2019–20 North American winter

Record breaking temperatures and snowfall caused disruption throughout the Midwestern United States in early November. Approximately 1000 flights were grounded at Chicago's O'Hare International Airport as 3.7 inches of snow fell on November 11, breaking the previous record of 1.9 inches on November 11, 1995.[6] In areas of Michigan's lower peninsula, over two feet of snow fell.[7] In Canada, Southern Ontario and Southern Quebec had their first major winter storm of the season on November 11 and 12 respectively, which was followed by record January-like cold.[8] 10–20 cm of snow fell across much of the region crippling large cities such as Montreal and Toronto. In Montreal, local officials announced the city's earliest ever snow removal operation in the aftermath of the storm. Over 10 school boards province-wide closed the day after the storm.[9]

Satellite imagery of winter storms crossing the US on November 27, 2019

Moving ashore November 26–27 near the Oregon/California border as an over-achieving bomb cyclone, it produced wind gusts in excess of 100 mph near its point of landfall. The storm produced a record low pressure reading of 973.4 millibars in Crescent City, California. From November 27–30, the low merged with the subtropical jet as it tracked slowly eastward across the Rockies, plains & Midwest. The combination of cold air, moisture and high winds produced a wide swath of blizzard conditions from Colorado through western South Dakota, including the Denver Metro. In Rapid City, 14.5 inches of snow fell on the 30th, breaking the one-day snowfall record for November. In Duluth, where 21.7 inches of snow accumulated, it was the city's heaviest snowstorm in 10 years. As the first major winter storm of the season in the northeast, it dumped 22.6 inches of snow in Albany, where it was the heaviest snowfall since the 1993 Superstorm. Widespread totals in excess of 20 inches occurred in the Albany Metro, Southern New Hampshire & Northwestern Massachusetts with a regional peak of 36 inches of snow in New Ipswich, New Hampshire. The low finally moved out to sea December 3.[10]

A large complex of low pressure systems began developing January 9 over Central North America. A large trough dug into the jet stream over the Southwestern United States, providing arctic air that had been settled over Canada to move southwards and clash with warm, moist air moving northward from the Gulf of Mexico.[11] In the warm sector, severe thunderstorms and tornadoes broke out in the south central United States on the morning of January 10. Tornado warnings were issued for more than 1.7 million in the Dallas-Fort Worth Metroplex, at 7:52 pm CST a PDS tornado warning was issued for Scranton, Arkansas and surrounding communities and more than 111,000 customers were left without power in Texas alone. Severe weather continued in the deep south into following day, with Alabama being affected particularly severely.[12] North of the boundary, a mix of heavy snow and freezing rain caused travel woes across the Midwest. Along the Great Lakes, winds were forecast to whip up 23 foot waves as lakeshore flooding had already begun in Chicago.[13] Central Michigan through Eastern Ontario received a swath of crippling ice accretion. Several January rainfall records fell in Southern Ontario, as event rainfall totals over 50 mm were widespread, which is highly unusual for that time of year.[14][15]

A major arctic outbreak affected western Canada and the Pacific Northwest from January 12–19. Extreme cold warnings were issued across all of Alberta, the Yukon, the Northwest Territories, most of BC, most of Saskatchewan and part of Manitoba during this period, as a cross-polar flow caused arctic air to settle in the region. Much of Central Alberta dipped below -40 °C, colder than it was in Siberia at the time.[16][17]

Following the storm that would go on to become the North Atlantic bomb cyclone, the Ohio River Valley area and parts of the Midwest suffered brutally cold temperatures on January 19.

On February 14, the Ohio River Valley region suffered brutally cold temperatures again this winter with temperatures plummeting to a low of -2 °F at Chicago O'Hare Airport, regionally the coldest temperatures recorded in the 2019–2020 season. Considering the windchill factor, temperatures ranged from -10 °F - -20 °F; dangerously cold for anyone outdoors. It was Chicago's coldest Valentine's Day in 77 years.[18] Temperatures in Minnesota were also record breaking; an overnight low of -35 °F was reported at Preston. New Hampton, Iowa broke a near-century old record when they fell to -18 °F.[19] North of the International border, temperatures fell into the -20 °C range as far south as Toronto, where several frostquakes occurred.[20]

Large storm complex over Eastern North America February 6

On February 4 and 5, snow fell in the deep south, primarily in Texas and Oklahoma, where several highways were closed.[21] Snow fell as far south as Austin, 14 inches of snow fell in Jayton, Texas, and thundersnow occurred in Big Spring. I-70 in central Missouri was temporarily shut down as road crews cleaned debris in the aftermath of a collision. Schools closed in portions of Texas, Oklahoma and Missouri. 9,000 were left without power in the Oklahoma city metro. The following day, severe thunderstorms produced flash flooding and tornadoes in the Southeastern United States. In Simpson County, Mississippi, a possible-tornado destroyed several mobile homes. A PDS-tornado warning was issued for Charlotte, where those at the airport were relocated to the building's interior.[22][23] Severe thunderstorms and tornado warnings occurred as far North as Maryland and Delaware.[24] Winter weather advisories were issued from Tennessee to Maine, with warnings concentrated over North-central Pennsylvania, Western New York, Northern portions of Vermont, New Hampshire and Maine. With a precipitation shield of 2500 km, the storm impacted 16 million across 6 provinces in Canada.[25] The storm was dubbed "Winter Storm Kade" by The Weather Channel.[26]

A broad area of low pressure brought snow to parts of the Southeast beginning on February 19, when snow began to fall in the mountains of Tennessee. 4.2 and 4 inches of snow accumulated in Waynesville and Mount LeConte respectively. Similar but slightly lesser amounts occurred in surrounding areas of Eastern Tennessee and Western North Carolina. Another swath of snow occurred in Eastern North Carolina and Southeastern Virginia on February 20–21, ending a 400+ day snow-free streak in the region.[27] In preparation for the storm, most school boards closed or had delayed openings, hundreds of flights were cancelled and all of North Carolina was put under a Winter weather advisory.[28]

GOES 16 water vapor image of the Northern Rockies as the late season blizzard moves over.

An area of low pressure incoming from the Pacific drifted down the California coastline the week of March 16, bringing scattered thunderstorms with hail to Southern California.[29] Continuous flow of moisture into California's mountains produced extreme snowfall totals during an otherwise unimpressive winter there. 114 inches of snow fell at Homewood, 92" at Sierra-at-Tahoe and 77" at Kingvale, for example.[30] Several rounds of severe thunderstorms occurred in Texas during this time period with the Dallas Metro being especially hit hard. Following >4 inches of rain, street flooding was reported.[31][32] The responsible low pressure area was observed to finally move ashore mid-day on the 18,[33] and the Colorado low began forming shortly afterward. In the Rocky Mountains and Great Plains, blizzard warnings were issued March 17 in anticipation of a very heavy snowfall to be accompanied by strong winds.[34] Snowfall totals in NWS Boulder's forecast region peak at 23 inches 4 miles NE of Nederland.[35] Combined with winds gusting >62 mph,[36] widespread blizzard conditions occurred.[37] At Denver's airport over 1,000 flights or ~80% of air traffic that day, were cancelled.[38]