Mountain Waves, Jet Streams, and a Puget Sound Convergence Zone

More satellite eye-candy today! Take a look below (note – if you are receiving this post via email, you may have to go to the actual post to see the loop).

One thing that immediately stands out is the powerful jet stream centered over NW Oregon/SW Washington. Note how much faster the high-elevation clouds in the jet stream are moving compared to the lower-elevation showers.

Winds at 300mb (approx. 33,000 feet). Note the ~140 knot jet stream centered of NW OR/SW WA
Credit: Storm Prediction Center

Mountain waves were even more notable than yesterday and span the entire Inland Northwest. Some mountain waves can even be seen over Bellingham and the Strait of Georgia in the wake of the mountains of Vancouver Island. And if you look extremely closely, you can see some much smaller, minute ripples moving over the Portland area towards the end of the loop. They are hard to see in the gif due to Facebook’s compression algorithms, but they can be seen in the higher-resolution image below.

GOES-17 True-Color Visible Satellite at approx. 5:30 pm PDT 9/25/2020. Note the tiny “waves” in the clouds over Portland and the very pronounced Puget Sound Convergence Zone.
Credit: College of Dupage

And finally, today featured one of the Pacific Northwest’s most beloved local weather features: the Puget Sound Convergence Zone (PSCZ). The PSCZ is visible as that “wedge” of clouds over North-Central Puget Sound towards the end of the loop. It occurs because the Olympics force onshore, WNW flow to travel through the Strait of Juan de Fuca to the north and Chehalis Gap to the south. When these air streets meet, or “converge,” over North/Central Puget Sound, air is forced upward, creating clouds and precipitation.

Particularly pronounced convergence zones also have clear skies to their north and south due to sinking motion on either side of the convergence zone. This afternoon, those over the North Sound and Elliot Bay west towards the Kitsap Peninsula saw mostly sunny skies, but folks in Everett saw heavy rain.

Credit: University of Washington

Showers will persist tomorrow, mainly for Western Washington. Sunday will be dry, and next week will be absolutely beautiful… likely our warmest week for at least the next 7 months. Be sure you make the most of it!

Charlie

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