August 4, 2023

Weekend Forecast Update

Last updated 11:40 PM, Friday, August 4th, 2023 

By Joseph Renalds

I hope everyone had a good Friday.

The forecast for the weekend has changed quite a bit since yesterday’s blog. Instead of being clear and warm, it looks like there will be rain around the Seattle area and even the slight chance of a thunderstorm. The Blue Angels were able to do their iconic high show this afternoon under a few high clouds and sunny skies. However, they could have to change plans this weekend depending on the conditions the next couple afternoons.

The main driver of this weather is a push of monsoonal moisture from the desert southwest. We started to see the impacts of this disturbance today as clouds moved in from the south. You can see this moisture on the satellite view shown below.

This push of moisture will bring with it rain showers, a chance for thunderstorms, and increased humidity. Let’s start with the rain chances. 

For Saturday, it looks like most of the rain will be in the mountains and the eastside of the state, but rain making it into the Seattle area cannot be entirely ruled out. Temperatures around Seattle will be in the low 80s with dew points getting into the upper 50s, so it will feel a bit muggy for Seattle standards.

Sunday is not quite as certain with some models bringing heavier rain in the morning but clearing by lunchtime. Others are not quite as bullish with bringing rain to the lowlands, but it is still a good idea to be prepared. The models are more consistent with showing thunderstorms in the mountains and heavier downpours in eastern Washington. So if you are heading into the mountains this weekend, make sure to be aware of possible storms around you and have a plan to take shelter if it becomes necessary. 

Of course a summer blog cannot go by without an update on the status of wildfires in the state. The big headline tonight is the Sourdough Fire which had explosive growth over the last 24 hours. This growth produced a pyrocumulonimbus cloud visible across parts of the north Sound on Friday evening. The North Cascades Highway (SR-20) has also been closed indefinitely over an over 30 mile stretch in response to the fire. 

Make sure to stay weather aware this weekend as there are many moving parts to the forecast. Have a great weekend and enjoy Seafair!

Reach forecaster Joseph Renalds at theuwdawgcast@uw.edu, on Twitter @TheUWDawgcast, or on Instagram @uwdawgcast.