Call it Novembruary.

Temperatures have cratered to record territory across much of the continental U.S. during the past week and a half, due to a chain reaction that stretched from the snow-covered wilderness of Siberia, across the Bering Strait, and into North America. How cold is it? Well, Minneapolis-St. Paul, which is no stranger to cold weather, is within reach of setting a record for the longest streak of sub-freezing November days, if it stays below 32 degrees Fahrenheit there through Nov. 25. This record dates back to 1880.

Then again, Minnesotans know how to deal with the cold, regardless of its timing:

Of course, guy from Minnesota is eating ice cream in a blizzard pic.twitter.com/Hd6kw9h9nG — Tom VanHaaren (@TomVH) November 15, 2014

Temperatures have cratered as low as minus 29 degrees Fahrenheit in Wyoming, and snow has fallen from Portland, Oregon, to Denver, and all the way east to Cleveland. A reinforcing surge of cold air will likely challenge records from the Midwest to the East Coast early next week. Already, as of Saturday at 2 p.m. ET, 41% of the continental U.S. had an air temperature at or below freezing.

At the same time that people in the lower 48 states have been reaching for their winter coats earlier than usual, Alaskan residents have been thrown off by unseasonably warm temperatures. And by "unseasonably," we're talking about temperatures up to 50 degrees above average. Barrow, Alaska's high temperature of 35 degrees Fahrenheit on Nov. 13 was warmer than the high temperature in St. Louis, Missouri, and 28 degrees Fahrenheit above average for the date. This mild air is remarkable considering that Barrow, which is above the Arctic Circle, only receives about three hours of sunlight at this time of year.

Residents in Anchorage, Alaska, have been unable to start their ski season on time, given the mild temperatures and lack of snow. Meanwhile, some Rocky Mountain ski resorts have seen more than 2 feet of snowfall in just the past few days.

Bare ground observed at Hatcher Pass, Alaska, on Nov. 15, 2014. Image: Chugach National Forest Avalanche Information Center

The dome of high pressure sitting on top of Alaska and Northwest Canada has set records for its strength, and — like an 18-wheeler blocking an intersection — is effectively rerouting storm systems well to the north of Alaska, and opening the refrigerator door to the Arctic. Essentially, the air flow into the U.S. is coming directly from the North Pole, thanks in large part to this high-pressure area.

1. Jet stream winds

This jet stream map shows the air flow at about 30,000 feet, with arrows and an oval drawn to indicate the direction of air flow and the position of the blocking high-pressure ridge over Alaska:

Jet stream winds as of Nov. 15, 2014. Image: Climate Reanalyzer modified by Mashable

The high-pressure area developed partly due to Super Typhoon Nuri's transition into one of the most intense storm systems on record in the North Pacific Ocean, as is fully explained, here.

2. Temperature anomalies

The following map illustrates where it's unusually cold, and where it's unusually mild right now. The deep purple hues signify colder-than-average temperatures, while the orange and red colors show milder-than-average conditions.

Temperature anomalies for Nov. 15, 2014.

The weather pattern aloft also reflects the unusual dichotomy between a mild Arctic and a frigid U.S., with record high geopotential heights recorded over Northwest Canada and Alaska.

Since cold air is denser than warm air, it causes pressure surfaces to be lower in colder air masses, while less dense, warmer air allows the pressure surfaces to be higher. Higher geopotential heights are a sign of a warm air mass. Right now, geopotential heights are extremely high over Northwest Canada and parts of Alaska, an indication of the unusually mild air there at this time of year

850 mb November temperature record over Fairbanks shattered at 12 & 00 UTC in association with the über ridge pic.twitter.com/LcwmQl15UC — Stu Ostro (@StuOstro) November 14, 2014

The record heights and record mild air temperatures, as measured by weather balloons, are an important clue to how extreme this weather pattern is. They signify that the dome of high pressure has pushed up into the mid-layers of the atmosphere to such an extent that pressure surfaces around 18,000 feet have been displaced far above that, like an expanding balloon of air.

3. Geopotential heights

Geopotential height anomalies of the 500 millibar pressure surface, showing the extremely strong high-pressure area near Alaska on Nov. 15, 2014. Image: WeatherBell Analytics

4. Deviation from average

This is another way of showing how rare the intensity of the high-pressure ridge near Alaska is, from a tool that National Weather Service forecasters use to anticipate unusual or unseasonable weather conditions:

Standardized height anomalies at different altitudes, showing that the heights over Northwest Canada and Alaska are about four standard deviations from average for this time of year. Image: National Weather Service

After the cold air gets some reinforcements, and a snowstorm zips from the Midwest to the interior Northeast during the early part of next week, temperatures should begin to moderate across the lower 48 states.

5. Model projections

The evolution of the temperature departures from average shows this progression, with dark blues being replaced by lighter colors toward the end of the animation period.