The 1996 annual average snow cover in the Northern Hemisphere was 25.3 x 106 km2, and was above the median for the first time since 1985 (Fig. 18). Overall, 1996 was the fifth snowiest year in the 24 years of satellite record considered here, with above-normal snow cover observed primarily during the following eight months: January, March-June and September-November (Fig. 18). In comparison, above-normal hemispheric snow cover was observed for 8-10 months of the year during the four snowiest years (1978, 1985, 1977, and 1972).
During DJF 1995/96, North American snow cover averaged near normal (16.6 x 106 km2), despite the fact that locally anomalous conditions were experienced over much of the United States. For example, the frequency of snow cover was above normal in the eastern United States, the Ohio valley, and the northern plains states, and below normal throughout the intermountain region of the western United States (Fig. 19a). This pattern of anomalous snow cover reflected enhanced ridging, reduced precipitation, and above-normal surface temperatures in the West, and enhanced troughing, above-normal precipitation, and cooler than normal surface temperatures in the East (see section 5, Figs. 59, 60 ). In Eurasia, above-normal snow cover extended across eastern Europe and southwestern Russia during DJF 1995/96, while below-normal snow cover frequency was observed over large portions of northwestern Europe.
During MAM 1996, the above-normal hemispheric snow cover reflected a late retreat of the winter snow pack across central Canada, the north-central United States, and across northeastern Europe and western Russia (Fig. 19b). These conditions were consistent with vast areas of below-normal temperatures throughout the season across central North America and much of western Eurasia (see section 5, Fig. 61). In contrast, below-normal snow cover was again observed over the western United States during the season, in association with a continuation of abnormally warm surface temperatures.
During SON 1996, the above-normal hemispheric snow cover frequency reflected an early buildup to, and an abnormally large southward extent of, the snow pack across much of Canada, Alaska, and the eastern half of Siberia (Fig.19c). Interestingly, 1996 was the first year since 1982 that above-normal hemispheric snow cover was observed during all three fall months (Fig. 18). Again, this above-normal snow cover was associated with vast areas of below-normal temperatures across much of North America and eastern Siberia (see section 5, Fig. 65).
