The Real–Time Mesoscale Analysis (RTMA) effort

A comprehensive weather and climate observing system requires the synthesis of observations into coherent gridded analyses of the past and current states of the atmosphere. In fact, many weather and climate applications either require or would significantly benefit from gridded analyses at fine scale (1-5km), for which global (~200 km) and regional (~30 km) analyses are much too coarse. Prior to this work, none such single fine-scale analysis existed that was run in real time and covered the contiguous 48 United States.

High resolution analyses are especially needed now to help create and verify experimental gridded forecasts issued by the National Weather Service (NWS) out to 7 days. The National Digital Forecast Database (NDFD) has a nominal grid spacing of 5 km across the United States and represents a blend of objective forecast guidance and forecaster edits.

Early evaluation efforts of the new gridded forecasts have been hampered by the lack of gridded analyses of the forecast parameters; which include, among others, temperature, dew-point temperature, wind, precipitation, clouds, and weather. In addition, analyses play an important role in the forecast process and in generating forecast guidance. Thus, the NWS has an immediate and critical need to produce real-time and retrospective analyses at high spatial and temporal resolution in order to facilitate the creation of the NDFD forecasts as well as verify their accuracy.

This presentation will report on a prototype Real-Time Mesoscale Analysis (RTMA) project that has taken place over the past year. This effort, building on the consensus recommendations reached at a June 2004 forum sponsored by NOAA/NWS and the U.S. Weather Research Program, is intended to at least partially meet immediate needs for such analyses as well as serve as a proof of concept for a more robust, scientifically rigorous, mesoscale analysis effort hoped to be developed over the course of the next several years.

The prototype analyses are being generated on an NDFD-matching grid with a grid spacing of 5 km. Initial efforts include five parameters: temperature, dew-point temperature, wind, sky cover, and quantitative precipitation. Analyses are conducted each hour and delivered at approximately t + 45 min. We will report on initial assessment efforts, including objective cross-validation analyses and subjective evaluations. Summary comments will include identified deficiencies and recommended steps required to remedy these deficiencies.