At Cleveland Water, our water quality staff frequently use scientific models based on years of previously recorded data to help predict what lake conditions will be like in the future. One such prediction is ice cover.
Water quality staff prefer a nice moderately thick coating of ice on Lake Erie each winter as it calms the lake, eliminates turbidity, and allows diatoms, which are the base of the sport-fish food web, to thrive.
More importantly, models and ice add consistency and predictability to the water treatment process.
Unfortunately for this winter, the models that predict weather conditions and corresponding ice cover are unsure of what to expect. Most models are predicting a roller coaster winter with temperature and precipitation widely fluctuating each week.
The National Weather Service (NWS) Cleveland office's Great Lakes Freeze-up Outlook states the probabilities for La Nina extending through winter are approximately 95%. Yet, “there is high uncertainty in the December, January, and February temperature forecasts for the Great Lakes region,” and there are “equal-chances of below, near, or above-normal seasonal mean temperatures.” The NWS forecast also predicts below normal temperatures heading into spring, and if ice forms, the cold spring could extend the ice season.
The Old Farmer’s Almanac 2020-2021 Long Range Weather Forecast for Cleveland agrees that the only consistent thing about the weather for the next few months is lots of changes. The Almanac states that for some months, precipitation will be higher than normal this winter, but overall temperatures will also be higher. This means we’ll be getting more days of rain, with a few days of bitter cold mixed in.
The staff at NOAA’s Great Lakes Environmental Research Laboratory (GLERL) also predict winter ice cover. Their research has shown that the inter-annual variability of Great Lakes ice cover is heavily influenced by four large-scale climate patterns referred to as teleconnections: the North Atlantic Oscillation (NAO), the Atlantic Multi-decadal Oscillation (AMO), the El Nino/Southern Oscillation (ENSO) and the Pacific Decadal Oscillation (PDO).
These teleconnections influence the location of the westerly jet stream over North America. The position of the jet stream largely dictates the origin of the air masses that will reach the Great Lakes region. The temperature and moisture content of the air masses play a key role in determining ice cover on the Great Lakes. The air masses that reach the Great Lakes are themselves impacted by factors like arctic sea ice, snow cover, and the polar vortex.
All of these factors can be thought of as waves. When they work together, they can tilt the odds of certain weather patterns – such as a harsher or milder winter. This year there is no dominant signal and many factors are out of phase. If they stay out of phase, we will get a roller coaster, which will still likely include more snow than last winter.
Last winter, there was only about 30-35 inches of snowfall around the Cleveland area. During an “average” winter, the Cleveland area gets 65-70 inches of snow. Snowfall, however, does not equate to a frozen lake.
For Lake Erie to freeze there needs to be multiple days of very cold air to pull the heat out of the water and turn the surface to ice. Because the air temperatures are predicted to widely fluctuate, we may see that Lake Erie gets only a glaze of ice over a majority of the surface area; however, the ice will be gone as soon as winds whip up the waters, breaking apart the frozen molecules and scattering them in the other 127.7 million gallons of unfrozen water.
Water temperature at our intakes is 44.2 degrees Fahrenheit as of December 7, 2020. The surface of Lake Erie will not begin to freeze until that temperature stays consistently below 39.2°F, based on the science of water density.