Dangerous Windchills in Minnesota:
February 17, 2006
While the winter storm that dumped a half foot of snow over the southeast corner of Minnesota was impressive, the strong high pressure that moved in behind it was perhaps even more so. The pressure gradient between the two created strong winds and dangerous windchills. For the first time this winter a Wind Chill Advisory was issued for the Twin Cities for wind chill temperatures colder than -25 degrees. The coldest windchill seen on February 17th at the Twin Cities International Airport was -34 degrees at 10am. The coldest windchill found statewide was -54 degrees at Thief River Falls.
Since the National Weather Service changed the windchill formula on November 1, 2001 there have only been a handful of Wind Chill Advisories issued for the Twin Cities since then. This is due mainly to the relatively tame winters of the past few years. There has been one cold episode where a Wind Chill Warning was issued for the Twin Cities and that was the arctic outbreak of January 29-30, 2004. The coldest windchill observed during that period was -43 at 8am on January 30, 2004.
What is the coldest windchill ever seen in the Twin Cities or Minnesota? The answer can be a little tricky because on November 2001 the formula on how to calculate the windchill was changed. Perhaps the coldest windchill the Twin Cities has ever seen was -67 with the new formula (-87 with the old formula) back on January 22nd 1936. The temperature was -34 with a wind speed of 20mph. All traffic in the Twin Cities was severely hampered and a number of fatalities were caused by the cold. Without a lengthy state-wide wind record, it is difficult to say when was the coldest statewide windchill. There are some candidate dates though besides January 22, 1936. On January 9th and 10th, 1982 temperatures of -30 and winds of around 40mph were reported in Northern Minnesota. This would translate to -71 by the new formula (-100F by the old formula.)
The strength of this cold air was marked by the very high pressure across the region. In the Twin Cities, the atmospheric pressure was 30.75 inches or 1041mb during the early afternoon of the 17th. The highest pressure ever recorded in the Twin Cities was coincidentally exactly 17 years ago on February 17, 1989 with 31.09 inches of mercury or 1052.9mb.