I’d take a 12/16 to 1/8 cold snap!
Cosgrove this morning….
When Arctic air interacts with the southern branch storm track.
I will admit that the numerical model runs of this past weekend gave me fits, especially the GFS series. The newly revised American model suite put on yet another "nothin' but warm" show, while the ECMWF and GGEM panels slowly turned back to colder solutions, starting in the medium range period. But when you size up the atmosphere around the Northern Hemisphere, it seems apparent that we will return to a mild West vs. cold Central/East alignment.
There are two key drivers to the evolving pattern in North America. One is the building and retrogression of a blocking ridge in Greenland, which looks to shift into Nunavut AR in the third week of this month. The ridge displaces the current Arctic cold pool and 500MB vortex, and forces the chill to stream into coverage to the right of the Continental Divide.
Another factor favoring a more wintry look to the lower 48 states is the southern branch jet stream. Aided by an energy/moisture input form the Madden-Julian Oscillation, and already nudging into the American Southwest, the subtropical wind field will contain disturbances that will wear down the heat ridge complex straddling the southern Gulf of Mexico. The initial impulse should bring heavy rain and thunderstorms in the near term in a belt close to Interstate 40 (Oklahoma City OK to Wilmington NC). But the second and third storms will be stronger, tap into colder air next week, and may yank the snow line further south into the Ohio Valley and middle/upper Appalachia by December 15.
If model projections of the ridge complex near the Arctic Circle verify, we may see another two storms riding the rim of a very cold air mass over the eastern two-thirds of the U.S. between December16-25. The CFS platform suggests that this configuration will last until about January 8 2023, then give way to what looks to be a very impressive, ten to fourteen day "January Thaw".
I hibernate when it gets above 75 degrees!