97L
03/1145 UTC 14.5N 62.9W TOO WEAK 97L