Active Fall Weather Coming To Western Washington

After a relatively calm start to October, active fall weather is in store. Starting Friday afternoon, multiple weather systems will impact our area through late Tuesday. Let's dive into the forecast!

Here is an overview of the Euro Model forecast. This forecast is for Puyallup, from Friday to Saturday.

To read the forecast, from top to bottom: Date, time, sky condition, temperature, rain (if any), sustained wind, wind gust, wind direction.

Friday will likely be breezy, with winds gusting 20-30 mph. Stronger winds (45+ mph) are likely at the coast and in the Bellingham area.

Rain will start between 4 and 10 PM Friday. Expect moderate to heavy rain Friday night through Saturday morning. Below is the UW model forecast for rain from Thursday-Saturday afternoon.

The green shading indicates 0.64-1.28 inches of rain. This is consistent with other predictions, so I would expect this amount of rain. This amount of rain is due to a frontal system moving through, bringing widespread rain to Western WA.

If we refer back to the Friday/Saturday forecast, we see winds gusting 25-40 mph on Saturday. Expect localized power outages and possible tree damage as the winds push out the frontal system.

Behind the front, there will be increased instability and a chance of thunderstorms. Here is the UW model forecast for instability (CAPE) at noon on Saturday.

CAPE is in the 200-600 range. This is more than normal for Western Washington, and it is safe to expect scattered showers with potential lighting/thunder, heavy rain, small hail, and gusty winds on Saturday. 

Moving on to Sunday...here is the Euro model forecast for Puyallup from Sunday to Tuesday night.

There's three things I want to draw your attention to. Those things are cooler temperatures (48-63 degrees), another 0.5-2.0 inches of rain, and winds gusting 20-50 mph.

Let's go in chronological order...

Sunday will have a drier start (you'll also notice cooler temperatures). Rain associated with another frontal system will move in by Sunday night. Expect another 0.4-1.0 inches of rain late Sunday. As rain moves in, winds will increase. Winds on Sunday night will gust 25-45 mph. Again, expect localized power outages and possible tree damage.

Monday will be breezy (gusts 20-35 mph) but will likely be the driest day in this stretch. Rain is possible later in the day. 

Now we get to Tuesday. A low pressure center will move into Western Washington on Tuesday morning. On the forecast above, Tuesday morning has winds gusting 40-50 mph. Due to the extended nature of this forecast, these winds could occur earlier or later than the forecast says.

The low pressure center will be strengthening as it approaches our shore. This means that winds will be stronger than if it was a weakening system. Take a look at the UW forecast model for 2 PM Tuesday.

See the low center (labeled "L 1003") located in North Central Washington? That is the wind-producer. The storm will have a tight pressure gradient behind it that will bring winds gusting 35-50 mph across Western Washington on Tuesday. Expect localized power outages and tree damage.

Let's end with a very interesting stat...here is the 10 day precipitation total from the Euro model (10/8-10/18). The pointer is on Puyallup.

Wow!!! There is a decent chance that the next 10 days will feature 2-5 inches of rain for the Puget Sound area.

It will sure feel like fall! Stay tuned for another update Friday night regarding the upcoming weather!