Strange Snowfalls

Although there were no spectacular snowstorms in the contiguous U.S. this past January there were a couple of interesting snow events. On January 20th the residents of Vermont were amazed to find their yards and fields covered with large snow rollers. A week later, on January 27th, giant snowflakes “the size of cotton balls” were observed near Moline, Illinois. Here is a summary of some strange snow events.

A Vermont TV station, WCAX, reports on the snow roller event that occurred in Vermont on January 20, 2013.Video still from WCAX and rebroadcast on CNN and The Weather Channel.

Snow Rollers

This rare and interesting phenomenon occurs when surface conditions are just right following a fresh snowfall. The surface snow must be light and sticky but not too wet. Strong, gusty winds in excess of 30 mph must then ‘scoop’ the fluffy snow into small balls on the surface and then blow the balls along forming small barrels. The stronger the winds and deeper the snow, the larger the barrels or ‘rollers’ become. Of course, the process is the same as making a snowman. Reports of snow rollers up to five or six feet in diameter (the “size of rolled hay bays”) have been reported in the Great Plains but cannot be substantiated.

Perhaps the largest snow rollers ever photographed were these barrels some 20” in diameter and three feet long that formed in Vermont’s Lamoille River Valley in February 1973. Photo by Ronald L. Hagerman.

For some reason New England and especially Vermont seem to be where snow roller formation is most often observed, as was the case in January. The event received national media attention being widespread and photographed by thousands in the Mad River Valley area and towns of Plainfield, Craftsbury, and St. Albans.

A beautiful shot of the recent snow roller event taken near Plainfield, Vermont in January. Photo by Janet Steward.

Giant Snowflakes

Reports of large snowflakes of 2” in diameter, as observed near Moline, Illinois on January 27th, are relatively common. Of course, these are not individual snowflakes but rather aggregates of entwined snowflakes. These aggregates normally occur when the temperature at the surface is near or just above freezing causing the wet flakes to bump into and stick to one another as they fall through the sky. Sleet often accompanies these giant flakes. The wind must be near calm in order for the aggregates to stick together.

A couple of close up images of large snowflake aggregates. One can see how these are composed of many different individual snowflakes entwined with one another. Top photo taken by Ruth Zschomler in Vancouver, Washington in 2010. Bottom photo by Thomas Niziol, the Weather Channel’s Winter Weather Expert.

Some truly extraordinary giant aggregates up to 5” (14 cm) in diameter and even larger have been verifiably observed. On January 24, 1894 ‘snowflakes’ of this size were observed in Nashville, Tennessee. In Berlin, Germany flakes up to 4” in diameter were seen on January 10, 1915. A weather observer noted:

On this occasion a large number of snowflakes had diameters of 8 to 10 centimeters (3-4″), and these giant flakes fell with both a greater speed and more definite paths than did the smaller flakes. They did not have the complicated, fluttering flight of the latter. In form the great flakes resembled a round oval dish with its edges bent upward. During flight they rocked to this side or that, but none were observed to turn quite over so that the concave side became directed downward.

There is a report from Fort Keogh, Montana of snowflake aggregates reaching a diameter of 15”/38 cm (the “size of sauce pans”) on January 28, 1887. If true, these would be the largest such ever recorded.

Giant snowflakes up to 2-3” in diameter blanket Kashgar, China during the winter of 2001. Photo by Michael Yamashita.

Colored Snow

I devoted a few paragraphs of my book ‘Extreme Weather: A Guide and Record Book’ to this phenomena and quote myself herein:

In Dr. Seuss’s The Cat in the Hat Comes Back, the Cat and his Hat’s mischievous inhabitants, Little Cats A, B, and C make a terrible pink mess in the home of two children. The Cat and the Little Cats manage to get the pink stains out of the house—and into the snow, which then becomes bright pink.

Preposterous as it may seem, it has, on very rare occasions, snowed pink. Not only pink but other unnatural shades as well. Pink snow was reported to have fallen in Durango, Colorado on January 9, 1932. Red snow coated the Alps on October 14, 1775, and again on February 3–4, 1852, over a wide area from Bergamo, Italy, to Zurich, Switzerland. Brown snow was reported on Mt. Hotham in the Snowy Mountains of Victoria, Australia, in July of 1935.

In the above cases, the coloring factor in the snow was dust which had risen into the atmosphere during desert dust storms. The dust that mixed with the snow in Europe was carried there by winds from the Sahara; the coloring in Australia originated in its interior desert.

Black and blue snowfalls have been reported on several occasions in New York State. The N.Y. State Weather Service report for April 1889 records black snow falling over Lewis, Herkimer, Franklin, and Essex Counties. Upon examination, the snow was found to contain a “sediment consisting principally of finely divided earth or vegetable mold.”

A blue snowfall was reported in many towns of western New York State during January of 1955. Yellow snow that fell on South Bethlehem, Pennsylvania, on March 16, 1879, was found to contain pollen from pine trees that were in bloom throughout states further to the south. Unfortunately, there are no known verifiable photographs documenting these rare and unusual events.

This photograph purports to be of a colored snowfall that occurred in Saaksjarvi, Finland on January 16, 2010. However, it is difficult to tell if this is actually colored snow or just a lighting effect. Photo from Flikr page by ArtemFinland.

Christopher C. Burt
Weather Historian

from:    http://www.wunderground.com/blog/weatherhistorian/article.html