So the storm that came through Sunday night into Monday failed to weaken and remained much stronger than expected by almost all the models.  Its what us weather nerds all an over-performer.  I was wrong on my snow totals, as was the weather agencies who do this for a living!  Environment Canada said 2-4 cms for Ottawa, but then updated it Monday AM to 5 – 10 cm when it was clear the storm was remaining strong.  TWN said around 3 – 6 cm.  Ottawa recorded 8.2 cm and I recorded 12 cms west of Ottawa.  These storms can surprise once and awhile and the reason why weather can be hard to predict, the models can’t get it right all the time.  The Euro model did depict a fairly strong storm early on last week but backed down as we got closer.

The storm coming tonight into Wednesday and Thursday looked much stronger and warmer last week, but has now weakened and split into 2 low pressures systems; one far west over Thunder Bay/Kenora, and one on the US east coast near southern Ontario.  They will sort of merge together tonight but all models agree they will not strengthen like initially thought.  The means snow and rain totals will be lower.  In my opinion the models won’t get this one wrong!

Here is the storm look for tonight:gfs-tonight-1

Most of southern Ontario will be a mix of rain and snow, while eastern Ontario will be snow overnight, mixing with rain tomorrow AM.  I believe Environment Canada’s totals and Ottawa should remain around 2 cm of accumulations.

By Friday, the arctic air I have been talking about will make it’s appearance.  Come Saturday things will be very cold.  This will get the Lake Effect snowbelt regions to kick off their season.  They could be measuring snow by the foot come the weekend of December 18th, with off and on lake effect squalls.

Models also have a decent sized storm for Sunday Dec.11th into Monday the 12th.  Most locations in Southern, central and Eastern Ontario could be looking at 10 -15 cms.  Here is the current look:sunday-night-storm

More to come later this week on that storm.  The week of Dec.12th – 18th continues with a cold look, especially out west, lows in the -20’sc out there!  Dec.19th 25th still looks questionable with mixed signals at this point, especially near Christmas with rain and warmth.  However I am not convinced since there is guidance to support a continued cold look.