The Elusive Snow Tornado

UPDATE: A correction at the bottom of this entry, also, here is a map of where the snow and tornado damage correlate:

We're seeing something rare, but not unprecedented this morning: snow on tornado damage. Here's an image from Twitter this morning via my Facebook friend Chickage Windler, a meteorologist for WTHR:

It's not terribly unusual for spring storms to bring snow after tornadoes, but this much snow (up to 6.5 inches reported in Kentucky) on top of this much damage (EF-4 in southern Indiana and EF-3s in Kentucky) is extremely rare - I personally have never seen it.

But has a tornado ever happened to an already snowcovered area? My friend, meteorologist Paul Douglas, had some excellent observations pointed out this television screen capture, forwarded to him by a friend, may show a tornado over snowcover:

He said on Twitter: "Never seen this before: Nebraska tornado with patches of snow still on the ground? Highly unusual." I would agree. This capture, which came from Mike Umscheid Photography's Facebook page does look like snow at first glance, and another video appears to show something similar. The tornado was in Stapleton in central Nebraska.

The elusive "snow tornado" (even more elusive than a purple squirrel) has been rumored by many but proven by no one. It's a meteorologically tricky situation that wouldn't normally occur. You'd need snow before the tornado that didn't get melted by the approaching warm air associated with the twister or melted by its rain. It's much more often to have snow after a tornado, when the cold front passes and temperatures fall.

What weather data can we use to confirm this? According to AccuWeather.com, weather data from the nearest airport (North Platte, 20 mi. SW) indicated that there had been "zero" snowcover for the last 11 days, though they did report a trace of snow on Feb. 20. Given high temperatures in the 50s since then, it should all be gone. A map from NOAA NOHRSC says that there was no little snow cover near Stapleton yesterday, but this is only a satellite estimate.

If it's not snow, what is it? It could be standing water from the storm, reflecting the bright sky above the twister, or it could be ice (lows at North Platte have been below freezing for the last 10 days). I have an email out to Mike, who should know the answer, and I'll post here when he replies.

P.S.: This tornado outbreak was NOT brought to you by Climate Change. Global Warming doesn't make weather more extreme and could reduce tornadoes (I had previously said "thunderstorms" instead of "tornadoes" -- see Comments below which clarify Harold's stand).

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