Probability of snowfall for the given period.
Within the context of hourly data, snowfallProbis reported every 6th hour (with 5 intervening null values). The reported snowfall probability is for the 6 hour period ending with the hour that contains the reported data. For example, if there is a 20% snowfall probability reported for the 8 A.M. hour, this means that there is a 20% chance of snowfall occurring between 2:00 A.M. and 8:00 A.M.
