S5 A documentation of observed heavy snowfall rates in the contiguous United States, 1980-2010

Sunday, 23 January 2011
Sara Ganetis, Albany, NY; and J. L. Guyer and J. Racy


     The NOAA/NWS Storm Prediction Center (SPC) provides hazardous winter storm guidance in the form of Mesoscale Discussions (MDs). A main criterion of an MD is the expectation of heavy snowfall rates, i.e. greater than 1 in h-1 at or below 4000 ft MSL. Heavy snowfall is a hazard to life and property because it can cause dangerous transportation conditions. The purpose of this study is to document the frequency and spatial distribution of snowfall rates greater than or equal to 1 in h-1. While only a portion of official surface stations report  ≥1 in h-1 snowfall rates (SNINCR), 34452 surface observations were obtained and analyzed for the months of September to May for 30 seasons (1980-81 to 2009-10) for the continental United States east of the Rockies. Snowfall rates of 1 in h-1 are most commonly observed in January (10 yr-1). The average observed for a season is 1148 and the most observed for a single season is 2236 in 1992-93. The stations that reported the most SNINCR remarks (≥ 200 observations over 30 seasons) are situated in New England and around the Great Lakes.

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