Shoreline SafetyJuly 5th, 2013 at 2:09 am by Bill Steffen under Bill's Blog, Weather
Click the graphics to enlarge. This is Great Lakes drownings and water rescues from 2002 – 2011. Note that most of the incidents have occurred in Lake Michigan and that many rescues are related to structures. Lake Superior is often pretty cold for swimming. Lakes Erie and Ontario are smaller and the American side is the leeward side with the prevailing SW winds of summer. Lake Michigan is big, generally warmer, with lots of nice sandy beaches. Michigan is also often on the downwind side of the prevailing wind. 64% of the drownings/rescues are related to breakwaters (we sometimes call them piers, but they are truly breakwaters – they break the water, it can’t flow underneath. In general, days that are breezy or windy are days when currents are more apt to form. The breakwater currents occur when the wind pushes the surface water and the water “piles up” against the breakwater. The water has no place to go, but to go around the breakwater, creating a current that will move out toward deeper water. At Grand Haven St. Park, this will occur with a south or southwest wind. At Pentwater and Holland St. Park, this occurs with a north wind. To be safe, it’s best not to swim very close to a breakwater, but remember currents occur when the prevailing wind is pushing water against the breakwater. The most likely wave height when there was a beach incident was 2-4 feet. At this height, many people are in the water, splashing in the waves. Watch for the flags (green, yellow or red) that are posted at many of the lake beaches. Click here for more information on rip currents and beach safely.