The weather pattern will undergo another shift across North America late this week, leading to an outbreak of cold weather for most of western Canada.
In addition to the turn to colder weather late this week and into next week, the western mountains should see some snow.
The map below shows the progression of the initial strong cold front coming down from the Yukon late this week...
As is usually the case, when the West turns cold and the East turns mild.
Going into next week, the GFS model ensembles below are in good agreement showing widespread cold covering much of western Canada, especially from BC to Alberta, where temperatures from Monday to Wednesday next week could be as much as 8 to 12 C below normal.
With cold air this widespread, there will likely be widespread snow showers, especially in the mountains from the end of this week into early next week, but heavy accumulations are unlikely with the absence of moist, Pacific air. That could change by midweek for BC as there are indications of a stronger Pacific storm system coming inland into the colder air.
The latest indications are that Rafael, which will pass not too far east of Bermuda Tuesday evening, will track far enough southeast of Newfoundland later Wednesday resulting in minimal impact (rough surf) for southeastern Newfoundland.
A stalled out storm in the upper levels of the atmosphere over the Upper Midwest of the U.S. late this week could send a batch of heavier rain up into southern Quebec on Friday, then perhaps the Maritimes by Saturday, though there are major timing issues between the latest computer models.
The AccuWeather.com Canada Winter forecast for 2012-2013
We will be releasing the winter forecast for Canada this Wednesday. I will discuss some of it beforehand on Tuesday in my blog.
Some needed rainfall for southern Ontario this week.
Mild air masses likely to outnumber the chilly air masses for a good part of October.
Jet stream pattern across North America will become amplified across North America into next week, which means more extremes in weather.
Warm weather will dominate in the eastern half of the country for the next week. Pattern change possible during the last week of September.
The jet stream will strengthen from the Pacific across southern Canada over the next 1-2 weeks which will keep any sustained chilly/cold air masses up across western Alaska and eastern Siberia.
The latest clues to the long range into the month of October.