Another in a series of Pacific storms will dive southeastward tonight spreading another round of steady precipitation into western BC through Wednesday.
With just enough cold air in place just above the surface there will be another round of wet snow for many of the coastal areas, including Vancouver, tonight and into Wednesday morning.
I expect the steadiest snow to fall late tonight in the Vancouver area. Warmer air coming in aloft will turn the snow over to rain by midday Wednesday, but not before we see a general 4-8 cm. There should be another dump for the Coastal Mountains and the Cascades.
Strong storm headed for the Great Lakes by Thursday... significant snow possible from Sudbury to Ottawa.....
A significant storm will track up into the Great Lakes on Thursday then will slowly drift eastward through Friday night as it slowly weakens.
Computer models are in very good agreement for a change on this one and show a track right into Michigan then eastward into Ontario.
The models did shift the storm a little farther south as it crosses through Ontario on Friday which keeps the dry slot south of the Ottawa region, which keeps the snow going. Right now, I can easily see over 15 cm from Sudbury to North Bay and Ottawa with this one, even if there is a little mixing in Ottawa.
Montreal and the eastern townships will be a tougher call as easterly winds could bring in just enough mild air for a change to mixed or some rain for a time on Friday. However, I do believe there is a good chance of steady, accumulating snow later Thursday night and early Friday. Any rain or mixed precipitation should go back to snow Friday evening in Montreal.
This storm should be all snow for Quebec City and into northwestern New Brunswick Friday/Friday night.
The snowfall map below only goes through Thursday night, so accumulations will be higher than what is shown from eastern Ontario through Quebec and into northern New Brunswick since it will snow in these areas on Friday/Friday night. A new map will be posted tomorrow to reflect this.
Also, even though the map says "blizzard" this will not be a blizzard for Canada. The blizzard reflects expected conditions from northern Kansas to Wisconsin and the UP of Michigan.
Lake effect snow Friday-Saturday
As the storm pushes into eastern Canada on Friday cold air wrapping around the back side of the storm will eventually lead to an outbreak of lake-effect snow downwind (winds from WNW to NW) of Lake Huron and Georgian Bay, especially late Friday into early Saturday.
Due to the duration of this event and the limited instability I so not think this will be a major lake-effect event for these areas, but decent, especially by this and last year's standard.
We will issue a lake-effect snow map for this region tomorrow.
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My look at the overall pattern across Canada for this week.
Some forecast model clues through the end of August and an update on global sea surface temperatures.
Tornado threat into Tuesday from southeastern Saskatchewan to northwest Ontario.
Latest weekly clues to the long range forecast through mid-August.
Major storm for the Prairies early next week could bring heavy rainfall and severe thunderstorms.
Severe thunderstorm threat later Thursday and a general look at the upcoming weather pattern.