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Report notes flaws in Irene forecast

Saturday, October 6, 2012
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The Stockade section of Schenectady sustained severe flooding as a result of Hurricane Irene in late August 2011.
The Stockade section of Schenectady sustained severe flooding as a result of Hurricane Irene in late August 2011.

— Meteorologists at the local National Weather Service office knew Tropical Storm Irene was going to be damaging but didn’t expect the catastrophic nature of the storm.

“Locally it was epic,” said Raymond O’Keefe, meteorologist in charge at the National Weather Service in Albany.

The rainfall levels and river volumes generated by the enormous storm were never seen before by the staff at the Albany office.

Read the report

The entire National Weather Service report assessing its performance before, during and after Tropical Storm Irene can be found on the Capital Region Scene blog at http://dailygazette.com/weblogs/capital-region-scene.

The damage from the flooding along the Schoharie Creek, Mohawk River, and, to some extent, Hudson River was much greater than expected or predicted, he said. Flooding from the storm also caused at least two deaths in the greater Capital Region.

O’Keefe’s comments on Friday came after the release of the National Oceanic and Atmospheric Administration’s 129-page assessment of the National Weather Service’s performance before, during and after Irene.

“It’s a fair report that highlights the successes and challenges [of the National Weather Service],” O’Keefe said.

The report out of Silver Spring, Md., covers the entire area of the Hurricane Irene event from Aug. 21 through Aug. 30, 2011, and does not have detailed information specific to the Capital Region.

The national report did note that the National Weather Service “did not clearly convey the threat for historic flooding and its associated catastrophic impacts.”

O’Keefe provided the specifics and assessed the positive and negative things the local Weather Service office did before, during, and after the storm.

He stressed that meteorologists need to gather better scientific information on how such an extreme and damaging storm occurred so they can be better prepared in the future.

“It was the first time ever that the Albany office issued a tropical storm warning and watch,” he said.

He said one of the successes of the local Weather Service office was issuing a flood warning at 4 a.m. Friday, Aug. 26, 2011, well before the Aug. 28 event.

What the local office didn’t predict was the extent of heavy rain from the storm.

The New York state 24-hour rainfall record before Irene was 11.15 inches, set in 1903 in New York City. The Albany Weather Service office predicted between 9 and 10 inches of rain in the Catskills.

“That was almost like a new record,” O’Keefe said about the 10-inch prediction. “We knew there would be major flood threats to homes and dwellings,” he said.

“But we didn’t expect the catastrophic nature of the storm.”

Instead of the predicted 10 inches, 18 inches of rain fell in the Maplecrest area of Greene County in the Catskills.

That rain quickly flowed into the headwaters of the Schoharie Creek.

The Weather Service didn’t expect such extreme conditions, O’Keefe said.

At Prattsville as well as several other locations on the Schoharie Creek, all-time water level and water volume records were set.

“Irene was off the chart,” he said.

For example, at Prattsville the river gauge, which had been there many decades, was swept away but experts from the U.S. Geological Survey went back to the gauge site and determined that at peak flow on Aug. 28 the water was running at 120,000 cubic feet per second.

The old record at Prattsville was 50,000 CFS, set in 1996. The top 10 Schoharie Creek flows over the years were all within the 40,000 to 50,000 CFS range.

“It was extreme in every sense of the word,” O’Keefe said.

“We want to understand the science for the next time,” he said. “What were the processes? We want to advance the science to recognize record flooding, catastrophic flooding.”

Weather Ready Nation is the Weather Service’s national initiative to be better prepared for expected extreme weather events in the coming years.

One thing the local Weather Service office has done is upgrade its Doppler weather radar, which is located near Thacher Park in Albany County and gives a 120-mile picture of weather conditions in all directions.

A dual polarization system was installed on the Doppler equipment this spring, giving meteorologists a better idea of the droplet size and magnitude of rainfall in a given area.

The local Weather Service office is also doing its own study and assessment of Irene. O’Keefe said the Weather Service often collaborates with the professors of atmospheric science at the University at Albany.

Chief Shawn Taylor of the Rotterdam Junction Fire Department said what was surprising about the Irene flooding was the direction from which it came.

Taylor said a tremendous amount of debris was caught up in dams along the Mohawk, forcing the floodwaters over the river’s banks and into low-lying areas.

“At first it looked like a spring thaw [river level] we see in March or April,” he said.

Then water started rushing into an area behind the hamlet, possibly following a portion of the old Erie Canal.

This caused mandatory evacuation of residents and damaged roads and bridges in Rotterdam Junction.

“We were seeing a major amount of water coming from behind us. It was from the river but from a different direction,” Taylor said.

A spokesman from the state Canal Corporation said corporation officials had just started reviewing the Weather Service report and did not yet want to comment on the lengthy document. Locks and dams on the canal were damaged by Irene.

Gilboa Dam in Schoharie County held but was damaged by flood waters. The dam is owned and maintained by the New York City Department of Environmental Protection.

“DEP officials will review the report and although the Gilboa Dam did suffer some damage during Hurricane Irene it was extensively inspected and was declared safe and remains so today,” says a DEP statement.

“The dam is currently undergoing a full-scale $400 million rehabilitation that will bring it into accord with stringent state standards for new dam construction,” the statement said.

A DEP spokesman said his department is still reviewing the National Weather Service report on Irene and couldn’t comment on specifics.

 
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