The influence of snow cover on wintertime nor'easters

McGowan, Laura
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University of Delaware
The largest alteration that can be made to surface albedo is the addition or removal of snowcover; therefore understanding snow-atmosphere interactions is critical to understanding climatology. The storms of 8-10 February 1969, 25-28 December 1969, 18-20 February 1972, 12-14 March 1993, and 24-26 January 2000 were simulated with the Weather Research and Forecasting Advanced Research Model to examine the impact of snowcover in the continental United States on Nor'easters. Each case was simulated twice. One simulation was initialized with a 50-cm deep snowpack over the Northeast and the other simulation was initialized with the ground void of snow. The model results for the snowpack runs indicate a strong decrease in surface energy budget components leading to a decrease in lower atmospheric temperatures, an increase in pressure, and an increase in stability; however these atmospheric changes did not significantly alter the modeled nor'easters. The nor'easters influenced by the snowpack only had a slight increase in central low pressure and total precipitation and the storm tracks were largely unchanged. The atmospheric modifications from snow are not strong enough to considerably alter the existing upper-level dynamics and geographic controls (cold air damming, land/ocean contrast, etc.) that create and drive cyclones in the Northeast.