Cool & Rainy Start to the Week

FastCast--Monday, Oct. 9 to Friday, Oct. 13:

After a record-breaking Saturday and cooler Sunday, a return to rainy weather is expected for the Northwest. Showers are expected at times on Monday, with a trace to 0.15" possible across the lowlands. Highs will drop to the low to mid 60s in the lowlands. Tuesday will be much wetter, with totals of 0.5-0.75" expected for the lowlands. It will also be cooler, with highs dropping to the mid to upper 50s. An additional 0.3-0.75" is possible on Wednesday, with highs remaining in the mid to upper 50s. Temperatures will rise with decreasing clouds on Thursday as rain departs the area. Highs will reach the mid 60s, increasing to the upper 60s on Friday, though high clouds are possible. Through the week, expect low temperatures in the mid 40s to low 50s, coldest on Friday morning.

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Continue reading the full blog below!

After a few nice & warm days, rain will return to Western Washington over the next few days, with the most rain on Tuesday and Wednesday. Let's take a look at the forecast!

Let's start with the forecast for total rain through Wednesday night, from the European Ensemble (EPS) forecast.

Through Wednesday night, expect 0.5-1.3" of rain from Everett southward, with 0.4-0.6" from Everett north & west, due to the rain shadow. The Cascades will receive 1-1.5", the Olympics will get 1.5-3", and the coast will get drenched with 2-3" of rain through Wednesday.

Little rain will fall on Monday, with the majority of the rain on Tuesday & Wednesday.

Let's compare this to the GFS forecast, also through Wednesday night.

The GFS shows a similar forecast. It shows a smaller rain shadow (mainly from Port Angeles to Oak Harbor), with the rest of the lowlands getting 0.7-1". The Cascades will get 1-3", the Olympics will get 3-5", and the coast will get 1.5-2.5". As with the EPS, most rain falls on Tuesday & Wednesday.

Now, let's take a look at temperatures. There will be a noticeable cooldown, especially given the record-breaking temperatures on Saturday. Let's start with the European model forecast for Monday's highs.

On Monday, expect lowland highs in the low to mid 60s, coastal highs in the upper 50s to low 60s, Willamette Valley highs in the low to mid 60s, and Eastern Washington's highs in the mid 70s to low 80s, as heat slowly moves east and out of the area.

Noticeable cooling is expected area-wide on Tuesday, as seen in the European model forecast below.

On Tuesday, expect lowland highs to plummet to the upper 50s to low 60s. The coast will reach the mid to upper 50s, the Willamette Valley will reach the low 60s, and Eastern Washington will cool 15-25° to the upper 50s to mid 60s. The mountains will stay cool, with mountain towns remaining in the mid 40s to mid 50s.

Continued cooler weather is expected on Wednesday, as seen in the European model forecast below.

On Wednesday, expect lowland and Willamette Valley highs in the low 60s. The coast will also reach the low 60s, and Eastern Washington will reach the mid 50s near Spokane to the upper 60s near the Tri Cities.

To round out the blog, let's take a look at confidence in precipitation forecasts for Seattle and the coast. Below is the 24-hour precipitation forecast from the European Ensemble (EPS) forecast.

From top to bottom, each left-to-right bar is one of 50 "members" of the ensemble forecast. The dates are across the bottom, with the ensemble mean (most likely forecast) below the dates in the bottom bar. Rule of thumb: if all the members show rain, it'll rain.

This forecast for Seattle shows light rain possible on Monday, with heavier rain on Tuesday and Wednesday, with many ensemble members showing 0.8-1.2" of rain in 24 hours!

Let's compare the Seattle forecast to the Hoquiam forecast, seen below.

The Hoquiam forecast shows more rain overall, with up to 1.5-2.5" of rain in a 24-hour period on Tuesday & Wednesday.

Notice in both the Seattle and Hoquiam forecasts that there are many ensemble members showing heavier rain next week and through mid October...so stay tuned for more updates over the coming days & weeks!