A Warm & Sunny Week Ahead

6pm Sunday…

It’s been a pleasant early fall day outside but somewhat chilly.  Portland only hit 68 which ties for the coolest day so far this season.  The average for this date is 74.

We have a lot of sunshine ahead for this work week as very strong high pressure builds just west of the Pacific Northwest.  Here’s the 500 millibar height forecast (in pretty TV colors) for midweek.  Heights get up to around 588dm, that’s summertime warm.
Jet Stream Forecast 2017

850mb temps don’t reach “heatwave” levels though, topping out around +16 to +17 Tuesday-Thursday.  This time of year we CAN hit 90 or even higher, although it’s rare.  In those cases those 850mb temps get up above +20.  We will get some light offshore flow Tuesday-Wednesday, maybe 2-4 millibars worth of easterly wind through the Gorge those days.  Not exactly a big start to the east wind season, that’ll come later in October.  That plus the warm atmosphere overhead should be enough to push temperatures west of the Cascades into the low-mid 80s.  Models seem to be running a little cool for some reason with surface temps.  Notice the ECMWF shows highs only around 80, this is the EPS (ECMWF ensemble system)….


You can see a pretty clear end to the warm weather next weekend too.  As a cold upper-level trough drops out of Canada next weekend, another wave moves east across the eastern Pacific and merges with it…looking like this by next Sunday

Jet Stream Forecast 2017_b

That’s the GFS, but the ECMWF is similar.  This is the setup we get in winter when we go from cold northerly flow quickly to mild southwest flow.  Of course the jet stream, cold air, and moisture flow is all far less dramatic this time of year.  So we’ll go from very warm weather Friday to cool and somewhat showery by Sunday/Monday.  It appears October may start cool.

The operational run of the ECMWF gives us a ton of rain the first few days of October, but the ensembles say hold on…not quite as wet.  0.60″ instead of 2.50″ as you can see on the ensemble plot (blue is operational run, green is ensemble average)


So enjoy the warm sunshine this week, because it may be the last time we see several (or any) 80 degree days.  Even in September in this “cool-ish” pattern we have gone two weeks without hitting that number.  A cool pattern in early October means even low-mid 70s will be hard to do.

By the way, a quick update on fire season.  Fire danger WILL go up west of the Cascades this week with dry east wind so be careful with any burning.  Of course it’s not going to dry out like it does in summer but a fire CAN spread in the weather Tuesday-Friday.  There are only 3 large fires left burning in Oregon.  All are showing minimal behavior/spread.  The two on the map below west and NE of Grant’s Pass both started during that lightning storm on July 15th…still going 2.5 months later!

Mark Fire All Oregon

Chief Meteorologist Mark Nelsen

37 Responses to A Warm & Sunny Week Ahead

  1. Andy says:

    On 1858 October 2nd a hurricane hit San Diego with widespread damage. Also on 1939 a tropical storm hit Long beach California. We often forget what has happened in the past. Are we seeing our weather patterns changing more to the past with wild swings.Time will tell. Currently even with are technology with are models we still have many forecast issues with long rang forecasts.

  2. Ken in Wood Village says:

    I don’t know what to think about the models lately. Now the Euro wants to bring that tropical system just South of California now (the GFS is doing the same thing). I don’t think I have seen such a difference the models are doing right now. Now the GFS gives us the goods next week were the Euro gives us a very dry week. Also, the GFS gives us a lot of South wind. I guess all we can do is wait until we get a couple of days away from next week.

  3. Ken in Wood Village says:

    The 18Z GFS came around but it’s only one run. At least it finally took the tropical system further south of California. Let’s hope the GFS keeps this trend up.

  4. Nichole C. says:

    I know it is hard to say for sure but what do you see the weather being like on Saturday, October 6th? My daughter is getting married outside. We live 30 miles East of Salem near Detroit Lake. Thanks in advance.

  5. Ken in Wood Village says:

    What is going on with the GFS? It’s just a little weird!!!

    • Joshua Lake Oswego says:

      The ECMWF is all over the place too. I have a feeling that what once looked like 3 warm days followed by a good soaking this weekend or early next week will become endless warm to average days with zero precipitation. The ECMWF 00z operational is absolutely brutal. The ensembles are much better.

      • Ken in Wood Village says:

        Yea, not liking the 00Z ECMWF either. I think both models are having issues with the Cyclones in the West and East Pacific. One thing I have noticed in the past and that is cyclones always change weather patterns. I’m guessing we will see the models flip flop the next few days because of the them. I did notice the GFS is a little wetter now. Last night it was completely dry with no rain what-so-ever.

        So Joshua, why did you move down to the banana belt? You know it will be harder to get snow down there…lol 🙂

        • Joshua Lake Oswego says:

          Ha. At least the nights are much cooler where I live now than in the Pearl District. Compared to PDX, the days and nights are generally 2-4 degrees cooler based on my observations.

        • Ken in Wood Village says:

          Hehe, then you should have moved to Vernonia…lmao…j/k 🙂 You could have moved East…lol.

        • Ken in Wood Village says:

          If only we went by the CFS model. I really like it because of the colder air…lol.

  6. Roland Derksen says:

    I think we’re done for any more rainfall this month here. I’ve measured 4.61 inches for the month, and that’s above average, It’ll make my water year here slightly above average as well- this is because January and April were so wet here. Might see afternoon maximums in the high 70’s later this week, but I don’t think we’ll touch 80F.

  7. Ken in Wood Village says:

    I think the GFS has a drinking problem…lol. The Euro seems more accurate. The GFS still want’s to have a Tropical Storm or Hurricane into California (rolling my eyes). The Euro has the same TS or Hurricane moving West. I’ll go with the Euro on this one…lol

  8. bg says:

    A classic rex block this screams el nino is developing with this strong ridge something will see this winter.

  9. Ken in Wood Village says:

    I wouldn’t take the 06Z GFS at face value. First, the wind and gusts are mixed up. It shows the gusts for the sustained winds and sustained winds for the gusts. Second, it shows a Hurricane going close to California and moving inland, then going East of Las Vegas. I think it’s time for them to upgrade the software.

    I still like the Euro. Things are looking good for next weekend. Close to the end of the run, it shows a massive low dominating the Pacific. I totally forgot what someone told me on what that low is called. Sorry 😦 I am hoping this trend keeps up with the Euro. 🙂

  10. Paul D says:

    Summer, you have worn out your welcome. Go away.

    • W7ENK says:

      You must have missed these parts of Mark’s post…

      “Portland only hit 68 which ties for the coolest day so far this season. The average for this date is 74.”

      “It appears October may start cool.”

      “…it may be the last time we see several (or any) 80 degree days. Even in September in this “cool-ish” pattern we have gone two weeks without hitting that number. A cool pattern in early October means even low-mid 70s will be hard to do.”

      I know, reading is hard.

  11. Jason Hougak says:

    Pasture seed has gone gang busters in the field the past two days with cooler/ showery weather. The showers and breaks lead to ideal soil conditions for the seed to germinate and take root without drying out. Wish the cool showery weather would continue but more heavy watering ahead to keep it strong. Been battling Tansy Ragwort for 3 years and I finally had enough. It was time to recover my pasture. Goal to kill Tansy, till field, cook under hot sun through summer, till, cook again, and till again. Buy pasture seed, spread seed, water morning and evening. Look for dry spots. A lot of work.
    In regard to the weather models, I guess I’ll believe it when I see it when this pattern breaks.

  12. Ken in Wood Village says:

    Thank you for the update Mark. I’m hoping this will be the start of a nice cooler and wetter pattern for us. We need the rain to put out all the wild fires around the West Coast. Second 🙂

  13. JERAT416 says:

    Summer returns for a few days, and the cool nights make it fun. Could be some good nights to stargaze under a blanket out in the boonies too drinking hot chocolate from a thermos…..my prediction a while back was when the cool, rainy season hits, it will be obvious, sudden, early, and not let up for a while. Of course I could be wrong. Enjoy this coming week everyone!

    • Ken in Wood Village says:

      JERAT416, I think you could be right. I was thinking the same thing about our rainy season too. I think it maybe a lot more active than last year (which wasn’t much).

      • JERAT416 says:

        That’s what’s so fun about our location here. It’s always a guessing game. We can all be wrong or right and add something to the discussion.

        • Ken in Wood Village says:

          Hehe, it’s more of a hunch. Back in the winter of 2016/2017 I had told my mom that I thought this winter would be full of wintery weather. In fact we had a bunch in December then a huge snow storm in January. I don’t feel like we will have that this year but I think we will see some snow, ice and cold temps. One thing we haven’t had in a very long time and that is a Artic Blast. I’m going out on a limb and say we will see one this winter. If it doesn’t happen then I’ll be wrong…lol.

          Like I said, it’s more of a hunch…hehe.

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