State Climatologist: Spring Flooding in Southeastern NH Appears Unlikely
By Lori Wright, Media Relations
April 15, 2009
Southeastern New Hampshire is in better shape than previous years going into the spring season in respect to local flooding, according to Mary Stampone, NH State Climatologist and assistant professor of geography at UNH.
“April has gotten off to a rainy start throughout the entire state, a pattern that will most likely continue over the next few weeks. However, only minor flooding has been reported within a few watersheds. Flooding is still a possibility, especially if we receive high amounts greater than two inches over short time periods, but so far so good in the southeastern portion of the state. Northern areas are at greater risk given the significant snowpack that remains but only minor flooding has been reported so far this spring,” Stampone said.
So far for the month of April, precipitation in Durham is between 2.15 inches (measured at Kingman Farm) and 2.25 inches (measured at Thompson Farm), which is below the average 4.53 inches. In 2008, April rain totals were 3.91 inches at Kingman Farm and 3.74 inches at Thompson Farm. This was down considerably from the previous year, when Kingman Farm recorded 10.03 inches of rain and Thompson Farm recorded 8.48 inches.
Looking at the December-to-April period, the area is below precipitation levels from previous years. In 2007-2008, Kingman Farm recorded 27.99 inches of precipitation and Thompson Farm recorded 28.37 inches. In 2006-2007, 25.16 inches of precipitation fell at Kingman Farm and 25.06 inches of precipitation fell at Thompson Farm. However, from December 2008 to April 2009, Kingman Farm has recorded 15.86 inches of precipitation and Thompson Farm has recorded 17.09 inches of precipitation.
According to Stampone, NOAA’s Climate Prediction Center indicates that there is an equal chance of either above or below normal precipitation through June 2009. However, the area is in an active precipitation pattern, which may result in at or above normal levels through the next month.
“River levels in southeastern New Hampshire are slightly above, but near normal and most of the snow has melted, reducing the potential for snowmelt induced spring flooding. With the exception of December 2008, precipitation has been near normal this winter,” she said.
Locally in March 2009, both the Lamprey and Oyster rivers were slightly above normal levels (average for the years 1934 to 2006) but below that of March 2008.
“As of the morning of April 8, 2009, river levels were decreasing from high discharge levels recorded overnight during the precipitation event of April 7-8. Although high, discharge levels were below the historic maximum average daily discharges recorded during the month of April for the period of record 1934-2006. These high levels were due mostly to rainfall, which amounted to just over an inch of liquid precipitation,” she said.
2009 Flood Potential: http://www.unh.edu/news/docs/2009floodpotential.pdf
2009 Precipitation Data: http://www.unh.edu/news/docs/2009precipitation.pdf