NOAA's National Centers for Environmental Information
Approximately three and a half percent of the contiguous U.S. (CONUS) was covered by snow at the beginning of November according to NOAA's National Snow Analysis. The highest elevations of the Rockies and Cascades received late-October snowfall that remained on the ground at the beginning of the month. By mid-month, a powerful low pressure system swept across the northern half of the CONUS, across much of the West to the Great Lakes and into the Northeast, bringing cold air, snow and strong winds, which fueled lake effect snowfall downwind of the relatively warm Great Lakes waters. By the 16th, 41 percent of the CONUS was blanketed by snow — the maximum extent for the month. In the ensuing days, temperatures warmed and snowdepth waned with only small amounts of additional snow falling across portions of the Pacific Northwest and central Rockies. By the end of the month, approximately 26 percent of the CONUS was covered by snow, in the Sierras and from the Pacific Northwest to the central Rockies and into the Upper Midwest and portions New England. Overall, November snow cover across the CONUS was the sixth-highest extent on record. This was the result of winter storms that brought heavy snow across much of the West, northern Plains, Great Lakes and Northeast for the month. The city of Buffalo, New York set a new daily snowfall record on November 19, with 21.5 inches shattering the previous record of 7.6 inches set on November 19, 2014.
According to NOAA data analyzed by the Rutgers Global Snow Lab, the November snow cover extent for the contiguous U.S. was about 740,000 square miles, 229,000 square miles above the 1991-2020 average. This was the sixth highest value in the 57-year satellite record. Above-average snow cover was observed in the northern Sierras and Cascades to the northern Plains as well as parts of the southern Plains, Great Lakes and Northeast. Below-average snow cover was observed across the central Plains, southern Rockies, and in pockets of the Sierras, Great Lakes 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). At the end of November, SWE values in excess of 150% of median were observed across the Sierras, Great Basin, Cascades, Bitterroots, northern Rockies, and portions of the Great Basin and southern Rockies. Below-average SWE values existed across the southern Rockies and portions of the central Rockies.