MET can read gridded data in GRIB1, GRIB2, or 3 different flavors of NetCDF:
- The "internal" NetCDF format that looks like the output of the pcp_combine tool.
- CF-compliant NetCDF3 files.
- The output of the wrf_interp utility.
If there are the NetCDF output from WRF, use UPP to post-process it. It does not need to be "lat-lon"... it can be post-processed to whatever projection is needed..
There is in general no easy way to convert NetCDF to GRIB. If the NetCDF data is self generated, make it look like the NetCDF output from pcp_combine, or preferably, make it CF-compliant.
Looking at the accumulation interval of the precipitation data in the WRF output files from UPP, use the "wgrib" utility to dump out that sort of information:
... and so on
The question is whether the output actually contains 1-hourly accumulated precip, or does it contain runtime accumulation. Runtime accumulation means that the 6-hour wrf file contains 0 to 6 hours of precip; the 7- hour file contains 0 to 7 hours of precip; and so on. The precip values just accumulate over the course of the entire model integration.
The default for WRF-ARW is runtime accumulation. So if WRF-ARW is running and the output bucket interval wasn’t specifically changed, then that's very likely.
If that is the case, you can change these values to interval accumulations. Use the pcp_combine "-subtract" option instead of "-sum". Suppose the 6 hours of precip between the 6hr and 12hr forecasts is wanted. Run the following:
pcp_combine -subtract wrfprs_d01.12 12 \
wrfprs_d01.06 06 apcp_06_to_12.nc
That says... get 12 hours of precip from the first file and 6 hours from the second file and subtract them.