https://www.wxcaster.com/gfssnow.txt
1) Find the maximum temperature in the lowest 500 hPa in degrees K (MAXTMP)
2) If MAXTMP is greater than 271.16K, then the liquid equivalent ratio (RATIO) is 12.0 + 2.0*(271.16-MAXTMP)
3) If MAXTMP is less than 271.16K, then the liquid equivalent ratio (RATIO) is 12.0 + (271.16-MAXTMP) The 3-hourly snowfall (SNOW) is RATIO multiplied by the three hour liquid precipitation total. The accumulated snowfall (ACCUM_SNOW) is the sum of all the SNOW v