NOAA's National Centers for Environmental Information
Approximately 51 percent of the contiguous U.S. (CONUS) — the maximum snow cover extent for the month — was covered by snow at the beginning of February according to NOAA's National Snow Analysis. Snow covered much of the mountainous West, central and northern Plains, Great Lakes, Northeast and portions of the southern Plains to the Ohio Valley. Snow cover decreased steadily over the subsequent two weeks before increasing to more than 42 percent on the 17th of the month. Snow covered much of the mountainous West to the Great Lakes and parts of the Northeast. The minimum extent for the month — 29.1 percent — occurred on the 21st, prior to another event that peaked on the 23rd with 45 percent snow cover across much of the West, northern and central Plains, Northeast and in parts of the Great Lakes. During the final days of the month, warmer temperatures reduced the snow cover across much of the central Plains and in parts of the northern Plains and West. By February 28, snow cover was reduced to 38.5 percent coverage.
According to NOAA data analyzed by the Rutgers Global Snow Lab, the February snow cover extent was 1,416,000 square miles, 38,600 square miles above the 1991-2020 average, and the 24th-highest value in the 57-year satellite record. Above-average snow cover was observed across much of the Cascades, Sierras, Great Basin, Rockies, central and northern Plains and western Great Lakes. Below-average snow cover was observed from the southern Plains to the Mid-Atlantic and Northeast.
Melting of winter and spring mountain snowpack provides a crucial summer water source across much of the western United States. The total annual water budget for agriculture and human use in the mountainous West is highly dependent on the amount of snow melt that will occur in spring and is proportional to the amount of snow on the ground, which can be approximated by a measure of the snow water equivalent (SWE).
On January 31, SWE values were at or above 100 percent of the median across much of the Sierras, Great Basin, central and southern Rockies and in parts of the Oregon Coast and northern Rockies. By the end of February, SWE values were at or above 100 percent of the median across much of the Sierras, Great Basin, central and southern Rockies and in parts of northern Rockies. Conversely, SWE values across much of the Cascades, Bitteroots and parts of the northern and southern Rockies were near- to below-normal at the end of the month.
