EDIT: Map has been issued below.

The first widespread, more significant snow storm of the season looks to impact Southern Ontario on Tuesday December 12th.

I have discussed in the White Christmas blogs that the amplified pattern would bring cold and some Alberta clipper storms that can sometimes develop into more than a 2 to 5 cm storm.

Most models have a clipper coming in Monday night into Tuesday that rather than speeding through Ontario, it slows down as the storm strengthens and transfers to a stronger coastal storm.

Here is the latest from the GFS – with snow totals (direct hit for S.Ontario, all snow):GFS

GFS snow

From the GEM (CMC) with snow totals (earlier and further north with some rain around Lake Ontario):Gem stormgem_asnow_neus_20

And the CFS with snow totals (similar to the GFS):CFSCFS snow

The thing to keep in mind with the coastal transfer systems:

  1. Sometimes the strengthening does not occur over our region and the storm continues on its quick path to the coast,
  2. the energy transfer to the coast can happen very quickly and the storm essentially dies out over Ontario (this commonly happens over E.Ontario and SW. Quebec and we loose a great deal of moisture)

Also the system could slip south of Ontario, as the Euro model suggests, which would also limit totals.

Here is the Euro’s latest placement of the low further south of Ontario:Euro

and the snow totals:ecmwf_acc_snow_ne_126

For now here is my thoughts for snow totals: (the timing is late Monday, overnight into Tuesday evening):

Ottawa – 5 to 10 cm

Belleville and area – 5 to 10+ cm

Toronto and the GTA – 5 to 10 cm

Hamilton down to Niagara SW Ontario – near 5 cm, possibly more near Lake Erie

Windsor to London –  5 to 10 cm, (possibly 15+cm up towards Lake Huron and snowbelt regions)

Wasga Beach over to the Muskoka’s, Barrie and Central Ontario – 10 to 15+ cm

Sault Ste Marie over to Sudbury & North Bay – 5 to 15 cm (depends on whether the lows stays south or goes further north)

I will add a map to this post and update totals this weekend once we have some more model run consistency.

Map issued Dec.10th:

Dec.12 storm post