Western Washington Windstorm Update

No FastCast tonight...continue reading the full blog below for a windstorm update (and an updated look at rain and mountain snow forecasts). Heavy rain and strong winds are likely with frontal passage early Saturday morning. There is also a chance of thunderstorms in post-frontal showers on Saturday.

Across Western Washington, expect winds to peak from late Friday night to early Saturday morning.

Let's start with the high-resolution HRRR forecast, showing peak winds during this storm.

This forecast has consistently shown stronger winds than other forecasts, but has been accurate as of 10 PM. This forecast shows 50-60 mph gusts from Everett northward, including gusts near or just over 60 mph near Bellingham. Areas from Everett southward will gust 40-50 mph in this forecast. The coast will gust up to 45-55 mph in this scenario as well. If this forecast verifies as shown above, power outages and tree damage is likely.

Let's compare this to the NAM high-resolution forecast, seen below at 1 AM Saturday.

At 1 AM, the NAM forecast shows gusts of 45-55 mph from Seattle northward. From Seattle south, the NAM shows gusts reaching 40-45 mph around 1 AM, with gusts up to 50 mph on the coast.

Fast forward to 5 AM Saturday, seen below on the NAM forecast.

Around 5 AM, expect gusts in the lowlands to reach 45-50 mph, as frontal passage nears. As with the previous forecast, tree damage and power outages are possible with this storm. Localized gusts over 50 mph are possible in the lowlands.

Finally, let's take a look at the European model forecast for peak wind gusts, showing the entire state.

This forecast is in knots, so actual miles per hour speeds will be stronger. This forecast shows gusts in the lowlands reaching 40-45 mph, with 45-55 mph gusts from Everett northward, but mainly on the water and in western Whatcom County. Eastern Washington will gust 40-50 mph, strongest east of the Tri Cities and around the Spokane area. 

Let's take a look at the rain forecast from the European model, seen below. I've zoomed in these graphics to Western Washington, since Eastern WA won't have much rain (if any).

This forecast, through early Sunday morning, shows 0.7-1" of rain for most of the Puget Sound region, with a rain shadow from Seattle to Everett. The foothills could get 1-1.5" of rain, and parts of the coast will get up to 2", along with the mountains, where up to 3" is possible.

The GFS (American) forecast below shows agreement with the European model.

The GFS shows 0.7-1" for most of the region, with a rain shadow from Whidbey Island to Seattle. The coast and mountains will get 1-3" with this forecast.

Finally, the snow forecast for the mountains, seen below on the European model.

This forecast shows significant snow for higher elevations of the North Cascades, with up to 12-18" for the North Cascades Highway and Mount Baker, along with 6-12" at Paradise. The higher passes (Stevens & White) will get up to 6" of snow, while Snoqualmie Pass will get up to 2". Winter weather impacts will be relegated to areas over 4,000-4,500 feet.

Remember to be prepared for power outages and tree damage with the winds. Charge your devices and be careful out there!