Rapidly-Developing Storm Bringing Strong Winds & More Rain to Western Washington

Update 8:50 AM Wednesday: This storm tracked further south than models showed at the original writing of this blog. Impacts for the metro area will be limited to heavy rain and a Convergence Zone north of Seattle Wednesday afternoon. Areas from Tacoma southward could see winds gusting up to 30-35 mph at times, but most wind impacts have been relegated to the coast.

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No FastCast tonight...continue reading the full blog below for an update on the incoming storm.

A fast-developing storm system is moving toward Western Washington, and it will bring strong winds and heavy rain on Wednesday.

Below is a satellite image of the storm at 9:45 PM Tuesday from the GOES-18 satellite (watch satellite loop here).

The storm center is offshore of the mouth of the Columbia River, and the storm is moving northeast. Landfall of the storm center will likely be on the North-Central Washington coast, between Ocean Shores and La Push.

Here is another view of the storm from the satellite viewer tool on weathernerds.org.

Notice all the recorded lightning strikes near the storm center, as it continues to intensify as it moves in. Over 100 strikes have been detected tonight.

This storm will likely bring a good punch of strong winds to the region on Wednesday. Let's take a look at some forecasts for wind gusts, starting with the European model, showing gusts at 11 AM Wednesday.

This model forecasts in knots, so gusts in miles per hour will be higher than what's shown. Generally, expect gusts from Seattle southward to reach 35-45 mph, strongest from Sea-Tac south to Chehalis. North of Seattle and on the Kitsap Peninsula, gusts will reach 25-35 mph, except 35-40 mph near the water, mainly along Admiralty Inlet. The coast will gust 40-50 mph, mainly from Moclips/Seabrook south toward Astoria. Isolated coastal areas could briefly gust up to 50-60 mph, especially on the northern Long Beach Peninsula.

Next, let's compare this to the NAM high-resolution model, showing gusts at 9 AM Wednesday.

The NAM shows gusts from Seattle south of 30-40 mph, except 40-45 mph from Federal Way south toward Grand Mound. The coast will gust 40-50 mph, but mainly in Pacific County in this forecast.

Before we take a look at some rain & low pressure graphics, we'll finish looking at wind forecasts with a slightly different graphic. This is the high-resolution HRRR forecast showing peak gusts for the entire event, not just a specific time.

The HRRR shows the entirety of the lowlands reaching 35-45 mph, with areas from Tacoma to Everett reaching 40-45 mph, along with areas near the water from Whidbey Island northward. This forecast shows the immediate coast gusting 40-50 mph, with gusts over 60 mph just offshore.

It is important to note that due to trees being fully loaded, recent heavy rainfall, and trees being weakened by persistent dry weather this summer, there is a higher potential for tree damage and power outages with this storm. In late fall and winter months, this would be a somewhat garden variety storm, but the first wind event of the season usually causes more impacts than others.

Now, let's take a look at rain forecasts through Wednesday night, starting with the European ensemble (EPS) forecast, seen below.

This does factor in Tuesday's rain, so expected new precipitation on Wednesday in this forecast is 0.5-1" in the lowlands and on the coast.

Next is the GFS rain forecast, also showing total rain through Wednesday night.

The GFS forecast shows 0.8-1" of new rain for the lowlands and parts of the coast, with less rainfall from Everett northward due to a broad rainshadow.

Finally, the NAM high-resolution rain forecast through Wednesday night, seen below.

This forecast shows rain being a lot more hit-or-miss, with a Convergence Zone from Shoreline to Seattle bringing 0.8-1.2", and the rest of the lowlands (except the NE Olympic rainshadow) get 0.3-0.5". The coast will pick up an additional 0.7-1.4" in this forecast.

Overall, a quick storm with potential for some impacts is ahead. Again, this storm's main impacts will be potential tree damage & power outages and another round of standing water & ponding on area roads. Standing water could be much more widespread with wind blowing leaves off trees and clogging up storm drains.

Stay safe, stay aware, and enjoy the beginning of our storm season!