Resurrecting old question. . . . I have the same question about viewing GRIBs in Viewfax.
I've subscribed to Saildocs sending me a GRIB for the Bahamas
each morning at 5AM local time, or 1000z, asking for WIND
at 3, 6, 12, 24, 36, 48, 72, and 96 hours out.
What I receive from Saildocs says "Grib extracted from file gfs100130-00z.grb dated 2010/01/30 04:38:34" So that sounds like local time.
When I view the GRIB in viewfax, the top line says "GRIB valid 2010/01/30 03:00" and the little time stamp that accompanies the pulldown menu of forward times also says that, e.g., as I step through 3, 6, 12 etc hours ahead, it will say "2010/01/30 . . . 06:00 . . . 12:00 etc."
So are those UTC times in the GRIB viewer? I normally would assume so, but it seems strange that a GRIB arriving at 5AM local time would start retroactively at 0300z, or 10PM the night before. It would certainly be convenient for viewing and planning if those times were local. But I'd guess that since many GRIBs span multiple time zones, the software
is set for UTC time only. (?)
So then my question becomes: How do I construct a GRIB subscription request that will actually start each day at 5AM or so?
Any GRIB gurus, please advise!