It’s Friday and the first major heat event of the season, is on for the Pacific Northwest. The last few days the Desert Southwest has been suffering from record-setting heat, with temps of 120 degrees F or hotter in a few places and quite a few all-time records.

Luckily we will only get a “glancing blow” of hot air in the PNW this time around, not a week-long stretch of temps 95-110. Furthermore, the heat will be most ‘impressive’ over Southern and Western Oregon. Not *quite* as dramatic, relatively speaking, for those of us eastside. A thermal trough with NE offshore flow arrived in Brookings yesterday, giving the airport there a high of 100 followed by overnight temps in the 80s. That’s usually the “canary sign” that a big dry heatwave is about to break out for Western Oregon and Washington.

Today with offshore flow, both Portland and The Dalles appear to be headed for the low 90s (after a cool crisp morning low of 51 at DLS). Eugene and points south look to be in the mid-90s to low 100s, since they are already under the influence of the big thermal trough. That said, I wouldn’t be too surprised if The Dalles sneaks up to 94 or 95 this afternoon.

Dry and light offshore flow should allow the eastern Gorge to cool rapidly again overnight, though probably not as cool as last night due to the hotter airmass building in. Meanwhile the east wind should keep Troutdale and Corbett unusually WARM overnight!

Saturday should be the “big day” for heat west of the Cascade crest. NNE flow, low humidity, and then airmass temps explode during the day. Probably 98-102 for Portland and Salem depending on the fine details. But well into the 100s in southwest Oregon! In fact a few spots down around Grants Pass and Medford could be flirting with 110. The Gorge will still be at a “thermal disadvantage” Saturday, but I bet we still see upper 90s.

Then Sunday the epicenter of the hot air shifts east of the Cascades. In theory it’s possible for the scorching hot temps to miss The Dalles entirely, IF the thermal trough shifts eastward during the middle of the night AND the marine push is quick enough the following day. Unfortunately, I don’t see that happening. With hot air overhead as per the WRF-GFS, we will probably have to endure one day of solid triple-digit temps.

Fortunately it looks to be just a two-day hit; by Monday the heat is breaking down over north-central Oregon due to a resurgent west wind, and Tuesday should be back to comfy temps. Still…if you live in the hotter microclimates of the Gorge, your A/C will get plenty of exercise tomorrow Saturday, through at least Monday morning.