Will 2006 Be Another Active Hurricane Season
By Patrick Prokop, Meteorologist, WTOC-TV
A Dry Spring
As we close out the season of spring, one must ponder as to what is in store for those “Tropical months” that lie ahead. March , April and May have been extremely dry over our area this spring with only 40% of normal rainfall. (This is with the average of five stations in Chatham County of: the airport, WTOC, Coffee Bluff, Downtown and Tybee). Normal for the three month period is 10.57 inches with the average of the five station totaling only 4.25 inches. The official rain value, which is the one gauge at the airport, was only 2.83 inches for the period which is a scant 27% of normal. However, the long range outlook from the Climate Prediction Center of the National Weather Service is hinting at normal or even above normal rainfall for our area during the summer months ahead. Could this mean a shift in the wind currents allowing more tropical system to move our way?
Normal Rainfall Patterns
Traditionally, most of our annual rains accumulate during the warm humid months of June through September where each month's average is between 5 to 7 inches, as compared to around 3 inches per month during the winter season. November is even less with averages around 2 inches. This above average forecast is hinting at an influx of additional tropical activity.
Savannah is located in a geographical region in which our weather is split, with the winter season under the influence of the "Prevailing
Westerlies". These west to east flowing winds in the mid and upper level of the atmosphere causes weather system to advance from the west
coast to the east coast bringing in cold fronts and low pressure system to our area from the middle of the country or Gulf of Mexico. The
Gulf of Mexico systems bring most of our winter rains, but this year, have been low in frequency, hence the dryer than normal rainfall so far
for this year. During the summer months, the large high pressure system in the central Atlantic, known as the "Bermuda High Pressure System"
migrates northward. During the winter months, while the center of this high is south of our latitude (32 degrees north), the
counterclockwise circulation around it, produce those "Westerly" winds (winds blowing from the west to east). But as the high drifts
northward during the summer, the center of circulation passes to our north resulting in the bottom side of the circulation to flow into our
area. These "Easterly" winds flow from east to west and bring in weather from the sub-tropical and tropical Atlantic into our region during
The Steering Winds ... The Circulation of the Bermunda High
It is these same winds that dictate the flow of tropical weather systems that approach our area. Last year, the Bermuda high pressure was a
bit stronger than usual and the western edge extended past our coast and entered into the Gulf of Mexico. This drove numerous tropical
systems into the Gulf and then forced them northward into the southern Mississippi Valley and the Florida panhandle. If the high was even
stronger, it would have driven the storms into Texas and Mexico or even Central America (and a few did wander south of Texas into the Mexican
and Central American coasts). If the Bermuda high pressure system is weak, tropical system would curve northward before reaching the east
coast of the US. This is usually accompanied by the "East Coast Trough" which is a strong SW to NE flow of winds over the east coast of the
US. When this trough is present, no storms would make landfall in our area and most curve northward and remain out at sea. (This same
trough aided the sailing vessels to travel up the coast where they eventually would pick up the westerlies and head home to Europe.)
The Big Question
So the question; "Will this be an active storm season" or more appropriately, "Will this be an active storm season for us"? The results will
be determined on the position and intensity of the Bermuda high pressure system when storms are roaming the tropical seas.