First Taste of Summer This Week!

9pm Monday

I’m back at work this evening and it appears I missed nothing weatherwise the past week.  Just rain and some mountain snow.

This first week of May sure looks interesting.  The #1 thing we’ll all notice?  Summer temps arrive Wednesday and Thursday.  Then a chance for thunderstorms later Thursday and Thursday night both east & west of the Cascades.  Last year we saw 9 days in the 80s in May, but we had a very warm spring.

80 Degree Days in May 2017

In the short-term, a warm front moves overhead tomorrow…that means gloomy skies and drippy conditions at times.  Temperatures will remain a bit below normal.  Then on Wednesday a warm upper-level ridge builds overhead with the warmest airmass so far this season.  850mb temperatures reach +15 or +16…midsummer values for our area.  The combo of thick cloud cover tomorrow and then the sudden break to sun Wednesday plus warming atmosphere means a dramatic jump in our temperatures here at sea level.  We’ll jump at least 20 degrees in one day.  We won’t see any records set since they are around 90 this time of year.

By the way, assuming we hit 80 on Wednesday as forecast, it’ll be the first time we’ve seen the first 70 AND first 80 degree day at once here in Portland.  We have been close…on April 14th 1984 we hit 79 degrees in Portland and that was our first 70 of the season.

We don’t get any sort of decent offshore flow Wednesday or Thursday, which means we likely won’t reach the upper 80s; that’s possible with such warm 850mb temps in May.

There are two other parts to our mini warm spell;  Humidity and Thunderstorms

Humidity:  Plenty of moisture gets left by the warm front (along with our wet ground) so all models are pointing to relatively high dewpoints Wednesday and Thursday.  That means a humid feel for our first warm spell and very warm nights.  Low temps will likely be within a few degrees of 60 both Tuesday and Wednesday nights.

Thunderstorms:  All models also develop strong instability in the warm and humid airmass later Thursday afternoon & night.  This plus the southerly flow is usually a good setup for thunderstorms.  We could see some good weather action!  I’ll be keeping a close eye on that.

Chief Meteorologist Mark Nelsen


34 Responses to First Taste of Summer This Week!

  1. J. Patrick Moore says:

    Reached 83.4 degrees around 7 pm, Tower Vista neighborhood in Oregon City

  2. Lee Wilson says:

    Freaking hot weather station says 89 phone says 80, we’re freaking roasting!, I was mowing the yard…until it spiked ! To hot to fast and now I am feeling like puking..

    Mark, take that new system that is giving bad data and send it to where it came from!…

    At least tomorrow we can prepare by having the Ai conditioners plugged in to the solar units to compensate. .today we had no warning and not even the house outlets can cool the place so we’re resorting to 1 bedroom with A/c.

    Oh and we have the shower running with a fan out side the bathroom door….that helps a little.

  3. W7ENK says:

    71 degrees with 73% humidity.

    I rode my bike to work this morning, I guess I’ll be swimming home.

    More fuel for tomorrow’s thunderstorms, I guess…

  4. Roland Derksen says:

    I wish it was tomorrow-NOW. Steady rain here all morning, (I measured 1.07 inches at noon) Temperature around 55F. Still seems strange to hear it’s supposed to go above 70F on Thursday here.

  5. GTS1K' says:

    Vigilant, we must be…

  6. Paul D says:

    It’s almost 9:30 and completely cloudy in Hillsboro. Let’s start a forecast bust pool! I’m guessing a high of 72.

  7. Dean Suhr says:

    Would love to see the “since October 1st” numbers from Tuesday’s 10pm broadcast summarized here … # of rainy days, total inches of rain, number of record broken (rainiest months, etc), tied for # of days between 70 degree days, etc.

    Good to have you back! We’ve been enjoying you since you were a teenager it seems!

  8. All I can say is happy wife, happy life. If is isn’t 75 plus, she isn’t happy. Yay! I can do honey dos outside and then go fishing! 🙂

  9. Roland Derksen says:

    I get even less thunderstorms here in Vancouver(BC) than Portland, so every one of them is memorable! 🙂 Anyway, looking forward to the warmth. 70F here, maybe…

  10. Jason Hougak says:

    Deport those Portland rioters

  11. oldwxwatcher says:

    Last evening on the 10 PM news when giving his lawn mowing forecast Mark said “Of course, you didn’t mow your lawn today.” Wanna bet? Those of us who live on the west side of the Cascades are well-conditioned to take advantage of any small break in the weather, even if the grass is a bit damp, and mow the fast-growing stuff whenever we get the chance. I mowed mine yesterday between spritzes of mist.

  12. Jason Hougak says:

    Mark I don’t know how you can’t call Timberline going up to a 204″ base and season total up to 612″ not interesting weatherwise but whatever??? I thought last week brought a lot of active weather. It rained, showers, sunbreaks, rainbows, and heavy end of April mountains snow. Worked south of Sandy on Friday and was had about a 1/2″ of pea size hail. I think you must be thinking that your vacation didn’t have much action weatherwise.

  13. Mike near Clackamas Town Center says:

    Did I hear that right on Mark’s last post. That our weather is hardly interesting during the Summer?
    I’ve been living in Portland all of my life and remember some pretty memorable t-storm episodes. Like Jun 2005, Jun 2009, Sep 2013, Aug 2011. Most of which are far more memorable than a run of the mill April rain storm.

    • Dallin Burnett says:

      T-storms in Portland are only memorable because they’re so few and far between. They’re definitely fun when they appear, but they just don’t form often enough and they’re usually weak.

  14. Y’know, I’ve been wondering if we would have our first 70/80 temps on the same day. I’m beginning to feel I have psychic abilities.

  15. pappoose in scappoose says:

    Mr Mark is back! Happy day!

    • pappoose in scappoose says:

      Relentlessly on watch we are! (close eye on that)

    • GTS1K' says:

      en garde to your South, Poose ~ 7 miles.

      I got a feeling……

    • pappoose in scappoose says:

      SPC continues to have the valley and
      Cascades in a marginal risk for severe thunderstorms on Thursday, meaning isolated severe thunderstorms are possible.

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