Flooding in the Catskills: The bad news about climate change

On Saturday, the Watershed Post attended the Ashokan Watershed Stream Management Program's annual Ashokan Watershed Conference. The subject this year was a timely one: "Flood Resilience for Towns, Businesses and Landowners." We'll be posting about what we learned in various conference sessions all week. This first post focuses the effect of climate change on weather, "extreme precipitation events," and flooding. 

Storms are getting more severe, rainfall is getting heavier, droughts are getting dryer, and flooding, a great Catskills bugaboo, is getting worse. That was the message that Dan Zarrow, a meteorologist at Cornell University's Northeast Regional Climate Center, told a packed room of landowners and municipal authorities at the Emerson Resort on Saturday.

"The dry get dryer, the wet get wetter, the heavy gets heavier, the light precip[itation] gets lighter," Zarrow said as he explained how climate change is affecting weather across the United States.

Dan Zarrow speaking at the EmersonDan Zarrow speaking at the Watershed Conference

Unfortunately for us, those trends are particularly extreme in our part of the country, Zarrow said.

"The northeast US is the most sensitive region of the country to climate-change induced-extreme precip increases," he said.

Zarrow's audience was scores of Catskills-area landowners and public officials who witnessed the region's "extreme precipitation events" firsthand during last fall's October 1 and December 1 floods, which closed roads across the Catskills and swept one woman to her death. During the October storm, up to eight inches of rain fell in one day. 

Zarrow spoke of the October storm, a meteorological event that hit Ulster County so ferociously that it supposedly happens only once a century, with something like awe:

'This was an incredible storm to watch as it transpired," he said. "As I recall, it turned really cold afterward. So we had flooding that then flash-froze over. This was an incredible storm as a meteorologist."

Storms like that are becoming more common, Zarrow said. The Climate Center's new interactive website, www.precip.net, says that "100-year-storms" now happen about once every 50 years.  

Statistics about rainfall and storms in Ulster County near Slide Mountain -- including the village of Phoenicia -- a bit of an anomaly, Zarrow said. A rainfall analysis made in the 1960s, dubbed TP-40, was "drawn by hand," Zarrow said, and its estimates for Phoenicia-area rainfall during extreme storm seem much too large. 

"They didn't know what they were doing," Zarrow said. "[So] values are going down for this area. A 10-day 100-year storm was 18-inches in TP-40. We estimate that same storm to be just over 12 inches. It's a big difference."

This makes it hard for meteorologists to tell whether Phoenicia's extreme storms are getting worse, Zarrow said. But generally, weather seems to be getting worse everywhere, which means that Phoenicia, and the rest of the Catskills, should plan to endure worse storms more often. 

Phoenicians in the audience reacted to Zarrow's remarks with gallows humor. At once point, when Zarrow recommended that audience members "go to their local library" to check out a book about Catskills weather, someone yelled, "It burned down!" That got the loudest laugh of the morning.

For more information on extreme precipitation from Cornell, visit their new "Extreme Precipitation" website, which allows users to map out rainfall estimates and statistics in any location.