Forecast Verification for Eta Model Winds Using Lake Erie Storm Surge Water Levels*

Abstract

This article has two purposes. The first is to describe how the Great Lakes Coastal Forecasting System (GLCFS) can be used to validate wind forecasts for the Great Lakes using observed and forecast water levels. The second is to evaluate how well two versions (40 km and 29 km) of the numerical weather prediction step-coordinate Eta Model are able to forecast winds for the Great Lakes region, using the GLCFS as a verification technique. A brief description is given of the 40- and 29-km versions of the Eta Model and their surface wind and wind stress output. A description is given of the GLCFS for Lake Erie. This includes the numerical Princeton Ocean Model (POM), observed winds from surface meteorological stations and buoys, and water level gauge data. The wind stresses obtained from both the 40-km Eta Model and the observed winds are used to force the POM for Lake Erie for several periods in 1993 when water level surges were recorded. The resulting POM water levels are then compared to observed water levels to provide an indication of the accuracy of 40-km Eta Model forecasts. The same experiments are made with the POM using wind stresses from the 29-km Eta Model and observed winds in 1997. Twin experiments are made with the GLCFS to determine: 1) how well it can predict (hindcast) water levels using observed winds as forcing, and 2) how well it can predict water levels using both the 40- and 29-km Eta Model forecast winds as forcing. The use of this forecast validation technique for other coastal forecasting systems is discussed.