Canada and the United States to Experience Severe Cold Wave and Heavy Snowfall

Affected by the eastward movement of an upper-level trough (Figure 1), it is expected that from the 17th to the 20th, parts of western and southern Canada, as well as northern United States, will experience a temperature drop of 8-12°C, with localized decreases exceeding 16°C (Figure 2). Most of these regions will see moderate to heavy snowfall, with localized severe to extreme snowstorms, accumulating snowfall of 10-30 mm, and in some areas, totals could exceed 40 mm (Figure 3). Coastal areas in the northwestern United States are expected to face heavy rain to torrential rain, with localized extreme downpours. Additionally, parts of Saskatchewan in Canada, and Washington, Idaho, Montana, and North Dakota in the United States will be accompanied by strong winds of 6 - 8 on the Beaufort scale, with gusts exceeding 10 levels (Figure 4).

This wind and snow event exhibits a certain level of extremity, necessitating attention to the adverse impacts of severe wind and snow conditions on local power infrastructure, transportation, and other industries.

Figure 1  Forecast of 500 hPa Geopotential Height (Units: dagpm) and 850 hPa Wind Field(Unit: m/s) at 08:00 (BJT) on December 18

Figure 2  48-hour Temperature Change at 2 meters above ground level as of 20:00 (BJT) on December 18 (Unit: °C)

Figure 3  Accumulated Precipitation from 20:00 (BJT) on December 17 to 08:00(BJT) on December 21 (Unit: mm)

Figure 4  Maximum Gust Speed (Unit: m/s) for 24 Hours as of 20:00 (BJT) on December 18

                   Author: Hu Yingying                                 Reviewer: Cai Xiangning

English reviewer:Wang Yi                                                                       Issue approver:Dai Kan