Update, 4:20 p.m.
Independently, our search of the xmACIS2 weather database uncovered a low of minus-30 in Humboldt, Mich. on that same date. The database lists Stambaugh’s low of minus-24 this year as the second lowest April temperature recorded in Michigan.
Original post from 3:11 p.m.
The city of Stambaugh, in the Upper Peninsula of Michigan, unofficially watched its temperature free fall to unthinkably cold levels early Sunday, bottoming out at minus-24 degrees.
Frigid by even midwinter standards, this low temperature is exceptional for the second week of April. It requires verification from the National Weather Service, but if it stands, it will become the coldest temperature ever recorded in Michigan during the month.
It smashed the state’s previous April record of minus-17, set in 1982 and 2003, by 7 degrees. For comparison, the average low temperature this time of year around Stambaugh is in the mid-20s.
How did it get so cold? To begin, an unusually cold pool of air for the time of year was parked over the region, unleashed by the polar vortex late last week.
Stambaugh is about seven miles north of the Wisconsin line in Michigan’s Iron Hills. According to Justin Titus, a meteorologist at the Weather Service office serving Marquette, the cold in Stambaugh may have been intensified by a localized effect known as “cold air drainage.”
Without knowing the exact position of the temperature sensor in Stambaugh, Titus theorizes that it must have been in a low spot where cold, dense air can sink on calm, clear nights as heat escapes back into the atmosphere.
The drainage would have been enhanced by several inches of snow on the ground. The snow helps creates a localized inversion, where surrounding elevated areas are actually warmer than in valleys and river bottoms.
This drainage situation would help explain why other areas with different topographies, but only miles apart, did not get nearly as cold as Stambaugh.
Michigan may have become the second state to witness its most extreme April low temperature this year.
Paxton, Ill., plummeted to minus-2 on April 2, tying Illinois’s lowest April temperature. Like Stambaugh’s record, Paxton’s record is also preliminary, pending validation.
Temperatures across the Northern Plains and Upper Midwest have been brutally cold for much of the month. Most locations have seen temperatures average 15 to 20 degrees below normal.
Minneapolis witnessed its coldest first week of April in recorded history. St. Cloud, Minn., had its second coldest April day on Thursday.
On Monday, snow even covered Guaranteed Rate Field, home of the Chicago White Sox.
Somebody running the scoreboard has a sense of humor. #WhiteSox pic.twitter.com/fKll1CPDQU— Brian Sandalow (@BrianSandalow) April 9, 2018
In Upstate New York, a police department was so sick of winter that it sought to place it behind bars.
“Dear Winter,” the Depew Police Department wrote. “You are hereby placed under arrest. You have the right to remain silent and out of sight, but apparently not the ability.”
The department’s arrest of winter comes just two weeks after a sheriff’s office in eastern Pennsylvania issued a warrant for Punxsutawney Phil’s arrest, because the season lasted more than the six weeks the groundhog predicted back on Feb. 2.