12Z GFS ENS member tracks: operational an outlier?

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LarryWx
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12Z GFS ENS member tracks: operational an outlier?

#1 Postby LarryWx » Wed Sep 10, 2003 4:09 pm

To show how much of an outlier is the 12Z operational GFS and to also show the somewhat typical myriad of possible tracks this far out in time, I looked at the surface charts of the 10 other available members of the 12Z GFS ensemble to compare. NONE go into the Gulf with a discernible surface low representing Isabel:

Member 1: hits Maine day 9
Member 2: hits south/central FL day 7 and then does a slow version of a Hazel-like move up into SE canada on day 11
Members 3, 6 and 9: no discernible surface low through 252 hours; so I'm throwing these three members out for my analysis
Member 4: hits near SC/NC border on day 8 and then does a rapid Hazel-like move up into SE Canada on day 9 (looks just like Hazel)
Members 5,7, and 8: out to sea
Member 10: Canadian Maritimes day 11

Compare these tracks to the operational GFS into the Gulf near day 9 moving westward and just about hitting Mexico/Brownsville day 14.

So, to summarize for these 11 members:

- I've thrown out 3 of them leaving 8
- 4 of those 8 hit the U.S., one hits Canada, and three miss the U.S. out to sea although one comes very close to Bermuda.
- For the 4 that hit the U.S., they hit on days 7, 8, 9, and 14, respectively; this averages to day 9.5 fwiw
- For the 4 that hit the U.S., the hits are TX, ME, FL, and SC/NC (i.e. a huge spread but one that arguably averages near FL)
- The ensemble mean has a hit on FL near days 7-8 fwiw.
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#2 Postby WeatherEmperor » Wed Sep 10, 2003 4:10 pm

As per the 5pm NHC discussion, the GFS model is again going crazy and should not be trusted for this particular model run. I am getting more and more concerned here in South Florida with every advisory issued.
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Steve
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#3 Postby Steve » Wed Sep 10, 2003 4:17 pm

Larry,

It's possible GFS is sensing energy from the Caribbean in a south Texas/Mexico hit. That's the only plausible explanation I can find.

Also, check out the JTWC's prediction for Super Typhoon Maemi and see if it provides any clues for the SE Coast next week!

Steve
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