Do you any publicly accessible ground observations which have both solid and liquid precipitation rate? Preferably for many sites in different regions.
Assuming that ground measured data is the most reliable for the snowfall rate.
Synoptic stations have to observe both solid and liquid precipitation, plus the depth of snowpack on ground for the 3 hours time interval . Where you can find them; that needs a little bit search and comunication. I may have the data for some of the stations in Iran and US, but they are not new data. Please let me know if you need help