US: Adverse winter weather forecast across Southwest and West North Central regions through at least early Oct. 21

Adverse winter weather is forecast across parts of the Southwest and West North Central regions through at least early Oct. 21. A powerful Pacific storm system continues to make its way through the Intermountain West Oct. 18, bringing showers and thunderstorms, heavy mountain snow, gusty winds, and much cooler temperatures. Heavy snowfall totals of 10-20 cm (4-8 inches), with locally higher totals of up to 30 cm (12 inches), are forecast across the higher elevations of areal mountain ranges from the northern Rockies southward through the Great Basin and into the Four Corners region over the coming days. Below-average temperatures are likely, especially across the Great Basin and into the Southwest. Highs of 4-15 C (40-59 F) are forecast across the Intermountain West, with 15.5-29 C (60-84 F) for desert locations in the Southwest. Freeze or hard freeze warnings have been issued for many valley locations as these frigid temperatures could kill or damage crops and may freeze external pipes. Hazardous travel conditions are likely due to reduced visibility caused by blowing snow.

As of late Oct. 17, the National Weather Service (NWS) has issued winter storm warnings across southwestern Colorado, far southwestern Montana, and central, southwestern, and northeastern Utah. Winter weather advisories are in place across parts of north central and northeastern Arizona, central Idaho, the rest of southwestern Montana, eastern and northern Utah, and central Wyoming. Officials could update and extend the coverage of the weather alerts over the coming days.

Snow accumulations are likely across the affected region, especially at higher elevations. Lesser accumulations are possible where sleet and freezing rain mix with the snow, and precipitation is less intense. In addition to the heavy snow, strong wind gusts will likely lead to periods of blowing and drifting snow in some areas. Sporadic power outages could occur throughout the affected region.

The winter weather will likely cause further ground and air transport disruptions over the coming days. Traffic and commercial trucking delays are probable along regional highways. Dangerous and challenging driving conditions are likely on secondary and rural roads in the affected states as maintenance crews prioritize clearing major routes. Authorities will probably close stretches of highways if driving conditions become too hazardous. Flight delays and cancellations are likely due to ground stops and deicing operations at regional airports.