U.S.: Arctic air and lake effect snow continues, storm approaches west this week
KEY POINTS
- Storm totals may reach 2-4 feet in the favored snow belts
- The cold temperatures and in combination with dangerous wind chills will create a potentially life-threatening hazard
- Conditions are expected to slowly improve as the system weakens
The large and robust low pressure system lifting through southeastern Canada is expected to slowly progress eastward while weakening.
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On the backside of this departing low will be blustery West/Northwesterly winds that will continue to filter in cold Canadian air to the eastern two-thirds of the nation, with only slow moderation of temperatures into Monday.
Freezing rain potential will extend to northern Idaho and western Montana
Storm totals may reach 2-4 feet in the favored snow belts.
Conditions are expected to slowly improve as the system weakens; however, traveling in these conditions will be extremely dangerous in the most intense snow bands.
The life-threatening cold temperatures and in combination with dangerous wind chills will create a potentially life-threatening hazard for travelers that become stranded, individuals that work outside, livestock and domestic pets.
If you must travel or be out in the elements, prepare for extreme cold by dressing in layers, covering as much exposed areas of skin as possible and pack winter safety kits in your vehicles.
In some areas, being outdoors could lead to frostbite in minutes.
Ensure outdoor animals and livestock have sufficient shelter.
Across the western states temperatures are forecast to stay milder than seasonal average.
An Alberta clipper forming along the boundary between the two air masses will deliver a period of snow across the Northern Plains into the Midwest during the next couple of days, with areas of rain/freezing rain over parts of the Northern High Plains on Christmas.
Meanwhile, warmer and increasingly moist air streaming inland across the Pacific Northwest will overrun cold air trapped in valleys which could yield mixed precipitation or significant icing.
Freezing rain potential will extend to northern Idaho and western Montana as well.
By Christmas night into Monday, the next low pressure system coming from the Pacific will deliver the next surge of moisture toward the Pacific Northwest and then into northern California.
This system will usher in an atmospheric river so there may be locally enhanced precipitation that may lead to excess runoff.
The potential threat for local flash flooding will continue to be monitored. ■