National Snow & Ice - April 2011
Please Note: This will be the last monthly U.S. Snow and Ice Report until October 2011.
About 22 percent of the country had snow on the ground at the beginning of the month—mainly across the Northeast, Great Lakes, the northern Plains, and the high terrain of the West. Most high elevation locations in the West had snow pack levels which were near to above normal, with the exception of the southern Rockies where snow pack levels were below average. With little precipitation falling over the Southwest during April 2011, drought conditions remained or worsened in the area, according to the U.S. Drought Monitor. Although cooler-than-average temperatures were present across the northwestern U.S. during April 2011, much of the country experienced normal to much-above-normal temperatures, resulting in an above-average temperature for the nation as a whole. The springtime temperatures felt through most of the country led to rapid snow melt and prevented little additional snow accumulation. By the end of the month, only 10 percent of the U.S. was snow covered—which was mostly concentrated in the northern and central Rockies. According to data from the Rutgers Global Snow Lab, a NOAA-supported facility, the central Rocky Mountains had below-average snow cover during the month. Conversely, the Northern Plains and parts of northwestern U.S. had above-average snow cover.
Based upon Rutgers Global Snow Lab satellite analysis, the contiguous U.S. had above-average April snow cover extent, 151 thousand square miles (243 thousand square km) above the long-term average of 467 thousand square miles (751 thousand square km)—ranking as the eighth largest April snow cover extent for the contiguous U.S. in the 45-year period of record.
Summary of Notable Snow Events:
National Snow Depth 15 April 2011
A spring blizzard brought record snowfall to parts of north central and western Nebraska on April 14–15, 2011, dumping over 10 inches (25 cm) of snow. These significant snow accumulations, combined with high winds, created snow drifts up to 5 feet (1.5 m) deep. Nineteen new daily snowfall records were broken across the state during April 15, 2011. (For information on snowfall records, please visit the U.S. Records page.) The severe weather condition forced the closure of the state's main highway (Interstate 80) for 170 miles (273 km), stranding many people on the road, and was responsible for numerous accidents.
Snowfall Accumulation Analysis 19 April 2011
A major storm, stretching from the Southern Plains to northern Illinois, produced a mix of rain, snow, and sleet across parts of the Midwest during April 19–20, 2011. Snowfall accumulation ranged from 1.0 inch to more than 9.0 inches (2.5 cm to 22.9 cm) across Iowa, Minnesota, and Wisconsin. A new April snowfall record was set in Green Bay, Wisconsin when a total of 9.9 inches (25.2 cm) of snow fell, surpassing by 0.1 inch the previous record set in April 1977. However, a total of 121 daily records were broken (36 broken on April 19th and 85 broken on April 20th) across the three states. For information on snowfall records, please visit the U.S. Records page. The system dumped 1.3 inches (3.3 cm) of snow on the Twin Cities, Minnesota, which brought the 2010–2011 winter season to a total of 86.6 inches (220 cm)—resulting in the fourth snowiest winter on record for the Twin Cities. The snowiest winters on record are 1983–1984 (98.6 inches [250.4 cm]; snowiest), 1981–1982 (95.0 inches [241.3 cm]; second snowiest), and 1950–1951 (88.9 inches [225.8 cm]; third snowiest).
Williston, North Dakota (located in northwestern North Dakota) received 107.2 inches (272.3 cm) of snowfall during the 2010–2011 winter season, setting a new seasonal snowfall record and shattering the previous record by 12.5 inches (31.8 cm). The previous record of 94.7 inches (240.5 cm) was set during the 1895–1896 season. Williston's April snowfall totals ranked as the sixth snowiest April since records began in 1894. April 1896 is the snowiest April on record when a total of 26.6 inches (68 cm) of snow fell. Meanwhile, Bismarck, North Dakota received a total of 85.4 inches (216.9 cm) of snow during the 2010–2011 winter season, ranking as the fifth snowiest winter season since records began in 1886 in Bismarck. April 2011 also ranked as the fifth snowiest April on record for Bismarck with 13.4 inches (34.0 cm) of snow.
Glasgow, Montana received an additional 3.3 inches (8.4 cm) of snow during April 2011, setting a new seasonal snowfall record of 108.6 inches (275.8 cm), which is 372 percent of its 29.2 inches (74.2 cm) average snowfall through April.