Getting Toasty This Week!

Sorry for such a hiatus on blogs pertaining to Pacific Northwest weather! I had a backlog of storm chasing blogs to finish up, but now that they have all finally been posted, it’s time to get back to talking about the weather in our neck of the woods.

But before we focus on the Pacific Northwest, I want touch on the obscenely hot weather we saw over Southern California the past couple days. With an upper-level trough offshore, an amplified ridge over the Intermountain West, and a resulting strong offshore pressure gradient, Southern California experienced the hot, dry Santa Ana winds that are more typical of autumn than summer this past Friday and Saturday. But replace that autumn warmth with the insufferable heat that plagues the Desert Southwest this time of the year, and you have a recipe for record-high temperatures for Southern California. Here are some charts showing the 2-meter temperatures, 10-meter winds, and 500mb height anomalies over the area at the time (unfortunately, I’ve yet to make charts specifically for Southern California – there’s so little weather there that I’d rather use my bandwidth for other locations).

This slideshow requires JavaScript.

Here are some of the high temperatures on June 6 around Southern California. UCLA reached 111 later in the day – an all-time record. Props to the Los Angeles and San Diego National Weather Service offices for creating these charts.

Now that we’ve reviewed how satanically hot Southern California was on Friday, let’s focus on our neck of the woods. We’ll start by looking at what any forecaster worth his weight in salt looks at: a chart of 500mb heights.

We currently have a classic summertime monsoonal pattern over the Intermountain West, with southwesterly flow aloft due to a trough offshore/ridge over the Intermountain West and southerly flow at the surface due to a thermal low over the Intermountain West.  All of this directs moist air originating from the Eastern Pacific/Sea of Cortez northward, where it interacts with the hot landmass and terrain to form thunderstorms. The ridge does not extend far enough north to send these thunderstorms into our area.

This trough will continue to track to the northeast tomorrow, and it will spread increasing clouds and onshore flow into the area as it does so. We’ll get a big marine push Monday evening as the trough axis approaches, and we should begin Tuesday with a thick deck of stratus clouds.

We’ll undergo a significant pattern change Tuesday afternoon as a ridge builds over the area behind this departing trough. Temperatures should warm to 80 degrees on Wednesday for Seattle and should bump up to the mid 80s for Thursday through the weekend, with sunny skies each and every day. Portland will be significantly hotter, with temperatures rising to 90 degrees on Wednesday and hitting the upper 90s on Thursday before “moderating” to the low-mid 90s for Friday through the weekend. Both the GFS and its ensemble members agree that the warmer-than-normal weather will persist through at least the middle of next week, so if you’ve been looking for an excuse to go swimming at Sauvie Island on the Columbia River, now’s your chance!

However, there’s one thing this heat wave is lacking, and that is strong offshore flow. As a result, we’ll have trouble breaking the 90s in Western Washington and the triple digits in Western Oregon, but I wouldn’t rule out an isolated 100-degree reading somewhere in the Willamette Valley.

This week, I’ll neither be lounging on Sauvie Island nor swimming through Lake Washington (or working, for that matter). Instead, I’ll likely be digging geoduck clams on Whidbey Island for at least part of the week, as the tides this week are some of the lowest of the year. If you are in Western Washington and would like an introduction to the fine art of geoducking, let me know in the comments below! It’d be great to dig clams with some fellow weather geeks.

Have a great week,
Charlie