MOBILE, Alabama — In observance of the beginning of the 2012 hurricane season, the Mobile Public Library asked meteorologist Bill Williams to make a presentation at Bernheim Hall in the Ben May Main Library.
Even though the season did not begin until June 1, Williams reminded his audience there had already been two named storms in the Atlantic Ocean this year, adding that storms before the official beginning of hurricane season were rare, but not unprecedented.
The founder of both the Coastal Weather Research Center and the meteorology program at the University of South Alabama, Williams addressed the 2012 hurricane season in both an historical and meteorological context. He was aided by a slide presentation that looked back at hurricanes from the beginning of the 20th century, starting with the 1900 hurricane that leveled Galveston, Texas.
That storm, he explained, came before sophisticated storm tracking and caught the citizens of the Texas coast virtually undetected, taking more than 6,000 lives.
From that point, Williams offered a look at the major hurricanes that struck the United States by decades, noting that major hurricanes caused significant damage to the Mobile area every 10 years beginning in 1906, but following the 1926 storm, Mobile was mostly spared on Hurricane damage until Frederic in 1979.
The slides he presented showed that the paths of major hurricanes varied over the years, with more storms in the Atlantic in some decades, more in the Gulf in others, but a fairly even distribution in most.
Along with the maps charted the paths of the hurricanes, the slides included the devastation of some of the more powerful storms, such as the Labor Day hurricane of 1935 that hit the Florida Keys, derailing a train of workers being evacuated and killing more than 600 of these evacuees.
Also shown was damage caused by the Great New England Hurricane of 1938, which picked up speed as it raced up the Atlantic Coast and hit the Long Island Sound, killing 600-800 people and destroying thousands of homes. Photos from 1969’s Hurricane Camille, which devastated the Mississippi Coast in 1969, and the damage caused on Dauphin Island and in Mobile were also shown.
While Category 3-5 hurricanes are considered the “major storms,” Williams noted weaker storms can also have a significant impact. He reminded his listeners of Hurricane Danny, which dumped an estimated 40 inches of rain in the Mobile area in 1997, describing it as “probably the biggest rainfall event ever in the United States.”
Rain gauges on Dauphin Island recorded 36 inches, which is remarkable when considering hurricane winds were driving the rain horizontally.”
While predicting the strength of hurricanes and tracking their paths have improved with the hurricane hunters and satellites, Williams added, the many factors involved can still play tricks on those trying to warn those in their paths. He noted that weaker storms, such as Elena in 1985, are harder to predict, because “steering currents can get weak. Stronger storms develop their own environment and become more predictable.”
However, even the larger hurricanes can be affected by changing weather patterns, Williams said, citing 2004’s Ivan as an example. It appeared to be headed to Mobile, but as it approached, the westerly flow of air usually found along the coast caused it to turn slightly and cause more damage to the east.
Williams discussed the factors that affect the strength and number of major storms each year. The weather phenomenon known as El Nino causes higher water temperature in the Pacific Ocean, producing a westerly flow of air, reducing the number and strength of tropical storms in the Gulf of Mexico and the Atlantic due to wind shear.
Williams noted El Nino was strong in 1992, 1997 and 2006. He added that it was once thought that El Nino only appeared every 25 years or so, but is now known to appear about every five years, with a significant strengthening every 25.
However, even when El Nino reduces the impact of these storms, it does not eliminate the threat of a major storm. “In 1992, we had five named storms,” he added, “but the first one was Andrew.”
That Category Five hurricane, which was the first of the year, formed in August off the coast of Africa. When it reached the Florida Coast, it flattened large swaths of neighborhoods, restrengthened over the Gulf of Mexico and did more damage when it hit Louisiana.
Another factor is the Loop Current in the Gulf of Mexico. Williams explained that while the surface of the Gulf is always warm in the summer, the Loop Current causes deeper water to warm. As a storm moves over warm water, it causes the cooler lower water to rise, but over the Loop Current, the water that rises is warm, fueling the intensity of the storm. This was one of the factors in the strength of hurricanes Katrina and Rita in 2005.He also explained that the landfall of Katrina, in the concave Mississippi Coast, also caused the storm surge that moved floating casinos across U.S. Highway 90.
Williams also spoke of the idea that global warming has increased the number of intensity of hurricanes. While he acknowledged global warning, Williams explained that the fact that the technology has improved so much that to compare today’s storms with hurricanes 100, 50 and even 25 years ago was nearly impossible. As for the number of storms, Williams said before the days of aircraft and satellites, many tropical storms and hurricanes at sea probably went undetected.
As for this summer, Williams expects the cooler water temperatures in the Atlantic to cause storms to develop in the warmer waters of the Gulf and around the Bahamas, meaning fewer large hurricanes taking the long trek from the coast of Africa. However, Williams reminded everyone that it only takes one big storm hitting the right place to make a memorable hurricane season.
Williams is associate professor emeritus at the University of South Alabama, where he began teaching in 1967. Although retired from full-time classroom work, he still teaches climatology in the meteorology program, which is the eighth largest in the nation. He continues as an advisor and forecaster at the Coastal Weather Research Center, which has 100 clients in nine states.
This story was written by David Clothier, Press-Register Correspondent.