Lowland Rain and Mountain Snow Forecast for Western Washington

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Since June 18, Seattle has received only 0.55 inches of rain. This is one of the driest stretches in the city’s history.

SEATTLE — Relief from wildfire smoke has finally arrived, and the days of dangerous air quality in western Washington seem over thanks to a weather system moving through the region.

The shift to overland flow helped push cool, coastal air into the Puget Sound area early Friday morning. State data Department of Ecology showed that most areas in the region had good air quality at 8 a.m.

The air quality alert in effect for most of western Washington is set to expire at 10 a.m. Friday, according to the National Weather Service.

RELATED: Western Washington Forecast

While the system has helped improve air quality, it will also bring the first major mountain rain and snow event of the season.

From lowland rain to mountain snow, here’s a look at what to expect from our first significant front since early June:

Rain and snow timeline

The heaviest rainfall amounts are expected for the Pacific Coast and the Cascade foothills, where 2 to 3 inches of rain could fall Friday through Monday.

Lighter amounts are expected for the Puget Sound lowlands, but we still expect a good dip with around 0.75 to 1 inch possible by Sunday morning. A few areas in Snohomish and King Counties may see higher amounts due to improved Convergence Zone action.

Seattle could pick up more than an inch of rain. That’s more rain than the city has seen in four months. Since June 18, Seattle has received just 0.55 inches of rain, becoming one of the driest stretches in city history.

RADAR: Tracking the Rain Over Western Washington

Snow will fall in the high elevations of the Olympics and the Cascades. The higher passes will be hit with either wet snow or a rain/snow mix as snow levels drop to as low as 3,500 feet in some places on Saturday, with the possibility of a rain/snow mix.

Gusty winds are sometimes possible with every meteorologist. While sustained winds generally remain below 20 miles per hour, some gusts could exceed 30 to 40 miles per hour, with stronger gusts near the strait and in outlying areas. Although these winds should not be strong enough to cause widespread tree or power line problems, foliage remaining on trees, some branches could fall, and isolated power outages are possible. This shouldn’t be a major or widespread concern at this time.

Friday

Clean Pacific air blew in overnight, washing out most of the smoke from the wildfires, except for a few spots near the North Cascades where moderate air quality will persist Friday but clear Friday night.

Expect more and more rain Friday morning, with rain expected in most places by noon. A wet afternoon and evening are expected, so drivers should be prepared for the possibility of an evening ride on Friday.

The weather system will also bring much cooler temperatures to western Washington as highs are expected to fall in the low to mid-50s on Friday.

Regular rain will change to intermittent showers later Friday evening.

Saturday and Sunday

The showers are expected to gradually decrease during the day on Saturday with some clearing.

Snow levels are expected to drop to nearly 3,500 feet in the North Cascades and 4,500 feet in the South Cascades on Saturday, according to KING 5 meteorologist Rich Marriott. No significant snow accumulations are expected below 5,000 feet, but there could be a few inches of snow on the sides of the roads at higher elevations like the North Cascades Highway and Chinook Pass.

Snow could be briefly in the air at Stevens and White Passes on Saturday, but Marriott said the main passes – Stevens, Snoqualmie and White – are expected to see only wet roads this weekend.

Saturday’s highs will be in the low to mid-50s.

Sunday is expected to see mostly sunny skies after some early morning fog, but another system is expected to move in late Sunday night bringing more and more rain.

Snow levels will increase slightly with this system as there is less cold air, but snow levels will still be between 4,500 feet and 5,000 feet Sunday through Monday.

Monday and beyond

Drivers should be prepared for a wet morning drive as rain is expected to persist Monday morning.

Regular rain will change to intermittent showers Monday afternoon and taper off, but another system will move in with more rain during the day Tuesday.

Storms will continue to move through the northwest and wet weather is expected to continue intermittently into the following weekend.

Flood risk

The risk of flooding is currently expected to remain low, but this will be closely monitored. As always, if you live in a flood zone or near recently burned areas, it’s always best to stay on top of weather conditions.

Areas near burn scars are more likely to see isolated flooding and even debris flows. There is particular concern near the Bolt Creek Fire.

The National Weather Service tweeted advice to prepare for the debris flow. They advise to plan an emergency kit and an evacuation route.

Washington State Department of Transportation urged people living near the Bolt Creek Fire to get groceries, pick up prescriptions and restock emergency supplies in case debris forces US 2 to shut down.

Watch the mountain and pass the cameras as the snow falls

Interested in seeing the first snow of the season or just checking out the latest road conditions for some of the local passes?

Observe the latest conditions in the mountain and pass areas as snow begins to fall over the weekend.

Top of Mount Rainier Gondola at Crystal Mountain, 6,872 feet:


White Pass US 12, 4,500 feet:


Stevens Pass US 2, 4,061 feet:


Snoqualmie Pass I-90, 3,022 feet:


This is an important reminder to give you more time on the roads in the region with rain. It’s been a while since we’ve seen widespread wet rain, so the roads in the area could get slippery due to dust, smoke and oil buildup.

Also, with the foliage still on the trees, any leaves that fall on the roads when paired with water are as slippery as ice. This means that rapid braking could cause problems.

Get the latest road conditions for all of Washington.

LOOK: Playlist of the best KING 5 stories on YouTube

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