FAIRHOPE, Ala. — A new study funded by a NOAA operational grant and being conducted at The University of Alabama in Huntsville might one day help determine how the lay of the land makes some Southeastern locales more or less likely to be hit by tornadoes. That knowledge, combined with current forecasting methods, could help meteorologists better determine when to issue weather watches and warnings.

Dr. Tim Coleman, a research scientist in UAH’s Earth System Science Center, said that topography, such as mountains, lakes, bays, oceans, forests and concentrations of buildings might all have a role in encouraging or discouraging tornadic activity in some locations. Those same factors might also influence whether tornadoes become more or less powerful after they form, he added.

Much research has been done in the Plains states, where tornadoes often form, and they are easier to spot there. Little study has been focused on the Gulf Coast, however.

Coleman pointed out his research will begin where others have left off, while utilizing all they have learned. It is hoped looking at how tornadoes react to the topographic variables will add to that body of knowledge.

“We have as much tornado activity here, and the population density is greater,” Coleman said. “Their research has been helpful, but we’re trying to expand it east of the Mississippi where we have more topography. We’re really just scratching the surface of all this because it is new. This research is so new, we’re having to pull other people’s data for now.”

There are many bays from Houston to Panama City, and they have great potential to affect the strength of tornados. Coleman said, “Wind behaves differently over water than over land. It behaves differently over different types of land cover.”

As an example, he cited how hills, forests and groups of tall buildings slow wind speed, while crops produce only minimal resistance and water has almost no impact.

“We’re looking at when you have a great deal of difference (in topography) in one or two miles, does that create some spin in the atmosphere?” Coleman asked.

He will study radar and other records of tornadoes looking for insight into factors that might strengthen or weaken the rotation in a storm or a tornado. These factors include surface roughness or friction that slows low level wind, such as wind channeling between mountains and slopes.

The project began when Coleman started noticing patterns, especially in radar scans from Hurricane Katrina. He said storm cells would form in the front part of the hurricane then dissipate as Katrina’s rotation carried them along the Mississippi coast. He began to wonder if something about air flow over water and land might be affecting the storm cells inside the hurricane.

The work began by examining tornado data back to the 1950s and plotting those storms. It was known that air flow is influenced by surface roughness. If Coleman is correct in his theories, wind blowing ashore from a hurricane would be slowed as it shifts from sea to land, while wind still offshore would blow parallel but faster. The faster wind blowing alongside slower moving air might create spin in the atmosphere.

He explained that in the northern edge of a hurricane in the Gulf of Mexico, with the wind blowing east to west, the spin would be clockwise. That is opposite the spin of most tornadoes, which means the rotation of storm cells might be buffered.

Coleman has already looked at Doppler radar data from a summer field experiment at Wheeler Lake and from Mobile Bay once Katrina was inland. In both cases, wind was blowing faster over the water than over the adjacent land, whether it was a light breeze or the fringes of a powerful hurricane.

The Mobile Bay radar image clearly shows the fastest wind blowing north through the bay, Coleman noted, flanked by slower wind in both Baldwin and Mobile counties.

He also studied a storm that spun up a tornado over Panama City Beach during Hurricane Ivan. The storm wind was blowing from east to west, along the shoreline. The city’s condominiums are on a peninsula, so the slower air over the city had faster air over water on both sides. The natural spin or vorticity on the bay side would have spun counterclockwise. That counterclockwise spin might have contributed to the formation of the tornado.

One person was killed as a result of the tornado that formed near St. Andrews Bay.

The same kind of effect might be created by wind being channeled between mountains or through a valley, just as a mild breeze can accelerate to a buffeting wind if it is pushed between two buildings. The faster air current would create spinning vortices on both sides along the edges of slower air.

That channel effect could be enhanced if the valley has a lake on it. Coleman is studying two tornadoes that hit Lake Guntersville in the Tennessee River Valley in Marshall, Jackson and DeKalb counties in Alabama. The storms formed on one side of the lake and dissipated after making landfall on the other, he said.

Coleman said two of his theories regarding friction and wind channeling suggest the west side of Lake Guntersville would be an ideal place for the formation of tornadoes when winds are from the south or west, and two tornadoes formed there in two years.

“If something matches the theory and it matches more than once, you have to look at it,” he said. Mobile, Perdido and Pensacola bays are all large enough for Coleman’s theory to play out.

When asked, Coleman noted the same could happen on Lake Wheeler in northwest Alabama, which is only about two miles wide, if a tornado formed and traveled along the 20 or so mile length of the body of water.

“It just depends on the wind direction,” he said.

The remaining thing to be studied by Coleman and his team is the influence of slopes on tornado formation and strength. The theory is that a spinning storm is squeezed on a hilltop or mountain, reducing spin. As the storm passes the summit, it would stretch vertically on the downhill slope, increasing spin.

He calls it the “ice skater effect” because it is similar to a skater stretching their body vertically by putting their hands over their head. Coleman has several case studies of tornadoes that became more powerful and caused more damage on downhill slopes.

He cautioned that only 10 to 20 percent of all tornadoes are affected by these processes, but what is discovered will be useful.

“Only one or two papers has been done on this,” he said. “We’re in the preliminary stages of the study, but we have some models already developed. It is designed to help the National Weather Service provide better warnings. My job is to help the weather service and the TV guys warn for these storms.”