WOODS BAY, Mont. - A rare waterspout made an appearance on Flathead Lake Monday morning. Flathead resident Michael Marchetti was driving to work at around 7:30 am when something over the lake caught his eye. After pulling to the side of the road, he took pictures and his wife took video as a waterspout churned across the lake for over 8 minutes. "It was a truly amazing sight", he said.
For a waterspout above 30 degrees latitude, 8 minutes is an eternity. Marchetti says in the 15 years he's lived in the Flathead, it's only the 2nd waterspout he's seen. The remarkable thing is that this waterspout was accompanied by snow showers. Waterspouts should be limited to the warmer months; but in this case all the factors were just right for an incredible weather event.
Waterspouts look like tornadoes, but the classic waterspout is a much different animal. 99% of tornadoes form under massive supercell thunderstorms; the kind only found when hot tropical air and strong storm systems are present. Waterspouts work on a smaller scale. Any cloud with a decent updraft underneath it can form a waterspout if other factors are ideal.
The primary ingredient for waterspout formation is a clash of warm and cold air. The waters of Flathead Lake are relatively warm compared to the cold air with this storm system. That warm air is fuel for the snow showers crossing the lake, and the air begins to rise. This creates a strong updraft that combines with cross winds coming across the lake; a vortex is created. The waterspout begins as a dark blue patch on the lake surface, and moisture from the clouds works it's way down and a funnel is formed. While weaker than tornadoes, waterspouts can pack a punch with winds over 40 miles per hour. In warmer, waterspout-prone areas such as the Florida Gulf Coast, winds in a waterspout can even move at over 100 miles per hour.