Minnesota Lakes Thaw Tracker

Cumulative Snow

Snowfall is important because it does three things that prolong ice cover. Our forecasts use total annual snowfall because it measures snow cover and potential contributions to the formation of “snow ice.” 

1. It helps thicken ice by forming “snow ice.”
2. It reflects the sun’s heat.
3. It insulates the lake surface. 

Use this National Weather Service webpage to look up how much cumulative snow your area has received. 

1. Select your region on the map.
2. Select the nearest town from the “1. Location” list.
3. Select the “monthly summarized data” from the “2. Product” list.
4. Select “Snowfall” in the “Variable” drop-down from the “3. Options” list.
5. Select “Sum” in the “Summary” drop-down from the “3. Options” list.
6. Select “Go” from the “4. View” list. 

The result will show the snowfall for each month of the year and seasonal total snowfall. Our ice-out forecasts are made for a range of seasonal snowfall amounts for each part of Minnesota. 

Data for the Clock 

The forecasts generated by our Minnesota Lakes Thaw Tracker are based on:

1. Statistical analyses of past National Weather Service (NWS) weather data.
2. 15,000 historical ice-out dates recorded by the Minnesota Department of Natural Resources (MNDNR).
3. Lake location, latitude, and size data from the MNDNR.
4. Current season weather information from the NWS. 

Accuracy 

1. Forecasts give the most likely ice-out date at the time the forecast is generated.
2. Late-winter forecasts will be closer to the actual ice-out date than earlier forecasts.
3. The accuracy of all forecasts depends on the specific local weather that occurs between the date of the forecast and the date of ice-out on each lake.
4. Because our data come from NWS airport weather stations, forecasts for lakes closer to an airport weather station may have greater accuracy than lakes farther away from a station.
5. Timing of freezing and thawing matters. That is, thawing weather followed by lots of very cold weather will have a lessened effect.

Degree days 

We need to explain some science jargon. This clock uses "degree days," which are measures of how long and intense freezing (Freezing Degree Days) or thawing (Thawing Degree Days) has been at a location. It's helpful to remember that you can have more than one degree day in a 24-hour period. Degree days are the difference between the average daily temperature (high temperature plus low temperature divided by two) and the freezing point of water (32°F).

Degree days for a single (24-hour) day are calculated using the following formulas:

• Thaw Degree Days for a single day: [(High temp + low temp)/2] -32
• Freezing Degree Days for a single day: 32- [(high temp + low temp)/2] = FDD
• If the result of the formula is a negative number, then the answer is zero (0). 

Tourism

Among the most important problems of the tourism industry is seasonality, including the start and end dates of the high season as well as the duration of peak use. Variation in seasonality and a lack of means by which to forecast the timing of recreation seasons are among the most economically impactful pressures on Minnesota’s tourism industry. 

When a seasonal business lacks tools to accurately forecast when their season starts or ends, they can end up with excess or insufficient staffing and/or supplies and extraordinary pressures on local services. All of which can negatively affect the experiences of their customers and result in lost or unrealized economic gains. 

Variations in tourism seasonality can affect the environment in different ways. Intensified tourism or poorly timed tourism may lead to negative environmental effects, while extending a season may help reduce environmental pressures and promote sustainability. 

Variations in the seasonality of tourism can also lead to environmental impacts through intensification or poor timing of seasons or to environmental improvements if season extension decreases environmental pressure. 

Forecasting the timing and duration of tourism seasons may provide businesses with major benefits, particularly as weather and seasonality become less predictable. 

In Minnesota, fishing and boating have direct, annual economic benefits of $1.14 billion while snow-related recreation’s benefits are $240 million ($2023). For the Great Lakes states the equivalent numbers are $9 billion and $1.4 billion, respectively (Bureau of Economic Analysis).

2024 Webinar

2024 MNSG Webinar: Minnesota Lakes Ice-Out Clock