Improving COAMPS Forecasts of Low-level Winds and Significant Wave Heights in the Strait of Hormuz and Arabian Gulf

Fleet Numerical Meteorology and Oceanography Center (FNMOC), under the direction of the Commander, Naval Meteorology and Oceanography Command, has the mission to operate global and limited-area meteorological and oceanographic numerical weather prediction (NWP) models in support of the US DoD in operations, exercises, humanitarian assistance and disaster relief. Occasionally, the limited-area model COAMPS predicts high wind speed events near the surface that are not observed, often originating on the desert plain south of the mountainous areas of southern Iran. These events exceed surface wind observations by about 10 to 20 knots and have velocity maxima between 215 and 500 meters above ground level. When these jets reach the Strait of Hormuz and the Arabian Gulf, the high wind speeds also lead to an over-forecasting of significant wave height. Changes to the model’s land surface model and low-level vertical wind shear are explored to improve model performance. Verification efforts show model root-mean-square error and bias are improved in several surface parameters.