Weekend Rain Slow To Arrive = Drier & Warm Friday

8pm Wednesday…

I’ll be on vacation and out of town Thursday through most of next week, so here’s a quick update. It’s too bad I’ll miss the first soaking of fall this weekend!

Here’s the plan:

  • The next two days (Thursday/Friday) will be all or mainly dry from Portland south and east. Temperatures warm into the upper 70s the next two days too. There COULD be a sprinkles or a light shower during the daytime Friday, but that’s it.
  • Real rain, “the soaking”, doesn’t begin until sometime after sunset Friday evening. At this point it appears high school football games could be dry; or at least you shouldn’t see any downpours
  • The bulk of heavy rain (about 1/2″ in western valleys), falls Friday night through early Saturday morning.
  • Showers continue off and on Saturday, although they may not be very intense. Expect the usual downpours, then sunbreaks, then a rumble of thunder etc…
  • Sunday appears to be the wetter of the two days this weekend. More frequent and intense showers are likely. This can be the setup where we get funnel clouds too.
  • It’s back to warm and dry weather most or all of next work week. This is a “one-shot” deal, not the beginning of a cool and wet period.

In general, weather forecast models have been in good agreement on the wet pattern this weekend. A cool and broad upper-level trough settles over the Pacific Northwest late Friday through Monday. You see the much lower than normal heights (around 18,000′ up in atmosphere) midday Sunday.

Ahead of that cool trough, a wet Pacific frontal system first aims at Washington state on Friday. This is the change the past 24 hours. Originally models were thinking the system would be farther south to start. But now it’s obvious just about all rain remains in Washington on Friday. THEN, Friday night and Saturday it slides south through Oregon. In the end our total rainfall is still the same mentioned (previous blog post) a few days ago; about 1″ or so in the western valleys by the time we dry out Monday. This is the morning ECMWF model. It’s interesting that both GFS and ECMWF ensembles show about 1.5″…good agreement.

And you see the widespread 2-3″ in the Coast and Cascade ranges. This will put Fire Season 2021 partially into the grave. There won’t be much left of those fire complexes burning on the west slope of the Cascades.

Sunday’s snow level (the lowest elevation we’ll see sticking snow) in the Cascades is close to Timberline Lodge…could be a mix there, or even a dusting by Monday morning. But of course it’s too early and too warm for pass elevation snow.

After a few leftover (light) showers Monday, it’s back to mainly or all dry weather next week.

I see about 1/2 of the European’s model ensembles generate measurable rain again AFTER this weekend in the last week of the month. But 1/2 do not. It would be perfectly normal to see a round of showers again in the last week of the month. That said, my gut feeling is that the last week of September will be much improved from this coming weekend!

Enjoy the rain this weekend! After 3 months of dry weather, FOLLOWING the driest spring on record, we desperately need it. I will be back at work that last weekend of the month.

Chief Meteorologist Mark Nelsen

110 Responses to Weekend Rain Slow To Arrive = Drier & Warm Friday

  1. Zach says:

    Lmao, total forecast bust today.

  2. W7ENK says:

    THUNDER!! ⚡⛈️🌩️⛈️

  3. Anonymous says:

    Wasn’t expecting rain today but I’m glad to see and hear it

  4. JERAT416 says:

    Will it get hot for a week or 2 if I take my AC out of the window this weekend? Haha

    • Hank says:

      This week might be the last of the 80s, but there is a decent chance we will see Lower 80s again, since that almost always happens in october, but that’s not really necessary for the AC, Just open you windows every night. In conclusion, probably won’t need your AC Anymore, just open your windows after its cooler outside than inside.

  5. tim says:

    00z isn’t as impressive as 12z or 18z but at lest it’s cool and damp.

    • Anonymous says:

      Once again we’re at the mercy of the blob ridging. The high pressure seems to be holding steady when it’s contending with smaller systems that come in one at a time, but when they double up is when I notice the models trending wetter by pushing that high pressure out of the way.

      On a somewhat related note, the east coast also seems to be developing an area of persistent high pressure. In fact I was looking at the model earlier today and noticed a massive hurricane aimed at the NE states will end up getting detoured because of that.

  6. Anonymous says:

    Hmmm… 12z Euro suddenly showing another inch of rain Sunday afternoon – Tuesday.

  7. Jake says:

    A lot is weighing on this Winter for the West. I don’t think many realize how fragile our bio-region (Cascadia) is right now.

    Mt. Baker, world’s greatest recorded snowfall in one season, 1,140 inches (95.0 ft; 29.0 m) is for the first time in known history. Bare. At its summit. Mt. Baker also unofficially has the highest average annual snowfall of any resort in the world, with 641 inches (53.4 ft; 16.3 m).

    Mount Rainier in the first time of 120 years of tour guides taking people to the summit has all companies canceling all tours due to unstable conditions (50% failure rate, a risky adventure to begin with).

    Mount Shasta in the 21st century has lost 50% of its glacier volume. This Summer was its lowest recorded snow cover, ever, in known history.




    • W7ENK says:

      Without getting political, you have to remember — we’re (technically) still in the final warming phase coming out of the Pleistocene — so in the grand scheme of things, this really isn’t all that unexpected. That’s not to say that we humans haven’t severely contributed to and accelerated that cycle, but…

      Still though, ~200 years worth of natural warming in the span of roughly 10% of that time, there’s absolutely something wrong with that.

    • Zach says:

      To be honest, I think whether or not Baker has snow in September is the least of our concerns. Not really much stake in that.

      I would be much more concerned about a repeat La Nina and what that means for water supplier in the SW.

  8. W7ENK says:

    Looks like ENSO is taking a hard drive into La Niña territory.

    Sadly, this probably won’t mean much of anything exciting for us here in the PNW lowlands. Second consecutive “double-dip” La Niñas tend to produce really slow, mild and boring Winters for us, so I would recommend against getting your hopes up for anything other than several months of dark, cold rain. Winter 2017-2018 would be a good (and most recent) analog.

  9. Jake says:

    All total the rainstorm produced:

    2.41in (over here with the showers on Saturday and Sunday)

    Friday night alone it rained a total:


    An impressive rainstorm clearly considering November is not here yet:

    I wonder if Mark has some thoughts on it on how it occurred.

    Also heard a few thunderclaps Saturday. Current stretch of weather looks far more traditional to what we see.

  10. Anonymous says:

    The updated season forecast shows we have a heightened chance for cold outbreaks and low elevation snow in December this year! It would be nice to get decent snow before late January or February like we have the past few winters.

  11. tim says:

    Good thing we don’t have solar windmills here I don’t think anybody wants to get cancer for them.

  12. Weatherdan says:

    1.36 inches of precipitation Friday through Sunday. Pretty much all dry after 4:00PM on Saturday. I understand Portland had almost twice as much. The next two weeks look warm and dry. Peace.

  13. Hank says:

    Storm total – North Salem
    11 Pm Friday to 7 Pm Sunday
    2.07 Inches of rain

    More than what was forecasted, but people are still calling it a bust

  14. W7ENK says:

    Storm total – Upper N. Milwaukie:
    2200 Friday to 0000 Monday = 1.74″

    That is absolutely not a “bust” by any measure.

  15. Anonymous says:

    That was a nice fall teaser. Back to summer this week. I see 80 degree temps going into October too. I hope those fires are dead

    • Zach says:

      I see a warm weekend, and then pretty average weather afterwards.

      Heat in late -Sept is a cakewalk since it still gets down to the low 50s at night.

      • Anonymous says:

        Check out the first few days of October, Fri-Mon. GFS has been teasing 85+ for those days.

        The storm-killer ridge is still out there on the coast, ruthlessly karate chopping our much needed precipitation and cooler fall temperatures.

        • tim says:

          Most places either received or exceeded there monthly totals so it makes sense to go a couple of weeks without rain, nature likes to balance things out I guess.

  16. Zach says:

    North Metro scored with this storm. Many gauges saw between 2-3″ due to favorable cells yesterday:


    • Joshua Lake Oswego says:

      Yep, and I was in the absolute worst spot. W7 maybe too in Mikwaukie. Areas in the SE metro area like Beavercreek got hammered too. It was really depressing watching the radar. Anyway, great soaking all around even though I am disappointed that my location has been essentially totally dry for the last 24 hours.

  17. tim says:

    Crazy question, doesn’t the pollution from China get transported to the west coast by the jet stream?.

    • Jake says:

      Yes it is what gives us sometimes the amazing red sunsets in Summer with no regional forest fire in the area. The air pollution most first world countries release travels for thousands of miles on the jet stream.

      The jet stream in the southern hemisphere is visibly cleaner on satellite imagery because only a few countries pollute to similar levels.

  18. tim says:

    After all this record rain were gonna need a break good thing the cpc is showing above normal temps and below normal rain for the next two weeks, whoo.

  19. Ken in Wood Village says:

    Just looked at my lightning tracker and there are a lot of lightning strikes out on the ocean and close to the coast. Not sure if they will keep producing lightning as they come ashore but it’s cool to see ⛈🌩

  20. tim says:

    Fall definitely came early this year.

    • yigablademaster says:

      Yeah. 80F instead of 86F. Fall is definitely ‘early’ this year despite it going back to near 90F this weekened. 🤮🤮🤮

  21. Roland Derksen says:

    Well, this seems to be the summer when records are broken- one way or another. After record heat in June, yesterday we had the wettest day I’ve ever recorded in a day for September with 2.98 inches- at 10pm. After I went to bed, the rain continued for at least another 2 hours. The grand total for this storm: 3.30 inches. So for a 24hour total I had more than the 3 previous months (june to August), and it’s also the most for a summer day I’ve ever seen.(if you consider it’s still before equinox).

    • Michael says:

      I am at 3 inches at 7pm outside Beavercreek. Elevation 650′

      • Roland Derksen says:

        Nice to see the locations south of me got some good amounts- you all needed it!

      • Michael says:

        Things have really tapered off on the rain. So it looks like Beavercreek got a full 4 inches of rain from this storm. That was really good for my forest. When you walk around everything feels alive and fresh. I am very thankful. Keep the faith everyone.

  22. Anonymous says:

    Almost all areas have accumulated about an inch of rain so far. Nice!

  23. MasterNate says:

    Only 1 other time in my life I was this excited to see rain. Last year after the western fires.

  24. Zach says:

    From what I have seen it appears this system is mostly delivering about as expected. Just over 1″ out here in Gresham as of 8am.

  25. W7ENK says:

    Summer 2021.
    And that’s a wrap, folks!

  26. Anonymous says:

    The rain started a few minutes ago in the Cedar Mill area!

  27. Anonymous says:

    Wild!! Castle Rock area

  28. Ken in Wood Village says:

    Just looked at the Langley radar 😳 there are some nice heavy rain on that radar 🌧 also, I belong to a weather group on Facebook. They posted about some gusty winds up towards the Canadian border (over 60mph). The National Weather Service upgraded the wind advisory to a High Wind Warning ⚠️ I think that’s the first High Wind Warning for the PNW. Maybe we could see some decent winds tonight 😉🌬

  29. Anonymous says:

    The rain isn’t going to start for several more hours, but I swear I can smell rain when the wind/breeze gets going.

  30. Joshua Lake Oswego says:

    The 00z HRRR is nice and juicy for Western Oregon. 18z Euro was great too.

  31. Weatherdan says:

    81 and sunny at Salem at 2:52PM. At the same time Seattle is 58 with light rain. That’s a 23 degree difference. For now any way the rain seems to be staying up North. I hope it continues to do so until overnight. Then most of Saturday shouldn’t be too bad. Back to sunny weather next week. Peace.

  32. Ken in Wood Village says:

    I’ll admit, we have been having some good winds before the storm is even here 🌬 it’s been picking up a lot of dust since we haven’t had rain for a long time. I can’t wait to see rain again 🤗🌧

  33. Anonymous says:

    Where is this smoke and poor air quality coming from?

  34. Roland Derksen says:

    The rain began here at around 2:15 am. It’s not all that heavy, but it is steady, and with the intensity ramping up this afternoon, I expect to reach that 2 inch level by this evening.

    • Hank says:

      Are you from Seattle or somewhere else?

      • W7ENK says:

        Roland is just across the border into the Vancouver BC area.

      • Roland Derksen says:

        Yes, I’m north of the border. The rain is presently down to a drizzle here, but could re-intensify. We reached 2 inches already around 3pm. This could end up being my wettest summer day (for June21-sept.20) I’ve ever recorded.

  35. Zach says:

    Mesoscales are showing big time rain shadowing over Washington Co.

  36. tim says:

    It will be much warmer tonight with the increasing clouds.

  37. Jake says:

    Gale Warning (here we goooo…..):


    Visual satellite is just a wall billowing off the coast now. Pretty impressive while visually you can see the smoke from the fires:


  38. Roland Derksen says:

    We’re expecting the rain to arrive here on Friday morning. The latest predictions say the range could be from 30-60 mm. (that’s about 1.25-2.5 inches). if so, i’ll probably get around 2 inches at my place.

  39. Anonymous says:

    Not sure how you lot will be celebrating, but I plan on putting on my rainproof gear, grab a bottle of some cheap wine, put a chair out in the middle of my backyard where I’ll sit and just get poured on as I enjoy the wine. I did this last winter and it was glorious. I imagine this weekend it’ll be even better due to the anticipation of long awaited rain. Can’t wait!

  40. Zach says:

    Last night the Euro bumped it up to 1.9″

  41. W7ENK says:

    39 degrees this morning…
    BRRR!! 🥶

  42. Jake says:

    This jet stream is strong; 3,500ft on the Coquihalla pass in BC:

  43. Anonymous says:

    I’m not sure I’ve ever been this excited for some actual rain. It’s been way too long.

  44. Anonymous says:

    Almost as exciting as the first snow of the season!

  45. Hank says:

    00z Gfs very wet, 2.15 Inches salem, 2.75 Inches Portland, starting 11:30 PM Friday, ending 7 PM Sunday. seems too wet, 00z tommorw we should have a very good idea how it will play out.

    • Jake says:

      I’ve noted that the GFS has been trending more runs to 2.25 ~ 3.25 inches.

      The EURO has consistently has stayed at 1.00 ~ 1.25in and something has to give in the next 24 hours.

      Very exciting first Fall storm of the season. Hope it is something of a sign of things to come but I’m not guessing this far out.

    • Zach says:

      Time to start looking at the mesoscale runs tonight.

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