Ian remnants deliver snowy surprise for Blue Ridge mountains
Snow and sleet fell in the highest peaks as Ian turned post-tropical
Hurricane Ian quickly fell apart after landfall Friday as it moved inland. On the outside, it looked like a typical weakening tropical system. On the inside, it was undergoing a major remodeling during the hours that followed its destruction along the coast.
Shortly before midnight Friday, snow and sleet suddenly started mixing with the rain along the Virginia/Tennessee border. A few reports even came in from places like WhiteTop.
Evan Fisher witnessed the occurrence in the High Country. According to records, a September snow there has only been observed one other time there, in 1967.
What could cause this wintry weather in a system that was a Category One hurricane less than 6 hours earlier?
As Ian moved inland you may have noticed it went from the designation “Hurricane” Ian, to “Post-Tropical Cyclone” Ian. This occurs naturally as a storm moves from water onto land and the storm replaces its warm-cored characteristics with a cold-cored center.
The video below shows the transformation after landfall. Notice the cold air (blue) getting wrapped into the storm along with drier air. This took temperatures aloft from the 60s to the 40s as it moved over our area.
That alone wouldn’t create the snow and sleety mix. Phillippe Papin, Hurricane Specialist at the National Hurricane Center, also became intrigued and posted his analysis.
The key to getting the wintry weather was a layer of dry air also moving in which caused the raindrops falling into it to evaporate. The cooling process got it just cold enough to form frozen precipitation even when the majority of the air surrounding it was above freezing.
The only areas to see this sleet/graupel/snowy mix were the highest elevations where snow and sleet could remain intact to the surface without melting completely into raindrops.
This isn’t the first time this has happened. In fact, a more dramatic transformation occurred during Hurricane Sandy which dumped extreme amounts of snow in the higher elevations of the Appalachians.
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