Lake Michigan forecasts switching to Sullivan office
SULLIVAN – Lake Michigan is such a looming presence to Wisconsin’s east side, it changes the weather.
In the summer it’s cooler near the lake and in the winter, it’s often warmer because of the moderating effect of the water.
While each of the seven National Weather Service offices on Lake Michigan, including two in Wisconsin, produce nearshore forecasts for the area five miles out into the lake from land, only one office handles the forecast for what’s happening out in the vast middle.
For decades Lake Michigan’s open lake forecast has been handled by the National Weather Service office in Chicago. But starting this week, it will be done by the Milwaukee office, which is actually based in the Waukesha County community of Sullivan.
It’s not easy to forecast the weather on Lake Michigan. For one thing, it’s huge: more than 22,000 square miles, 308 miles long and 118 miles wide and an average water depth of 280 feet.
And there are few sensors feeding data to National Weather Service computers. Two weather buoys are dropped into Lake Michigan by the U.S. Coast Guard each spring and removed in late fall. The buoys are located about 50 miles east/southeast of Milwaukee and east of Door County’s Washington Island.
They record wave height, direction and frequency, air and water temperature, wind speed and direction, dew point and humidity levels. Meteorologists also rely heavily on ship captains reporting wave height and frequency.
So many unknown variables make it a challenge to forecast weather happening across Lake Michigan.
“From my experience in forecasting, it’s very humbling,” said Tim Halbach, National Weather Service warning coordination meteorologist in Sullivan. “You don’t have a lot of information.”
Meteorologists also use satellites to learn ice location, winds and lake water temperatures.
The weather buoys are removed in late November, depending on water conditions.
“For us, that’s one of the most critical times of the
year because of bad weather and companies that are trying to get their shipments out before winter,” Halbach said.
Though fewer people use the open lake forecast compared to the many boaters, anglers and swimmers who use the nearshore forecast, knowing the weather conditions in the middle of Lake Michigan is critically important to Great Lakes ships, freighters and ferries.
Many of the estimated 6,000 shipwrecks at the bottom of Lake Michigan were weather victims.
On Thursday, Halbach sat at his station in the nondescript weather service building near Dousman and gazed at five computer screens tuned to various maps and weather data. Several large screen TVs on the wall showed Hurricane Florence starting to hit the Carolinas.
One of Halbach’s computer screens featured a map of Lake Michigan colored yellow, lime green and tangerine orange illustrating water surface temperatures ranging from 64 to 69 degrees. Another showed a black and white satellite feed of clouds moving through Indiana and Ohio. On a third computer, Halbach clicked on the wind forecast for Lake Michigan showing arrows pointing in the direction of winds flowing south from Canada.
Even though Wisconsinites don’t have to worry about hurricanes, weather conditions can get pretty rough on Lake Michigan with gale force winds. That can cost lives.
“If a storm is coming, we’re putting out those warnings as soon as we can so boats can get to shore in time,” said Halbach, a Fond du Lac native who earned a master’s in atmospheric sciences at the University of Wisconsin-Milwaukee.
The Sullivan office is taking over the open lake forecast from Chicago, in part, because Chicago’s backup weather service office is not equipped to handle the forecasts. The move will also free up Chicago forecasters for aviation forecasts for the busy O’Hare and Midway airports.
No additional equipment is needed for Sullivan forecasters to handle the open lake forecast and people searching for the weather won’t notice a change. One additional forecaster will likely be assigned to the Sullivan office.