Record High Temperatures In U.S./Canada Are Insane For December

All of the Lower 48 was warmer than average Thursday.
Many areas had record highs especially in the Rocky
Mountains and parts of the Plains States

 December is definitely not known for its heat in the northern United States and Canada, but this December is getting off to a downright summery start in these usually frigid places.

A record was tied for the hottest temperature anywhere in Canada during December when  Penticton, British Colombia got up to 72.5 degrees earlier his week.   

Four states - Washington, Montana, Wyoming and North Dakota tied or broke records for the warmest temperatures on record for December.  At least a dozen cities did likewise. 

Towns in both Wyoming and Montana reached 78 degrees, tying the two states' records for warmest December readings on record, says 

Hettinger, North Dakota reached 71 degrees, establishing a new December record.

Other notoriously cold spots that were not playing to stereotype included record highs of 77 in Sheridan, Wyoming, 70 in Cheyenne, Wyoming and 75 in Rapid City, South Dakota. On Wednesday,  Mobridge, South Dakota, reached 71 to establish a new record high for the entire month of December. 

Record highs stretched across the nation yesterday from Washington State to Virginia. as Weather Nation notes.   Every place in the Lower 48 except possibly far eastern Maine was warmer than average on Thursday. (It was only a little on the mild side here in Vermont Thursday, but it counted!)

Some normally warm spots were even warmer than you'd expect this time of year. Tucson, Arizona set a record high of 85 degrees.  Palm Springs, California tied a record high of 91 degrees.

As you can imagine, snow is lacking in this warm regime.  About 8.6 percent of the Lower 48 had a snow cover Thursday morning. Usually, at least 20 percent of the nation is snow covered this time of year.

Denver, Colorado is still waiting for its first measurable snow of the season. That's a record for the latest first snow.

At one point Thursday, only two states had winter storm watches or warnings up - something that's normally a widespread hazard this time of year.

The two states with those winter advisories were Alaska, which you'd expect, and Hawaii, of all places. The summits of Mauna Kea and Mauna Loa were expecting snow, which accounts for the winter storm warning there.

Though the warmth might diminish some in the nation in the coming days, well above normal temperatures are expected to continue at least through mid-month, and maybe beyond. The early December warmth follows an autumn that was among the top 10 warmest on record in a broad area from much of the western U.S. across the Plains and into the Northeast. 

The reason for this widespread warmth is that the jet stream is riding further north than usual for this time of year. And the polar vortex, often the source of Arctic cold snaps down in this part of the world, is bottled up far to the north, trapped up there by the strong jet stream. 

Because of this arrangement, there are some cold spots in the world. Alaska, northwest Alaska, Scandinavia and parts of northern Russia are currently frigid.

Still, the fact that such a wide area of the world is so warm, is a sign of climate change. This weather pattern would have led to widespread warmth, but climate change is probably giving it an added boost.

For now, we here in Vermont are mostly bystanders to the warmth. Part of the state on Thursday did see some weather more common in summer than winter.  A line of strong thunderstorms crossed southern Vermont in the evening with frequent lightning, gusty winds and small hail. 

It will be chilly in Vermont through the weekend. However, a fairly strong storm will go by just to our west Monday.

That will bring in a quick squirt of very warm air, with highs reaching the 50s.  This kind of storm can create a surprising burst of warmth, so we'll see how high temperatures go on Monday. It's even possible that we could get some more unseasonable thunder on Monday.

We'll chill down again Monday night into the middle of next week, but the long term pattern favors mostly warmer than average temperatures for the Green Mountain State through mid-month at least.