The National Weather Service said the best chances of lowland snow will be in western Whatcom County, the northern Olympic foothills and the Cascade foothills.
SEATTLE — Parts of the Puget Sound lowlands saw some relief from the arctic cold and snow over the weekend, but that relief may be short-lived.
Cooler air is forecast to move into parts of western Washington again this week, bringing with it another chance of lowland snow. On Monday, the National Weather Service (NWS) said the highest chances of lowland snow will be in western Whatcom County, the northern Olympic foothills and the Cascade foothills Wednesday night into Thursday.
A weather system will bring heavy snow to the Washington Cascades Monday, making travel across the passes difficult or even impossible due to road closures.
Below is a forecast timeline of what to expect for the rest of the week:
Parts of western Washington woke up to more snow Monday morning, while other areas saw either rain or a wet rain/snow mix.
Easterly winds kept temperatures below freezing overnight Sunday into Monday in the Cascade foothills. The NWS said snow levels dropped to the surface in Kitsap in Snohomish counties overnight.
Snow levels will range between 500-1,000 feet Monday with highs in the upper 30s.
The NWS said most areas of western Washington will see mainly rain Monday, with heavier showers producing a rain/snow mix in some areas. Any snow accumulation in the lowlands is expected to be an inch or less.
A weather system moving into western Washington Monday night into Tuesday will keep precipitation in the forecast. Snow levels are forecast to drop overnight.
A Winter Storm Warning is in effect for the east Puget Sound lowlands from Snohomish County to Pierce County until 4 p.m. The NWS said heavy snow is expected to continue, with additional accumulations of up to 2 inches.
A Winter Storm Warning is also in effect for the Cascades of Whatcom, Skagit, Snohomish, King, Pierce and Lewis counties until 4 p.m. The warning includes the Mount Baker and Crystal Mountain ski areas and Stevens and Snoqualmie passes. Heavy snow is expected in areas above 1,500 feet with additional snow accumulations of 4-8 inches possible.
There is a “high” avalanche danger for all of the Washington Cascades, according to the Northwest Avalanche Center. An Avalanche Warning is in effect for the east slopes of the Washington Cascades south of I-90. Backcountry travel is not recommended in areas where avalanches can start, run or stop.
A Coastal Flood Advisory is in effect Monday for the north and central coast, as well as the Admiralty Inlet area and parts of San Juan County and western Whatcom and Skagit counties. Minor flooding is possible around high tide, which may lead to flooding of parking lots, parks and roads. The NWS said only isolated roads closures are expected.
Cooler air will drop temperatures into the low 30s overnight into Tuesday morning. Snow levels will remain around 1,000 feet or less for most of Tuesday.
Rain or rain/snow mix is in the forecast overnight Monday into Tuesday morning. The foothill and places away from the water have the best chance for snow accumulation, but any new snow isn’t expected to be significant.
Highs on Tuesday will be near 40.
The NWS said there will be a small break in the weather Tuesday night into Wednesday before another system moves in by Thursday, bringing a potential for “significant” snow to parts of western Washington.
Clouds will stick around Tuesday night, keeping lows in the low 30s and in the 20s in Whatcom County.
Wednesday and beyond
The NWS said a warm front forecast to move into the area from the southwest Wednesday has the “potential to be a real weather maker for portions of the area.” Fraser river outflow from British Columbia will bring cold winds to Whatcom County, keeping highs near freezing.
The NWS said precipitation from the front is expected to hold off until Wednesday evening, but some areas could see precipitation in the afternoon. Snow levels will be low, so precipitation Wednesday afternoon could start as a rain/snow mix.
The NWS said there is a possibility for “significant snowfall” in western Whatcom County and the northern Olympics foothills, along with a wintery mix of snow or freezing rain in the Cascade foothills Wednesday night into Thursday. The NWS added that “snowfall cannot be ruled out across much of the lowlands.”
The NWS said the type of precipitation in the foothills depends on the “depth of cold air.” The NWS said the Cascade foothills could see freezing rain or a wintery mix of snow changing to freezing rain.
Snow levels are expected to rise between 2,500-3,000 feet Thursday and Friday.