We are now in a short warm spell with temperatures getting into the mid 80s to lower 90s in western Washington. Cooler weather (and some rain) will arrive next week.
But for me, one of the most fascinating aspects of our warmth is how three-dimensional it is. How spatially varying the heat can be.
Let me show you, by starting with yesterday's highs (below). Mid-80s around Seattle, 70s and low 80s over Northwest Washington, around 100F in the Willamette Valley, and upper 90s in the Columbia Basin. An interesting feature is the near 100°F in the higher terrain between Olympia and the coast,.
In western Washington, the influence of the cool Pacific and inland waters results in cold air near the surface, but warmer temperatures right above. This is particularly true when (like yesterday) there is easterly (from the east) flow aloft moving warmer air from eastern Washington towards the west.
Yesterday (Friday) morning, this situation was so profound that there was an inversion (temperature increasing with height) above Seattle, something illustrated by the temperatures above SeaTac Airport at 8 AM (below). Temperatures in the mid-60s near the surface, but 70s above 2200 ft.
A profound inversion from 1000 to 2500 ft (more than 10 degrees). I bet morning hikers noticed this warming with height!
According to the latest National Weather Service forecast, the warmth will continue over the weekend, with cooling by mid-week. Possible rain next weekend.
In Whatcom County, the summit of Sumas Mountain, elevation ~3400', had an overnight minimum temperature of 69F and afternoon high (thus far) of 86F, while the top of the Mount Baker Ski Area (Panorama Dome), at an elevation of ~5000’, had an overnight minimum temperature of 68F.
ReplyDeleteRemarkably, the overnight minimum temperature at Camp Muir, at ~10000’ elevation on Mount Rainier, had an overnight minimum temperature of 51F.
With the very low relative humidity (<20%) being reported from some high elevation stations, there’s no wonder NWS Seattle has issued a Red Flag Warning for such areas.
I find it fascinating that Darrington (of all places) is a hot spot during these events. Darrington is far from the water, but it's also set up on the highest and easternmost part of the Stilly valley, so it seems like the downslope heat effect shouldn't be at its strongest. Yet, Darrington is 5-7 degrees warmer than the other Snohomish County communities that are east of I-5.
ReplyDeleteDarrington is well known as a regional hot spot, often reporting the highest daily maximum temperatures of any locations at similar elevation and geographic situation. This is, in fact, almost certain due to downslope flow from the immediately surrounding precipitously higher terrain - probably related to its proximity to and favorable location relative to the White Horse and What Chuck Mountain massifs.
DeleteDarrington has recorded daily maximum temperatures >90F from April - October with 100s from late June - late September. Darrington’s most recent 100F day was just a few years ago on July 27, 2022. Even during the winter Darrington isn’t immune from the particulars of its geography having recorded a legitimately balmy maximum temperature of 74F on January 31, 1940.
Other towns in the mountain valleys, far from the water, are often subject to similarly extreme conditions: Newhalem recorded a maximum temperature of 100F just yesterday.
Extreme temperature inversion this morning:
ReplyDeletePanorama Dome, the high point of the Mount Baker Ski area at ~5000’ elevation, reported an overnight minimum temperature of a toasty 72F while KBLI, at near sea level, reported a nice, crisp morning minimum temp of 53F.
It’s quite uncommon to see such an extreme and sharply increasing temperature gradient with temperatures climbing by a degree Fahrenheit for every 168’ increase in elevation! This implies a “reverse lapse rate” of just under 6F per 1000’ increase in elevation. Again, it’s no wonder that the Red Flag Warning remains in effect for the mountains with such dry and unstable air in place.
Correction:
ReplyDeleteThe morning minimum temperature of 71F at ~3400’ on Sumas Mountain had a “reverse lapse rate” of ~5.5 degrees Fahrenheit per 1000’ increase (~1F per 180’) in elevation compared to KBLI with its morning minimum temp of 53F - still quite impressive and, again, along with the very low humidity values being reported in the mountains, an indicator of high fire potential weather under very dry and unstable conditions.
It's Sunday the 24th and just got back from getting some lunch and it's quite warm out, low to mid 80's at nearly 2pm.
ReplyDeleteBeing warmish nights, kind of reminds me of the summer of 2019 when the Blob was around and while it was not much above normal range during the day, the overnight low was easily mid 60's and high humidity, capped off by that extraordinary thunder storm that hit in early September.
The difference is, temps will be near 90 in many areas.