Fix_afwa snow:

The afwa snow is on two grids, a north and south polar stereographic
grid in grib1 format.  Unfortunately the Lov angle, 100 degrees,
and is off by 180 from what NCEP uses. This program changes
the LOV to -80 and changes the center to NCEP and subcenter to CPC.

USE:
    rcdas_fix_afwa_snow AFWA_SNOW

    AFWA_SNOW, nps or sps grib1 with snow cover from AFWA
    Changes LOV from 100 to -80
    changes CENTER/SUBCENTER to NCEP/CPC

INPUT:  AFWA_SNOW
OUTPUT: AFWA_SNOW