Published on 02/04/15

UGA climatologist predicts more active tropical season in 2015

By Clint Thompson

Tropical storms may cause havoc for coastal homeowners, but the rainfall they bring recharges the water balance and keeps soil moist in the summer, according to University of Georgia climatologist Pam Knox. Lack of tropical storm activity in 2014 contributed to Georgia’s prolonged drought, she said.

Knox predicts a return to a more active tropical season in 2015, leading to a wetter summer, which may be highlighted by heavy rainfall. This would be a welcome sight for Georgia farmers after last year’s dry growing season.

“Crops really depend on having an inch or 2 inches of rain every week. If you go through a long dry spell, then that’s a real concern,” Knox said. “During the summer, you’re running a zero or negative balance of soil moisture because it’s so hot.”

When the temperature warms above a certain threshold, usually around April 1, rainfall is either used by plants or evaporates, she said. Little is stored in the soil.

She also predicts a neutral weather season this year, not an El Niño — weather characterized by warm waters in the Pacific Ocean, leading to cool winter temperatures in Georgia — or La Niña — weather characterized by cold waters in the Pacific, leading to a warmer and drier winter in Georgia.

According to the university’s Georgia Automated Environmental Monitoring (GAEM) Network, from June 1 to Sept. 1 last year, the UGA Tifton Campus recorded just 7.38 inches of rain, below the 9.94 inches in 2013 and considerably under 26.15 inches in 2012. At the UGA Griffin Campus during the same time period, 7.54 inches were recorded in 2014, but 11.65 inches were accumulated in 2013 and 14.04 inches in 2012.

“Thunderstorms are certainly an important source of moisture in the growing season,” Knox said. “But they’re not always reliable because they can be hit or miss.”

A lack of summer moisture leads farmers to depend on irrigation to water their crops.

“Irrigation is all about timing. If you’re in a dry spell, for whatever reason, and you can apply an inch of water, sometimes that’s enough to save the crops or get them through a critical period, like pollination in corn,” she said. “Usually at the end of the summer, if the crops are growing, they’re taking in water at a pretty good rate. You’ve got to have rain from something.”

During a typical summer weather pattern, up to 30 percent of rain comes from tropical activity, Knox said.

What, if any, tropical activity that occurs this summer would be a welcome sight for farmers in the Southeast.

“It’s been almost 10 years since Florida’s had a major hurricane. You know it’s going to come back sooner or later with a vengeance,” Knox said. “There were those years in 2004-2005 with Ivan and Katrina and a whole bunch of other ones. Ever since then it’s been dead or very few have come across the Southeast at all.”

To see weather data from UGA’s 81 weather stations across the state, go to, online home of the GAEM Network. The UGA College of Agricultural and Environmental Sciences established the GAEM Network in 1991. Each station monitors air temperature, relative humidity, rainfall, solar radiation, wind speed, wind direction, soil temperature at 2-, 4- and 8-inch depths, atmospheric pressure and soil moisture every second. Data are summarized at 15-minute intervals, and at midnight a daily summary is calculated.

Clint Thompson is an agriculture writer based in Tifton, Georgia.