The long-range weeklies are getting closer to the Christmas holiday and the central theme of what they are showing for the first half of December is that the Rockies into the Prairies will be colder than usual.
There is a high level of uncertainty in the East, especially in the precipitation department (not unusual), while the overall pattern seems to favor a drier regime along the West Coast.
The Arctic Oscillation (AO) is extremely positive right now, which usually does not translate to the unseasonably cold weather that we have seen in the eastern two-thirds of the U.S. and parts of southern Canada lately. However, the pattern across North America over the next five days will be more typical +AO with a strong west to east, zonal jet stream flow which allows Pacific air to weep across southern Canada and the U.S.
The AO is predicted to trend more neutral over the next week and possibly more negative toward the end of the month, which could eventually help send the Arctic cold back down into the central and east areas, despite what the weekly long-range models say.
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Arctic air will pay a brief visit to southwestern Canada early this coming week.
Update on the white Christmas probabilities
Update on white Christmas probabilities and other thoughts.
Update on White Christmas probabilities for Canada
Update on the long-range forecast model data.
A look a the storm systems that could impact Christmas Eve and Christmas Day in Canada.