Table 4.203 https://www.nco.ncep.noaa.gov/pmb/docs/grib2/grib2_doc/grib2_table4-203.shtml Clear Cumulonimbus Stratus Stratocumulus Cumulus Altostratus Nimbostratus Altocumulus Cirrostratus Cirrorcumulus Cirrus Cumulonimbus - ground-based fog beneath the lowest layer Stratus - ground-based fog beneath the lowest layer Stratocumulus - ground-based fog beneath the lowest layer Cumulus - ground-based fog beneath the lowest layer Altostratus - ground-based fog beneath the lowest layer Nimbostratus - ground-based fog beneath the lowest layer Altocumulus - ground-based fog beneath the lowest layer Cirrostratus - ground-based fog beneath the lowest layer Cirrorcumulus - ground-based fog beneath the lowest layer Cirrus - ground-based fog beneath the lowest layer Unknown Missing