87th AMS Annual Meeting

Wednesday, 17 January 2007: 8:30 AM
Mesoscale processes in precipitation systems (Invited)
206B (Henry B. Gonzalez Convention Center)
Richard Rotunno, NCAR, Boulder, CO
Perhaps the most important end product of meteorological forecasting is the forecast for the timing, distribution and intensity of precipitation. The precipitation forecast is also the most difficult as it involves scales of atmospheric motion that are well below routine observational capabilities and whose ranges of predictability are relatively short compared with desired short-term forecast lead times. Precipitation occurs in association with rising motion produced either through forced uplift, thermal convection or some combination of both. Examples of the former include the lifting associated with developing baroclinic waves, frontal lifting and stable orographic precipitation; examples of the latter include air-mass thunderstorms, squall lines and other organized convective systems. In each of these examples something from the large scale is assumed to be known (i.e., the baroclinic wave, the front, the orogaphy and mean flow, the initial sounding, etc.) and through physical theory and modeling one attempts to predict the mesoscale scale processes leading to the precipitation. This talk will review some of the basic mesoscale processes involved in a variety of precipitation systems.

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