Uncertainty Over Upcoming Pattern Change

FastCast--Saturday, Oct. 21 to Tuesday, Oct. 24:

A general cooling pattern is ahead for the Northwest over the coming days. In Western Washington, cooler and cloudier weather is expected for the next few days. Expect highs over the weekend and into next week to remain in the upper 50s to low 60s, with lows cooling from the upper 40s to low 50s this weekend to the low to mid 40s next week. Showers will move into the region later on Tuesday, but much of the forecast beyond then remains uncertain. Additionally, expect fog and areas of low visibility at times through Monday.

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Continue reading the full blog below!

An uncertain future is ahead for the Pacific Northwest, as weather models continue to disagree on the upcoming forecast. Let's take a look at some forecast models.

First, we will take a look at the GEFS (ensemble version of the GFS) seen below, showing late Tuesday night.

Notice the large green area over the Pacific Northwest. That shows an upper-level trough over the region, which will bring colder and likely more active weather.

Let's compare this to the EPS forecast for a similar time.

The EPS shows a much weaker trough over the Northwest, bringing less cold and generally calmer weather. 

Now, we can compare these upper-air forecasts to the temperature forecasts for Seattle and Spokane. Let's start with the forecasts for Seattle (starting with EPS).

The EPS forecast for Seattle shows a general cooling trend through the middle of next week, before temperatures remain steady through the end of the month.

Let's compare this to the GEFS forecast for Seattle.

The GEFS forecast is noticeably cooler, but also brings cooler temperatures later than the EPS. 

Now, let's take a look at the forecasts for Spokane, starting with the EPS.

The EPS shows a significant cooling trend for Spokane through the middle of next week, with colder temperatures late next week, then moderating slightly through the end of the month.

Let's compare Spokane's EPS forecast to the GEFS forecast, seen below.

The GEFS forecast for Spokane shows the potential for frigid temperatures in a strong trough. Lows could reach as low as 20° in this stronger trough scenario.

However, much remains to be seen over the next few days. Stay tuned to the blog for more updates as the forecast gets more accurate!