They're extremely hit & miss - and for here at least, most/all in the past couple of decades at least have been as disappointing as you describe, although I've got memories of a few of snowy breakdowns in the 80's and 90's.
I therefore view the GFS forecast with scepticism, more in hope than expectation. As someone whose snowfalls this spell have been pitifully small (with little prospect of that changing in the current set-up), a snowy breakdown and seeing snow pile up for 24-36 hours before the rain moves in (all per GFS) is better than a continuation of cold and predominantly dry. I appreciate those who've fared better for snow won't agree.
The worst letdown was on NYE 2000 (into 2001). Thick snow on the ground already from a few nights previous, heavily frozen. An active front coming in from the west. BBC forecasting several hours of heavy snow starting around 8-9pm as the front hits the cold air (and you always hope they're underestimating the cold block). I could almost see the headlines of thousands of NYE revellers having to spend the night in clubs and bars as snow chaos reigned. Here, it snowed for about 5 mins, another 10 or so mins of sleet, then the heavy rain set about washing away the standing snow.
Originally Posted by: Saint Snow