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Blizzard and Prolonged Snow Event

Duluth, MN

February 23 to 27, 2007

A large storm system moved northeast across the middle valley and into the Western Great Lakes. Smaller waves of low pressure rotating around the main storm early in the event produced several periods of snow from Friday afternoon February 23 to Saturday afternoon February 24. Most of the snow was light but a period of heavier snow Friday evening produced 1 1/2 and 2 inches from 5 PM to 7 PM.

After a break in the precipitation, the main event finally started at midnight on Sunday, February 25 as intermittent light snow, but then by 1 AM, the bottom fell out. Snow fell at least an inch per along with winds gusting to around 40 mph. The heavy snow continued through 8:45 AM. Light snow then fell to 11 AM then ended. Up to this point, 13.3 inches had fallen at the National Weather Service. I measured 12.5 inches. The snow was unusually dense. The feet of my 200-pound body hardly sunk into the snow.

East winds into the higher terrain and the head of Lake Superior resulted in significant enhancement of the snow. Cold air and instability over the lake resulted in the formation of a large mid-lake snow band extending from east-northeast to west-southwest into the head of the lake. Radar between 3 AM and 6 AM indicated increasing evidence of the snow band. From 6 AM to 8:45 AM the lake snow was firmly established. The western end of the band was shaped like an enlarged bulb sitting over Duluth and the surrounding area to the north and west. The lake snow was critical to snowfall totals since the original synoptic (large scale) snow decreased in intensity after 6 AM.

Later in the day on Sunday, periods of mostly light snow began again and continued for several days all the way through the evening of Tuesday, February 27. The storm had stalled over the Western Great Lakes and Upper Mississippi and slowly weakened. The surface trough component of the storm system lingered south and west of Duluth and help maintain a flow from the lake to enhance the snow. Of side interest, the eastern portion of the storm broke away from the rest of the storm and moved to the east coast to produce a decent snowfall there as well.

Final Snow Totals:
National Weather Service 18.5 inches
My Total 17.6 inches

The radar images and surface map analyses show the advancement of the storm during the overnight and early daylight morning hours of February 25. This period of time is when the storm produced blizzard conditions, the heaviest snow, and most of the accumulation. The northwest to southeast axis of the low pressure system and its slow eastward movement helped sustain flow off the lake to enhance the snow.

Radar mosaic images from the National Climatic Data Center now called the National Centers for Environmental Information

12 AM CST (0600 UTC) February 25, 2007

4 AM CST (1000 UTC) February 25, 2007

8 AM CST (1400 UTC) February 25, 2007

Surface analysis images from the Weather Prediction Center archive

12 AM CST (0600 UTC) February 25, 2007

3 AM CST (0900 UTC) February 25, 2007

6 AM CST (1200 UTC) February 25, 2007

9 AM CST (1500 UTC) February 25, 2007