UNIVERSITY PARK, Pa. -- These days, with repeated stark TV images of flooding and anarchy in New Orleans and devastation in states bordering the Gulf of Mexico -- all wrought by Hurricane Katrina -- Bryan Swistock almost hates to mention it.

But in dry years like this one, he points out, it is often heavy rains brought north by hurricane remnants that save Pennsylvania agriculture, water supplies and wildlife.

"Often, what gets us out of droughts is tropical moisture," says the Penn State Extension water resources specialist. "In dry years such as this one, the hurricane season (generally July through November) sometimes provides enough rain to recharge groundwater and stream flows across the state."

Ironically, according to Swistock, even though Katrina was one of the largest, most vicious and most damaging hurricanes in history, it mostly fizzled by the time it got to Pennsylvania. "Katrina really only had an impact in the northwestern part of the state, where we generally got a couple inches of rain," he says. "In the central and southcentral parts of Pennsylvania, where we have very dry conditions, some places got a drenching thunderstorm but others didn't see more than a few sprinkles."

One place where they were probably glad to avoid rains from a hurricane's remnants was the Pittsburgh area, where historic flooding occurred last September, caused by the deluge generated from the remnants of Hurricane Ivan, which caused millions of dollars of damage in the western portions of the commonwealth.

"This whole business of Pennsylvania getting needed moisture from tropical storms in the fall is a dicey proposition," says Swistock. "At the end of dry summers such as this one, we need the rain. But the key, of course, is for the hurricanes to have lost most of their punch so that they deliver only steady, moderate rains. When they still pack tropical-storm velocity winds and so much moisture that they cause flooding, as Ivan did last fall, they are more damaging than helpful."

Besides Ivan last year, Pennsylvania has been victimized by heavy wind and water damages from the remnants of a number of hurricanes over the years, the most notable of which were Hurricane Agnes in 1972 and Hurricane Floyd in 1999.

So far, 2005 has been a dry year. "Most of Pennsylvania is several inches below normal rainfall levels," Swistock says. "We need the tropical moisture because in spots, the state is really dry. We haven't had a general rainstorm all summer caused by a front coming through. All we have had is thunderstorms popping up here and there from the heat and humidity.

"With pop-up thunderstorms, either you get lucky or you don't," he continues. "There are farms that are very dry and you can see the corn is suffering, and 20 miles down the road they have gotten plenty of rain and the crops are doing very well."

Tropical moisture from the remnants of a hurricane or two would take care of that disparity, according to Swistock, but he's not sure he wants to see one. "Despite all the damage from Katrina, the reality is that it is very early in hurricane season and we are likely to see more tropical storms, whether we like it or not," he says. "We need to get some prolonged rain in Pennsylvania this fall to recharge groundwater across the state so we don't face a drought situation next spring. It would be nice if we'd get it without the high winds and floods."

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EDITORS: Contact Bryan Swistock at 814-863-0194 or by e-mail at brs@psu.edu.

Writer/Editor: Jeff MulhollemOffice 814-863-2719