SEATTLE — UPDATE 7 a.m. Sunday: Power was restored to many, but there are still approximately 10,000 people without power around western Washington.
UPDATE 10 p.m. Saturday: According to Puget Sound Energy, there are 100 outages in western Washington resulting in approximately 18,000 people without power.
UPDATE 9 p.m. Saturday: A flood advisory has been issued due to excessive rainfall for portions of northwest and central Washington. This includes Grays, Lewis, Thurston and Pierce counties until 1 a.m. Sunday, Aug. 18. Minor flooding could occurred in low-lying or poor drainage areas and people should watch for water over roadways.
UPDATE 8:25 p.m. Saturday: The National Weather Service issued a Severe Thunderstorm Warning for South Central King County and East Central Pierce County until 9 p.m. due to 60 mph wind gusts and penny-sized hail. This can damage roofs and trees. Move into an interior room on the lowest floor of a building for protection.
UPDATE 8 p.m. Saturday: The thunderstorms have moved into Washington. Currently, a band of strong showers is approaching South Sound. The storms are moving from the south up to the north. The thunderstorms moved through Oregon earlier this evening bringing significant thunder and lightning, plus half-dollar-sized hail was reported.
The National Weather Service has issued a Flood Advisory for South and Central Sound, plus most of the Olympic Peninsula and into the Cascade Foothills. This is due to the threat of minor road flooding and is set to expire at 10:45 p.m. Saturday.
Original Story:
After a relatively quiet and comfortable stretch of weather this workweek, be prepared for possible thunderstorms in the region this weekend bringing rain, hail and lightning.
KING 5 is calling for a First Alert Day on Saturday because of storms producing strong wind gusts and heavy rain resulting in potential mudslides for the South Cascades.
The National Weather Service Seattle (NWS) said widespread thunderstorms arrive Saturday afternoon into the night, impacting Puget Sound lowlands and the Cascade Mountains. The main threat with these will be the possibility of strong wind gusts and potential flooding and mudslides (especially in burn scar areas), due heavy rainfall.
Most storm activity will occur between 6 to 11 p.m. Saturday, Aug. 17.
When the storm will arrive across Puget Sound
Here's a timeline of when thunderstorms are expected to arrive in different parts of the region. The storm system is fluid, so timing could shift by an hour in either direction.
8 p.m. South Sound, including Tacoma, Olympia and Chehalis
9 p.m. Seattle metro area, including Bellevue and Bremerton
10 p.m. Snohomish and Jefferson counties
Midnight: Whatcom and Skagit counties and Port Angeles
Futurecast radar from Saturday to Sunday
KING 5 Meteorologist Adam Claibon said a cutoff low pressure system parks itself off the Washington coast Saturday and as it moves closer, we'll see multiple rounds of rain wrap around it across the area.
Most of the day is expected to stay quiet with mainly sunny skies in the morning and into the early afternoon hours as high temperatures reach the mid to upper 70s.
Into the late afternoon and evening, clouds will begin to move in from the south with storms not too far behind. The window right now for those storms is looking to be from 5 through 11 p.m., with the majority of the storms and heavy rain occurring between 7 and 10 p.m.
Also, because of its orientation, there is an elevated chance of storms in the atmosphere, prompting the Storm Prediction Center (SPC) to say there was Marginal and Slight Risk for severe weather for parts of the southern Washington Cascades and into the Oregon Cascades.
Marginal Risk is the lowest tier on SPC's severe weather scale which is a scale from 1 to 5 with a Marginal Risk being a 1 and a High Risk being a 5 on that scale. Slight Risk is the second highest level of risk on the scale.
Eastern King, Pierce, and Lewis counties, and southeastern Snohomish County are under Marginal Risk Saturday evening to Sunday morning.
The southern Cascades are under Slight Risk.
While locations farther north in the lowlands and across Puget Sound are not expected to see severe storms, general thunderstorm activity is still in the forecast for Saturday, Claibon said.
Latest forecast models show a 20-35% chance of thunderstorms across the Cascades and Puget Sound, according to NWS. Coastal areas will have at least a 10-15% chance as of Thursday.
Puget Sound could see up to 1 inch of rainfall, with similar levels of rain on the Olympic Peninsula and Cascade Mountains.
The main threats of the thunderstorms include lightning, gusty and erratic winds, hail, and heavy rainfall. Officials are monitoring for any potential for landslides, especially in the burn scar areas in the Cascades. A Flash Flood Watch is in effect for the west and east slopes of the Cascades from Saturday afternoon through Sunday morning due to the excessive rainfall.
Temperatures could jump to the mid-70s over the weekend.
By early Sunday, most of the storms should be gone, with just a few showers lingering through the morning before eventually disappearing by the afternoon.
Storms could bring some relief to western WA fire crews
There are several wildfires burning in western Washington. The storm could bring enough precipitation to aid crews in their firefighting efforts.
While this weekend's system won't be enough to fully extinguish the fires or bring an end to fire season, any precipitation can help firefighting efforts.
"While this weekend's system won't be enough to fully extinguish the fires or bring an end to fire season, any precipitation can help firefighting efforts," according to KING 5 Meteorologist Adam Claibon.
Timing could change with the exact arrival of the storms Saturday.
This is a developing story. Check back for updates.
