Storm Update: Strong Winds, Heavy Snow, and Heavy Rain Through Saturday

No FastCast tonight…continue reading the full blog below for a storm update.

An impactful storm is ahead from late Friday night through Saturday. The biggest impacts will be strong winds early Saturday morning, heavy mountain snow, and heavy rain, with a potential for thunderstorms as well.

A Wind Advisory is in effect for the lowlands from 11 PM Friday to 6 AM Saturday, for sustained winds of 30-40 mph, gusting up to 50 mph. Tree damage and power outages are possible across the region. Additionally, the strongest winds (likely 12-4 AM) will be accompanied by heavy rain and potential thunderstorms.

Let’s start with the wind. Below is the high-resolution HRRR forecast for peak winds through Saturday morning.

The HRRR forecast shows winds in the lowlands gusting 45-50 mph, with gusts up to 60 mph possible around Bellingham in this forecast. The coast will gust up to 55 mph. 

Let’s compare this to the NAM forecast, showing wind gusts at 3 AM Saturday.

The NAM agrees with the HRRR, showing wind gusts in the lowlands gusting 45-50 mph. Isolated gusts up to 55 mph are possible across the lowlands, especially near the water.

Next, let’s take a look at the HRRR forecast for lightning flash density, which shows lightning is possible. This forecast is valid through Saturday morning.

The highest chance of thunderstorms looks to be from Everett northward to Whidbey Island and from Olympia to Tacoma. Of course, an isolated lightning strike and rumble of thunder is possible anywhere across the lowlands.

Next, the forecast for mountain snow. We’ll start with the European model forecast for snow through Saturday night.

This forecast shows an additional 12-18” at the passes through Saturday night, with up to 4-6” for Spokane, Pullman, Ellensburg, and Wenatchee. 

Let’s compare this to the NAM high-resolution forecast for snow through Saturday night.

The NAM forecast agrees with 12-18” of snow at the passes, but shows less snow for Ellensburg and Wenatchee. This forecast also shows 4-6” of snow for Spokane and Pullman.

Finally, let’s take a look at how much rain is expected through Saturday night, starting with the European model, seen below.

The European model shows a rain shadow over the lowlands (relative to totals for the rest of the region), with lowland totals of 0.5-0.8”. The coast and Willamette Valley will receive 0.9-1.3”. This will all fall as snow in the mountains (3,000+ feet).

Let’s compare this to the HRRR high-resolution rain forecast, seen below, also showing total rain through Saturday night.

This forecast shows less rain overall, with 0.4-0.75” for the lowlands, with 0.5-1” for the coast and Willamette Valley.

Much more active and impactful weather is ahead for the next few days, including a major atmospheric river early next week. Stay tuned & stay safe!