Strong west coast trough

No changes to my thoughts for the rest of December.

The ECMWF and GFS continue to advertise a MAJOR trough slamming into the western US by day 7. Could get very stormy and cold for them. An intense jet stream will round the bend in the SW, then travel northeast to the north of the region. This will bring a period of above normal temperatures for the eastern third of the nation. However, the jet stream will be so strong that ridging will not get any chance to amplify, so no blowtorch is expected. This period, December 14 to 21 should be fairly inactive as storms fail to amplify in the very progressive jet stream. A moderate positive NAO will remain in control.

Beyond this period, GFS ensembles and operational like the idea of the trough shifting into the east. I think with the help of a significant storm around the 22 to 23, we'll be sent back into a -NAO / cold regime for the end of December and the first half of January.