NWS To Warn of Dangerous Current Conditions

By Tim State in News on Jul 20, 2008 4:50PM

Only days after a Chicago Heights teen drown in a dangerous rip current, the National Weather Service announced they will be issuing specific rip current warnings. The program has been in the works for some time, reviewing data on incidents that span years. Originally, it was thought that the Great Lakes were immune to the dangerous tides, commonly found on the coasts.

Meteorologists say they will issue forecasts based on conditions known to produce the currents. Likewise, the most dangerous beaches were identified through drowning reports. But even concerted efforts may fail to predict all rip currents, area rescuers say, because there simply are too many.

While there are only a few other locations in the Great Lakes where rip currents are a dangerous problem, officials say the wide beaches on the southeast shore of Lake Michigan in Indiana and Michigan are the most treacherous, accounting for 26 deaths and seven rescues between 2002 and 2007.

Four factors are thought to determine whether rip currents will form in the Great Lakes. Wind must blow quickly and directly toward shore, and it must cause waves that are both tall and wide to pile onto the beach.

As the wind piles water on the shore, sandbars temporarily hold it there above the lake surface. Gravity eventually wins out, pulling water past the sandbar and back into the open lake. A current forms where the water widens tiny channels in the sandbar into an open rip—a violent burst that creates a river through the waves back into the lake.

[Trib]

Photo by odenfield.