Feb. 8 -- Following Punxsutawney Phil's prediction of six more weeks of winter, a blast of Arctic air infiltrating from Canada has ushered in the coldest air of the winter season across the Plains and Midwest and will likely settle in for days.
Above-average temperatures that were observed across much of the Plains and Upper Midwest to start the month of February will quickly become a distant memory, as temperatures some 30-50 degrees Fahrenheit lower will become commonplace over the coming days.
Residents of Rapid City, S.D., may have had to double check the calendar to make sure it wasn't April last week when the high temperature topped out at 59 degrees. A harsh return to reality has already begun to settle into the area as the high temperature rose to just 12 degrees Saturday and 2 degrees Sunday.
"The press of Arctic air will coincide with a large southward lunge of the jet stream associated with a break-off lobe of the polar vortex and should give the frigid weather a free ride into much of the Central states starting this weekend," AccuWeather Senior Meteorologist Brett Anderson explained, adding,
"Reinforcing waves of cold air will arrive through at least the first part of the week."
The southward shift in the polar vortex will yield bone-chilling cold for nearly every city across the Plains and Midwest through a majority of the upcoming week.
A multi-day snap of cold weather will undoubtedly prove costly in the form of increased heating demands, as forecasters are calling for temperatures to fall a dozen or more degrees below average for several days.
Aside from increased heating demands, bitterly cold air of this magnitude can also prove life-threatening for those caught outside for an extended period of time.
Chicago on Sunday observed its first sub-zero temperatures of the season courtesy of the polar vortex. Through at least Thursday, low temperatures are expected to fall within a few degrees of zero in and around the city.
Chicago topped out at 5 degrees and bottomed out at 7 below, making it the second-coldest Feb. 7 on record. The coldest was set in 1893 when the mercury reached zero.
Unseasonably cold conditions will persist for Monday.
Hypothermia and frostbite become serious threats in this type of air mass, especially with strong winds blowing or when people are trying to walk or jog. For those who venture out, extra layers of protective clothing will be needed to avoid severe weather hazards.
If the low temperatures aren't enough, rounds of snow will also be a threat in some locations. Quick-hitting storms capable of dropping swaths of accumulating snowfall will traverse along a path from the northern Rockies into the Plains and Midwest into midweek.
Following the round of snowy conditions to end the weekend, another quick-hitting storm system is expected to ride along the heels of this storm system early this week. Many of the same areas dealing with snow to end the weekend can expect another fresh coasting of snow Monday into Tuesday.
Lake-effect snowfall will also be a concern in the coming days, as the Great Lakes still remain largely ice-free.
Despite the lack of ice coverage, it still has not deterred local ice fishermen. For some 60 or more ice fisherman on Sturgeon Bay, Wis., ice floes became detached from the shore last week amid windy conditions, prompting a Coast Guard rescue effort. A similar scenario occurred on Michigan's Saginaw Bay.
The upcoming weather pattern will likely expand the ice in these areas.
It may have been a slow start to the 2020-21 winter across the northern tier of the United States, but winter is now returning with a vengeance.