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Weather Wise: Rocky Mountain Front Perfect Storm

Weather Wise: Rocky Mountain Front Perfect Storm
Posted at 5:27 PM, Feb 21, 2022
and last updated 2022-02-22 09:59:03-05

HELENA — Where's all the snow from the recent storm system that moved through Montana? While many places saw a light dusting of a few inches, it was deep up on the Rocky Mountain Front that saw the large accumulation.

The heaviest snow total anywhere in Montana from the weekend was up on the Rocky Mountain Front where 18" accumulated at Teton Pass Resort.

This was a perfect storm setup for the Rocky Mountain Front. Pacific moisture streamed in from the west at the mid and upper levels of the atmosphere. The higher terrain of the Bob Marshall Wilderness and the Rocky Mountain Front provides lift that squeezes out moisture in the form of snow.

At the same time, an arctic cold front pushed through the state with bitterly cold air in the lower levels of the atmosphere. This shallow cold, dense air also provides additional lift, pushing the warmer pacific air up which enhances precipitation.

Finally, there were great conditions for dendrite crystal growth, forming the best-shaped snowflakes for accumulation. There are many types of snowflakes but that classic "perfect" six-sided dendrite crystal flake uses its tree-like structure for efficient accumulation. The arms or branches hold each other up. These crystals form best when falling through higher humidity at a temperature around 5 degrees.

The same meteorological setup occurred several years ago when Teton Pass saw 65" of snow in one storm.