A 100 Degree Day For Some, More Ahead

August 18, 2016

9:30pm Thursday…

What a scorcher today!  Even without east wind showing up much yet in the western Gorge (at least more than a light breeze) we saw high temperatures poke into the low 100s in parts of the northern Willamette Valley.

Here in Portland we officially made it to 99 at PDX, breaking the record of 96 set just last year on this date…


Check out the 100 Degree Club!


Even Astoria briefly got in on the act…a day early, with an 88 degree high.  That gives you an idea of what is possible tomorrow with a downslope easterly wind out there.  Forks, Washington made it to 96 as the easterlies arrived mid-afternoon.

Tonight rising pressure east of the Cascades means the east wind kicks in through the Gorge and maybe a little over the Cascades as well.  That means we will totally mix down the dry and hot air mass overhead.  I haven’t changed our forecast this evening since everything still appears on track for another record-breaking day tomorrow.  But there are a few minor tweaks…


  • Two more days of record-breaking hot weather ahead.
  • Areas AWAY from the Gorge will likely see another 1-3 degree rise in high temperatures.  That means high temps could be up around 104 degrees in a few spots like Hillsboro, Salem, or Battle Ground.
  • Areas that get the gusty east wind NEAR and IN the Gorge will actually be slightly cooler.  Troutdale likely stays below 100 degrees Friday.
  • The official high temperature forecast at PDX is problematic because too much wind could keep it below 100 again, or if the wind stays light enough it could be 104!  We went in the middle and have a 102 degree forecast.
  • Exact numbers don’t matter because it’s going to be baking hot tomorrow and the heat will begin earlier in the day.  Today it was 81 at noon in Portland. Tomorrow it’ll be 85-90 in those windy locations already at noon.


For the weather geeks out there, the 850mb temperature ended up just as forecast this afternoon over Salem.  It was 24.2 degrees.  The atmosphere overhead will be about the same tomorrow, but offshore flow really kicks in, thus the thoughts above in the highlights.

Looking further ahead, we DO get some quick cooling Sunday with a major marine push.  That should drop us a good 15 degrees, then another 5-10 degrees cooling Monday.  Much better!

That said, it appears there will be one more warmup the 2nd half of NEXT week.  This time temperatures will remain below 95 degrees, hopefully only up around 90.  No rain in sight!

Chief Meteorologist Mark Nelsen





The Big Heat Wave Begins

August 18, 2016

9:30am Thursday…

Hunker down (or find a cool river/lake to enjoy), it’s going to get really hot!  The NWS has a plethora of excessive heat warnings, advisories, and red flag warnings for most areas WEST of the Cascades from this afternoon through Saturday.


  • High temperatures the next 3 afternoons will be somewhere between 98-104 degrees in the lowlands of western Oregon and SW Washington.
  • We have never seen 3 consecutive 100 degree days (or even two) after the 15th of August, so if we get two or three that will be unprecedented.  That said, we’ve been quite close a few times in the past.
  • Breezy north wind today turns to a gusty easterly wind coming down off the Cascades and through the Gorge Friday.  That wind continues through Saturday morning, then it goes just about calm (hot!) Saturday afternoon.
  • Much more reasonable Sunday with highs at best around 90 degrees as a strong marine push begins
  • At the Oregon Coast, today will be much warmer with a few 80s possibly showing up, but FRIDAY is the scorcher with east wind pushing high temps well into the 90s for many towns.


Everything is on track this morning for a very late season heat wave.  Once we get past mid-August it’s very rare to hit 100 degrees.

A hot atmosphere has developed overhead.  850mb temps during the balloon sounding over Salem showed a +21.8 degrees, just what models have been forecasting.  They also say it’ll peak out around +24  to +25 for the next 3 afternoons with the trusty ECMWF forecasting those numbers.  That’s crazy hot, especially for 3 consecutive days with offshore flow.  I think the all-time highest August temp at 850mb is +27 during the 1977 heat wave.  It hit 105 in Portland that day.  So I’m pretty confident that we’ll get at least one day above 100 and we might possibly do all 3.  This is what we’re forecasting right now for highs at PDX and the records we should break:


Friday or Saturday will likely be hottest since 1) Friday has the best offshore flow and we start “pre-warmed” from today, but not so crazy windy that it holds the temp down a few degrees AT Portland airport and, 2) Saturday we start with offshore flow and then the wind goes calm in the afternoon, yet we don’t start to get a cooling northwest wind up the Columbia River.  Those are just about perfect heating conditions for PDX.

Offshore flow has already begun this morning, even at the surface there is a very light easterly gradient through the Gorge.  In the Cascades an easterly wind has begun with gusts to 30 mph at Three Corner Rock north of Bonneville and 30-40 mph gusts at the top of Upper Bowl Chair at Skibowl.

I expect temps to slowly rise through noon, then really take off.  During a heat wave in 2008 the temperature rose from 82 to 102 from noon to 5pm, proving that the warm air above can surface quickly!

As mentioned earlier, hitting 100 this late in the season is tough to do…in fact the last time we got above 100 in the 2nd half of August (or early September) was way back on September 2nd, 1988!  I remember shoveling corn and carrot slop on that day working at National Frozen Foods in Chehalis (my job for 6 summers in high school and college) inside the plant.  Geez it was hot!  Obviously no air conditioning in a place like that.  There’s nothing like warm carrot “goo” at 100 degrees.  Yet, it did allow me to get out of college almost debt free!


Stay cool…

Chief Meteorologist Mark Nelsen