FORECASTING 700-MB. DEWPOINT DEPRESSION BY A 3-DIMENSIONAL TRAJECTORY TECHNIQUE

Abstract

Quasi 3-dimensional forecasts of 700-mb. dewpoint depression are made for periods up to 36 hours using observed 700-mb. charts and initial and 12-hr. forecast vertical motion charts from the JNWP Unit's ?thermotropic model.? Results show that moisture can be successfully forecast by this technique. Through establishment of a relationship between 700-mb. dewpoint depression, instantaneous vertical velocity, and large-scale weather, a forecast scheme is devised using forecast 700-mb. dewpoint depression and forecast vertical motion from the thermotropic model as arguments. Preliminary results of some experimental forecasts are favorable.