ops-gfsv16.3.20

We are pleased to announce the release of ops-gfsv16.3.20.

Note: this release is an older version of UFS_UTILS that was only created to support the operational GFS v16.3.20.

General users are directed to use the latest release version - "Version X.Y.Z."

New to this release:

• Updates to the emcsfc_snow2mdl program to process global AFWA/Air Force Grib2 snow data.
• Updates to exemcsfc_global_sfc_prep.sh and emcsfc_snow.sh for this global data.
• Improved script error handling per NCO request.

The OPS GFS will no longer use the AFWA/Air Force Grib1 hemispheric snow data.

Fixes #973