A fuzzy logic weighting for each precipitation type can now be set between 0.0 and 1.0 to adjust the relative frequency of precipitation types recorded.
A parameter can be set between 0.0 and 10.0 adjusting the ratio of snow grains to snowflakes for snow grains to be reported independently of other settings. This allows the user to set the proportion of particles that have to be snow grains for snow grains to be reported. For example if the parameter is set to 0.0 then SYNOP code 77 will be reported if there are any snow grains present. If it is set to 10.0 then snow grains will only be reported if they are in overwhelming numbers. The default is 1.0 which results in the snowflakes/snow grains criteria being in line with those for other precipitation mixtures.
The RH criteria for fog/haze and mist/haze can now be set individually and separately for METAR and SYNOP coding according to local practice.
A simple visibility only calibration procedure is now supported by the PWS100. This can be used instead of the full calibration process that covers particle size and speed carried out with a PWC100 calibration kit. A visibility only calibration device is now available.
WMO code 35 for freezing fog is added (METAR code FZFG already exists).
Improved resistance to false large hail detection in wind and snow is added. Combined with improvements to the treatment of the non-spherical shape of larger raindrops this will result in improved accumulation measurement.
METAR codes can now combine slight precipitation simultaneously to a visibility code, for example -RAFG or -SNHZ.