Waiting for the Thaw - Lake Ice Out 2014

lake ice photo

(Updated April 18)

The long, cold winter has Minnesotans yearning for signs of spring. An important spring benchmark is lake ice out. As of April 18, some lakes in the southern one-third of Minnesota are without ice cover. Even in those counties, some larger, deeper lakes remain totally or partially ice covered.

Historical data indicate that spring lake ice dates are extremely variable from year to year, ranging by as much as six to eight weeks between the earliest recorded ice out date and the latest (see maps below). Accurate long-term projections of lake ice out dates are currently beyond the reach of science. Lake ice melt is driven by a number of factors such as ice condition, snow cover, temperature, precipitation, and wind. The related weather elements cannot be accurately forecasted beyond three to five days. Therefore, we must use the past for a look into the future.

A first guess at projected ice out dates is the historical median date. The median ice out date for a given lake is the date where one half of the lake's historical ice out dates were earlier, and one half of the historical ice out dates were later (the "50/50" date).

Clicking on the median lake ice out date map below will show that the Minnesota's "50/50" dates are in late-March/early-April for the southern three tiers of counties, in the second week of April for the metropolitan area, the third week of April in the Brainerd and Detroit Lakes areas, the final week of April in the Bemidji and Grand Rapids areas, and early May for lakes near the International border.

Given present ice conditions, it is obvious that lake ice out dates are not earlier than historical median dates. However, the question of how long ice out will be delayed beyond the historical median dates is impossible to answer.

Monitor 2014 lake ice out progress on the DNR lake ice out date reporting page.

earliest ice out map median ice out map latest ice out map

 

For more information contact: climate@umn.edu