NOAA's National Centers for Environmental Information
NH Snow Cover Extent
Analyses of NOAA data were provided by the Global Snow Laboratory, Rutgers University. Period of record is 1967-2010.
April 2010 snow cover extent was below the 1967–2010 average for the Northern Hemisphere. This marked the hemisphere's seventh consecutive April with below-average snow cover extent. Warmer-than-average conditions over North America, Europe, and parts of Russia contributed to the region's fourth-lowest April snow cover extent during the period. The average Northern Hemisphere April snow cover extent for the 1967–2010 period of record is 30.5 million square kilometers.
Across North America, snow cover for April 2010 was 2.2 million square kilometers below average—the lowest April snow cover extent since satellite records began in 1967 and the largest negative anomaly to occur in the 521 months that satellite measurements are available. Unlike the previous two years, which had above-average snow cover extent, April 2010 low extent could be attributed to the anomalous warm conditions that engulfed much of North America during the month, resulting in low snowfall amounts and rapid snow melt. The average North American April snow cover extent is 13.2 million square kilometers for the 1967-2010 period of record. For information on the U.S. April 2010 snow events, please visit the April 2010 Snow and Ice report.
According to Environment Canada, Ontario's snow season (September 2009–April 2010) was extraordinarily below average, setting many record low seasonal snowfall amounts. Toronto had a total of 46.2 cm (18.2 inches) of snowfall, surpassing the previous seasonal record low of 44.8 cm (17.6 inches) set in 1952–1953. Toronto's average seasonal snowfall is 133.1 cm (52.4 inches). Meanwhile, Kapuskasing had a total of 164.2 cm (64.7 inches) of total seasonal snowfall, resulting in a new record low snowfall amount. This value is 138.9 cm (54.7 inches) below the average of 303.1 cm (119.3 inches). The previous record was set in 1941–1942 when a total of 206.2 cm (81.2 inches) of snow fell during the snow season.
Although much of Eurasia had warmer-than-average conditions, the average Eurasian snow cover extent during April 2010 was near average. In contrast to the past three years, which ranked among the top four lowest April snow cover extents, April 2010 was near average—ranking as the 24th lowest (21st largest) April snow cover extent. The 44-year average Eurasian snow cover extent in April is 17.3 million square kilometers for the period of record. According to Beijing Climate Center, parts of northern China had snow storms and frost during April 2010, resulting in more than six billion yuan (878 million U.S. dollars) in direct economic losses.
Sea Ice Extent
Arctic sea ice reached its maximum extent of the year on March 31st, 2010—the latest date for the maximum sea ice extent since records began in 1979—and has begun its annual retreat, typically reaching a minimum in September. Arctic sea ice extent during April 2010 was marked by a typical decline, contributing to a near-average monthly extent. According to the National Snow and Ice Data Center (NSIDC), the April 2010 Northern Hemisphere sea ice extent was 14.7 million square kilometers (2.1 percent or 310,000 square kilometers below the 1971–2000 average), resulting in the 15th lowest (18th largest) April Arctic sea ice extent and the largest April Arctic sea ice extent since 2001, when sea ice extent was just 0.9 percent below the 1971–2000 average. It was reported that slightly above-average sea ice extent was present in the Bering Sea and Sea of Okhotsk, while below-average conditions remained in the Barents Sea north of Scandinavia and in Baffin Bay. April Arctic sea ice extent has decreased at an average rate of 2.6 percent per decade since 1979.
April 2010 Southern Hemisphere sea ice extent was 0.3 percent below the 1979–2000 average. Unlike the two previous years, which are the largest and second largest sea ice extent years, April 2010 was near average. Southern Hemisphere sea ice extent for April has increased at an average rate of 2.9 percent per decade.
For further information on the Northern and Southern Hemisphere snow and ice conditions, please visit the NSIDC News page, provided by NOAA's National Snow and Ice Data Center (NSIDC).