Volume inflow forecasting procedures, Hungry Horse Reservoir, Montana

Several streamflow forecasting formulas are developed using combinations of several possible variables. (1) Precipitation only, (2) snow courses and precipitation, (3) snow courses, precipitation and base flow. A statistical comparison with the usual parameters is presented to show the weight carried by each independent variable. In discussion Mr. Harold Hafterson and Mr. R.E. Lindgren indicate several improvements in using short term records. The April-September precipitation as an independent variable is difficult to evaluate when the forecast is made on April first, where the forecaster must use a normal or average figure, or attempt to estimate a plus of minus normal figure. This variable alone carries a large weighting factor and a misestimate could spell disaster in forecasting the inflow to Hungry Horse Reservoir.