Development of a Discriminant Analysis Mixed Precipitation (DAMP) Forecast Model for Mid-Atlantic Winter Storms.

ABSTRACT The frequency of "wintry mix" precipitation--freezing rain and ice pellets--is considerable in the mid-Atlantic region of the United States. Despite the fact that the general conditions necessary to support the various winter precipitation types have been known for years, in that region, the proper forecast of type and duration of winter precipitation is one of the most difficult challenges in operational meteorology, with extensive public safety and economic ramifications. The purpose of this project is to report on an improved methodology for winter precipitation forecasts. This study analyzed precipitation type and surface temperature data from NOAA's hourly surface airway observations and temperatures and heights for all mandatory and significant levels from NOAA's Radiosonde Data of North America from Washington Dulles International Airport, Virginia (1962-95), and Greensboro, North Carolina (1948-95). Precipitation that occurred within 2 h of a sounding for the months November through March was used for analysis. The upper-air data were combined to create vertical temperature profiles for each observation of precipitation type--rain, freezing rain mix, ice pellets, and snow. Those profiles were then categorized by the number of freezing levels (i.e., the number of times the sounding crossed the 0 Celsius isotherm) and examined to determine if they could be used to isolate specific precipitation types and as a result... [ABSTRACT FROM AUTHOR]