The penetration sex videosU.S. weather pattern during Christmas week is going to be what forecasters call "highly amplified." This means that the jet stream, which separates air masses and steers weather systems, will be undulating sharply — with large northward bulges, or high pressure ridges, and deep dips, or low pressure troughs, toward the South.

For Christmas week, this jet stream configuration will allow Alaskans to enjoy an unusually mild holiday, while residents of virtually the entire lower 48 states (except Florida) experience a colder-than-average period.

There are still many uncertainties involved in the forecast for the next few weeks, including where the core of the frigid air will set up — some data indicates it will hit the Midwest; other information suggests a glancing blow as the coldest air stays north of the U.S.-Canada border — as well as whether any snowstorms will zip up the East Coast or slam the Colorado Rockies.

What forecasters are confident about, though, is that a lengthy period of colder-than-average temperatures are likely across large parts of the U.S.

That doesn't mean this is the polar vortex winter of 2013-14 redux, or even that many cold temperature records will be broken (in fact, Alaska has more record-setting potential with the unusually mild air there).

However, this will be the coldest air of the season for some, arriving at the right time to produce a white Christmas in parts of the country.

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What's odd is that Alaska, which is America's only Arctic state, is missing out on a lot of this snow and cold. Many locations throughout the state are on their way to recording the warmest December on record, with temperatures climbing above freezing in Fairbanks, where the normal high temperature for this time of year is just 5 degrees Fahrenheit.

In Barrow, Alaska, the northernmost city in the U.S., temperatures have been so far above average lately that a computer algorithm caused the weather data to be tossed out of calculations made by scientists at the National Oceanic and Atmospheric Administration (NOAA).

Residents of Barrow, also known as Utqiaġvik, have been experiencing the effects of missing sea ice cover this year, which exposes the shoreline to pounding waves and erosion from storms.