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Fluffy Snowstorm Enhanced by Strong Band of Lake Effect Snow

Duluth, MN

February 24, 2006



Intermittent light snow fell from 8 AM to 11 AM, then fell in earnest from 11 AM to 7:30 PM CST. A burst of heavy snow produced 2 inches in an hour from 1 PM to 2 PM. A strong single band of lake-effect snow followed the back edge of the main snow area late in the afternoon. The lake-effect snow dumped 2 1/4 inches from 6:15 PM to about 7:30 PM, then abruptly ended. The snow was very fluffy, especially what came off the lake.

Total snowfall (inches):
National Weather Service 11.4
My total 12.7

Radar mosaic images show a persistent band of heavy snow focused over the western Tip of Lake Superior from late morning through the afternoon. The heaviest snow parked itself right over Duluth, MN, and city of Superior, WI as indicated by the darker green and yellow colors. The trailing band of snow off the lake is depicted on the larger last image by the darker green pixels along the back edge of the lighter green radar reflectivities. The snow fell through a layer of temperatures favorable for dendritic crystal growth. Snowflakes composed of ice crystals with a strong dendritic component tend to produce fluffier snowpacks.

Radar images from the National Centers for Environmental Information

10 AM CST February 24, 2006


12 noon CST February 24, 2006


2 PM CST February 24, 2006


5 PM CST February 24, 2006

Surface maps show that this snowstorm is a case where a major event was not produced by a "southwest storm" as highlighted in the Duluth winter climate profile.

Surface maps from the NOAA NWS HPC

6 AM CST February 24, 2006


12 noon CST February 24, 2006


3 PM CST February 24, 2005

The following upper air map plots with interpolated isotherms in oC show that temperatures over Duluth, MN and the city of Superior, WI were generally in the -12 to -18 oC range at 925 mb, 850 mb, and 700 mb through the duration of the storm. Temperatures in that range are favorable for dendritic crystal growth. The temperatures at 925 mb warmed to above -10 oC by 00 UTC (6 PM CST) but were in the lower end of the dendritic range at least near the start of the storm. The temperatures at 700 mb stayed close to the upper end of the dendritic range. The layer from 925 mb to 700 mb is roughly around 7000 feet deep.

Upper air maps are from the Storm Prediction Center upper air map archive.

925 mb - 12 UTC February 24, 2006 (6 AM CST February 24, 2006)


925 mb - 00 UTC February 25, 2006 (6 PM CST February 24, 2006)


850 mb - 12 UTC February 24, 2006 (6 AM CST February 24, 2006)


850 mb - 00 UTC February 25, 2006 (6 PM CST February 24, 2006)


700 mb - 12 UTC February 24, 2006 (6 AM CST February 24, 2006)


700 mb - 00 UTC February 25, 2006 (6 PM CST February 24, 2006)