The AccuWeather.com Canada winter forecast for 2012-2013 will be released tomorrow, but I wanted to give my readers a brief, early preview....
In making up this seasonal forecast, we considered some of the following...
1. Northern hemispheric jet stream patterns throughout this year and how they compared to earlier years (finding similarities and coming up with analog years).
2. Sea surface temperature anomalies across the Pacific and Atlantic, including the El Nino Southern Oscillation (ENSO), the longer-term PDO and AMO oscillations.
Odds now favor that the ENSO will have little impact on the winter weather in Canada this season as it hovers near-neutral, perhaps very weak El Nino. A lack of an El Nino connection does not make this forecast any easier.
3. Lower-than-normal sea ice extent in the Arctic, Hudson Bay and Gulf of St. Lawrence.
4. Significant longer-term warming over the far northern latitudes.
5. The hurricane season this year in the Atlantic/Pacific.
6. Established snowcover across the Prairies will be critical to the strength of the cold shots that come into Ontario.
7. Long-range seasonal computer forecast modeling.
The changing Pacific North American, North Atlantic and Arctic Oscillations throughout the season will play a major role in the winter weather pattern as they usually do, but there is really no forecast skill in predicting the phases of those oscillations this far out (months).
However, we can look at longer-term trends of these oscillations which may give us some clues to what the dominant phase may be this winter. Low sea ice in the Arctic and warmer-than-normal sea surface temperatures could also impact the Arctic Oscillation.
Last winter, the Arctic and North Atlantic Oscillations remained in the high, positive range for an unusually long time. This overwhelmed any impact from La Nina and kept the Arctic air trapped in the far north while mild; Pacific air overwhelmed the country much of the season.
The odds of this happening again this winter seem low based on what we have been looking at.
A few selected winter forecast highlights........(full details on Wednesday)
1. In general, December looks fairly mild across the country relative to normal, then more typical winter conditions for January and February.
2. The winter looks stormier, but warmer than normal for most of Atlantic Canada.
3. A drier winter for most of BC.
4. The winter as a whole should be much colder compared to last winter (record warmth) across the Prairies, but still averaging near to slightly colder than normal overall. Latest computer model trends over the past month have been going in the colder direction across this region.
5. Ski season off to good start in the west. In the East, the season might start out a little slow but should recover nicely in January and February. I promised my daughter I would take her skiing more often this winter, so there is a lot riding on this!
6. Pretty confident in going with above-normal temperatures and snowfall for far northern Canada once again.
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My thoughts on the snow through Tuesday in the East and West.
Other than a blast into western Canada next week, most of the Arctic air will remain north of the Arctic Circle into December with just brief intrusions while mild, Pacific air takes hold from west to east.
Still happy with my old snow map.
Accumulating snow this weekend for parts of southern, central and eastern Ontario.
Wild storm in the West through Tuesday. A little snow in the east for the weekend?
The latest clues to the weather pattern over the next several weeks.