Word of the Week: Thundersnow

Thundersnow: An unusual winter thunderstorm accompanied by snow instead of rain. (Sometimes spelled thunder snow.)

Thundersnow is most likely to occur in a coastal area, because storms can form over the comparatively warm ocean or lake water and then move inland, where they encounter much colder weather. That's what happened earlier this month when a storm dropped six to nine inches of snow on the Puget Sound area. The Seattle Post Intelligencer reported on Dec. 18:

Thursday's storm started off with a bang as two bands of air barreled across the region from opposite directions and collided, producing a rare combination of thunder and lightning, with driving snow that quickly whited-out much of the city.

According to David Schultz, formerly a meteorologist with the National Severe Storms Laboratory in Norman, Oklahoma, and now a professor in Helsinki, only 0.07 percent of recorded snowstorms are associated with thunder. Part of the problem lies in documentation:

Shultz points out that heavy snow has a way of obscuring sound and light — the telltale signs of a thundersnow.

"Where you might hear a regular thunderstorm from four to five miles away, you may not hear or see a thundersnow from a mile away," he said.

Here in the San Francisco Bay Area, and in much of coastal California, thunderstorms are exceedingly rare at any time of year; our summers and autumns are dry. I'm always skeptical when I see movies set in San Francisco or Los Angeles in which thunder and lightning are added for dramatic effect.

Comments

[Jonathon]

I've experienced thundersnow once or twice in my life. It's pretty surreal.

[Nick]

Off the point a bit, but reading about the word,"thundersnow" brought to mind seeing a rainbow during a light snow flurry. I thought of the word,"snowbow" but never checked to see if the word really existed. I just did a little search and...
Snowbow is not listed in Merriam-W online and Urban Dictionary defines it as the result of a kind of "high" (not the altitude kind). However, if you search Flickr Photos for ,"Snowbow" you will find a nice photograph of one.

[Nancy Friedman]

According to the Goddard Space Flight Center, a "snow bow" is scientifically impossible: "Since snow is composed of hexagonal crystals and not spherical drops, the physics of light scattering is considerably different in falling snow than it is in the case of falling rain drops. Consequently, bows of light, opposite the Sun, won't be seen when snow is falling. Light entering hexagonal ice crystals results in halo phenomena."

However: "Even though rainbows don't occur when snow is falling, it's indeed possible to see a rainbow over snow-covered ground. This can occur on rare occasions when rain is falling over snow-covered terrain and the Sun is unobscured by clouds. Another special case when a snow bow has been observed is when spray from Niagara Falls, for instance, is blown away from the Falls on a sunny day and remains briefly liquid before freezing. Robert Greenler has a photograph of such an occurrence on the jacket of his book Rainbows, Halos and Glories."

Link: http://is.gd/edhk

[Nick]

Yes! We are getting closer! The link also says this: "The colors of some halo phenomena are every bit as vibrant as those found in rainbows. Meaning that there are very colorful halo pnenomena caused by sunlight reflected or refracted off of falling snow. And this "colorful halo phenomena" has no name! Awww let's call it a snowbow.