Evaluation of a Regional Model with an Update Cycle

Abstract Improvements have been made to the Navy Operational Regional Atmospheric Prediction System (NORAPS). A complete description of the latest version of NORAPS is presented. Also, tests have been performed to determine the cause of NORAPS consistently underforecasting cyclogenetic intensity. It was found that two changes to NORAPS led to significant improvements in forecast skill, particularly in forecasts of cyclogenesis. First, the objective analysis procedure was modified such that it more closely reflected the observed data. Second, a 12-h update cycle was incorporated into NORAPS. Individual forecasts and average statistics are presented for the tests.