An operational ingredients-based methodology for forecasting midlatitude winter season precipitation

An ingredients-based methodology (IM) for the operational analysis and pred iction of midlatitude winter season precipitation is developed. Diagnostics for five fundamental physical ingredients involved in the production of pr ecipitation-forcing for ascent, moisture, instability. precipitation effici ency. and temperature-are incorporated into the IM. The forcing ingredient is combined with the instability ingredient to form a new parameter, PVQ, t hat serves as an indicator of heavy precipitation potential by identifying regions where these two ingredients coexist. The diagnostics and PVQ are in corporated into ingredients maps that facilitate a systematic approach to f orecasting the duration, intensity, and type of winter precipitation.