Minnesota likely chalks up another mild winter record this week.
The thermometer at Minneapolis-St. Paul International Airport bottomed out at zero on New Year’s Day. But a subzero temperature has not yet been recorded in the Twin Cities this winter season.
The latest date on record for the season’s first subzero reading is Jan. 18. The occurrence of the first subzero temperature of the winter season happened on that date in 1889, 2002, and 2012.
Looking at the forecast this week, the best shot at a subzero temperature at the official recording station at MSP airport appears to be Sunday morning Jan. 20.
Jan. 20 would break the record for the latest first subzero temperature on record.
It’s interesting to note that late onset of subzero temperatures in winter doesn’t always guarantee fewer than average sub-zero days over the entire winter.
Here’s some perspective from Minnesota Department of Natural Resources senior climatologist Kenny Blumenfeld from an email chain today with me and MPR News meteorologist Ron Trenda. The conversation references the graphic at the top of this post.
(Above) is the current top ten for “latest first “ subzero readings at MSP. Look under the “First” column. Interestingly, five of the top ten ended up being way, way below average for the number of subzero lows (ranging from 2 to 10), but the other five ended up with 16-24 subzero lows (the period-of-record average is 28, the average from 1981-2010 is 23, and the 30-year average through 2018 is 21 ).
So in half of the cases, a normal or even somewhat harsh winter kicked after a long delay.
Colder 2nd half of winter?
Looking at the long-range maps I suspect the second half of winter in Minnesota will be (much?) colder than the first.
So far winter is running a solid 7 degrees warmer than average. That changes dramatically over the next two weeks. The upper-air pattern buckles into northwest flow. A series of cold front will push south over the next two weeks.
The current upper-air forecast map for Jan. 28 features a deep polar vortex over Hudson Bay. That would send bitterly cold subzero air south into Minnesota.
The first half of winter has been unusually mild. This winter is still likely to end up significantly milder than average overall. But all signs point to a temperature “correction” over the next two to three weeks.