Scientists closer to predicting danger on Lake Michigan
By Jeremy D. Bonfiglio
South Bend Tribune
Posted August 14, 2005
Most summer days, the shoreline of Lake Michigan looks inviting:
warm, soft sand. A gentle breeze. Rolling waves.
But in an instant such serenity can turn deadly.
That's what happened on July 4, 2003, when seven people
drowned within hours along a three-mile stretch of Berrien
It's what happens each summer on American waterways,
contributing to about 100 deaths a year.
It's a called a rip current, a fast-moving and deadly
force of water, once thought only to occur on ocean shorelines.
Scientists have only recently confirmed that the phenomenon
occurs daily along Lake Michigan's 1,638 miles of sandy
coastline. In fact, rip currents can be found on any sandy
shore where waves are present. And at almost any time.
"A lot of people don't know rip currents occur on
the Great Lakes. We didn't know until recently,"
says Ron Kinnunen, a Marquette, Mich., agent for Michigan
Sea Grant, a joint program between the University of Michigan
and Michigan State University that studies this natural
occurrence. "Some of the rip currents on Lake Michigan
can rival those of Southern California."
Rip currents form when wind and wave conditions combine
to push water onto a beach, forming a sandbar close to
"You get water picking up, and eventually there's
too much pressure," says Jennifer Read, associate
director of Michigan Sea Grant. "The sandbar rips
open, and water pours out through that point. It's very
swift, and it's almost literally perpendicular to the
These minirivers of fast-moving water can cut across
the surf zone, carrying sand, debris and sometimes swimmers
out to sea.
Although rip currents usually run out of steam beyond
the breakers, they can move faster than 5 mph and carry
even Olympic swimmers hundreds of yards offshore. Many
swimmers who try to fight rip currents quickly exhaust
themselves and drown.
"There were about 30 drownings related to rip currents
in Lake Michigan in 2002 and 2003," says Kinnunen,
who has been with Sea Grant for 24 years. "People
don't even have to be swimming. They can be in waist-deep
water when a rip current knocks their feet out from under
Which may be why rip currents are often erroneously called
riptides or undertow, but they are not caused by tidal
action. Although waders may end up underwater, the currents
themselves pull people along the surface, not down.
According to the United States Lifesaving Association,
80 percent of all rescues on U.S. beaches are related
to rip currents. So far this summer, scientists suspect
rip currents in five incidents on Lake Michigan, including
two separate drowning deaths near Muskegon in late July.
Because such drownings and near drownings occur one by
one up and down the shore, rip currents have only recently
been recognized as a major hazard, although they claim
more lives annually than floods, hurricanes and tornadoes.
The National Weather Service, the United States Lifesaving
Association and the National Sea Grant Program have pooled
resources to better understand rip currents and educate
the public as meteorologists and coastal geologists continue
to collect data.
"We're getting to the point where we can almost
tell where they are going to occur," says Kinnunen.
"If you have a long stretch of water and the wind
is blowing toward shore, all that energy has to dissipate
Guy Meadows, a professor from the University of Michigan,
has studied rip currents for 35 years.
He says the conditions on Lake Michigan are not only
conducive to rip currents, they are ideal.
Underwater erosion has created a steep drop off on the
shoreline, which has allowed larger waves to break closer
to shore. This creates more water piling up and more rip
"The beach is changing very rapidly," says
Meadows. "Our prediction is that the frequency and
intensity of rip currents on Lake Michigan will increase
over the next few years."
Which is why researchers are hoping to devise better
ways of predicting when and where rip currents are most
likely to appear.
But, Meadows says, rip currents aren't easily predicted.
"Can we say, 'There will be a rip current on this
beach at this time'?" says Meadows. "We're a
long ways away from that."
What scientists can do is predict when conditions are
right for rip currents by using wave height, wind direction,
wind speed and a few other variables.
"I think we're closer to predicting the where and
when," says National Weather Service meteorologist
Dave Guenther. "We are making bigger strides every
year. Hopefully, within a year or two, we will be able
to forecast various strength levels."
The National Weather Service now includes a basic rip
current forecast on its hazardous weather outlook for
Lake Michigan (www.crh.noaa.gov/grr in Michigan and www.crh.noaa.gov/iwx
In the future, Meadows says, scientists hope to use such
forecasts to detect rip currents before they form with
a portable shore-based radar unit.
"This would be a real-time tool like Doppler radar,"
says Meadows. "That's one of the things we're really
pushing for on Lake Michigan."
In the meantime, swimmers can protect themselves by recognizing
subtle signs of rip currents.
"There might be debris on the surface," says
Read. "The color of water may be different. In general,
it's going to look different than the water around it."
"If people are caught in a rip current they should
know what to do," Kinnunen says, "and if they
can't swim, they shouldn't even be in waist-high water
when conditions are right."
Staff writer Jeremy D. Bonfiglio: