Rain Returns to Western Washington

 FastCast—Monday, July 24 to Tuesday, July 25:

The blog is back, as I have returned from a 2-week road trip around California! I’m excited to continue blogging as interesting summer weather continues. It has been 32 days since my weather station in Federal Way last reported rain, but that will likely change on Monday. A weather system will move into the region, dropping temperatures, increasing clouds, and bringing July’s first rain to Western Washington. Expect showers throughout the day. Rain will total 0.1-0.3” in the lowlands, 0.4-0.75” on the coast, and 0.9-1.5” in the Olympics and north coast. The Cascades will receive 0.3-0.5”. Eastern Washington will get no rain, due to the sharp Cascade rain shadow. A lesser rain shadow will prevail for the NE Olympic Peninsula, where rain will total a trace to 0.1”. Some residual showers are possible on Tuesday, but that is relatively unlikely. Temperatures will decrease to the upper 60s to low 70s in Western Washington and down to the mid 80s to mid 90s in Eastern Washington. Winds will increase as well, with 20-30 mph gusts in Western Washington and 30-35 mph gusts in Eastern Washington. Critically, this will increase the spread of the 51,700 acre Newell Road Fire in Klickitat County. Areas to the north and east of the fire should be on high alert for rapid fire spread. 

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Continue reading the full blog below!

Rain is heading back to Western Washington after over a month! Plus, cooler temperatures and an increased fire threat in Eastern Washington are in store as well. Let’s take a look at the forecast!

First, the European model forecast for rain through 11 PM Tuesday.

In the lowlands, expect 0.2-0.5”, with more north of Mount Vernon (up to 0.8”). The coast will receive 0.4-1”, most from Grays Harbor northward. Notice the abrupt cutoff in rain totals east of the Cascades. It will be a challenge for Eastern Washington to get measurable rain, but some areas could squeeze out a trace.

Next, let’s compare this to the NAM high-resolution forecast, also through 11 PM Tuesday.

The NAM forecast shows much less precipitation in the lowlands from Everett south, with a trace to 0.2” in this forecast. However, it shows 0.2-0.5” from Everett north, 0.4-1.25” on the coast, and 0.5-2” in the mountains, though that’s likely overdone.

Finally, the NWS NBM forecast, also for rain through 11 PM Tuesday.

This forecast shows 0.1-0.3” in the lowlands, and 0.4-0.6” from Skagit County northward. The coast will get 0.4-1.25”, and the Cascades will get 0.4-1”. 

Overall, this won’t be a major rain event, but will be the most significant rain in months, especially in the mountains. This won’t lower fire danger in Western Washington, but it will make it harder for fires to spread (but only for a couple days). 

However, fire danger will increase in Eastern Washington, especially around the Newell Road Fire in Klickitat County. Below is the European model forecast for wind gusts on Monday afternoon.

Winds in Western Washington will gust 20-30 mph, maybe up to 35 mph in some areas. Eastern Washington will gust 30-40 mph, with winds gusting 35-40 mph around the Newell Road Fire in Klickitat County, which has burned 51,700 acres as of Sunday. Winds will be from the west/southwest, so areas north and east of the fire should be on high alert for rapid fire spread.

Finally, temperatures will significantly decrease across the state on Monday, as seen below in the European model.

Highs will decrease to the upper 60s to low 70s across the lowlands, the low 60s on the coast, and “down” to the low 80s to mid 90s in Eastern Washington. 

This is seen better in the 24-hour temperature difference forecast for 5 PM Monday, seen below from the European model.

Temperatures in Western Washington will be 5-15 degrees cooler on Monday evening than on Sunday, with 5-20 degree drops in Eastern Washington. 

For most areas, especially west of the Cascades, it will be a refreshing break from typical summer weather! Stay tuned!