December 19-20, 2012 Winter Storm Summary

After nearly two years without a significant winter weather event in the local area, a major winter storm impacted the region from the evening of Wednesday December 19th through the morning on Thursday, December 20th. Despite temperatures in the upper 30s to lower 40s, warm and moist air streamed in aloft just after sundown, ingiting showers and thunderstorms across the region. The lightning was prolific at times and a few of the stronger thunderstorms even produced small hail. 

A powerful cold front then began to sweep across the region after midnight, resulting in a brief period of sleet (and more thunder) before the precipitation changed to snow. As temperatures fell into the 20s, northwest winds increased dramatically, reaching sustained speeds of 20 to 35 mph with frequent gusts of 40 to 50+ mph during the early morning hours. The wind was the greatest impact with this storm, resulting in blizzard conditions as visibilities dropped to near zero for several hours early this morning due to significant blowing snow. Periods of snow fell heaviest across western Missouri during the pre-dawn hours and then shifted toward northeast and mid Missouri by mid to late morning. Strong winds continued throughout the day, with winds chills in the single digits and teens.

Snowfall totals generally ranged from 1 to 3 inches across the area, with localized amounts upwards of 5". The heavy wet snow, coupled with the very strong winds resulted in widespread power outages reaching into the tens of thousands by late Thursday morning, although improvements were noted by afternoon as weather conditions improved. Driving conditions were equally impacted, especially during the morning commute with many interstates, major highways and secondary routes suffering from closures due to numerous vehicle accidents. Rainfall during the overnight hours froze to the surface once temperatures fell below freezing, creating a thin glaze of ice beneath the freshly fallen snowfall. The road and weather conditions led to widespread school closings across the area.

The graphic below depicts the peak wind gusts observed this morning across all the official observation sites.

 Peak Wind Gust Graphic

 

 


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