Beginning in late October, Winter 2020-21 was packed with several significant weather events across the United States’ Snow Belt. Impactful winter weather events lasted through Mid-March before temperatures warmed and the wintry pattern finally settled down. Overall, the 2020-21 Winter season featured near-to-above-normal temperatures across much of the US. December and January were very mild, but February featured well below normal temperatures for the midsection of the country. Precipitation was near to slightly below normal for much of the country. Areas that saw above-normal precipitation were the Pacific Northwest and the coastal southeastern regions. Here’s a recap and analysis of the most significant snow and ice events from the past winter.
Southern Plains Ice Storm
An early season winter storm brought heavy snowfall to Colorado, New Mexico, and western Texas from Oct. 26 to Oct. 28, 2020, but much worse were impacts from heavy freezing rain in Oklahoma. An extremely rare freezing rain and sleet event brought up to 1.5-2 inches of ice to central Oklahoma, causing widespread destruction. Extreme tree and power line damage aided in over 340,000 power outages. National Weather Service offices in Norman and Tulsa issued their first-ever ice storm warnings in October, and a State of Emergency was declared for 47 counties. The storm is estimated to have caused over $125 million in damage.
[Image: Ice Storm Reports Oct 2020, source: National Weather Service]
Late November Lake Effect Snow
A strong, slow-moving low-pressure system brought accumulating snowfall to the Ohio Valley on Nov. 30, 2020. Over the next two days, the system stalled over Lake Ontario and a major lake effect snow event took hold. Lake effect snowfall persisted through Dec. 1st and 2nd, bringing accumulations of up to two feet in northeastern Ohio. Widespread snowfall of 8 to 16 inches was observed across the lake effect belts of northern Ohio and northwestern Pennsylvania. On top of heavy, wet snowfall, winds gusted to 30-40 mph and caused tree and power line damage. The event is estimated to have caused at least $100 million in damage.
[Image: Late November LES, source: National Weather Service]
Early December Nor’easter
After developing along the Mid-Atlantic coast on Dec. 4, 2020, a rapidly strengthening ‘bomb cyclone’ brought significant impacts to New England on Dec. 5th and 6th. These impacts included widespread snowfall of 6 to 12 inches across northern New England and localized higher amounts to 18 inhes, hurricane-force winds, blizzard conditions, and coastal flooding. The storm caused over 280,000 power outages and an estimated $25 million in damage.
[Image: Early Dec Nor’easter, source: NOHRSC]
A second, even more powerful nor’easter impacted the Mid-Atlantic and New England states from December 15-17, 2020, bringing widespread snowfall of 8 to 18 inches to the region, with a swath of 18 to 44 inches extending from north-central Pennsylvania to southwestern Maine. This single snowfall event surpassed New York City, Philadelphia, and Washington D.C. snowfall totals from the entire previous winter season. In addition to the snowfall, coastal flooding and strong winds were also observed, along with tens of thousands of power outages. The storm is estimated to have caused over $125 million in damages.
[Image: Mid Dec Nor’easter, source: NOHRSC]
Just before Christmas, widespread blizzard conditions impacted eastern portions of the Dakotas, northeastern Nebraska, much of Minnesota, and northwestern Iowa. While snowfall was minimal for much of the area at only 2 to 5 inches, higher snowfall amounts of 8 to 12-plus inches were observed in northeastern Minnesota and northern Wisconsin. Winds gusted to 60-75 mph at times creating whiteout conditions, interstate pileups, and power outages. The blizzard and associated severe weather in the southeastern US are estimated to have caused over $340 million in damages.
[Image: Christmas Blizzard, source: National Weather Service]
An extremely powerful and damaging storm pushed ashore in the Pacific Northwest on Jan. 12, bringing heavy mountain snows and rainfall to the region. Damaging winds were observed in Washington and Oregon, and winds continued to increase in speed as they pushed east of the Rockies. Wind gusts reached 125 mph in Missoula county, Montana. As the storm pushed into the Great Plains and Upper Midwest on January 15th, widespread Blizzard Warnings were issued. Snowfall amounts in portions of Minnesota and Iowa reached 6 to 12 inches. Higher amounts of 16 to 24 inches were observed in the interior Northeast. The event caused $525 million in damages across the northern US.
[Image: Mid Jan Blizzard, source: NOHRSC]
Groundhog Day Nor’easter
A low-pressure system developed off the West Coast in late January, and brought flooding rains, heavy mountain snows (up to 127 inches at Mammoth Mountain), and damaging winds to California. Hundreds of thousands of power outages occurred as result, as well as mudslides. As February opened, the same system brought widespread 8 to 12 inches of snowfall to Illinois, Indiana, and Ohio, then developed into a strong nor’easter and dumped widespread 12 to 24 inches of snowfall to the Northeast, and up to 37 inches in eastern Pennsylvania, southern New York, and northern New Jersey. This was the biggest snowstorm to hit the area since 2016.
[Images GDay 1 and GDay 2, sources: NOHRSC]
February Cold Blast
The astronomical Winter season (December through February) ended with record cold throughout the month of February. A weakened Polar Jet Stream allowed for arctic air to push toward the equator through most of the month, with the contiguous U.S. seeing an average temperature that was 3.2F below the 20th century average. This placed February 2021 as the 19th coldest February on record for the nation (a 127-year period), and the coldest since 1989. Over 3,000 high- and low-temperature records were broken. Many locations saw temperatures that were 30 to 50 degrees below normal! Oklahoma City, Oklahoma broke temperature records (a low of -14 degrees!) on Feb. 16 that dated back to 1899, while Dallas saw a low of -2 that was the coldest since 1930 and second coldest temperature ever recorded in the city. Alaska also observed its coldest February since 1999. The Texas power grid suffered greatly during the record cold, with more than 4.5 million homes and businesses losing power. Rolling blackouts lasted for several days. Damages from the blackouts alone are estimated to be over $195 million, making the cold blast the costliest disaster in Texas history.
[Image: February Temp Anomaly, source: NCEI]
Mid-February Winter Storm
Amid the arctic outbreak, a winter storm brought record-breaking snowfall amounts of 9 inches to Del Rio, Texas and 11.8 inches to Little Rock, Ark. Little Rock’s snow depth reached 15 inches during the event, breaking the all-time record. Aside from snow, freezing rain (ice) accumulations of 0.25-0.50 inches impacted Texas and Louisiana. Dozens of vehicles became stranded on roadways in Alabama due to the wintry precipitation as well. The system is estimated to have caused at least $500 million in damages.
[Image: Mid Feb Winter Storm, source: NOHRSC]
Rocky Mountain Blizzard
Heavy snowfall set up in the Rocky Mountains from Cheyenne, Wyoming to Denver, Colorado from March 12-14, with widespread snowfall of 24-36 inches. Cheyenne officially measured 30.8 inches, the city’s largest two-day snowfall. Denver measured 27.1 inches, coming in at the second largest March snowfall on record, and fourth largest ever. The highest snow total from the storm was observed in Laramie Range, Wyo. at 52.5 inches. Aside from the heavy snow, wind speeds increased to 50 mph which prompted widespread blizzard warnings for the region. Western Nebraska and southwestern South Dakota also saw significant snowfall of 12 to 24 inches.