Question for PurdueWX80

[EDR1222]

Or anyone else. Is the change once again with the GFS in response to Gaston and Hermine possibly strengthening the building high pressure ridge? Or is it just normal for the GFS since it is attempting to forecast too far into the future?

[PurdueWx80]

I'm not sure I can totally answer your question, as it would be pretty hard to prove that Hermine and/or Gaston strengthened the ridge. Where the ridge forms and how strong it becomes is dependent upon a number of things, many of which are upstream over the Pacific and Canada. Frances should miss any weakness created by these other two storms, however. What would actually start to recurve her is either a trough that is forecast to develop E or SE from the Pacific NW (don't necessarily think this option will happen) or a weakening of the ridge over the Gulf caused by an upper level low (which will pinch off and back west from the trough currently in the central US). I think the GFS is a very viable option, and many of the other models from today are in the general agreement of a W to WNW motion following by a trend to the NW. Just when that happens will depend on how far west the edge of the ridge is. The 12Z ECMWF has an almost identical track to the 18Z GFS. The 18Z Eta also looks relatively similar to the 18z GFS at 84 hours. Because of all of this, I'm really starting to take the GFS more seriously. I'm assuming you can find the GFS, but here is the Euro out to 240 hours:

[EDR1222]

Thanks for the info.

[AL Chili Pepper]

I was about to say that for that last couple of days it seems as if the GFS has had the best handle on the track. It has been showing a west or WSW movement as it nears the Northern Leewards for 2 or 3 days now, and taking Frances very near Puerto Rico. That seems to be very viable now. Also, even though the long range solution for the GFS has varied and switched from a GOM to a FL east coast threat, it has been more consistant than most models I've seen.

Too, the NHC track has been very consistent. It seems as if splitting the difference and adding a little human intel has worked well for them. They are getting good with that 5 day forecast.