Near Real‐Time Forecasting of Large Lake Supplies

Abstract

The Great Lakes Environmental Research Laboratory (GLERL) has developed conceptual model‐based techniques for making outlooks of basin moisture conditions, basin runoff, water supplies, and lake levels several months into the future for large lake basins. The techniques consider the water stored in the basins about the lakes and the uncertainty of future meteorologic conditions. We estimate a large lake basin's current moisture storage with GLERL's tank‐cascade runoff model, applied to each of the subbasins about the lake, and with near real‐time meteorology. We select historic meteorologic sequences, representing anticipated meteorology, based on the National Weather Service monthly and seasonal forecasts of precipitation and air temperature probabilities, for use with the runoff model to generate our near real‐time outlooks. Error analysis for the Lake Superior Basin identifies the outlook error components and their relative magnitudes, indicates the outlook is superior to climatology, and suggests that improvements await better weather forecasting and lake evaporation modeling.