Session III: Weather and climate extremes in the Americas
We use observations and numerical model experiments to examine the influences of the Atlantic Warm Pool (AWP) on Atlantic hurricane activity. It is shown that a large (small) AWP increases (decreases) the number of Atlantic hurricanes and reduces (enhances) the possibility for hurricanes to make landfall in the southeastern United States. The increased number is through AWP-induced changes of vertical wind shear and moist static instability of the troposphere in the Atlantic hurricane main development region. A large AWP shifts the hurricane genesis location eastward, decreasing the landfalling possibility. A large AWP also induces the eastward and northward steering flow anomalies along the southeastern seaboard of the United States. Due to these two mechanisms, hurricanes are steered toward the north and northeast without making landfall in the southeastern United States during large AWP years. The opposite is true during small AWP years.