Dartmouth-Led Study Finds Heavier Precipitation in the Northeast Began in 1996

Over the past century, the Northeast has experienced an increase in the number of storms with extreme precipitation.  A Dartmouth-led study finds that the increase in extreme Northeast storms occurred as an abrupt shift in 1996, particularly in the spring and fall, rather than as a steady change over several decades. The findings were published in an early online release of the American Meteorological Society's Journal of Hydrometeorology.

With climate change, a warmer atmosphere is able to hold more moisture, which is likely to affect the frequency, intensity and location of extreme precipitation.  Understanding historical changes in extreme storms, including in the Northeast, can improve our understanding of future precipitation projections with continued climate change.

"Looking at where the increases in extreme precipitation are occurring across the Northeast, interestingly we find that it's not just one part of the Northeast, say the coast, that is experiencing more heavy rainfall events, it's relatively uniform across the region," says Jonathan M. Winter , assistant professor of geography at Dartmouth, who served as one of the co-authors of the study.

For the study, the Northeast is defined as Maine, New Hampshire, Vermont, Mass., Conn., R.I., N.J., N.Y., Pa., Md., DC, Del., and W.Va., and draws on weather station data from the Global Historical Climatology Network, which is compiled by the National Oceanic and Atmospheric Association National Climatic Data Center.  The threshold for extreme precipitation events depends on the station but regionally averaged is about 2 inches or more of rain in a day.

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