The Regime Dependence of Degree Day Forecast Technique, Skill, and Value

Abstract

Abstract An investigation into the manner in which forecasters adjust their reliance on particular pieces of forecast information as the large-scale flow pattern evolves into different regimes, and the relationship between those adjustments and forecast skill and value is presented. For the cold season months (December–February) of the period 1 January 1973 through 31 December 1992, a total of three regime types (identified through cluster analysis) comprising 63% of the days were identified. A framework for investigating the weighting of pieces of forecast information, based upon multiple regression techniques, was applied to National Weather Service (NWS) degree day forecasts (constructed from the 12–24-h minimum and 24–36-h maximum temperature forecasts) for this period. It was determined that substantial changes in the usage of Model Output Statistics (MOS) by NWS forecasters have occurred with the advent of the improved numerical model guidance represented by the Limited Fine Mesh (LFM) MOS, and that...