Ice Data

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. Once our official ice in or out dates are determined, the data is provided to several agencies, including the MN DNR Climatology Office and the Hubbard County SWCD that track ice.

Explanation of how the data is gathered:  
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 the late Bill Anderson who lived close to the deepest part of the lake toward the North end. 

Vern Campbell, a friend of Lou Schultz, works on the statistics for Long Lake based on these observations.  Their control graphs allow us to predict our future, average (mean) ice-in date.  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.



2024 Ice Out Date was April 8

According to Vern Campbell: The following are the charts for Long Lake Ice Out.  The average date is April 20, so 2024 was about 12 days earlier than the average.  The charts indicate that although the Ice Out this year was slightly earlier than average, it is still within the bounds of normal random variation.  Just as a reminder, the UCL = May 22 and the LCL = March 19 are calculated values and are +/- 3 standard deviations from the mean date of April 20.  Therefore, basically if dates are normally distributed and fall between May 22 and March 19, then we can basically conclude that any deviation we see from the average is simply normal random variation.  Thus far, the Ice Out dates indicate random variation about the average ice Out date of April 20.

(to find Long Lake (# 29016100) DNR data use this link )


Ice-In was determined be January 12, 2024 

This year's ice-in spotters had to work very hard.  The weather just was not consistent. Our ice spotter that is positioned on the very steep west bank looking directly east across the lake, using binoculars, noticed a long narrow strip of water, running north to south, that opened up in the ice Tuesday 1/9/24 in the late afternoon.  The temperatures started dropping Thursday afternoon and by Friday, January 12, 2024, the lake finally froze over. Thank you to all the ice spotters around the lake.  It takes teamwork!  

From Vern Campbell, our volunteer statistician.
It was a “unusually” late Ice In.  We are experiencing a similar mild winter up here in Canada until just after Christmas when the temperature turned to -20 C or so.  Statistically, the charts indicate that the variation in “Ice In” is random.  I ran a few additional tests on the data and thus far they indicate the variation is random although visually it does appear that there is a trend upwards (Ice In later) although the analysis that I did indicates the statistical evidence is not there to draw the conclusion that there is a trend.

The Mean “Ice In” from 1987 to current is December 15.  The UCL (Upper Control Limit) and LCL (Lower Control Limit) are +/- 3 Standard deviations from the mean.  This year’s “Ice In” date is approaching the upper control limit which means that the probability of a January 12 ‘Ice In” is around 1%.  To have 2 “rare” occurrences (2011/12 – January 14 and 2023/24 – January 12) within 12 years of each other is not impossible but statistically “unlikely”.  Something to watch in the future.