Performance of the GFS in predicting tropical cyclone genesis during 2007

There is an ever-increasing need for improved operational forecasts of tropical cyclone (TC) genesis. Recent modifications to the National Centers for Environmental Prediction's Global Forecast System (GFS) are believed to have had a positive impact on tropical forecasts. This paper will evaluate GFS predictions of TC formation in the Tropical Prediction Center/National Hurricane Center's area of responsibility during the 2007 hurricane season. The contrasting cases of Hurricanes Dean and Felix will be highlighted. Although the GFS predicted the formation of Dean quite well a number of days in advance, the GFS forecasts did not depict Felix's genesis very accurately. A diagnosis of the model fields will be shown in an attempt to explain these differences in model performance.