Southern Alaska and Western Canada will experience exceptionally heavy snowfall

From January 11th to 16th, the low vortex and trough over the Aleutian Islands gradually moved eastward and northward, with warm and moist air from the Pacific continuously being transported to the coastal areas of Alaska and western Canada (Figure 1). The combined effect of topographical uplift will bring heavy rain and snow to these regions. From the 11th to the 14th, the Aleutian Islands, the southern coastal areas of Alaska, and the northwestern coastal areas of Canada will experience a transition from sleet to snow, with heavy to extremely heavy snowfall in high-altitude areas. The accumulated snowfall during this period can reach 30–60 mm, locally exceeding 80 mm (Figure 2), with the maximum depth of new snow reaching 80–100 cm. From the 15th to the 16th, the precipitation area will shift southward to the southwestern coastal areas of Canada, and the process is expected to end by the 17th.

Figure 1: Potential height at 500 hPa (contours) and wind field at 850 hPa (barbs) over North America from January 11 to 16, 2025 (Beijing Time)

Figure 2. Accumulated precipitation (unit: mm) in Alaska and Western Canada from January 11 to 14, 2025 (Beijing Time)

Author: Huo Da                                 Reviewer: Huang Xinqing 

English reviewer:Wang Yi                                                                       Issue approver:Dai Kan