Epic Winter Snow Accumulation Increasing Spring Flood Risk
Credit: Paul Douglas
I half expect polar bears to start showing up on my Doppler radar one of these days. Anywhere from 110-120" of snow has submerged the Northland this winter. The Duluth National Weather Service reports over 3 feet of snow on the ground, the most since 2005. And another snowy storm is brewing for the end of the week. Of course it is. At this rate spring will come no later than the 4th of July.
Concern is growing about the potential for flooding across the Upper Midwest, based on how much liquid water is trapped in the current snowpack, something meteorologists refer to as SWE or "snow water equivalent". Over 8" of liquid water is locked up in those snow banks over the western Lake Superior watershed.
As is often the case, we don't know what we don't know. Stated another way, in spite of gleaming Doppler radars and fancy supercomputers running the most sophisticated weather models on the planet, we have NO IDEA how rapidly things will warm up later in March and April. The faster it warms, the greater the potential for river and stream flooding, especially if warm fronts are accompanied by heavy rain, capable of accelerating snowmelt.
The Duluth office of the National Weather Service issued a Spring Flood Outlook late last week, which is summarized above. "The spring flooding potential across the Northland is above normal. One positive: all that snow has acted as an insulator, limiting ground frost, so more of the melting snow will be able to soak into the ground vs. running off into streets and streams.
Good luck trying to predict how quickly things will warm up in the coming weeks. All that snow will act like a "brake", cooling the air from below, reducing the rate of warming to some degree. NOAA's Climate Prediction Center predicts "equal chances" looking out March into May, with more rapid warming across the southern and eastern USA.
I hate to sound like a broken record - skipping CD - distorted MP3 stream, but the current situation calls for caution, preparedness, and a dash of mild paranoia, especially if you've experienced serious spring flooding in the past.
Remember, the weather never repeats, but sometimes... it rhymes.