Cooler Thursday, Then A Hot Weekend!

9pm Wednesday…

That was a windy bike ride that I just took between shows!  Obviously not a stormy-type of wind, but gusts 25-30 mph coming in from the northwest.  Quite a chill in the air (for July) too.  We are getting a strong push of cool marine air as an upper-level disturbance passes by.  The breezes and cool temps are refreshing after an 83 degree day here in Portland.

The result will be most noticeable tomorrow morning in the form of low clouds in the northwest part of Oregon and southwest Washington.  These “northwesterly pushes” don’t tend to have the extensive thick low cloud cover in the mornings that southwest pushes do, so temperatures won’t be dramatically cooler tomorrow, just down about 5 degrees.  You can see our RPM model forecast of cloud cover…


After that it’s on to sunshine again in the afternoon.

I’ve upped forecast temperatures for this weekend a few more notches today.  It’s looking pretty obvious that our current onshore flow will go flat or even slightly offshore.  850mb temps jump from +9 tomorrow morning to +20 (celsius) Saturday afternoon.  It’s going to get hot!  According to my July “magic chart”, that should get us to at least 90.  Easterly wind flow situations have been as warm as 98 in these conditions.  We should be closer to 90 than 98 both Saturday and Sunday.  Either way we’re likely going to add two more 90 degree days to our summer total.


That’ll make 18, just 7 away from breaking the all-time record.  If we have typical summer weather through early September, there’s a chance we’ll break that record of 24 days set in 2009

It looks unlikely that we’ll hit 90 after that for at least a week.  Take a look at the ECMWF ensemble chart


you see the big rise this weekend and then a big fall as an upper-level trough tries to set up over us later next week.

It is interesting to note one week ago it appeared we would have a cool a showery weekend; now that weekend will be in the 90s.  In this case it was because models were too far west with the trough dropping over us.  Instead of coming over us, it’s dropping into the Intermountain region Friday and Saturday.

Enjoy the cooler temps tomorrow!

Chief Meteorologist Mark Nelsen

19 Responses to Cooler Thursday, Then A Hot Weekend!

  1. WEATHERDAN says:

    80 at 4:00 PM. Mid to high 90,s over the weekend. Might hit 90 tomorrow as well. If so that will be our third heat wave of the Summer. Somewhat cooler mid to late next week as a cool upper low drops down into the Northern Rockies. Then a good shot of more 90,s around the 29th-1st. The thing is I seem to recall somebody lol about my forecasting last Friday mid to maybe high 80,s by tomorrow. I wonder if they are still lol. Peace.

  2. Boring Oregon says:

    Power went out for almost 4 hours last night. I don’t know why though.

  3. Light rain in NE Portland.

  4. Sandi (Wilsonville) says:

    It’s raining in Wilsonville now. Light, but nice!

  5. timbers15 says:

    It’s raining in Tigard, on Bull Mountain. First rain in almost two months. Fog is present too. Interesting weather this morning. It feels and looks like fall out there. I enjoy the rain before the heat comes this weekend.

  6. MasterNate says:

    I wouldn’t mind seeing some monthly runs to check if there are any signs of another prolonged heat wave in the makings.

    • runrain says:

      Yes, it would be interesting to see what the long term thoughts are about August. I’d still like to see a triple digit high. Salem has had one or two, but the weather is always better/more interesting/more exciting there than in Portland. Their catastrophic earthquake chances are slightly higher there though than Portland.

    • Boydo3 N. Albany says:

      Latest ECMWF depicts a below average temp range for the latter part of the month…summer’s over 😉

  7. I think as long as we have this huge patch of 65f water off our coast we will remain generally warmer and drier than the models want to be. I wouldn’t be surprised to see summer like weather well into October this year. I’m particularly interested to see where the jet sets up this fall. El niños tend to push energy south but what influence will a super strong PDO have?

  8. Paul D says:

    Gonna get out and enjoy that wonderful weather today and do some biking! Glad to see the 90’s are short-lived this weekend. That’s much better than having them here for over a week straight.

  9. Kyle says:

    Hard to believe our record low minimums actually go into the 30s this time of the year! An impossible feat in this age!

  10. schmit44 says:

    7/15/2015 Oregon (All) Temperature Summary

    High:93 at EW1735 Central P(1285 ft) & LAKE OWHEE AND O(2400 ft) & Rye Valley(I-84(2230 ft) & BOARD(290 ft) & EW1140 Umatilla(364 ft) & Ontario Municipa(2188 ft)
    Low: 68 at JUNIPR(359 ft) & Celilo, East of(225 ft) & ROWEWS(104 ft)

    High:58 at HOWARD Mt Howard(8150 ft) & ANEROID LAKE #2(7400 ft)
    Low: 33 at CROW FLAT (5172 ft ) & MCKENZIE (4770 ft )

    Largest Diurnal Change: 46 degrees
    CW5507 Camp Sher (86/40 ) (3020 ft )

    Heaviest Rainfall:
    0.07″ at Bend(3650ft)
    0.03″ at HEREFORD(3599ft)
    0.02″ at LAKE OWHEE AND O(2400ft)

  11. Mark, does that upper trough for next week look anywhere as strong as the one we had in late July 2007? In that July all my rainfall for the month came from the 17th to the 23rd. (2.67 inches)

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