A warm December is shaping up
November was cold, like really cold. Temperatures averaged 5 to 7 degrees below normal for most of the viewing area.
December looks to shape up a bit warmer, like much warmer.
Take a look at the picture above. It shows the position of the jetstream by this weekend, and a Low pressure system setting up in the north Pacific.
When the jetstream digs south over the Pacific, the way we expect it to by this weekend, it almost always forces the jet north over central North America. This means cold weather for the north Pacific and warm weather for most of North America.
And this is not an easy pattern to break.
By the looks of it, Low pressure system after Low pressure system will develop in the north Pacific over the next two weeks. Like a constant parade of never ending Lows. This will enhance and cement the trough over the north Pacific.
And on and on we go. When do we stop? No buddy knows.
As long as this MASSIVE dip in the jetstream remains over the the north Pacific there are really only a few efficient ways of breaking it up.
One is the polar vortex. Another is High pressure.
If the polar vortex were to spin it's way down into eastern Siberia, it would force the jetstream in the north Pacific northward, breaking up the everlasting Low, south of Alaska.
Also, if High pressure were to build in from the southwest, this would cause a similar break up of the jet's position.
A third option would be for the trough over the north Pacific to back track to the east and intensify, this could help force some colder air to the south over the U.S., perhaps even a piece of the polar vortex.
One thing is for sure. The pattern of above normal temperatures will continue thru at least the 20th of December. Not exactly the start to winter that the Climate Prediction Center was thinking of when they issued their winter forecast for the U.S., which highlighted much of the southern U.S. for a colder than normal Dec-Jan-Feb.
As for all you folks hoping for a white Christmas, lets hope this north Pacific Low takes a hike soon. Sure, our chances for snow on Christmas are never really all that good. But, if this pattern doesn't break, our chances aren't much better than Jacksonville, Florida.
Meteorologist Darby Bybee