The experimental Great Lakes waterspout forecast displays forecast values of the Szilagyi Waterspout Index (SWI). The SWI is derived from the Waterspout Nomogram which uses output from the Canadian GEM model. Values of SWI range from -10 to +10. Waterspouts are likely to occur when SWI ≥ 0. Only these values are plotted. SWI = 0 is the waterspout threshold. Increasing values of SWI represent higher probability of waterspout occurrance. Additional consideration of areal coverage of the SWI field is equally important in assessing waterspout potential. Further information on the SWI at A Waterspout Forecasting Technique.
*Note: Boating season has ended. Waterspout forecasts will resume
June 1, 2013.