The Arctic air has now returned to the metro area, but just how cold will it get? Well, that is the million dollar question.
Really cold winter nights depend on 3 major factors; cloud cover, wind speed, and snow cover. Snow cover isn't much of a variable because we have a lot, but Saturday's melt has changed it a little.
In order to get temperatures to plummet, winds need to be calm. That allows the very dense air to sink to the surface, leading to the coldest possible temperatures.
Cloud cover is what can really make or break a very cold night. If you have the exact same conditions, but in one scenario you have some clouds and the other scenario is clear, there can be a 30 degree difference in overnight temperatures! This presents a challenge in forecasting upcoming overnight lows.
As for Sunday night, it does look like skies will be mostly clear through at least midnight, but winds will still be calming through midnight and then clouds should increase from there. So will winds calm fast enough and will clouds hold off long enough to give us a few hours of optimal cooling? Only time will tell. So here is a look at the winds around midnight.
Still breezy from the metro southeastward. Now look at the clouds.
I drew a line for the leading edge of the clouds which is pulling through western Minnesota. So here are the overnight lows predicted by this model.
Still really cold, however the clouds and winds appear to prevent us from really tumbling with lows in the single digits and teens below zero.
But, there are some indications that temperatures may drop phenomenally fast after sunset despite the wind speeds. Here is a hyper-local model that shows an 18 hour forecast for just the MSP area. This shows forecast temperatures for 10 p.m. Sunday night.
Look at the widespread temperatures of 20 below zero. The model places those lows over all of central and northern Minnesota including the metro! If it comes to pass, Sunday night will be the coldest since 2008! Still some variability in the forecast, but either way, it will stay frigid right through Monday.