(cover photo credit of PureVacations.com)

Those who have followed seasonal changes in the Pacific Northwest, know that our seasons can be rather lopsided:  Temperatures normally drop a lot more quickly in the fall, than they climb in the spring.  In particular, the month of October seems temps drop nearly twice as fast, as they climb in April and May.

Basically what is happening is that the sun angle starts to warm the lowlands up beginning around mid/late February.  However, the middle levels of the atmosphere stay cool throughout most of the spring; our average 850mb temps in early May, for example, are slightly cooler than they are in early November!

The result, from the perspective of the lowlands, is a slow and gradual spring that is pushed along mainly by solar heating at the surface- while cool airmasses off the North Pacific keep getting in the way.  Not until well into June most years, does the atmosphere warm enough to put us into consistently warm weather (i.e. summertime).

But sometimes, summer-like airmass temps DO occur in the spring.  And the next 3 days are going to be a perfect example.

Today was the transitional day from cool to warm weather:  PDX had a low temperature of 40 degrees, which is 7 degrees below normal.  But the high temp of 75 was 9 above normal!  That 35-degree temperature range is impressive for the airport.  It’s common to get these big diurnal swings at the start of big warm spells in spring and summer; the dry offshore flow in these patterns also helps things.  Interestingly, The Dalles had a low of 36 and high of 73 today; cooler than Portland!  Today’s temps and wind were actually very similar to a crisp, sunny day in the first couple weeks of October.  (But the early August-like sun angle imparts a much different feel to the day.)

Tomorrow through Sunday the ridge along the West Coast amplifies.  At the same time an unusually cold May trough dives into the Northeastern U.S., with rare late snow across parts of New England.

Here in the Northwest we will see a ramping up of the heat by Saturday.  Airmass temps over Portland climb from +9C this afternoon, to around +16 by Saturday afternoon:

It’s possible to hit 90 in May with that kind of atmosphere, if everything is just perfect in the lower levels.  Most likely it will be 82-85 tomorrow and then 86-89 Saturday in Portland, as the hot air moves overhead.  Notice that the Columbia Basin remains somewhat cooler, at least through Saturday.  This will not be a “big” May heat event over there. Pretty warm by this weekend, but not record-setting.  Nights east of the Cascades should also remain seasonably cool under the dry air.

One more thing: East wind makes it to the northern Oregon coast tomorrow Friday, giving them one day in the 80s as well.  It’s about the only kind of way that you can get really warm temps right along the beaches.  Sadly, we can’t safely go out and enjoy them at the moment.

Nearly all models agree we cool down again next week and get at least “some” showers.  But there isn’t clear agreement on just how much rain lies ahead.  We are nearly out of time to make up any of our rainfall deficits for the season.  The drought maps for this week show severe and extreme drought conditions plaguing a majority of the state of Oregon now:

After several days of additional hot and dry east wind, I can only imagine how much worse next week’s maps might look.  It’s almost certainly too late to avoid a significant drought episode this summer, though late May and June rains could still lessen its bite somewhat.

That’s about it for now.  I’m busily working the grocery front lines during the COVID pandemic, plus trying to practice French horn and/or saxophone every day, transcribe solos, and work out at least 2-3 days per week.  Definitely not a vacation time for me!  But I will be doing some research on my economics blog next week. THAT is going to be interesting.

Enjoy the warm sun safely and distantly this weekend! -Karl