Round #2 of Summer Heat Arrives Sunday

June 19, 2021

2pm Saturday…

I’ll make this a brief post and get straight to the point since it’s a weekend:

  1. We have entered into a long period of warm to occasionally hot weather that began Wednesday. There’s no sign of cooler than normal weather for the next two weeks. Think midsummer heat and dependably dry weather through the end of June.
  2. Most likely this will be the warmest June in six years, in fact we haven’t seen a “cool” June in 9 years! #WarmingClimate
  3. There’s no sign of rain across the region over the next 7-10 days, unless some falls out of thunderstorms midweek to our south and east. Luckily we picked up an inch earlier this week, but that’s it for a soaking until fall rains arrive, hopefully in late August or early September (not October)
  4. The next two days will be hot…92-98 degrees
  5. Another round of (likely hotter) weather arrives next Friday. It’s still 6-7 days out, but models are strongly hinting 100+ in the lowlands of western Oregon.
  6. It’s possible we see 6 days at/above 90 in the next week and a half.

Today is another beautiful early summer day! Just some spots of morning clouds that gave way to sunny skies. Temperatures will rise into the lower 80s. A perfect day; I took a bike ride in the western Gorge, then did a little garden work.

The upper-level ridging (warm overhead atmosphere) strengthens quite a bit tomorrow. The ECMWF ensemble average of heights at 500mb shows 588dm almost up to Portland. The colors represent anomaly…red is higher (warmer) than average, blue = cooler.

That’s “hot” territory for us. Typically 90+ for an afternoon high in P-Town in that case. 850mb temperatures climb up to around +19 to +20 (C)…that also leads to 90+ degree days down here where we live. The icing on the cake is weak offshore flow tomorrow, and at least the first half of Monday. This shuts down any cooling off the Pacific ocean; our natural air-conditioning is turned off inland. The WRF-GFS cross-section (I’ve circled the easterly wind) shows that, although the GFS has been faster pushing onshore flow in here Monday afternoon than the Euro and Canadian models. The terribly written S, M, & T refers to Sunday/Monday/Tuesday. This typically isn’t a 100 degree setup, but it can get close!

We’re going with 93 tomorrow and 97 Monday, we’ll see how that plays out. Anything beyond 95 will make it the hottest day of the year. By Tuesday, the ridging has weakened quite a bit and the upper-low to the south is sending thunderstorm moisture into central/eastern Oregon.

That will end our little “mini-heatwave” #2 of the summer. I think I better start keeping track; I thought we might finally get a cooler summer. Apparently not.

#188/95/90 May 31+June 1-2

#293/97/85 June 20-21-23

Now if you look at that map above, notice warm colors still cover the entire PACNW Tuesday afternoon. Yes, the hot weather is mainly gone, but heights are still well above average for late June. Temperatures will only cool down into the upper 70s and lower 80s next Wednesday/Thursday. Now check out a week from now…Saturday the 26th…Wow!

A massive, scorching hot upper-level ridge directly over the Pacific Northwest. This is the ensemble average…the “operational” ECMWF model has even higher heights around 597dm. Both are major heatwave material, likely INTO the 100s. This is still a week away, but all models look similar. Just like everything has to be “perfect” to get a snow/ice storm here, it has to be just right to go into the 102-107 range. The ECMWF ensemble 850mb chart is nuts. Blue line is operational model, red is average of all 51 members, each member is a thin black line. This shows a peak around +20 or +21 on Monday, then the average next Saturday is around +24. For reference, PDX has never been above +28, or technically the sounding over Salem has never reached above +28. Notice the red line is well above average (green line ) through the end of June.

For now the screaming message is that warm to hot weather is here to stay through the rest of the month. I’ll be back at work Monday.


Chief Meteorologist Mark Nelsen