Forecasters are always striving to find ways to improve cn the guidance products from Model Output Statistics (MOS). Over the years, certain "rules of thumb" are developed at National Weather Service forecast offices that help accomplish this task. These rules are designed to enable forecasters to consistently "beat" MOS in certain weather situations (i.e., "MOS fails to handle station XXX's minimum temperature with snow cover on the ground" or "MOS overestimates temperatures with a cold front in the vicinity of station XXX"). A summary of such rules concerning precipitation events was presented by Hendrickson (1983).

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