Beautiful Weather; Last of the 80s?

6pm Wednesday

Today has been another fantastic fall day.  A chilly start with lows in the 40s and lower 50s, then all areas west of the Cascades in Oregon made it well into the 80s.  Check out those lower 70s on the coastline as well

Todays Observed Highs OrWa 2017

I saw someone mention somewhere on social media that this is summer weatherwise.  Most definitely not.  The long nights and low sun angle give a totally different feel.  It gets warm between about 2 & 6pm in this pattern, but cool during the lengthening nights, mornings, and evenings.  Even here in the city it was still only 69 at noon.

Todays Observed Temps in Portland 3D City Earth Scene 2017_2

Strong high pressure centered to our west over the Eastern Pacific remains in place through Friday and that guarantees us two more days above 80 degrees.  Then lowering upper-level heights plus a strong onshore push drop us 10-15 degrees Saturday for a more typical late September day.

So is this the last of the 80 degree temps?  It could be.  Check out the past few years…specifically the last date we hit 80 each of those years.

Last 80 Degree Day Heatwave

The average for Portland (in any year) is September 29th.  Last year we hit our last 80 on this date (the 26th).  After this Friday there’s no sign we’ll hit 80 in the following week, although the ECMWF ensemble forecast highs for Portland do hint at warming again late next week.


That said, models have not been doing real well handling a split-flow setup Sunday and beyond so I have low confidence beginning that day.  I’m not a fan of putting question marks on the 7 Day forecast (and we don’t do that here) but early next week would be the time to use them!

Here’s a plot I use regularly…the ECMWF 850mb temperature ensemble plot.  This is temperature in celsius up around 5,000′.  Each thin line represents one of the 51 members of the “ensemble forecast system”.  Basically each line is one run of the model and it’s done 51 times every 12 hours.  The blue line is the actual “operational” model run and has a bit higher resolution.  Red line is the average of all the ensemble members.  You can probably guess what the yellow/green line is…climatology.  Temperatures up around 5,000′ drop quickly the first two weeks of October.  You can glean a bit of info from this chart; I noticed two items today.

tseries_850t_000-360_Portland (1)

  1. Good agreement among ensembles (all the lines close together) through Sunday…the 30th, then they are all over the place.
  2. Temperatures are well above average through Saturday AM, then plunge to below/near average after that time.  Looks like we’ll be all done with the 80s down here at sea level after Friday.
  3. BUT, look at that range the middle of next week!  That could give us a high of 85 or as cool as 58, best to just keep the 68-70 for now until the solutions come together.

By the way, today is the 71st day we’ve hit 80 this year in Portland

80 Degree Days Yearly

As we all know, the past 5 warm seasons have been VERY warm; quite a contrast with those much cooler years 2010-2012.

Chief Meteorologist Mark Nelsen

33 Responses to Beautiful Weather; Last of the 80s?

  1. Roland Derksen says:

    If anyone’s longing for a rainy day down there, you can come up here(Vancouver BC); Weve got an all day rain for today and another forecasted tomorrow.

  2. Ken in Wood Village says:

    I’m starting to like the models again. They seem to be coming into good agreement for this week. Let’s just hope they keep it up.

  3. This morning’s forecast was for clouds and showers by afternoon, but it turned out surprisingly sunny; the rain didn’t start until around 8:00 PM. Was out picking wild cranberries and the sunshine was nice and warm. Fun fact: bogs get warm quickly in sunny weather because the peat soil has low heat capacity.

  4. Kyle says:

    I forgot a link to the Bernoulli Principle here is an animated form and ocean currents are a fluid movement.

  5. Kyle says:

    here is the only 2018 one since Google did major modifications to their searches the summer dumbing it way down even more for propaganda making more users aware and mad.

    and finally a CNN one for you brain dead fools out there.

    don’t say I never gave you anything. 🙂

  6. Kyle says:

    But never fear! If it’s not on CNN it must not exist

  7. Kyle says:

    You can thank the trash in the ocean and it’s on some news channels. There are plans for several robotic ships by the end of the year to patrol and scope it up somehow and by next year there will be several dozen of them. I am curious where they are going to put it when they collect it and how the trash is there in the first place as it’s not our trash it’s microscopic pieces of plastic that look bizzare up close.

    This would create the Bernoulli’s Principal which will effect currents and that drives the jet stream patterns. That will cause the ridiculously ridge to never truly go away as long as the cause is still there.

    It’ s like having medicine to numb the effects of cancer.

  8. Ken in Wood Village says:

    I wish we went by the CFS. I really really like it…lol

  9. Roland Derksen says:

    Fantastic say today here with sunny skies and a high of 74.8F. Saturday. the clouds move in and overnight into Sunday we’re expecting rain. September 2018 here is probably going to finish with over 5 inches.

  10. Joshua Lake Oswego says:

    Does anybody remember the last time we had a rainy day? I mean one where the whole day has low clouds, dark, wet, no sun breaks. You know, what out-of-towners think we have 9 months out of the year. Me neither!!!

    • Ken in Wood Village says:

      Actually, NO. I can’t remember the last time we had a really good rainy day. All I hear from Mark is “showers possible”. I haven’t heard him say, “it’s going to rain all day”. Everyone else in the U.S. seems to be having more rain than we are and it’s a little frustrating. 😦

      • Paul D says:

        Just looked at the ten day forecast on Weather Underground, and there’s no rain in it 😦

        • Ken in Wood Village says:

          Sorry Paul but I don’t trust Weather Underground…lol. I do noticed something on the 18Z GFS but it’s way out there.

        • Paul D says:

          Fox 12 shows no rain on their 7-day forecast. I’m not geeky enough to look at those fancy charts some of you look at, so I just go by Fox 12 and WU and know not to depend on them 🙂

        • W7ENK says:

          Well, I’m glad that didn’t verify, now did it.

  11. JohnD says:

    88-80’+ days (including 29 @ 90’+)

    71 (or 72)-80’+ days (including 31 @ 90’+)


    We all know too that Oct. incurs the greatest statistical ave. temp. change–beginning to end–than any other month!

  12. bg says:

    Mark any thoughts on the upcoming El nino winter?.

  13. W7ENK says:

    Goodbye, Summer. It’s been fine, but your time has passed.

    Until next year!

  14. WEATHERDAN says:

    Going back to April 17th we have had 1.23 inches of precipitation in Salem. Dry indeed. Peace.

  15. Roland Derksen says:

    I’ve given up on the possibility of seeing another 80 here for the year. 70’s is another story, I usually see a few before the mid-point of October. After that, it’s usually goodbye until next spring. (April)

  16. Ken in Wood Village says:

    I’m tired of the never ending summer’s around here. I wish we could actually have a normal/average season’s. I gave up on watching the models for now. I’ll look at them on Friday. They are all over the place and trying to predict what the weather will do is almost impossible. 🙄😒

    • Mark Nelsen says:

      This month is as normal as it gets for September…even very slightly wet.

      • Joshua Lake Oswego says:

        True for PDX. A lot of the metro area has far less precipitation though. I am at .55” for the month. Well below normal. PDX happened to score some very heavy showers during the hit or miss event a couple of weeks ago. What we have not had is a widespread soaking.

      • Ken in Wood Village says:

        Mark, you said “this month”. I said seasons but if you look at the whole water year we are below normal. We have had more dry weather than we have had rainy weather. I’ve lived here all my life (51 years) and have noticed year after year the temperature rising. One reason why I loved living here was the milder summers. We would get some HOT days but not like we have been seeing the past few years. If I wanted that type of HOT weather I would have moved to Las Vegas 😒😂😜

        • WEATHERDAN says:

          While we seem to have reached a very warm plateau since 2013, I think some additional warming is in our future. Especially overnight and during the Winters. This is the new normal. Peace.

        • Paul D says:

          Agreed! I moved here 25 years ago because the summer weather was just above 80 and nights cooled off nicely. It has drastically changed in the past few years – far too many 90’s each summer!

  17. Paul D says:

    Hoping that Friday is the last 80+ for 2018 – it’s long overdue!

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