So just building on the previous posters comments:
Progs potray forecasts of selected weather conditions at
specified valid times. Each valid time is the time at which the forecast conditions are expected to occur. A 12 hour-hr prog is a forecast of conditions which has a valid time 12 hours after the obeserved data base time, thus a 12 hr forecast. For example, a 12 hour forecast based on 00z observations is valid
at 12z.
I guess you are asking this question based on the fact so what do I look at at 1132z? or 1035z?
The correct way is to treat exactly like FD forecasts: yes, interperlate....if on a 00z sig wx front 'A' is at X and on the 06z prog at Y then work on the basis that at 03z it is.....answers on a post card!
