The leading edge of Arctic air will trigger a band of accumulating snow into tonight across the Rockies and western Prairies then into extreme southern Prairies early Saturday. The map below shows the projected snowfall.
Temperatures Saturday and Sunday night behind this front will drop to between -30 and -35 C from eastern Saskatchewan through southern Manitoba and into extreme northwestern Ontario.
This same front will drift into central Ontario and southern Quebec through Saturday night and will bring a small accumulation to the region below....
A storm will spread northeastward from the Gulf of Mexico Saturday and will bring snow and mixed precipitation from Quebec to the Maritimes Sunday night into early Monday.
There is the potential for heavy accumulations over southern New Brunswick, PEI and extreme northern Nova Scotia, while areas just to the south will likely see the snow change to sleet and perhaps rain, which will limit accumulations greatly.
This storm will be loaded with moisture, but its quick, forward speed should keep the highest amounts under 30 cm for the most part.
Once all this storminess moves out, it will open the door to the core of the Arctic air and the graphic below shows the expected pattern early next week as the main polar vortex shifts toward James Bay and forces the motherlode of the Arctic air toward Quebec by the middle of the week.
The graph below shows the expected actual low temperature ranges for Monday night, but it gets worse in the east by the middle of the week.
Even though our current low temperatures for Wednesday night/early Thursday do not reflect this as of yet, we believe that January record low temperatures for southern Quebec could be in jeopardy. There is also the slight chance that the all-time, annual record low in Quebec City -36.1 C (-33 F) could be at least challenged. I will keep you posted.
You can also follow me on my twitter @BrettAWX for quick updates on changing weather.
Here is my latest interpretation of the ECMWF weekly long range forecast model through the 3rd week of August.
Damaging thunderstorms and possible tornadoes for the western Prairie region Thursday.
The western heat wave finally winding down, but some hot weather headed toward the eastern Prairies and northwestern Ontario by early next week.
Widespread record heat for BC
Pattern of extremes into next week and a look at August.
One of the worst wildfire seasons in recent time across the Northwest Territories is causing a massive plume of smoke....