NOAA's National Centers for Environmental Information
Snowfall at the beginning of April covered approximately 13.6 percent of the contiguous U.S. (CONUS) according to NOAA's National Snow Analysis. Snow blanketed the highest elevations of the western mountains, the northern Great Lakes, and parts of New England. On 3 April, snow fell across the Northern Rockies and Plains and parts of the northern Great Lakes bringing total CONUS snow cover to 23.7 percent. The notable ridge of high pressure in the Gulf of Alaska mid-month, which contributed to the large trough of low pressure over the central U.S., brought a significant cold-air outbreak to the central Plains. In addition to the resulting severe weather across the South and the Southeast, the cold air trailing the strong cold front generated snowfall across much of the Northern Rockies and Plains, from Wyoming to the Great Lakes and from the southern Rockies to Oklahoma. This event brought the coverage of snow across the Lower 48 to 24.4 percent — the highest coverage for April 2020. After this system passed, much of the snow melted as spring began taking a firm hold across the Lower 48. Snow cover reached its minimum extent on 30 April with 4.3 percent coverage.
According to NOAA data analyzed by the Rutgers Global Snow Lab, the April snow cover extent was approximately 314,000 square miles, 32,000 square miles above the 1981-2010 average. This was the 22nd largest value in the 54-year satellite record. Above-average snow cover was observed across much of the Northern Tier, central Plains, and Great Lakes, as well as northern New England. Below-average snow cover was present across much of the Cascades, Sierras, central and southern Rockies as well as parts of the Northeast.
Melting of winter and spring mountain snowpack is 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 March 31, SWE values were similar to those from the end of February, although precipitation received during March allowed for SWE values to increase across the Sierras, the Bitteroots, and the central Rockies. SWE conditions worsened across the Painted Desert of Arizona. Much of the West reported SWE values that were at least 75 percent of the median value and were above 100 percent across much of the Rockies. By the end of April, SWE values began to drop across the West and were 75 percent or less of median across the Sierras and the Great Basin. Below-median values were observed across much of the Cascades and Bitterroots, Utah, and the southern Rockies. SWE values were at or above the median value across western and southern Montana, Wyoming, northern Colorado, and northern Arizona.
Source: NOAA-NOHRSC
Looking at the accumulated contiguous U.S. snowfall for the season-to-date (2019-20) and comparing it with the snowfall received over the previous snow season (2018-19), we can see that the overall blanket of snow for the 2019-20 season is not as extensive nor as deep and does not reach as far south as compared with the previous season. Regions where 2019-20 snowfall lacked include: the southern Ohio Valley, Mid-Atlantic and Appalachian regions as well as from Washington D.C. to Long Island. Regions which received much less snowfall this season compared with the previous season include: The Sierra Nevada range, the coastal ranges, Cascades, the northern and central Plains, portions of the Great Lakes and across parts of northern New England. In contrast, places such as Boulder, Colorado, on the front-range of the Rocky Mountains, experienced a record snowiest season with 152 total inches of snow. Caribou, Maine, also had significant snow during 2019-2020 receiving 146 inches and ranking ninth highest for any season on record.