SEATTLE — Western Washington is expected to experience several storm systems this week, bringing colder temperatures, gusty winds, periods of rain, and heavy snow in the mountains. The most widespread impacts are expected Wednesday, when heavier rain, stronger winds, and continued mountain snowfall are forecast.

A cold front moving through the region Sunday spread rain across western Washington. As colder air arrives, snow levels are expected to drop to around 3,000 feet. 

A convergence zone over King and Snohomish counties may persist into Monday morning, which could bring additional heavy showers to those areas, but heavy snow to Stevens Pass.

Weather alerts have been issued for the Cascade Mountains as significant snowfall is expected.

• Winter Storm Warning (in effect through 5 a.m. Tuesday): Areas from Stevens Pass and Highway 2 northward could receive 12 to 18 inches or more of snow, along with wind gusts up to 35 mph. Travel across mountain passes could become difficult.
• Winter Weather Advisory (5 a.m. Monday – 5 p.m. Tuesday): Areas from Snoqualmie Pass southward may see 6 to 12 inches or more of snow, which could create tricky driving conditions.

The unsettled pattern is expected to continue Monday and Tuesday, with colder air increasing the chance for a rain and snow mix in lowland areas, mainly during overnight and early morning hours.

Overnight temperatures are expected to hover near freezing, while daytime highs should reach the 40s.

Possible snow amounts include:

• Foothills: A few inches of wet snow could accumulate Monday and Tuesday mornings.
• Below 500 feet: Brief, light accumulations of less than one inch may occur during early morning hours.

Major disruptions in lowland areas are not anticipated.

A more powerful system is expected to arrive Tuesday night and continue into Wednesday, bringing the most significant impacts of the week.

A Winter Storm Watch is expected to go into effect from late Tuesday night through Friday morning.

KING 5 has activated First Alert for this weather event, which could affect lives, property or travel in the Pacific Northwest region. During this event, the First Alert Weather Team will bring you the latest information to keep you and your family safe.

In lowland areas, rain will increase and could become heavy at times, especially Wednesday. Wind gusts between 30 and 40 mph are possible, which could make commutes more challenging.

Mountain areas are expected to continue receiving heavy snowfall, with snow levels rising to about 2,500 to 3,000 feet on Wednesday.

Some communities may briefly see a rain-and-snow mix or short bursts of wet snow, but widespread disruptions in the lowlands are not currently expected. Minor impacts remain possible in foothill areas.

Through Friday, the region could see significant precipitation totals:

• Lowlands: 1 to 3 inches of rain, with the heaviest amounts likely Wednesday
• Coastal areas and the Olympics: 2 to 4 inches of rain
• Mountains: 2 to 5 feet of snow

Travelers, especially those heading over mountain passes, should prepare for winter driving conditions and monitor the latest forecasts throughout the week.

Forecast details may change. Check back in for updates