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Orographically Enhanced and Lake Enhanced Snowstorm

Duluth, MN

December 2 to 5, 2013


Summary

A smaller upper level wave (short wave) leading the main storm initiated flurries from 5 AM December 2, with snow starting in earnest shortly after 6 AM. Another short wave spread heavier snow into the area early in the afternoon, merging with the area of snow from the initial short wave. Widespread snow let up toward 6 AM December 3, but orographic lift from east winds helped maintain the intensity of the snow along the higher terrain of the north shore of Lake Superior during the day. Snow became very light during the evening and at times just flurries and a little freezing drizzle. A narrow band of light snow off Lake Superior enhanced the snow in Central Duluth, Canal Park, and city of Superior, WI late evening and overnight. The period of diminished snow lasted until about 5 AM on December 4. After 5 AM, the snow quickly increased in intensity as the main weather system approached from the southwest. Widespread moderate to heavy snow, with occasional 1+ inch per hour snowfall rates, fell all day into the early evening then let a bit toward 8 PM. A brief burst of heavier snow accompanied a wind shift at 9:10 PM (at personal observation location) from the east to the west-northwest. Wrap-around light snow behind the surface low pressure center continued through the night, decreasing to just flurries at 6:30 AM December 5.


Snow totals

Snowfall reports to the National Weather Service showed snow totals for Duluth ranged from 20 to around 30 inches. Specific measurements included 28.0 (personal measurement) near Central Entrance just over the ridge crest, 29.2 in Duluth Heights (NWS Meteorologist), and 23.3 at NWS Duluth.


Breezy conditions

Peak wind gust at DLH for 12/03/13:   38 mph from 100 deg (East)

Peak wind gust at DLH for 12/04/13:   46 mph from 90 deg (East)


Radar images

Four radar image loops show specific aspects of the storm. The first loop from the morning of December 3 shows the likely impact of orographic lift with the heavier precipitation undulating and pulsating over the higher terrain. The second and third loops show a band of lake effect snow that drifted slowly north from late evening December 3 through the overnight morning hours December 4. The last loop from the afternoon of December 4th shows the peak of the event.

Radar images from the National Weather Service, Duluth, MN

Loop ending 9:02 AM CST December 3, 2013


Loop ending 12:50 AM CST December 4, 2013


Loop ending 5:26 AM CST December 4, 2013


Loop ending 3:20 PM CST December 4, 2013


Satellite images

Notice the small patch of enhanced cloud tops identifying the initial weather system that got the snow started, followed by the much larger system that prolonged the event and produced widespread moderate to heavy snow.

Satellite images from the NOAA Geostationary Satellite Server

2:15 PM CST December 2, 2013


12:15 AM CST December 3, 2013


7:15 AM CST December 3, 2013


5:15 AM CST December 4, 2013


2:15 PM CST December 4, 2013


10:15 PM CST December 4, 2013




Surface maps

Surface maps from the Weather Prediction Center's surface map archive

6:00 AM CST December 2, 2013


6:00 PM CST December 2, 2013


6:00 AM CST December 3, 2013


6:00 PM CST December 3, 2013


6:00 AM CST December 4, 2013


6:00 PM CST December 4, 2013


850 millibar analysis

Source: Storm Prediction Center's data archive

6:00 AM CST December 2, 2013


6:00 PM CST December 2, 2013


6:00 AM CST December 3, 2013


6:00 PM CST December 3, 2013


6:00 AM CST December 4, 2013


6:00 PM CST December 4, 2013


500 millibar analysis

Source: Storm Prediction Center's data archive

6:00 AM CST December 2, 2013


6:00 PM CST December 2, 2013


6:00 AM CST December 3, 2013


6:00 PM CST December 3, 2013


6:00 AM CST December 4, 2013


6:00 PM CST December 4, 2013