“ Validation of WRF Forecasts of the Development of Hurricane Helene 2006 ” (original) (raw)

Every hurricane season, roughly 50-60 tropical low-pressure disturbances exit the West Africa coast and traverse westward across the Atlantic. Approximately one-fifth of these disturbances become tropical depressions, tropical storms, or hurricanes. One of the most difficult challenges facing tropical forecasters is how to differentiate which tropical disturbances will develop beyond an African Easterly Wave (AEW). Part of the answer to this question lies in the West African Monsoon, a seasonal reversal of wind that provides beneficial rainfall to the Sahel, a region bounded by the Sahara Desert to the north and a rainy belt to the south. This region includes Senegal, Mali, Mauritania, Niger, Burkina Faso, Chad, and Sudan. Most the time, dry winds blow out of the Sahara from the east or northeast. However, from June through September, southwesterly monsoon winds transport moist air from the tropical Atlantic over the Sahel causing heavy rains to fall closer to the southern edge of t...