Late summer and fall are the most likely times in metro Grand Rapids to catch an awesome natural phenomenon without risking life or limb -- waterspouts over Lake Michigan.
With the right weather conditions and luck, you may be able to spot waterspouts anywhere along the lakeshore of the metro Grand Rapids area. Residents of lakeshore communities say these vortexes that resemble pint-sized tornadoes are infrequent, but not rare.
Fair weather waterspouts generally are a result of a large difference between the lake's warm water and cold air above it. For instance, there was a 25 degree-difference between the warm water and a mass of cold air that moved into our area Sept. 25 that spawned an unusual number of waterspouts from Chicago to Milwaukee. While there weren't reports of waterspouts locally on that Sunday, National Weather Service records show that people saw several of these sprites dancing offshore from Holland and Saugatuck about five years ago on Sept. 29.
Grand Rapids residents Linda and Mike Rankin caught a waterspout show on Aug. 7 three years ago from a hillside cottage above the Bil-Mar restaurant in Grand Haven, which they caught on camera (see photo and boat in foreground). Thoroughly enthralled by the show, the Rankins and scads of others watched a family of water spouts play across the lake for several minutes.
Retired meteorologist Will Beaton, a permanent resident of Grand Haven, saw the same waterspouts as the Rankins and noted the "large temperature differential between the water -- in the mid 70s -- and the air -- in the low 50s." An avid surfer, Beaton maintains a website called http://www.surfgrandhaven.com/ that provides current information on air and water temperatures at Grand Haven, as well as a constantly running webcam.
But Beaton and a group of other surfers actually were caught in the water near a waterspout in the 1980s. The surfers were at the south side of the pier in mid-September, with lake water at about 75 degrees and cool air filtering into the area after several warm days. "The strange part of this day was how still it was -- even though we had good-sized waves and the sky was threatening," Beaton recalls. Shortly before sunset, a waterspout formed with some estimated winds of 40 to 50 knots. "Other than blowing our boards around and being blinded by spray, all of the surfers escaped unharmed," he says. "Other than being surprised, I was more excited than afraid."
Wayne Hoepner, meteorologist with the Grand Rapids office of the National Weather Service, says this type of waterspout -- a "fair weather" one versus simply a tornado over the lake -- is the result of vertical mixing of air. The warm water creates a rising current of air that at some point starts to rotate and evolves into a vortex, a whirling mass of air that draws water into its center and up its sides.
To help visualize how waterspouts form, think about the way water moves down a drain. When you first open the drain in a sink filled with water, the water appears first to fall straight down the drain, but then it starts to rotate into a vortex. This is the general principle for waterspouts, except that the air is moving up rather than down. (As a side note, water does NOT always drain counterclockwise in sinks, toilets and bathtubs in our homes in the northern hemisphere. There are many more forces of much greater magnitude that act on water in a sink or toilet than the Coriolis force -- which causes low pressure systems to rotate in a counterclockwise direction in the northern hemisphere. Water at rest for more than a week in a large, specially designed sink will drain counterclockwise due to the Coriolis force.)
Fair weather waterspouts form in relatively calm weather along the dark flat bases of developing cumulus clouds, usually early to mid morning or in the late afternoon. A stiff breeze will interfere with the vertical mixing of air, so fair weather waterspouts develop during light wind conditions. They move slowly and generally dissipate rapidly if they reach land. Experts say they have wind speeds of 40 to 60 mph that can flip a boat, but this equates to an F0 on the Fujita scale of tornado intensity.
So keep your eye on the air and water temperature reports, And even if you don't catch a glimpse of the elusive waterspout, what could be better than taking in a view of Lake Michigan on a beautiful fall day.