Notices

1. Bryan Lawrence (bnlawrence@mastodon.nz)'s status on Tuesday, 21-Feb-2023 09:51:17 CET Bryan Lawrence

   Is there anyone else out there using NOAA #GFS data as described here https://www.nco.ncep.noaa.gov/pmb/products/gfs/gfs.t00z.pgrb2.0p25.f003.shtml who can explain what is going on with the accumulated precip fields 596 and 597?

   It appears that for the 596 message, at the 3h forecast (f003), it’s a 0,3 hour accumulation, at 6h (f006), it’s a 0,6 hour accumulation, and at 9h forecast (f009) it’s back to a 3h accumulation 6,9.

   Is this behaviour documented anywhere, and why?

   • Pybonacci (pybonacci@mastodon.social)'s status on Tuesday, 21-Feb-2023 09:51:15 CET Pybonacci

     in reply to

     @bnlawrence
     field 596 is the accumulated since each 00, 06, 12, 18 step so the f007 is from 06 to 07, f016 is from 12 to 16, etc. So, every 6h the acpc is the beginning of a new 'cycle'.
     Field 597 is the accum from the start of the forecast.
     Have a look to the inventory files (idx).

     (If I'm not wrong).

   • Pybonacci (pybonacci@mastodon.social)'s status on Tuesday, 21-Feb-2023 10:55:27 CET Pybonacci

     in reply to

     @bnlawrence not so long ago forecasts outputs were delivered for each 6h or more. I guess this comes from these times.

   • Bryan Lawrence (bnlawrence@mastodon.nz)'s status on Tuesday, 21-Feb-2023 10:55:29 CET Bryan Lawrence

     in reply to

     • Pybonacci

     @pybonacci That makes sense. Thanks.

     (I had sussed the accumulation from the grib message attributes, which are effectively the info in the idx, but I hadn’t worked out the pattern. )

     I am left intrigued by the logic of this particular strategy of information production. Given these are hourly forecast fields, it would make sense for “the last one hour” in each, or the “last n hours”, but a variable number out to each six hour cycle makes little sense to me But there will be a reason ...