Transition from rain to snow overnight

Rain showers all day. Falling temperatures all day. Mud season at peak, with frost heaves at all the usual places on Pinnacle Rd. Yamaska river in Cowansville was above it's normal level, but well below its banks, with Sutton River similar. Transitioning to snow around 5:30 PM; 1.5 mm of rain collected in small gauge at this time and removed to let larger gauge capture snow. Large flakes of wet snow observed at this time with temperature +1.5 C. Was outside at 10:30pm for mixed bag of frozen precipitation with brisk winds blowing small (~1mm), stinging ice/snow pellets; transition back to snow in about 10 minutes. Brisk winds and blowing snow through night with overnight low temperature of -3.5C. 

Gauge catch: Temperature +1.5C at 9:30 observation time. Overnight gauge catch (large gauge) of 4.1mm consisting of roughly 2mm (+- 0.5 mm, measured) fused rain topped by powdered snow. 

Snowboard: about 20 cm off ground next to gauge has 1.7cm (+-0.2cm) of dry, powdery snow consistent with mixed bag of frozen overnight precipitation; snow starts tapering off about 15 cm from board edges, so sample taken from center of board. Bottom layer is frozen to plywood and difficult to remove from plywood. Melted value is about half of snow catch, suggesting a) runoff of rain and wet snow early in snow period b) snow blown off higher platform in latter stages; would say that 2mm of fused rain in gauge suggests the former (i.e. rain runoff). 

Observed discrepancy between precipitation board used for daily snow amounts and grassy lawn around rain gauge used for daily snowpack amount. Snow cover over grass is complete, with some longer tufts of grass poking through. Snow pack forms coherent mass supported by grass, with bottom surface 2-5 mm (measured roughly) above likely adding ~0.5cm to snow reading.  Easy to get spatula under gauge to take sample.  Snowpack is smooth on top, with powdery snow showing similar consistency and density to snowboard (~10%). Water content of pack measurement (3.8 mm) is similar to that of gauge catch for frozen precipitation period 5:30PM - 9:30AM  (4.1 mm) and likely more representative of actual snowfall in woods and open fields. /////// I have to question the rationale of using plywood snowboards as opposed to natural or representative surfaces (i.e. gravel, asphalt) for estimating snow amounts for a broad area. If these hydrological amounts are going to be used to predict stream flow, it makes more sense to use surfaces representative of the surrounding landscape.