Forecasting Maximum Temperatures through Use of an Adjusted 850- to 700-mb Thickness Technique

Abstract

A new technique is discussed for forecasting maximum daily surface temperatures at Dugway Proving Ground (DPG), Utah, a non-MOS site, using real-time surface data and the adjusted 850- to 700-mb thickness from 1200 UTC radiosonde profiles. Based on the hypsometric equation, this technique is easily computed, is less influenced by climatology, and allows the forecaster to weigh the various parameters influencing each forecast. The technique requires that empirical best-fit relationships between maximum temperature and the 1200 UTC 850- to 700-mb thickness be established by month for various sky conditions. These relationships are further adjusted and refined by empirical rules that account for thermal advection at 700 mb, state of ground, surface pressure, and surface wind circulations. As a result, this adjusted thickness technique has been used successfully at DPG to accurately forecast days ranging from ones with temperatures near the climatological average to ones with an extreme departure from average. Forecasters at DPG expressed greater confidence in their maximum temperature forecasts using this adjusted thickness technique. While only demonstrated at DPG, it has potential use elsewhere.