FHR 

     FHR is the forecast hour of freezing levels. FHR can be a single
     hour or a range. For example, 0, 3, 0-6, 6-12 all are valid 
     values.

     The defalut value is 0-6.

     When the freezing levels are written into a GFA elements, FHR is
     used to determine the GFA subtype. If the FHR is a single hour, 
     the GFA subtype will be set to snapshot. If the FHR is a range 
     that ends with 12, for instance, 6-12, the GFA subtype will be 
     set to outlook. Freezing leveles with FHRs other than these two 
     types will be written to FZLVLs with subtype of forecast.