Canada, US: Adverse weather forecast across western and southwestern British Columbia and western Washington through at least Jan. 31

Heavy rainfall and strong winds are forecast across parts of western and southwestern British Columbia and western Washington through at least Jan. 31. An atmospheric river is expected to continue to bring heavy rainfall across the region over the coming days, with strong winds also possible in coastal areas. Heavy downpours may trigger flooding in low-lying areas and melting snow may exacerbate the threat of flooding. Avalanches are also possible in mountainous areas due to loosened snowpack.

As of early Jan. 29, Environment Canada has issued red rainfall warnings (the highest level on a three-tier scale) for parts of southwestern British Columbia between Howe Sound and Whistler and for interior parts of the north coast around Kitimat through early Jan. 30. Rainfall totals of 6-10 cm (2.4-3.9 inches) are possible in these areas. Red strong wind warnings have been issued across parts of the north coast and Haida Gwaii. A special weather statement for storms and heavy rainfall has been issued for parts of southwestern British Columbia, including Vancouver Island.

The National Weather Service has issued flood warnings for the Nooksack River in Washington's Whatcom County and the Skokomish River in Mason County. A hydrological outlook message warns of further heavy rainfall and possible flooding across western parts of the state through at least Jan. 31.

Officials may update and extend the coverage of weather alerts over the coming hours and days.

Sustained heavy rainfall could trigger flooding in low-lying communities near rivers, streams, and creeks. Urban flooding is also possible in developed areas with easily overwhelmed stormwater drainage systems. Sites located downstream from large reservoirs or rivers may be subject to flash flooding after relatively short periods of intense rainfall. Landslides are possible in hilly or mountainous areas, especially where the soil has become saturated by heavy rainfall.

Authorities could issue mandatory evacuation orders for flood-prone communities over the coming days. Disruptions to electricity and telecommunications services are possible where significant flooding or landslides impact utility networks.

Floodwaters and debris flows may render some bridges, rail networks, or roadways impassable, impacting overland travel in and around affected areas. Ponding on road surfaces could cause hazardous driving conditions on regional highways. Authorities could temporarily close some low-lying routes that become inundated by floodwaters.

Severe weather could also trigger flight delays and cancellations at airports in the region. Authorities may temporarily suspend port operations or close beach fronts along the Pacific coast if strong winds trigger hazardous sea conditions. Flooding could block regional rail lines; freight and passenger train delays and cancellations are likely in areas that see heavy rainfall and potential track inundation.

Localized business disruptions may occur in low-lying areas; some businesses might not operate at full capacity because of flood damage to facilities, possible evacuations, and some employees' inability to reach work sites.