A computer program for determining and displaying the geostrophic winds on Lakes Superior and Michigan

The geostrophic wind has long been recognized as a useful tool for the forecaster. It is particularly useful in estimating the wind over large areas such as the Great Lakes where few or no reports are available. A semi-graphical solution of the geostrophic wind equation as described by Johnson (1971) has been used by WSFO Chicago as an aid in analyzing and forecasting winds on Lakes Superior and Michigan. The arrival of AFOS minicomputers has presented the opportunity to abandon the graphical method and solve the equation using a numerical scheme. A FORTRAN program is now used operationally to compute geostrophic winds at seven points on the Lakes using the sea-level pressure at ten stations as input. The program also generates an AFOS graphic which is used with a companion background to display the results of the computation. 1980 NWS (National Weather Service) CR (Central Region) Library Public Domain 1931