95 Degree Day Greets The Start of Meteorological Summer

June 1, 2021

9pm Tuesday…

After experiencing our warmest Memorial Day Weekend since 1992, the weather scene REALLY heated up today. A very warm airmass + light offshore flow + all sunshine led to a record setting hot day. Portland hit 95 degrees, but look at all the other records!

Each of those numbers is a record for the date…not the month. The Dalles made it to 103. Surprisingly, Astoria hit 80 briefly, even with the weak/flat thermal trough centered inland, not on the beaches.

Of course last night marked the end of “meteorological spring”. That’s March/April/May in the Northern Hemisphere. You may be thinking spring doesn’t end until the summer solstice on June 20th right? That would be “traditional spring” like you see on a calendar. But official spring (according to NOAA) has just finished. And what a spring it has been. I’ve never seen such a dry spring here, and almost no one alive has seen it this way either.

It wasn’t about the temperature…Portland ended up just a bit above average. A cool March was balanced out by a warm April and slightly warm May

But check out the rain! Over 6″ less than normal…which is just above 9″. Not only was this the driest spring on record at PDX, but only about 1/2 of the previous record! This spring blows all the others out of the water. Grasses are drying quickly as if it’s early-mid July.

This was a historic spring with respect to rain…here are some other rankings:

  • #2 Driest DOWNTOWN PORTLAND: 3.83″ (driest was 1924 = 2.76″, #3 was 1939 = 3.92″)
  • #1 Driest PENDLETON: 1.01″
  • #2 Driest ASTORIA: 7.51″ Records go back into 1880s!
  • #3 Driest MEDFORD: 1.84″
  • #8 Driest SALEM: 4.54″ Records go back to 1870s!

Who would have expected a slightly warm and record dry spring in an La Niña year? A bit dry would have been normal, but not the combo of record dry and warm-ish.

WHAT’S AHEAD?

Just about out of time so I’ll make it quick. The hot ridging overhead weakens slowly the next 2 days. By this weekend and next Monday, we’re under a cool upper-level trough

Then the trough lingers/weakens through the rest of next week. This is the ECMWF ensemble average of 500mb height for June 10th (NEXT Thursday). A little bit of troughing, but it seems to be centered farther south.

Considering there will be upper-level troughing nearby from Saturday through next week, models sure aren’t producing much rainfall. The 15 day ECMWF forecast takes us through the first half of the month

Less than 1″ through the Willamette Valley with many areas seeing less than 1/2″. That’s not good. CMC (Canadian) ensemble is similar

Same general idea…less than 1″ for the first half of the month in the western valleys. It’s ALMOST time to panic rain-wise. Even I’m worried now about well water as we go into the 2nd half of summer. We have just about run out of time to see any real soaking rain. How much rain did we have form this point forward through June the past 10 years? Only 3 of those 10 saw significant rain (2″ or more)

I’ll dig a bit deeper into this when I get back next week. I just worked 13 of the last 14 days so I’ve got a bunch of days off.

Chief Meteorologist Mark Nelsen