Science Update: Precipitation and Snowfall in the Narragansett Bay Region

This science update presents an update to the Precipitation chapter in the State of Narragansett Bay and Its Watershed. This update expands the data to include daily data (rather than the monthly data used before), data from Worcester Regional Airport and Westerly Regional Airport, snowfall events, and explores the use of CoCoRAHS for additional data.

Daily Precipitation and snowfall data were downloaded from NOAA’s National Centers for Environmental Information for regional airports: T.F. Green International Airport, Warwick, RI, Worcester Regional Airport, Worcester, MA, and Westerly Regional Airport, Westerly, RI. All data used in this update are available through NBEP. Linear regressions were performed to test for significance. Only statistically significant regressions are included on the figures.

Between 1948-2023, rainfall has increased 0.7-0.8 inches per decade in the Region. While the number of days with rain has not increased, the number of days with 0.5, 1, and 2 inches of rain appear to be increasing at both T.F. Green and Worcester and remain consistent at Westerly (data from 2000-2023). During the same time, snowy days have decreased 0.5-1 day per decade, yet snowfall is remaining largely consistent. T.F. Green averages 36.6 inches of snow per year while Worcester averages 67.2 inches. The difference is due to the locations of the airport. T.F. Green is about 1.5 miles from Narragansett Bay where humid air will discourage snow formation. No snowfall data is available for Westerly.