Snow + tornado

[Simone Lussardi]

One of the best snow-storm twister ever get on picture I think is this one happened in Italy on November 23rd, 2001:

In the picture above, 3 tornadoes over water at the same time (I did not call them waterspout because they did land and they last over land too). You can see all the fantastic series of picture at this link:

http://www.tornadoit.org/lefoto26.htm

A total of 5 tornadoes has been spawned by that cell. Before the tornado occur, the situation was in light south and humid winds, with temperature around 13C. All of a sudden, the wind start easterly and temperature dropped by 11C, when the storm approaches, sky changed yellow and started to snow directly. The weather situation was as below:

Here a last photo of Twister and snow at the same time:

All second series here:
http://www.tornadoit.org/lefoto22.htm

Bye !
Simone

 

[Andrew Khan]

Very nice photographs. I once looked into how common tornadoes occurred during the act of snowing, and it is extremely rare. There was a case I read when I was seven or eight that involved an F3/F4 occuring during a snow storm/blizzard. It brings back some memories.

 

[rdale]

I'm going to feel safe in saying there never has been an F3 or F4 during a snowstorm...

 

[Jason Persoff]

I know that "snownadoes" do occur over large bodies of water often through convective mechanisms similar to landspouts. However, the last photo in the series you showed was spectacular and much, much higher-based than the few I remember seeing on the news back in Denver. Very cool thread.

 

[Simone Lussardi]

I think call them "snownadoes" is a good idea. In fact, they are neither 100% landspouts nor waterspouts. In both cases, you have to have a flat cloud base and almost calm wind for them to form. In the above case, the many people who saw the event said that the cloud base was very turbulent and the wind picked up from the ENE quite nicely (25-30 kts). They are almost surely caused by very sharp temperature contrast.