What to expect as Western Washington’s first big fall storm arrives Saturday night

The fall season’s first strong weather system will sweep through Western Washington tonight, bringing strong winds and rain.

Fortunately, the center of the storm is well offshore and moving toward upper coastal British Columbia.  Yet, its associated frontal system will pack a punch as it moves onshore overnight.

Winds

Winds along the outer coast are forecast to peak around 60 mph during the night. Much of the rest of Western Washington will experience wind gusts up to 45 to 50 mph overnight.

The strong winds are likely to rip down some tree limbs and potentially blow down weaker trees, resulting in the potential for power outages.  Authorities are urging residents to prepare for the possibility of losing power overnight.

In addition, forecasters suggest northwest residents should avoid driving during the strong winds, particularly if they drive high-profile vehicles like big rigs and RVs.  Many windstorm fatalities occur when motorists are hit by falling trees.

Marine Waters

The center of this storm is close enough to the coast that a storm warning is in effect, with wind gusts up to 50 to 55 nautical miles per hour (knots) during the night.

This storm will also kick up rough seas and powerful surf along the outer coast beaches.  Seas of 20 to 26 feet are likely, with quick surf run-up on the beaches, carrying debris like logs and generating sneaker waves.  It’s best to avoid beaches during this storm and watch the action from higher and safer ground.

For the rest of Western Washington’s marine waters, a gale warning is in place for wind gusts up to 35 to 40 knots overnight.  Washington State Ferries is monitoring the weather and may have to cancel late-night crossings due to the strong winds and rough seas, such as the Port Townsend route.

Rain

This storm will bring a healthy amount of rain as well.  Along the coast and in the mountains, one to two inches of rain is likely.  Elsewhere in Western Washington, the forecast is from a half to one and a half inches.

With the strong winds knocking down more leaves, authorities encourage clearing storm drains to help avoid ponding of water on roadways and creating local urban flooding.

Mountains

This is a warm storm, meaning mountain snow levels will be quite high – around 7,000 feet overnight.  Mountain pass highways will likely have wet pavement for drivers going over the passes.

Sunday

The storm’s associated wet and windy frontal system is expected to move further inland and weaken Sunday. Winds in Western Washington should die down early in the day and the rain turn to scattered showers with sunbreaks.

Temperatures

Being a relatively warm storm, low temperatures overnight are forecast to drop only into the lower 50s.  Highs on Sunday are expected to be above average, ranging from the mid-50s to the lower 60s – quite mild for mid-November.

Coming Week

More weather systems are lined up across the North Pacific, poised to sweep onshore next week for periods of rain and breezy, but not as windy, conditions.  Temperatures again will be rather mild, with high temperatures in some locations warming into the lower 60s Tuesday and Wednesday.

Mountain snow levels will remain well above the passes, reaching as high as 8,000 feet or so.

November is usually the wettest month of the year.  The recent change in the weather pattern from the dry October suggests November is likely to retain its wet reputation.