After slow start, tornado season under way

OKLAHOMA CITY (AP) — Forecasters say a wetter-than-usual winter and a jet stream ripping over the part of the country known as ``Tornado Alley' could lead to an active spring — perhaps starting with the strong twister that nicked a small western Oklahoma town Monday night.

``It's time to get ready,' Michelann Ooten of the Oklahoma Department of Emergency Management said Tuesday as she surveyed damage from a storm that destroyed five homes and tore the roofs off several others in Hammon.

The nation typically will see 70-100 tornadoes by early March, but only 42 had been reported until Monday night's Oklahoma tornado. There was only one tornado nationwide during February.

``No one would argue that we're going to see a pretty good increase in the number of severe storms,' said Greg Carbin, the warning coordination meteorologist with the national Storm Prediction Center in Norman, Okla. ``But each year's a little different. The number, magnitude, number of days are all very tentative at this point.'

In the short term, storms will be generated and fueled by the usual tornado trigger — Gulf moisture colliding with storm systems driven by the jet stream.

In a few months, parts of the Plains that had above-normal precipitation during the winter could see storms fueled by the moisture stored within plants and the ground. ``Transpiration is usually a component later in the springtime. We won't have that for a little while longer,' Carbin said.

Monday's twister occurred when a low-pressure system in the Pacific Northwest kicked a strong storm system out of the Rocky Mountains and into the southern Plains. ``There are all sorts of connections,' Carbin said. ``The atmosphere is a dynamic thing. You can't really pin it down to one descriptor.'

The slow start to the season is no sign that later storms will be stronger, weaker or non-existent.

``That pretty much tells us nothing,' said Harold Brooks, a research meteorologist at the National Severe Storms Laboratory in Norman.

Brooks said that if the weather conditions that caused the Hammon storm — abundant moisture at the surface and a low pressure system in Northwest knocking the jet stream into Tornado Alley — are still in place when the warm weather arrives, then the upcoming tornado season might be ferocious.

``If we had this pattern in two months, that would mean something very different than we have now,' he said.

The only twister reported nationwide in February was in a San Joaquin Valley oilfield in California two weekends ago. A year ago, there were 36 February tornadoes — and the year's deadliest was Feb. 10, 2009, at Lone Grove, Okla., where eight people died in a storm with winds estimated at 170 mph.

Last year, 1,156 tornadoes were reported nationwide and 21 people were killed by a tornado, according to the Storm Prediction Center. In 2008, there were 1,691 tornadoes and 126 tornado-related deaths.

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