The snow falling out side the window didn’t come down in gentle flakes, but rather violently, spewing pellets of snow through the trees.  As I marveled at this outburst from Mother Nature, a flash of light burst through the clouds overhead, followed by a rumble of thunder.  The last time we had had a thunderstorm was late in the summer, some eight months ago.  Thundersnow!

My mom called during this event, as I talked to her, an audible click could be heard through the phone., followed by the roar of thunder.  I could tell from the 5-second rule, that the lightning was close by, less than a mile.  (The five second rule say to count the time from the flash until the thunder — every five seconds counts for a mile distance.) For a moment, I couldn’t remember — is it corded phones that are dangerous during thunderstorms or cordless?

This continued for some 20 minutes, with the burst of light,  snow falling like rain drops coming down from the skies above.  I wanted to go outside to observe this phenomena more closely, but doubted it would be safe.  Somehow snow and lightning seem like an oxymoron — they shouldn’t go together.

Thunderstorms in the Colorado Rocky Mountains are more synonymous with summer — during the months of July and August, they seem to roll in like clockwork each afternoon.  They form because of the hot temperatures of the plains below colliding with the cooler mountain temperatures.

But thunder snow is far less common, but the ingredients are the same — moist air from below colliding with colder air above.  The trick with thundersnow is that the temperature has to remain below freezing for it to snow instead of rain.

Yesterday’s thundersnow event remained stationary for almost two hours near Jamestown, Colorado, generating snowfall rates of 2-3″ per hour, with a total of almost a foot of heavy, dense snow when it was all over.

While thundersnow is pretty rare, I’ve seen it occur many times in the springtime here in the Rocky Mountains.  Ski resorts have to be cautious about these events, as any time there is lightning, it is imperative for them to shut the chairlifts down until the thundersnow has passed through the area.  Just like in summer, it is not safe to be outside in an open area while there is lightning present.

 

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