Extremely Rare Tornado In Snow. I'll Call It A Snornado

A tornado going over snow-covered ground, and
pulling up snow into its circulation in New
Mexico recently. This is an extremely rare,
if not unprecedented event I'm not aware
of any other tornadoes on snow. Photo by
Lydell Rafael, via Twitter.

Earlier this month, a relatively weak tornado touched down in New Mexico.

Tornadoes aren't super rare in New Mexico, but this one was really out-of-this world unusual. It was the first one I've ever heard of that moved over snow-covered ground. A lot of other weather weenies have said the same.

There was a pocket of very unusually cold air over New Mexico, part of this month's storminess that has brought feet of snow to some mountainous areas of the West and brought snow to oddly low elevations. It has even snowed a couple times on the Las Vegas Strip this month.

Pockets of cold air above the Earth, like the one in New Mexico, usually produce convection - that is towering clouds that form into thunderstorms, or at least very heavy showers of rain or snow.

This cold air aloft touched off snow squalls in New Mexico.  The air was so unstable, though, that it managed to produce a tornado.

Tornadoes are extremely rare on snow covered terrain because the cold snow almost always stabilizes the air in the lowest layers of the atmosphere near the ground. That is supposed to  cut off the ability for any columns of rotating air to actually touch down. Not this time.

The recent New Mexico storm was a landspout tornado, which is usually weaker than the traditional big Midwest tornadoes. A landspout is certainly one form of tornado, but there's a difference. Weather.com offers this definition describing the difference between a landspout and other tornadoes:

"A tornado is spawned from a parent thunderstorm with a rotating updraft, but a landspout isn't. A landspout requires a towering cumulus cloud to be present over a boundary of converging winds near the surface."

The New Mexico snow tornado was an odd duck of a landspout, meteorologist Bryon Morton, a meteorologist at television station KOAT Alburquerque explained on Twitter:

"This is not a traditional tornado. It's formed by colliding outflows from convective snow squalls that result in a spin up near the surface, whch is transported upward via an updraft. There are no rotating wall clouds or mesocyclones involved. Spectacular & rare nonetheless!"

By the way, a mesocyclone is an area of rotating winds in a supercell thunderstorm. Mesocyclones often, but don't always produce tornadoes.

I have not seen any reports of damage from this snow tornado (snornado?) near Tinian, New Mexico. But it sure was something!