Fall REALLY Arrives Next Week


I’ve shown this image in previous posts;  it’s the 6-10 day forecast 500mb heights and deviation from average.  You can see the negative anomaly centered over the northern Rockies.  This is quite a change from what we’ve seen the past few weeks.  Basically the Western USA is going to get a sudden cool down next week.  We can turn off the sprinklers and garden soaker hoses.  That’s a combination of much cooler temps plus off/on rain beginning Monday or Monday night.  You definitely need to enjoy the sunshine this weekend.  Sunday looks perfect with strong offshore flow (gorge east wind).  WRF-GFS cross section shows 35-40 kt. wind well above the surface Sunday PM.

I’ve been a bit lazy blogging the last few nights…under the weather, especially tonight.  Feels like some laryngitis approaching…

Chief Meteorologist – Mark Nelsen

112 Responses to Fall REALLY Arrives Next Week

  1. Tetra says:

    and the second one falls for some strange reason.


  2. Tetra says:

    Timmy you missed my question. 😮 😦 [url=http://www.smileyhut.com][IMG]http://www.smileyhut.com/naughty/axe.gif[/IMG][/url]

    63.1F here.

  3. Timmy_Supercell (Hillsboro) says:

    wow even the Weather channel is mentioning thunderstorms as a possibility on Tuesday. It does seem likely, with a very steep cold pool along the edge of this cold front.

    The last time we had cold convection was a little unusual though, I don’t think we will see anything close to EF-1 tornadoes and downbursts this time. Maybe some brief heavy rain and a clap of thunder or two with these showers.

    Well, thunderstorms may be over, but not cold thunderstorms! Hopefully… 🙂

    Do the thunder dance!

  4. Karl Bonner says:

    Two amazing Indian Summer days. Yesterday my very dear old friend came into town and we hiked Spencer Butte, then spent the night SW of Eugene on Wolf Creek road looking through a borrowed 8″ telescope. Today my roommate and I took a 350-mile round trip to Roseburg (got photos of domesticated palm trees), the Upper North Umpqua, Crater Lake, the Chemult area on Highway 97, Odell Lake, and Salt Creek Falls. The smoke was bad in the two mountain passes, making the evening sun literally blood red. Not a bad way to end the warm season!

    I hope we get some 35-40 nights (but no solid frost!) behind the rainstorms coming in this week, as it will help greatly in bumping up fall colors a week or two down the road.

    • Jesse-Orchards says:

      Why no frost?

    • Karl Bonner says:

      Frost could damage the foliage before it gets a chance to turn. At least if it’s a heavy one. You want it to be cold at night, but not cold enough to freeze the leaves. So about 37 or 38 would be just perfect, with afternoon highs in the high 60s or low 70s.

  5. Tetra says:

    Hey Timmy does Silver Falls Park get the cross gradient flow when that setup happens?

  6. Tyler says:

    My trip up to Mt. Rainier featured a lot of smoke on the first day, but clear skies (above the low clouds) the other two days. I’ll post a link for pictures later.

    Enjoying the sunset, on what could be the last real nice (and warm) day of the year.

  7. Rob "Wrath" S.E. Portland says:

    Hmmm my temp is down to 77.2° which I can only blame on the increasing east winds mixing things too much. Also the Gorge wasn’t exactly warm this morning and isn’t right now either. The Dalles is only sitting at 78°.

    Surface gradients
    As of 3 PM|Current|Hourly Change
    PDX-DLS: -4.2mb |0.2mb Increase
    TTD-DLS: -4.2mb |0.3mb Decrease
    OTH-GEG: -7.3mb |No Change

  8. Spoke too soon…east winds have ramped up here, as has the temperature…….


  9. Rob "Wrath" S.E. Portland says:


    Well judging by the 12z GFS cross section model it appears winds peak 7 PM – 12 AM Monday although I don’t expect any big increase. 12z WRF-GFS 4km wind model doesn’t show gradients exceeding 5 MB. We’ll see….

    Surface gradients
    As of 2 PM|Current|Hourly Change
    PDX-DLS: -4.0mb |0.3mb Increase
    TTD-DLS: -4.5mb |No Change
    OTH-GEG: -7.3mb |No Change

  10. Rob "Wrath" S.E. Portland says:


    Surface gradients
    As of 1 PM|Current|Hourly Change
    PDX-DLS: -3.7mb |0.6mb Decrease
    TTD-DLS: -4.5mb |0.5mb Decrease
    OTH-GEG: -7.3mb |0.2mb Increase

  11. Nice cool start to what promises to be a beautiful day…

    64.2F…light NNE wind

  12. Rob "Wrath" S.E. Portland says:

    Surface gradients
    As of 12 PM|Current|Hourly Change
    PDX-DLS: -4.3mb |0.3mb Increase
    TTD-DLS: -5.0mb |0.5mb Increase
    OTH-GEG: -7.1mb |0.6mb Increase

  13. Rob "Wrath" S.E. Portland says:

    Surface gradients
    As of 11 AM|Current|Hourly Change
    PDX-DLS: -4.0mb |0.3mb Increase
    TTD-DLS: -4.5mb |0.3mb Increase
    OTH-GEG: -6.5mb |0.8mb Increase

  14. Timmy_Supercell (Hillsboro) says:

    Did anyone finally see my comment? Mark, thanks. 🙂

  15. Rob "Wrath" S.E. Portland says:

    According to my weather station I bottomed out at 41.4° @ 7:30 AM.

    Surface gradients
    As of 9 AM|Current|Hourly Change
    PDX-DLS: -3.7mb |0.2mb Increase
    TTD-DLS: -4.2mb |0.4mb Increase
    OTH-GEG: -5.7mb |0.8mb Increase

    Offshore flow continues to strengthen and I see Three Corner Rock is approaching 50mph already.

  16. Looks like I am one of the few places this morning to have low clouds. Still managed a low of 40.5° this morning. Currently 44.5° and cloudy.

  17. …hope your feeling better, Mark!…

  18. Timmy_Supercell (Hillsboro) says:

    Looks like my comment never made it. And its almost not worth it now. 🙂

    Next week is a major cool down, I see a bunch of low 60’s and high 50’s mixed…

  19. Rob "Wrath" S.E. Portland says:

    As of 6 AM it is currently 42.8 at my house. VERY chilly. East wind has developed in the higher elevations such as Three Corner Rock and should by mid morning at Corbett, then increase spreading westward to Troutdale/Gresham by 8-11AM.

    Surface gradients
    As of 6 AM|Current|Hourly Change
    PDX-DLS: -1.3mb |0.7mb Increase
    TTD-DLS: -1.7mb |0.9mb Increase
    OTH-GEG: -2.6mb |1.3mb Increase
    Last night’s 00z and this morning’s 06z GFS both continue to show an abrupt change to Fall with no pattern change seen over the next 7-10 days. Last night’s 00z EURO shows a rather large and strong upper low dropping south out of British Columbia setting shop right overhead in the 7-10 day time frame. Cool and wet at times looks to be the theme. Get those furnaces ready to go as we will be needing them.

  20. Tetra says:

    😮 [url=http://www.smileyhut.com][IMG]http://www.smileyhut.com/naughty/axe.gif[/IMG][/url]

  21. Tetra says:

    You’d think with a major cooldown this blog would be hoppin.

  22. Tetra says:

    *Tetra uses his magical blog powers to heal Mark’s voice even though Tetra doesn’t know why his voice is gone*

  23. High 76.3°
    Low 43.4°

    Currently 57.8°

  24. Scott in SLC aka Scott in S. Corvallis says:

    Looks like we are headed for record heat Sunday/Monday 90, but man the bottom drops out, Tuesday night the front and trough approach and bamm down to a high of 52 in SLC at 4600 ft while snow is now forecast above 5000/5500, benches and Park city where i work could get hammered on Wed pm/Thurs. It’s kicking in quick. I’m excited. I’ll keep you posted. PS great today but Fire red sky tonight from all the smoke of yours & Cali’s fires. 77 right now at 9:35 mt. Enjoy the Sunday east winds…wow the ducks exploded! How did the Beavs do?

  25. Tetra says:

    Bonus question Timmy: Do you think the mid valley can get any rare September frost?

  26. Tetra says:

    2 questions Timmy:

    What were the links about?

    Also how cold do you think it will get here in the valley since GC might get some snow?

    Temps drop 4F for every 1K feet.

    • Timmy_Supercell (Hillsboro) says:

      Just some pictures of our sunrise. It wasn’t anything big though. Not sure about temperatures, maybe 59-62 on Tuesday.

  27. Timmy_Supercell (Hillsboro) says:

    I currently have a comment awaiting moderation, I posted it at 1:09 pm

    • Tetra says:

      That’s weird……………………………

      Sometimes even if it’s just one comment I get a message box saying “Your posting comments to quickly slow down” when it’s my first time all morning.

    • Timmy_Supercell (Hillsboro) says:

      Well this time it was because I posted 5 links on one comment. But it is odd that I still don’t see it yet. Usually it moderates after about 30-45 minutes.

    • …if there’s no moderators checking the blog, it takes until one does to get approved…….

  28. Josh "The Snowman" From Everett, WA says:

    DUCKS: 25
    CAL: 3

    Halftime…..GO DUCKS. Looks like that offense is starting to click. Masoli looks real sharp!!

  29. Shaping up to be a beautiful day….


  30. Timmy_Supercell (Hillsboro) says:


    Good morning everyone… (Afternoon actually 🙂 )

    Yes, Fall is here at last! Pretty soon there will be daily doses of “Dead Leaf Aroma” mixed with the fresh 40 degree sunrises every morning. If an early bird, this is the best season. Smell that fresh air while you can!

    I was at my friends place from 7 am to noon, doing a video game marathon! It was fun. And before that, took some snap shots of our cloudless sunrise we had this morning. Links are below.

  31. Cherie in Vernonia says:

    Try to take it easy on your voice for a few Mark. Hope you get better very soon.

    Thanks to all who have joined the group over at Facebook :0)

  32. Tetra says:

    I should’ve known since The Gorge is the most likely path for cold air to funnel down.

    Hey did anyone even READ any of my comments about what I thought? *insert confused smiley here*

  33. Tetra says:

    And now we are going to get something I didn’t even consider………………………COLD EAST WINDS!! 😉

  34. Tetra says:

    I told you we would likely have cold core convection as a result of the precip.

    54F here on my weather station and sunny.

  35. Currently 56.4°F (after a low of 45.1°F). . . Clear and sunny. . .

    Hope you’re feelin’ better soon Mark. . . . .

  36. Rob "Wrath" S.E. Portland says:

    Good morning.

    47.3F here with crystal clear skies. I really like the crisp feel to the morning.

  37. Tyler says:

    Hope you get better Mark. I thought your voice sounded a little scratchy on the 5 o’clock show.

  38. Karl Bonner says:

    It was inevitable that this would happen; hot weather cannot last very long at this time of year. We’re also getting to the point where it’s possible to stay below 60 all day long. From here on out, a warm spell means anything significantly above 70, and a heat wave is anything above 78 or 80.

    After the midpoint of October, we won’t be able to call anything a heat wave anymore and any day that gets over 65 with solid sunshine deserves a “10” rating.

  39. PaulB/Eugene says:

    i meant to post the 216h ECMWF map of NoAm 500mb

  40. Ben Randall says:

    I was looking at the ecmfw 850 m . model and I am think 40s and 50s next week on the coast maybe lower60s .

  41. Rob "Wrath" S.E. Portland says:

    Mark, thanks for the update. I just looked at the cross section model, and wow what a burst of east winds shown. This looks slightly stronger than the last east wind episode.

    Also the 00z WRF-GFS shows a little bit of CAPE over the area Tuesday. With a nice cold pool aloft seems we cannot rule out a t-storm.

    Get well soon.

  42. Sure does look like fall is upon us!


  43. Rob "Wrath" S.E. Portland says:


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