ATL: DORIAN - Post-Tropical - Discussion

[NDG]

Very light west winds started being reported at Burbuda. Prior to this it was very light northerly winds.

Antigua and Barbuda is reporting NE 3 mph.

http://weather.noaa.gov/weather/current/TAPA.html

Now back to a more northerly direction but the trough's axis is still to its NE so I expect that the winds will go back to a more westerly direction. This is the station to watch as it is the closest to 91L.

07 28 9:54 am NW 7.0 9.9 - - - - 30.01 - 83.7 - - - - -
07 28 9:48 am NW 5.1 7.0 - - - - 30.01 - 83.8 - - - - -
07 28 9:42 am W 1.0 4.1 - - - - 30.01 - 83.8

http://www.ndbc.noaa.gov/station_page.php?station=bara9

[gatorcane]

Looping the VIS floater, I can see evidence of some rotation with this blob of convection. Not sure if it is mid-level or low-level but you can start to see it with the last few frames that have come in:

http://www.ssd.noaa.gov/PS/TROP/floater ... -long.html

[wxman57]

I'm not seeing any rotation at the surface. Plotted some ships around Dorian and noted that the pressure is quite high around Dorian - 1017 to 1018mb, and 1016mb in the eastern Caribbean. Much higher than normal. Redevelopment chances still look to be low.

[Jimsot]

I would just like a few 'stray' thunderstorms and showers as we are very dry at the moment, then 91L can go out to sea.

[Blown Away]

ATLANTIC SHIPS INTENSITY FORECAST *
* GOES AVAILABLE, OHC AVAILABLE *
* INVEST AL912013 07/28/13 12 UTC *

TIME (HR) 0 6 12 18 24 36 48 60 72 84 96 108 120
SHEAR (KT) 12 10 11 14 13 9 14 9 16 6 14 7 11

12Z shear significantly lower than what was being predicted earlier...

[ronjon]

What are the GFS and ECMWF saying? Yep, you can throw SHIPS away in this situation.

I think throwing away might be a tad strong, lol. All the statistical models are ramping up. Yes we'll have to see bout the globals but they were clearly caught off guard with ex-Dorian's apparent strengthening over night too. Welcome to the wacky work of tropical meteorology.

[NDG]

I'm not seeing any rotation at the surface. Plotted some ships around Dorian and noted that the pressure is quite high around Dorian - 1017 to 1018mb, and 1016mb in the eastern Caribbean. Much higher than normal. Redevelopment chances still look to be low.

How about the surface reports out of Barbuda?

[cycloneye]

I would just like a few 'stray' thunderstorms and showers as we are very dry at the moment, then 91L can go out to sea.

A band of showers is about to arrive to NE Puerto Rico. Saved loop.

[abajan]

Very light west winds started being reported at Burbuda. Prior to this it was very light northerly winds.

Antigua and Barbuda is reporting NE 3 mph.

http://weather.noaa.gov/weather/current/TAPA.html

...

@NDG From where did you get that info about westerly winds? Initially, I thought that perhaps you mistook Bermuda for Barbuda but they haven't been reporting westerly winds lately either: http://weather.noaa.gov/weather/current/TXKF.html

[ronjon]

Is that a rotation off the PR RADAR I see to the NE - probably mid-level but interesting.

[CalmBeforeStorm]

What are the GFS and ECMWF saying? Yep, you can throw SHIPS away in this situation.

I think throwing away might be a tad strong, lol. All the statistical models are ramping up. Yes we'll have to see bout the globals but they were clearly caught off guard with ex-Dorian's apparent strengthening over night too. Welcome to the wacky work of tropical meteorology.

Also, the 6z GFS, as oppossed to the 00z and 18z, shows a stronger system with what looks like a closed low all the way into Florida. Not alot but the first run that doesn't actualy disapate the system.

[Blown Away]

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MIAMI FL
920 AM EDT SUN JUL 28 2013

AS FOR THE REMNANTS OF DORIAN...THE CONSENSUS AT THIS TIME CONTINUES
TO BE THAT THEY ARE LIKELY TO PASS TO OUR SOUTH AS A WAVE WEDNESDAY AND
THURSDAY WITH NO SIGNIFICANT LOCAL IMPACTS ANTICIPATED AT THIS TIME
BUT WILL CONTINUE TO MONITOR IN CASE THIS OUTLOOK CHANGES GOING
FORWARD.

[NDG]

Antigua and Barbuda is reporting NE 3 mph.

http://weather.noaa.gov/weather/current/TAPA.html

...

@NDG From where did you get that info about westerly winds? Initially, I thought that perhaps you mistook Bermuda for Barbuda but they haven't been reporting westerly winds lately either: http://weather.noaa.gov/weather/current/TXKF.html

Once again here it is, winds are back to the north but the trough's axis is still to the east of the Island, I would suspect that the winds will go back to more westerly direction as the system moves west, north of the island.

07 28 10:06 am N 4.1 6.0 - - - - 30.01 - 83.1 - - - - -
07 28 10:00 am N 4.1 9.9 - - - - 30.01 +0.02 83.8 - - - - -
07 28 9:54 am NW 7.0 9.9 - - - - 30.01 - 83.7 - - - - -
07 28 9:48 am NW 5.1 7.0 - - - - 30.01 - 83.8 - - - - -
07 28 9:42 am W 1.0 4.1 - - - - 30.01 - 83.8


http://www.ndbc.noaa.gov/station_page.php?station=bara9

[HURAKAN]

What are the GFS and ECMWF saying? Yep, you can throw SHIPS away in this situation.

I think throwing away might be a tad strong, lol. All the statistical models are ramping up. Yes we'll have to see bout the globals but they were clearly caught off guard with ex-Dorian's apparent strengthening over night too. Welcome to the wacky work of tropical meteorology.

Also, the 6z GFS, as oppossed to the 00z and 18z, shows a stronger system with what looks like a closed low all the way into Florida. Not alot but the first run that doesn't actualy disapate the system.

Saw it but it's only 1 run. Need to see persistence. My point is that overall, the global models have performed better. SHIPS is always too aggressive.

[NDG]

Is that a rotation off the PR RADAR I see to the NE - probably mid-level but interesting.

The vorticity is still far far away from the radar range, that is not it shown on radar from PR.

[HURAKAN]

07 28 10:06 am N 4.1 6.0 - - - - 30.01 - 83.1 - - - - -
07 28 10:00 am N 4.1 9.9 - - - - 30.01 +0.02 83.8 - - - - -
07 28 9:54 am NW 7.0 9.9 - - - - 30.01 - 83.7 - - - - -
07 28 9:48 am NW 5.1 7.0 - - - - 30.01 - 83.8 - - - - -
07 28 9:42 am W 1.0 4.1 - - - - 30.01 - 83.8

http://www.ndbc.noaa.gov/station_page.php?station=bara9

Those are very weak winds and could easily be a local factor. Overall across the NE Caribbean, like wxman57 mentioned, winds are east to northeast and pressures are very high.

[NDG]

Looking at the 14 hr water vapor loop the UL trough looks like it has started to die down a bit and starting lifting to the NW, but will it be enough as 91L approaches it not to shredd it to pieces? I guess we will see.

[CalmBeforeStorm]

Agreed, but the GFS showing an improved system aong with SHIPS showing less predicted shear in it's path is certainly interesting. The next GFS will be of interest for sure.

[Alyono]

SHIPS is useless as it assumes this is already a depression with a closed low

[NDG]

07 28 10:06 am N 4.1 6.0 - - - - 30.01 - 83.1 - - - - -
07 28 10:00 am N 4.1 9.9 - - - - 30.01 +0.02 83.8 - - - - -
07 28 9:54 am NW 7.0 9.9 - - - - 30.01 - 83.7 - - - - -
07 28 9:48 am NW 5.1 7.0 - - - - 30.01 - 83.8 - - - - -
07 28 9:42 am W 1.0 4.1 - - - - 30.01 - 83.8

http://www.ndbc.noaa.gov/station_page.php?station=bara9

Those are very weak winds and could easily be a local factor. Overall across the NE Caribbean, like wxman57 mentioned, winds are east to northeast and pressures are very high.

We all know SW quadrants of systems are very weak, to me a NW wind reported at 7-9 knots is sufficient enough to think that it now has a closed circulation.

BTW, winds now SSW and is not that light of a wind.

Wind Direction (WDIR): SSW ( 210 deg true )
Wind Speed (WSPD): 11.1 kts
Wind Gust (GST): 12.0 kts