How our unseasonably warm air muted snowfall totals in our latest storm
Did our trend of warmer winters play a role in reduced snowfall totals?
An unseasonably warm air mass for mid-January muted snowfall totals from our latest winter storm. The lack of Arctic air across the Upper Midwest is a factor in why snowfall totals were cut by about one third in this storm.
Where’s the Arctic air?
It’s January 15 in Minnesota. We’re now in what is climatologically the coldest two weeks of the year. But there is a remarkable lack of Arctic air anywhere near the Upper Midwest.
The average high for January 15 in International Falls is 15 degrees. Duluth’s average is 19 degrees. The Twin Cities? 23 degrees.
Temperatures are in the 30s again today. That’s 10 to 15 degrees warmer than average across most of Minnesota. Note the lack of any true Arctic air on the map Friday afternoon.
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Warmer than average Arctic
Check out the temperature departure from average map of the northern hemisphere today.
You can see the red blob over the Upper Midwest, Great Lakes, and Southern Canada. Also, notice the sea of red in the Arctic regions. There is a significant lack of seasonably cold air in the Arctic.
That’s one reason Minnesota is running about 6 degrees warmer than average so far this winter. The upstream air mass we typically draw from is just not as cold.
A few critical degrees
Most forecast models suggested precipitation would remain all snow overnight last night across the Twin Cities. But temperatures in the lowest mile of the atmosphere hovered just a couple of degrees above freezing. That mixed the snow, with a fine mist for several hours overnight. Check out the hourly observations from the Twin Cities Airport.
Climate change signal?
This was a weird-looking storm on the maps from the start. I mentioned in my posts, tweets, and on-air that this storm had bust potential from the beginning. The warm air mass and lack of Arctic air is always a concerning factor in snow systems. You need cold air to produce high-quality snow crystals efficiently.
This is just one storm. But longer-term climate trends may play an increasing role in our winter weather systems.
The Upper Midwest is the fastest-warming area of the country in winter.
The signal for warmer winters in Minnesota is getting louder. Overall winter temperatures have warmed about 5 degrees in Minnesota since 1970.
It’s still usually cold enough for snow even with our warmer winters. But as our winter warming signal gets stronger, a growing number of winter storms may teeter on the freezing mark.
The background hum of this climate change trend may create more winter weather systems warm enough to change what used to be high-quality snowflakes, to an icy or misty mix like we observed this week.