Next System Arrives Friday, Look at Extended Forecast

 FastCast—Friday, Jan. 5 to Sunday, Jan. 7:

More rain and mountain snow are ahead as a system impacts the Northwest on Friday and Saturday. In the lowlands, expect 0.5-1.2” of rain through Sunday morning. Snow levels will remain around 2,000 feet, bringing 10-15” of snow to the passes through Saturday morning. This will bring impacts to the passes, especially from Friday night into Saturday. Be very aware of conditions when traveling across the state. In the lowlands, expect highs on Friday in the mid to upper 40s, decreasing to the low to mid 40s this weekend. Lows will reach the mid to upper 30s, coldest by Sunday. Additionally, expect winds gusting 30-35 mph for the lowlands and 35-40 mph for the North Sound (up to 45 mph on the coast). Winds will be strongest from late Friday through early Saturday.

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Continue reading the full blog below!

Active weather is expected through this weekend for the region, with the main impacts being mountain snow and rain. Let’s take a look at the forecast!

We’ll start with the mountain snow forecast from the European model through early Sunday morning.

This forecast shows a total of 10-20” of snow at the passes. This will likely bring travel impacts, especially from Friday afternoon through Saturday.

Let’s compare this to the GFS forecast, also showing snow through Sunday morning.

This forecast shows similar snow amounts for the passes, with 10-20” expected. One notable difference is the much higher snow (3-6”) for the Spokane area. With the Euro showing 1-3” for Spokane and the GFS showing 3-6”, 2-4” is a good estimate. 

Now, let’s take a look at the rain forecast through Sunday morning, starting with the European model.

This forecast shows 0.6-1.4” of rain for the lowlands and 1-1.5” for the coast. Most rain would fall from midday Friday through Saturday morning.

Now, let’s take a look at the GFS forecast for the same timeframe.

This forecast is a bit less wet, showing a total of 0.4-0.9” for the lowlands and 1-1.3” for the coast. 

Now, for the most interesting part of the forecast…a brief look at the extended forecast. Extended forecast models have been predicting a potential arctic air intrusion late next week. Let’s take a look at the European model ensemble forecast (which shows the substantial uncertainty) for temperatures in Seattle. 

This forecast’s average shows highs in Seattle dropping to near freezing late next week, with potential lows into the mid 20s. However, note the faint gray and blue lines by the potential temperatures. This shows a huge spread in potential temperatures, indicating that uncertainty is still quite high. 

However, the potential for arctic air has been increasing over the next few days. In the next blog (this weekend), we will likely begin taking a look at what is possible. Remember…just because your weather app shows very cold temperatures and possible lowland snow does NOT mean it will happen. Weather apps don’t have human input to communicate uncertainty.

Stay tuned!!