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 12/02/13 with snow starting in earnest shortly after 6 AM. Another short wave spread heavier snow into area early afternoon, merging with the area of snow from the initial short wave. Widespread snow let up toward 6 AM 12/03/13 but orographic lift from east winds helped maintain intensity of snow along the higher terrain of the north shore of Lake Superior. After a period of diminished intensity from late evening 13/03/13 to about 5 AM 12/04/13, 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. Wrap-around light snow behind the surface low pressure center continued through the night, decreasing to just flurries at 6:30 PM 12/05/13.


Highlights

12/02/13
*Crustal habit dominantly needles late morning through noon.
*Snow mixed with a little rain by the lake front due to east winds off relatively warm lake.

12/03/13
*After 1 AM, weak orographic enhancement appeared to be occurring but was much better defined by 8 AM, continuing through noon.
*At 8 AM Noticed on radar what appears to be strong lake enhanced band extending onshore of southern Cook County.
*Increased dendritic ice crystal component to snow but at the same time some fairly large snow pellets.

12/04/13
*Well defined lake band (see radar images below) across central Duluth, Canal Park, and city of Superior, WI during the early overnight morning hours.
*Lull in snow intensity and coverage from late evening 12/03/13 to 5 AM 12/04/13, mainly flurries and some freezing drizzle.
*Moderate through daytime into early evening.
*At 8:30 AM, full spectrum of identifiable snow composition from well defined dendrites to small hard snow pellets.
*Shortly after snow intensity had diminished, a burst of heavier snow accompanied a wind shift at 9:10 PM (this observers location) from the east to the WNW.


Snow Totals

Snow totals for Duluth and vicinity in Minnesota ranged from 20 to around 30 inches. Specific measurements included 28.0 at DAK (me), 29.2 measured 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 from NWS Duluth Doppler Radar

9:02 AM CST (1502 UTC) December 3rd, 2013


Loop Ending 9:02 AM CST (1502 UTC) December 3rd, 2013


12:50 AM CST (0650 UTC) December 4th, 2013


3:20 PM CST (2120 UTC) December 4th, 2013





Satellite Images from the NOAA Geostationary Satellite Server















Surface Maps retrieved from the Storm Prediction Center's data archive














850 Millibar Plots retrieved from the Storm Prediction Center's data archive














500 Millibar Plots retrieved from the Storm Prediction Center's data archive