Beginning in Feb 2021, the polar cold air splits and stretch south, the North American trough is anomaly deep and strong and lasts for a long time that North America has been hit by continuous low temperature and cold wave. As of the 6^th February, the temperature in most parts of the south was 2～4℃ lower than normal, and some parts of the north were 10～20℃ lower; the lowest temperature in the northern United States was lower than -15℃, and the lowest temperature in midwestern Canada and Alaska in the United States below -30℃, the lowest temperature in some parts of central Canada reaches -35～-45℃, which is lower than or close to extreme record for the same period in history. Moderate to heavy snow and heavy snowstorms occurred in the midwest of Canada/western and northeastern United States.

    It is estimated that in the next 10 days, the cold air in North America will remain strong and will gradually spread east to south. Except for the southwestern United States, temperatures in most parts of North America will continue to be significantly lower. Temperature in southwestern Canada, central and northern United States will be 4～8℃ lower, and 10℃ lower in some places than normal. There will see moderate to heavy snow and local blizzards in central Canada, the Labrador Peninsula, the central and northern United States and Alaska (Editor: Yi Wang/Ningfang Zhou).

 Figure: 2-m temperature forecast for 00Z 13th Feb 2021 by GOWFS issued at 00Z 9th Feb 

 (Note: GOWFS is Global Objective Weather Forecast System of CMA)