Forecasting heavy rainfall in the Middle Atlantic region

A study was designed to improve the meteorologists ability to forecast heavy precipitation in the Middle Atlantic region. Preliminary results are presented. Two parts of the research are described below.

First, results from an expanded climatological study of extreme precipitation events in the mid-Atlantic region are examined. It will be shown that extreme precipitation in the Middle Atlantic region typically occurs at time frames of less than six hours. Variations in the frequency and occurrence of heavy precipitation is discussed in terms of topography and time of the year in the study area.

The second topic is the use of mesoscale models to improve quantitative precipitation forecasting. Examples are given using the MM5 and workstation Eta models that show how variations in resolution and convective parameterization can effect patterns of quantitative precipitation forecasts. Examples are also provided showing how the performance of the convective parameterization scheme feeds back on the grid scale forecast of precipitation. The determining of rules for which resolutions and convective parameterizations will work best in varying environments is discussed.