December 9th - Open water on Lake Minnetonka and most lakes in southern Minnesota
It looks like those little ice villages that pop up on Minnesota lakes will have to wait a while this year.
Ice fishermen and ice boaters are getting a little anxious these days. The late freeze up of many central and southern Minnesota lakes this year means no ice, or unsafe ice as of this weekend.
Friday's MODIS Terra high resolution (250 meter) visible satellite shot shows mostly open water from the Whitefish and Gull Chains to Mille Lacs on south.
Take a close look at the images below, and you can see which lakes have ice and which are ice free as of Friday afternoon.
There is partial ice on Mille Lacs and on Pelican Lake north of Brainerd. The average date for freeze up on Pelican is about December 1st, according to Moriya Rufer, the Lakes Monitoring Program Coordinator for RMB Environmental Laboratories in Detroit Lakes, which are still ice free as if Friday.
"Since 1910, the earliest freeze-up for Detroit Lake was October 25 in 1919. The latest freeze-up was December 13 in 2004. The average freeze-up has been getting later as our climate warms. The average freeze-up date in the 1990s was November 20, while the average date for the 2000s is November 28.
Pelican Lake Association keeps records of their ice-in and freeze-up dates as well: http://www.pelicanlakemn.org/information.htm. The average freeze-up date for Pelican Lake since 2000 is December 1. The latest freeze-up was December 16 in 2001 and the earliest was November 22 in 2002.
As you all know, water freezes at 32 degrees Fahrenheit. That doesn't mean, however, when the air temp reaches 32 the lakes freeze. Water is a great insulator and good at holding heat, which is why the lake temperature doesn't fluctuate much day to day like the air does. Therefore, below freezing temperatures are needed for a week or more to form ice on a large lake.
Since water is good at holding heat, the more water there is the more heat it will hold. This is why large deep lakes take longer freeze and melt than small shallow lakes.
Water freezes from the perimeter of the lake to the center. It happens this way because the water is shallower at the lake's edge so it cools off faster. Water is most dense at 39 degrees Fahrenheit, so when it gets colder than that, the cold, lighter water floats on top of the lake. This top layer of water interfaces with the cold air, which cools the top of the lake even further until it freezes. Windy days cool the lake surface off faster because the cold air moving over the water cools the lake faster. The cold wind this past week no doubt is helping the freezing process along."
Meanwhile Lake Minnetonka and other large lakes in the metro are open as of Friday. Some of the smaller alkes in the snow covered areas north of the metro managed to freeze over this week.
I don't have any hard data on the average freeze up date for the "Main Lake" on Minnetonka, but I have observed a shift at least two weeks later than when I was a boy back in the 70s. We used to skate consistently on Carson's Bay on Thanksgiving weekend back then. (Yeah, and the snow drifts were THIS high!)
I would estimate the average freeze up for Minnetonka has moved from about November 25th to around December 10th over the past 30-40 years.
Our mild November kept lakes warmer this year, and has delayed freeze up. I expect more lakes to freeze up early Saturday as winds drop and cold high pressure drifts overhead.
Any ice that does form will remain unsafe for a while as temps may run above average into mid-December. Be careful if you are going to venture out on the ice!
Weekend Forecast: Warming trend!
Saturday dawns clear and cold in Minnesota, but the warning trend is on. You'll notice less of a nip in the air by Saturday afternoon as temps climb through the 20s.
A milder Pacific air mass will nudge into Minnesota Sunday. Temps may push into the 40s in the snow free areas in western and central Minnesota Sunday afternoon. The Twin Cities will melt some snow Sunday, and temps may approach 40 degrees!
Watching "Panhandle Hooker" for rain & snow next Thursday
The next significant weathermaker for Minnesota is scheduled to arrive next Thursday.
A "Panhandle Hook" system will wind up in the Texas-Oklahoma Panhandle Region next Wednesday and shoot north toward Iowa and Wisconsin Thursday.
Early indicators point to rain at first, changing to wet snow as the system tracks toward Wisconsin Thursday.
This may be our last shot at a white Christmas for parts of Minnesota that are snow free.
Four degrees below zero in the valley of Eden Prairie this morning. Coldest temperature of the season. Enjoying the sunshine today.