Saturday, July 2, 2011

Tropical Storm Dynamics

The development of a tropical storm is dependent upon three factors: warm ocean waters, hot, humid air at the surface and light upper-level winds. For these reasons, early season Atlantic hurricanes usually develop in the relatively shallow waters of the Gulf of Mexico, across the Caribbean and along the Southeast Coast of the U.S. While tropical waves begin to move westward, out of Africa, in early summer, they encounter cool waters in the central Atlantic and tropical storms do not usually develop; by August, the ocean temperature has increased and the peak of the Atlantic hurricane season begins, continuing through September and into early October.

Once a tropical storm develops, favorable conditions, discussed above, may cause it to strengthen into a hurricane. Conversely, if the storm moves into cooler waters, makes landfall or encounters strong upper level winds, the storm dynamics break down and the system weakens or dissipates. In some cases, favorable conditions may be re-encountered and the storm may redevelop; this occasionally occurs in Central America, when Gulf of Mexico storms weaken over land and then re-blossom in the eastern Pacific.

Global warming may extend the hurricane season by producing warm ocean waters earlier in the summer and later in the fall. Then again, climate change might alter upper level wind patterns, shifting the zone of tropical storm development and impact. Time will tell.