Ice Data

Long Lake in winter from the Derr Family (2017) 

This page has information gathered by Lou Schultz and Sharon Natzel who are collaborating, with help from several observers around the lake, on the dates that the lake freezes over and the dates when it thaws in the spring.
 

 Overall, the system looks “stable” with the average “Ice In” expected to be mid-December. 
 2011 looks like an anomaly, but there does not appear to be a sustained trend.

The charts indicate that the Ice In process is “stable” and it would appear to be normally distributed.   The average Ice In is December 14 with variation from about November 20 – January 14.  The “control Limits in the first chart indicate that 99.73 % of the time, you can expect the Ice to come in between November 12 and January 14 with the expectation that in a high percentage of the time (about 68%), the ice will come in between December 3 and December 25.
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 Official Ice In date for 2017 is December 21.  (the first day of winter) 






According to Vern Campbell, April 19th is the average date of ice out, so this year was earlier than average.  The histogram appears to be centered on April 17(19) with a +/- 3 week spread. This year's  charts would indicate that the system is under control with no visible evidence of any special or unusual causes.



Long Lake has some very deep spots that make exact dates for the lake freezing over difficult to calculate.  The dates for ice-out in the spring are much easier.  The original Ice-In and Ice-Out data was provided by the late Bella and John Sanders, whose home was near the mid-section of Long Lake.  They collaborated with Bill Anderson who lives close to the deepest part of the lake toward the North end. 

Lou Schultz and his friend, Vern Campbell, work on the statistics for Long Lake based on these observations.  Their control graphs allow us to predict our future, average (mean) ice-in date as December 12.  The control limits are calculated from the data and are plus and minus three standard deviations from the mean.  The green lines depict the mean or average ice-in and ice-out. The red lines show the control limits or extremes of what can be expected.  They tell us in a stable system (no outside influences) we would only have three years out of one thousand where the ice-in could fall after January 3 or before November 20.

It appears to be a very stable process for Long Lake.  These control limits are calculated from the data and show that all the dates in the last twenty-two years are within normal variation.


If we should get an ice-in date BEFORE Nov 13 and then ice-out date "AFTER" March 29, then we might expect something happening to our system like global warming. Less than that, we are just experiencing normal variation of our weather system.