Forecasting Ceilings at Denver, Colorado

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  • 1 U. S. Weather Bureau, Denver, Colorado
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Objective forecasting techniques are established for the average value of the ceiling at Denver of duration of three consecutive hourly observations or longer during the 6-hour period beginning 6 hours after the surface map used. Due to marked diurnal effects on ceilings and forecast variables, the study is divided into two parts: one for the forecast period 1130–1730M from the 0530M map, and the other for the forecast period 2330–0530M from the 1730M map. Persistence of ceiling at forecast preparation time (0830M and 2030M) shows such a strong relationship to subsequent ceiling occurrences that rather extreme stratification is necessary to improve upon a simple “persistence” forecast.

Objective forecasting techniques are established for the average value of the ceiling at Denver of duration of three consecutive hourly observations or longer during the 6-hour period beginning 6 hours after the surface map used. Due to marked diurnal effects on ceilings and forecast variables, the study is divided into two parts: one for the forecast period 1130–1730M from the 0530M map, and the other for the forecast period 2330–0530M from the 1730M map. Persistence of ceiling at forecast preparation time (0830M and 2030M) shows such a strong relationship to subsequent ceiling occurrences that rather extreme stratification is necessary to improve upon a simple “persistence” forecast.

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