Probably association of La nina and AO+ patterns will until the end of April 2021 cause, that, many northern states of the USA and southern and central parts of Canada will be enjoying very to extremely and sunny warm weather next 6 weeks.
This pattern is evident from long-term ECMWF forecast for World / North America.
During traditional La nina, southern half of the USA should be warmer and drier, but during AO+, subtropical highs are shifting northward and anomalously anticyclonic weather hits mid-latitudes, instead of subtropical climate zone.
It means, that Spring 2021 should come in North America very early this year, because southern parts of the USA and Mexico will be nevertheless warmer and any bigger cold blasts in this circulation in mid-spring season are not expected.
Maybe, a period of 20.-25. March will bring last snowstorms in southern Rocky Mountains, yet /after extreme blizzard from mid-March 2021: https://mkweather.com/52-5-inches-133-cm-snowfall-after-historic-blizzard-in-wyoming/; https://mkweather.com/colorado-and-wyoming-see-record-blizzard-historic-snowfall-in-denver-69-cm-and-cheyenne-76-cm// and maybe, the next tornado outbreaks will suffer wider region of Midwest /https://mkweather.com/warning-extreme-tornado-outbreak-in-southern-states-next-hours-baseball-size-hails-possible/; https://mkweather.com/spring-2021-forecast-for-north-america-2021-mk//, but in the north will be persisting very warm anticyclonic air mass, which will be blocking many Arctic outbreaks from the north.
Period of warm spring weather for a time hits parts of Northeast, Mid-Atlantic, northern Rocky Mountains, Northwest, eastern or western Canada, too, but this anomaly will be the strongest in Northern Plains in the USA and south-central Canadian prairies.
Temperature anomalies in the World between 15.3.-26.4. 2021 per weeks: