Above graphic based on GFS output from 6am Tue 8 Dec 2009 model run / valid for time shown
UPDATE: 3:15p.m. Wednesday 8 Dec 2009 (map updated as well)
The models continue to trend to a milder weekend pattern. The next shot of cold (after Wednesday-Thursday) may arrive late Monday. It will probably be less intense than the past two blasts of winter chill.
The weather pattern continues very active through this week, typical for an El Nino environment.
See the regular weather discussion for day-to-day particulars; this blog focuses on the period beginning 11 Dec (Friday) through 14 Dec (Monday).
A straight west-east flow is predicted by the models for this time frame. This is an unfavorable pattern for cold air intrusions from Canada, but that’s pretty much what we had last weekend and the front made it here anyway.
Very cold air which builds over the arctic regions sometimes overcomes the upper flow by its density.
It’s very difficult to predict when this will happen and when it won’t, but the higher surface pressure, the more likely this may take place.
For now, it’s something to keep a close eye on for this weekend as the pieces come together.