FY 1982

Climate forecast verifications, U.S. mainland, 1974–82

Preisendorfer, R.W., and C.D. Mobley

NOAA Tech. Memo. ERL PMEL-36, NTIS: PB85-133379, 235 pp (1982)

An eight-year record (Dec. 1973–Feb. 1982; 33 seasons) of temperature and precipitation forecasts was examined and some conclusions about the predictability of these two fields over the U.S. mainland were drawn. The conclusions are a statistical distillate of the combined forecasts of four types of forecasters working independently, each in his own way. The forecasters are: J. Namias, National Weather Service (via D. Gilman and three colleagues), Analoger (via T. Barnett and R. Preisendorfer), and A. Douglas. Part I defines the forecasters and the method of verification. Summary details are depicted in Part II and extensively tabulated in Part III. Some salient results are summarized as follows: First of all, winter 1982 (i.e., Dec. 1981; Jan., Feb. 1982) precipitation was the least well predicted of the past five winters (1978–82). Winter 1982 temperature was less well predicted than in winter 1981, but better predicted than in winter 1980. In general, over the given period, temperature was better predicted than precipitation, either as a function of season or region, on the U.S. mainland. Both temperature and precipitation decreased in predictability through the seasonal sequence: best predicted in winter, then spring, then summer, and finally least well predicted in fall. Temperature as a rule was better predicted on the Pacific Coast, Southwestern Desert, Northern Plains; and was less well predicted in the Southern Plains, Gulf Coast, Atlantic Coast. Precipitation as a rule was better predicted in the Southwestern Desert, Great Northern Basin, Great Lakes; and was less well predicted in the Southern Plains, Gulf Coast, Atlantic Coast. It should be noted that these conclusions are based on forecasts and on climate records taken from a recent eight-year stretch, out of eternity, over a single country, and as seen through the imperfect crystal balls of eight mere mortals.