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Active Weather for the Rockies; Southern Plains Storm Taking Shape

Snow showers, squalls and strong winds will affect portions of the Cascades and Rockies through Wednesday. Meanwhile, a developing storm across the Southern Plains will track toward the Great Lakes into Thursday as severe thunderstorms, flash flooding and strong winds are forecast for the Mid-Lower Mississippi Valley. Heavy snow is possible for the Upper Midwest and wintry mix for the Northeast. Read More >

Overview

A strong cold front moved across the Western Slope of Colorado on the evening of December 22, 2020. The cold front, combined with a tight pressure gradient, instability aloft, and favorable upper level dynamics, produced strong winds at the surface. This led to the development of a snow squall which progressed through the portions of central Colorado. The National Weather Service defines a snow squall as "an intense, but limited duration, period of moderate to heavy snowfall, accompanied by strong, gusty surface winds".

Winds gusted upwards of 50 mph over the course of the snow squall which developed west of Craig, Co. Over the next several hours the snow squall progressed to the east-southeast. Impacts occurred along Highway 40, Interstate 70 and Highway 50. Temperatures ahead of the squall were above freezing which allowed for rain initially in spots. Flash freeze conditions were documented as temperatures quickly dropped below freezing. The squall was particularly strong near Steamboat Springs were lightning and white-out conditions were reported. There were at least 10-20 wrecks and slide-offs up and down the I-70 corridor between Gypsum, Wolcott, and Vail Pass.

The webcam at Craig Airport captured the snow squall moving through, and numerous people witnessed this impressive but dangerous phenomenon as it progressed into the evening. 

SnowSquall_Radar
KGJX Radar Data Showing Snow Squall Moving Through on December 22, 2020
Beginning of Squall (Credit: Aspen Snowmass) Behind Squall (Credit: Aspen Snowmass)
View of the Snow Squall Before it Moved Through Craig Airport View of the Snow Squall as it Moved Through Craig Airport
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