ATL: ISAAC - Models

[KWT]

There is a weakness opening up there Cycloneye right on the east coast, but its hardly a glaring weakness. I'd guess a track close to Earl/Bill would be likely on the 12z CMC, but who knows!!

[Riptide]

Some 12z GFS Ensemble members bring 94L quite close to East Coast, with one member showing landfall.

http://www.americanwx.com/bb/uploads/mo ... 225914.png

[KWT]

Bermuda right in the thick of alot of those runs there, certainly looks further west than previous runs.

[blp]

The NAO continues to be negative and is forecast to stay that way for the next few weeks. That seems to explain the weak high.



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[blp]

12z Euro much weaker and further west than 12z GFS.

http://raleighwx.americanwx.com/models/ ... SLP096.gif

http://raleighwx.americanwx.com/models/ ... SLP096.gif

[gatorcane]

The 12Z Euro is running now and is much further west than the GFS but does show a weaker cyclone. Very strong ridge across much of the Atlantic so won't be turning north into that. The trend is definitely further west for this system. Certainly bears watching IMHO given that a recurve is not a definite at all here.

[Blown Away]

On 8/15 the GFS was showing this area as a weak system moving over NE Caribbean and through SFL into the GOM, so I think weaker system will go farther west certainly applies here based on these model runs.

[gatorcane]

On 8/15 the GFS was showing this area as a weak system moving over NE Caribbean and through SFL into the GOM, so I think weaker system will go farther west certainly applies here based on these model runs.

Yes but look at that ridging the Euro shows. Even if it were stronger, it won't be turning north into that.

[tolakram]

Stronger ridging means a faster flow and likely means a very weak storm. IMO. After watching these for a few years now it seems the only real threat comes from a weak ridge as the storm develops followed by a strengthening ridge that drives the storm more west.

IMO that's why most of the stronger storms that form out here recurve.

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[blp]

At 144hr starting to move NW. It will be a close run for the islands.

http://raleighwx.americanwx.com/models/euro/12zeurotropical500mbSLP144.gif

[blp]

At 168hr looks like it will just miss the islands but very very close. Further west than the 00z. The trend continues.

http://raleighwx.americanwx.com/models/ ... SLP168.gif

[CrazyC83]

Some 12z GFS Ensemble members bring 94L quite close to East Coast, with one member showing landfall.

http://www.americanwx.com/bb/uploads/mo ... 225914.png

That landfall would have me driving right through it...

[gatorcane]

Looking at the 12Z Euro long-range, I don't see any fronts or troughs over North America that could recurve the system:

[cycloneye]

18z BAMS

A shift more west by them.

Code: Select all

WHXX01 KWBC 171844
CHGHUR
TROPICAL CYCLONE GUIDANCE MESSAGE
NWS NATIONAL HURRICANE CENTER MIAMI FL
1844 UTC FRI AUG 17 2012
 
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 (AL942012) 20120817 1800 UTC
 
        ...00 HRS...   ...12 HRS...   ...24 HRS. ..   ...36 HRS...
        120817  1800   120818  0600   120818  1800   120819  0600
 
         LAT    LON     LAT    LON     LAT    LON     LAT    LON
BAMS    11.2N  23.7W   11.4N  26.1W   11.7N  28.2W   12.0N  30.6W
BAMD    11.2N  23.7W   11.5N  26.2W   11.9N  28.6W   12.3N  30.7W
BAMM    11.2N  23.7W   11.4N  26.6W   11.8N  29.3W   12.2N  31.7W
LBAR    11.2N  23.7W   11.4N  27.0W   11.8N  30.7W   12.3N  34.2W
SHIP        20KTS          25KTS          33KTS          44KTS
DSHP        20KTS          25KTS          33KTS          44KTS
 
        ...48 HRS...   ...72 HRS...   ...96 HRS. ..   ..120 HRS...
        120819  1800   120820  1800   120821  1800   120822  1800
 
         LAT    LON     LAT    LON     LAT    LON     LAT    LON
BAMS    12.3N  33.3W   12.4N  39.3W   12.2N  44.3W   13.1N  47.1W
BAMD    12.8N  33.0W   13.9N  38.4W   14.3N  44.4W   14.1N  49.5W
BAMM    12.5N  34.2W   12.6N  39.9W   12.4N  45.4W   12.5N  49.0W
LBAR    12.8N  37.9W   13.0N  45.2W   11.7N  45.6W   13.1N  48.6W
SHIP        56KTS          75KTS          91KTS         107KTS
DSHP        56KTS          75KTS          91KTS         107KTS
 
         ...INITIAL CONDITIONS...
LATCUR =  11.2N LONCUR =  23.7W DIRCUR = 270DEG SPDCUR =  17KT
LATM12 =  11.2N LONM12 =  20.2W DIRM12 = 272DEG SPDM12 =  23KT
LATM24 =  10.9N LONM24 =  15.5W
WNDCUR =   20KT RMAXWD =   50NM WNDM12 =   20KT
CENPRS = 1009MB OUTPRS = 1012MB OUTRAD =  150NM SDEPTH =   S
RD34NE =    0NM RD34SE =    0NM RD34SW =    0NM RD34NW =   0NM
 
$$
NNNN


[Blown Away]

Doesn't look like strong enough ridging to keep it from moving NW at that position.

[gatorcane]

:uarrow:
Doesn't look like strong enough ridging to keep it from moving NW at that position.

The 240 hour came in and it is bending back west. Certainly will want to see if this keeps trending more west like this.

216 hour:


240 hour:

[CrazyC83]

Looking at the 12Z Euro long-range, I don't see any fronts or troughs over North America that could recurve the system:

With that setup, most likely it would just keep going WNW as far as the eye can see.

[cycloneye]

The 12z Euro last frame at 240 hours is North of Puerto Rico,in other words west of the Bermuda longitide (64W)

[KWT]

Wow, ECM 12z is a CERT for a US landfall, upper high starting to form over the NE states, system misses the weakness and is heading WNW.

First run that has suggested a serious threat.

Also, notice the shift westwards again before it lifts NW, I think we haven't finished with that west shift yet either...

Ps, that 12z ECM has the sniff of...Andrew...about it...

[gatorcane]

that 12z ECM has the sniff of...Andrew...about it...

Yes noted, but thankfully its 240 hours from now. I would agree the west shifts are probably not done yet. Will be interesting to see if the GFS also starts showing the west bend at the end in subsequent runs.