In the last Mkweather article, we have looked at ESRL composites for December 2021 in Europe /https://mkweather.com/esrl-composites-for-december-2021-in-europe//, now we will look at the USA (North America).
The warmest regions in December 2021: Texas, Midwest, Southeast, Mexico
The coldest regions in December 2021: the western half of Canada
The wettest regions in December 2021: Pacific coast, partly Rocky Mountains, Great Lakes region, Quebec, Ontario, Hudson Bay
The driest regions in December 2021: New Mexico, Texas, Midwest, East Coast, Mexico
The lowest geopotential in December 2021: the wider western half of the USA, wider NW USA region
The highest geopotential in December 2021: neutral in Mexico, southern and eastern USA
During all month, anomalous heatwaves were persisting above the USA, with only slowly shifting from central to east-central parts of the country /https://mkweather.com/the-warmest-christmas-in-history-the-usa-hit-tropical-heatwaves-farms-and-ranches-in-texas-are-in-fire/; https://mkweather.com/people-in-the-usa-in-short-t-shirts-outside-the-hottest-christmas-in-the-usa-ever-texas-96f-36c-oklahoma-86f-30c-illinois-75f-24c//.
Meanwhile, above western, later central Canada and the northwesternmost USA, extremely cold Arctic masses were bringing severe cold blasts /https://mkweather.com/canada-511c-the-first-50c-and-lower-temperature-in-december-since-1998/; https://mkweather.com/vancouver-canada-hit-the-coldest-temperatures-in-52-years-153c/; https://mkweather.com/seattle-with-the-coldest-day-since-1990-and-the-coldest-night-since-the-legendary-year-2010//.
The 1st decade was dry along the Pacific coast, yet, but in the 2nd and 3rd decades, anomalous rainfall and snowfall appeared /https://mkweather.com/sierra-snow-lab-in-california-455-cm-193-7-inches-16-feet-of-snowfall-a-historic-amount-of-snow/; https://mkweather.com/yosemite-national-park-with-record-early-snowfall-434-cm-171-inches/; https://mkweather.com/los-angeles-surprisingly-with-daily-rainfall-record-60-mm-2-34-inches-on-31-12-2021-and-mini-floods/; https://mkweather.com/phoenix-arizona-with-the-wettest-christmas-in-almost-80-years//.
The 2nd decade brought severe storms in the Great lakes region.
Low geopotential was persisting above western Canada and NW USA, while neutral/high geopotential appeared mainly above southern and eastern USA and Mexico.
The Caribbean was warmer than average.
The big temperature gradient between SE and NW of the continent caused many storm rounds with tornado outbreaks during the month, including deadly Kentucky event /https://mkweather.com/breaking-ef4-tornado-in-kentucky-killed-50-people-it-was-historic-winter-supercell/; https://mkweather.com/record-heatwaves-the-strongest-storms-since-2004-and-the-next-tornado-outbreak-december-in-the-usa/; https://mkweather.com/the-first-december-tornado-outbreak-in-minnesota-in-all-time-history-7-tornadoes-caused-damages/; https://mkweather.com/breaking-tornado-caused-damages-in-georgia-the-next-storm-round-on-1-january-2022-is-expected//.
December 2021 – the 1st decade
December 2021 – the 2nd decade
December 2021 – the 3rd decade