Lake McDonald freezes over; Flathead almost

After a frigid start to March, Glacier National Park’s Lake McDonald has frozen over in its entirety, save for a few holes here and there.

The Park’s biggest lake last froze over in the winter of 2016-17. The lake, which is about 465 feet deep, saw plenty of cold in February, but it also saw a lot of wind, which kept the water body open.

The lake also froze over in the winter of 2013-2014. Prior to that, the last time was 2007.

A large portion of Flathead Lake has frozen over as well.

Jim Craft, a research scientist at the Flathead Lake Biological Station at Yellow Bay, estimated that roughly 95 percent of Flathead Lake was frozen over on Tuesday last week, but wind since then has broken up some of the ice. The National Weather Service in Missoula noted that satellite imagery shows a huge chunk of ice floating in the middle of the lake.

Craft said the last time the lake was similarly frozen was probably 26 years ago, in March 1993.

Flathead Lake’s longest period in recent history of complete ice cover was between December 1985 and March 1986, according to Flathead Lake Biological Station records. The lake was frozen for 79 days.

He said Flathead Lake’s size, depth and currents typically preclude the lake from icing over completely. Flathead Lake is about 192 square miles and reaches depths of more than 300 feet. It’s the largest natural freshwater lake west of the Mississippi.

The Park Service warns people about ice conditions on the Lake McDonald — it has hidden springs and upwellings that soften the ice in spots. Right now, the ice is so clear you can see the bottom of the lake in many locations, particularly near Lake McDonald Lodge — which was the last section to freeze.

The National Weather in Missoula said that February was the snowiest ever in Kalispell, with 33.2 inches of snow at the Glacier Park International Airport. Overall it was the second coldest February on record for Kalispell, with an average of 12.6 degrees. The record was set in 1936 with an average of 4.9 degrees.

Polebridge saw some very cold temperatures in the beginning of March. On March 3 it dropped down to 38 below zero. On March 4 it was 31 below zero. East of the divide, St. Mary dropped down to 36 below zero March 3. Kalispell also set a new record with a 21 below zero reading March 4.

Since then day time temperatures have moderated, with highs close to 40 on Sunday in West Glacier, but nighttime lows have still been in the single digits with clear skies overhead. This weekend we could see temperatures above 40 and next week highs could be in the 50s, as spring makes an appearance. Duncan Adams contributed to this report.