Trashy posted something a couple of days ago stating unequivocably that “no way… is Ottawa getting snow before Christmas day”. The long range forecast on Environment Canada’s website suggests it’s going to be cold enough for snow and the latest aviation forecast suggests there’s going to be periods of snow overnight::

TAF CYOW 221744Z 2218/2318 24007KT P6SM SCT030 BKN100 TEMPO 2218/2220 BKN030 OVC100
FM222000 23005KT P6SM OVC025 TEMPO 2221/2301 6SM -SHSNRA OVC020
FM230100 33005KT P6SM OVC020 TEMPO 2301/2310 4SM -SHSN
FM231000 34012KT P6SM OVC030
FM231500 33006KT P6SM SKC
RMK NXT FCST BY 222100Z=

For those who need a translation, it basically says starting at 4pm this evening (2100Z), there will periods of light rain showers and light snow showers until 10pm followed by periods of light snow showers until 5am tomorrow morning. I suppose there could be a thin layer of snow that hangs around until Christmas but I’m not too hopeful. If you believe the long range forecast, there will be periods of snow on Christmas Day, but it’s still a bit early to tell for certain.