Next Storm Bringing Potential Winter Weather Across Western WA

Another storm is ahead for the region, bringing more potential winter weather impacts, including freezing rain, snow, and rain. Let's take a look at the forecast.

(School impacts: KOMO News School Delays/Closures Page)

Note on freezing rain: If freezing rain does fall, it will likely start between 6 and 9 AM Thursday morning, earlier in the lowlands, and later in the foothills/passes.

We'll start with the European model forecast for freezing rain on Thursday, seen below.

This forecast shows freezing rain mostly relegated to the Cascade foothills (0.1-0.3"), with up to 0.05-0.1" from Seattle/Bellevue northward to Bellingham. 

Let's compare this to the NAM high-resolution forecast, which shows temperatures slightly cooler to start, bringing a hugely different freezing rain forecast.

This forecast, with slightly colder temperatures, shows 0.2-0.5" of ice from Tacoma to Everett, with up to 1" in the foothills and on the Kitsap Peninsula, and even 0.2-0.5" at the passes. This also shows up to 0.2" of ice near Bellingham.

This solution is much less likely, but is still a slight possibility.

Next, let's take a look at temperatures as precipitation begins on Thursday morning.

The NAM (left) has temperatures of 29-32° from Tacoma to Everett, and around Bellingham, while the European (right) has temperatures of 32-34° from Tacoma to Everett, and in the mid to upper 20s in Whatcom County. This will be a situation where a couple degrees' difference is all it will take to bring rain or freezing rain. 

Additionally, there have been reports of areas (including Federal Way and Bothell) where it is quite icy despite temperatures being above freezing. This means it doesn't need to be sub-freezing to cause icy conditions. 

Next, let's take a look at the snow forecast, starting with the European model.

The European model forecast shows up to 8-12" at the passes through Friday, with a potential for a trace to 0.25" from Snohomish County northward, plus a dusting to 1" in the foothills and along the Strait.

Let's compare this to the NAM forecast, seen below, showing snow through Friday.

With a slightly colder and more dynamic system, the NAM shows a band of 1-3" of snow from Bellingham south to Marysville, including the San Juans. This forecast also shows 8-12" at the passes, with a trace to 3" along Hood Canal and in the foothills (mainly around North Bend), plus a dusting to 1" along the western Strait.

Finally, a look at expected rain through Friday, first from the European model, seen below.

This forecast shows 0.5-0.75" of rain in the lowlands, except a rain shadow around Everett (0.35-0.45"). The coast will get 0.8-1.2", with up to 0.9" around Olympia.

Here's the comparison from the NAM high-resolution forecast, seen below.

The NAM shows 0.6-1.2" for the lowlands from Everett southward, with 0.4-0.8" from Everett northward. The Kitsap Peninsula and Olympia area get 1.5-2" in this forecast, with 1.5-2.5" on the coast.

This is a difficult-to-forecast system ahead, with marginal differences in temperatures bringing vastly different conditions, especially in regards to freezing rain. Remember to stay alert and be careful outside!