Function sounding_analysis::nssl_precip_type

pub fn nssl_precip_type(snd: &Sounding) -> Result<PrecipType>

Analyze a sounding using the NSSL algorithm for precipitation type.

This algorithm also analyzes wet snow vs snow, but the precip codes we have in this module do not allow that distinction, so wet snow will be analyzed as snow. It also may analyze mixed freezing rain and ice pellets, for which we have no code. In that case we will analyze freezing rain since that is generally considered the more severe weather type.

In addition to the NSSL algorithm if the type of the sounding is type 1 - 4 (i.e. the surface wet bulb temperature is below 3C) and the RH is below 80% in the dendritic layer, then an appropriate drizzle type is selected. If the surface wet bulb is warm enough, there is nothing to prevent warm rain processes from generating rain so it is impossible to tell the difference between drizzle and rain.

Since the sounding generally doesn't come with information convective or stratiform and the amount of precipitation, this function can only determine the phase (ice or liquid) and whether it is likely to freeze once it reaches the surface (eg freezing rain). So all returned weather codes will assume stratiform conditions and a light intensity.