Weather Forecast


Weather Talk: Snow is hard to forecast because it's mostly air

Please cut the snow forecasters a little slack.

True, winter precipitation is a lot less variable than that which falls from summer thunderstorms. But snow accumulation is very hard to predict because most of snow accumulation is not snow, but air.

Whereas rainfall is a volume that can be easily caught and measured, accumulated snow is made from irregular and variably shaped crystals surrounded by air.

Most northern Plains snow accumulation is about one part precipitation surrounded by 10 to 15 parts air. Some of the dry, fluffy flakes we get in cold weather are one part water to 30 to 40 parts air. Even the wettest, half-melted snow accumulations contain three or four times more air than water and ice.

The shape of the crystals, the way wind breaks them up, and the way they settle into an accumulation are often much more important in determining accumulation than how much ice falls from the clouds.

John Wheeler

John was born in Baton Rouge, LA, and grew up near Birmingham, Alabama. As a teenager, his family moved to Madison, Wisconsin, and later to a small town in northeast Iowa. John traces his early interest in weather to the difference in climate between Alabama and Wisconsin. He is a graduate of Iowa State University with a degree in meteorology. Like any meteorologist, John is intrigued by extremes of weather, especially arctic air outbreaks and winter storms.  John has been known to say he prefers his summers to be hot but in winter, he prefers the cold.  When away from work, John enjoys long-distance running and reading.  John has been a meteorologist at WDAY since May of 1985.

(701) 241-5387