ATL: GABRIELLE - Models

[gatorcane]

18Z Guidance:

[Blown Away]

WPC has 97L in the NW Bahamas in 7 days after traveling over the north coast of Hispaniola...

Question, often the WPC long range forecast seems to differ from what the models show...WPC has 97L in the NW Bahamas and most of the current models take 97L out to see well east of the NW Bahamas?

[gatorcane]

18Z GFS running. It shows a little bit more defined 97L which moves WNW slowly to near Puerto Rico/Hispaniola then slows to a crawl just east of the SE Bahamas, then slowly moves north hitting a big weakness over Eastern North America and the Western Atlantic. It looks like a large and broad system here at 144 hours:



500MB flow at 144 hours shows a very large break in the ridge it can move through east of the United States:

[gatorcane]

18Z NAVGEM moves 97L WNW like the GFS but then bends it west in the SE Bahamas while it develops the system behind 97L moving it north:

[ninel conde]

http://moe.met.fsu.edu/cgi-bin/gfstc2.c ... hour=180hr

12z shows how timing is everything. we can see here the possible beginning of the newfoundland wheel. 97L could get trapped under it and if the wheel builds the next storm will be blocked from a recurve.

[cycloneye]

CHGHUR
TROPICAL CYCLONE GUIDANCE MESSAGE
NWS NATIONAL HURRICANE CENTER MIAMI FL
0036 UTC TUE SEP 3 2013

DISCLAIMER...NUMERICAL MODELS ARE SUBJECT TO LARGE ERRORS.
PLEASE REFER TO NHC OFFICIAL FORECASTS FOR TROPICAL CYCLONE
AND SUBTROPICAL CYCLONE INFORMATION.

ATLANTIC OBJECTIVE AIDS FOR

DISTURBANCE INVEST (AL972013) 20130903 0000 UTC

...00 HRS... ...12 HRS... ...24 HRS... ...36 HRS...
130903 0000 130903 1200 130904 0000 130904 1200

LAT LON LAT LON LAT LON LAT LON
BAMS 14.3N 60.5W 14.7N 62.1W 15.5N 63.9W 16.4N 66.0W
BAMD 14.3N 60.5W 14.8N 62.2W 15.5N 64.0W 16.5N 65.8W
BAMM 14.3N 60.5W 14.7N 62.0W 15.2N 63.7W 16.0N 65.6W
LBAR 14.3N 60.5W 14.8N 62.0W 15.9N 63.8W 17.3N 65.8W
SHIP 25KTS 30KTS 37KTS 45KTS
DSHP 25KTS 30KTS 37KTS 45KTS

...48 HRS... ...72 HRS... ...96 HRS... ..120 HRS...
130905 0000 130906 0000 130907 0000 130908 0000

LAT LON LAT LON LAT LON LAT LON
BAMS 17.4N 68.0W 19.1N 72.0W 20.0N 75.1W 20.5N 77.9W
BAMD 17.6N 67.5W 19.3N 70.1W 20.4N 71.6W 21.3N 71.5W
BAMM 16.9N 67.6W 18.4N 71.1W 19.4N 74.1W 20.3N 76.3W
LBAR 18.9N 67.9W 21.9N 71.6W 24.6N 73.2W 28.1N 72.1W
SHIP 55KTS 71KTS 80KTS 80KTS
DSHP 55KTS 58KTS 50KTS 35KTS

...INITIAL CONDITIONS...
LATCUR = 14.3N LONCUR = 60.5W DIRCUR = 280DEG SPDCUR = 5KT
LATM12 = 14.1N LONM12 = 59.6W DIRM12 = 285DEG SPDM12 = 4KT
LATM24 = 14.0N LONM24 = 58.8W
WNDCUR = 25KT RMAXWD = 100NM WNDM12 = 25KT
CENPRS = 1009MB OUTPRS = 1011MB OUTRAD = 200NM SDEPTH = M
RD34NE = 0NM RD34SE = 0NM RD34SW = 0NM RD34NW = 0NM

[Hurricane Alexis]

http://moe.met.fsu.edu/cgi-bin/gfstc2.cgi?time=2013090212&field=Sea+Level+Pressure&hour=180hr

12z shows how timing is everything. we can see here the possible beginning of the newfoundland wheel. 97L could get trapped under it and if the wheel builds the next storm will be blocked from a recurve.

Can you explain what the newfoundland wheel is please? I'm new to that term.

[Hybridstorm_November2001]

It is in essence, a blocking High Pressure Ridge (caused in part by warmer than average surface water temps) situated by Newfoundland that, in concert with a trough over Eastern North America, works as a funnel to pushes storms into the East Coast. It is a term invented by Joe Bastardi, as far as I can tell.

[tolakram]

Model rundown, with no conclusions.

So the euro has been forced, kicking and screaming, to recognize vorticity where 24 hours ago it said none would exist. This has dramatically changed the Sept 4th vorticity forecast so far.

12Z yesterday for Sept 4th


12Z today for Sept 4th


I wonder how much more this will change?

The GFS made the same mistake, and now has (in the 12Z run) a much better defined area of vorticity just south of PR.

12Z Yesterday for Sept 4th


12Z today for Sept 4th



The 18Z GFS has a very similar position, but a bit further south.


You can view the model output for the last week or so here: http://moe.met.fsu.edu/tcgengifs/

[TheStormExpert]

It is in essence, a blocking High Pressure Ridge (caused in part by warmer than average surface water temps) situated by Newfoundland that, in concert with a trough over Eastern North America, works as a funnel to pushes storms into the East Coast. It is a term invented by Joe Bastardi, as far as I can tell.

Levi Cowan from Tropical Tidbits too was saying how the warmer SST's south of Newfoundland would promote more ridging over troughiness. In other words, even though the models are showing troughiness in SE Canada it would most likely be very temporary and short lived due to the ridging trying to build back in cause of the warmer SST's.

[ROCK]

0Z NAM likes the global consensus currently

http://www.tropicaltidbits.com/analysis ... _watl.html

[ROCK]

18Z NAVGEM looks weird

https://www.fnmoc.navy.mil/wxmap_cgi/cg ... t=Tropical

[boca]

Rock,that could be the system behind 97L that the model is picking up on

[ROCK]

Rock,that could be the system behind 97L that the model is picking up on

I think so but it looks like it initialized to low. Not sure why the split in energy sending the organized system north while leaving the other piece around Cuba....seems like they should follow each other out....

[boca]

Levi Cowan said that the GFS was doing the same thing with splitting up the low and he was saying it was convective feedback

[Blown Away]

030
WHXX01 KWBC 031113
CHGHUR
TROPICAL CYCLONE GUIDANCE MESSAGE
NWS NATIONAL HURRICANE CENTER MIAMI FL
1113 UTC TUE SEP 3 2013

DISCLAIMER...NUMERICAL MODELS ARE SUBJECT TO LARGE ERRORS.
PLEASE REFER TO NHC OFFICIAL FORECASTS FOR TROPICAL CYCLONE
AND SUBTROPICAL CYCLONE INFORMATION.

ATLANTIC OBJECTIVE AIDS FOR

DISTURBANCE INVEST (AL972013) 20130903 0600 UTC
...00 HRS... ...12 HRS... ...24 HRS... ...36 HRS...
130903 0600 130903 1800 130904 0600 130904 1800

LAT LON LAT LON LAT LON LAT LON
BAMS 14.7N 61.3W 15.4N 63.2W 16.3N 65.2W 17.5N 67.4W
BAMD 14.7N 61.3W 15.3N 63.1W 16.1N 65.0W 17.1N 67.0W
BAMM 14.7N 61.3W 15.2N 63.1W 15.9N 65.0W 16.8N 67.1W
SHIP 25KTS 28KTS 33KTS 41KTS
DSHP 25KTS 28KTS 33KTS 41KTS

...48 HRS... ...72 HRS... ...96 HRS... ..120 HRS...
130905 0600 130906 0600 130907 0600 130908 0600

LAT LON LAT LON LAT LON LAT LON
BAMS 18.4N 69.3W 19.8N 73.0W 20.4N 76.1W 21.0N 78.5W
BAMD 18.1N 68.8W 19.6N 71.6W 20.7N 73.2W 22.6N 73.1W
BAMM 17.7N 69.0W 18.9N 72.2W 19.6N 74.7W 20.4N 76.3W
SHIP 47KTS 62KTS 67KTS 69KTS
DSHP 47KTS 34KTS 39KTS 30KTS

...INITIAL CONDITIONS...
LATCUR = 14.7N LONCUR = 61.3W DIRCUR = 295DEG SPDCUR = 6KT
LATM12 = 14.2N LONM12 = 60.2W DIRM12 = 291DEG SPDM12 = 6KT
LATM24 = 14.0N LONM24 = 59.2W
WNDCUR = 25KT RMAXWD = 90NM WNDM12 = 25KT
CENPRS = 1009MB OUTPRS = 1011MB OUTRAD = 200NM SDEPTH = M
RD34NE = 0NM RD34SE = 0NM RD34SW = 0NM RD34NW = 0NM

$$
NNNN

[tolakram]

6Z GFS initialized with a low, loses it (at this resolution anyway, then regains it in the Bahamas. In other words, it's starting to look like a weak Canadian run.

The 0Z Euro looks similar to the previous run, except it take the vorticity over Hispaniola and scatters it into the Bahamas, then scoots a large area of vorticity up the east coast.

So there is a bit of model consensus now with something moving over or very near PR, then bending north and east near the Bahamas.

http://moe.met.fsu.edu/tcgengifs/

Here's the latest day 5 UK model plot from http://ruc.noaa.gov/hfip/tcgen/

[Blown Away]

06z...

[CalmBeforeStorm]

The 6z GFS shows a closed 1008mb low (97L) above the DR at day 4.
http://mag.ncep.noaa.gov/Image.php?fhr= ... imageSize=
This low only drifts a little NE through day 6;
http://mag.ncep.noaa.gov/Image.php?fhr= ... imageSize=
The low continues to drift north eventually being taken out by a weakness created by another low that develops to it's north. A 1008 closed low in that position (SE Bahamas) at this time a year with what the GFS shows being weak steering currents is a bit worrisome for the SE U.S. in my opinion.

[Fego]

12Z run. More or less same scenario.