Fall Is Here

Between the last 2 days of weather (west of the Cascades) and looking ahead on the maps & models…it’s pretty obvious Autumn is arriving a bit earlier this year in the Pacific Northwest.  Two reasons for that:

  1. I don’t see any weather pattern in the next 7-10 days (just about to the end of the month) that would get temperatures above 80 west of the mountains.
  2. Rain will be an occasional to regular visitor the 2nd half of this month, based on the same information.

We had an early start to the warm season with fantastic warm temps and sunshine the first half of May, so apparently the last half of September will be makeup time…seems reasonable enough.  Plus the first half of September has been unusually warm, running 4 degrees above average at PDX.  So if the 2nd half of the month ends up 4 degrees below…that’s how we’d get TO average.

Lightning yesterday was exciting for some, but disappointing for others.  No one south of Portland or eastside of the metro area saw/heard anything, I wasn’t even aware of it until 1-2pm when I happened to briefly hop online.  But what a show in Puget Sound again and east of the Cascades.  I really like the 99 degree day at Pendleton Sunday followed by a severe thunderstorm with a southwest wind gust to 70 mph!  Crazy…

Looking ahead, we’ve got a round of convective showers tomorrow afternoon.  Could be some real good downpours or hail/thunder possibly.  These showers will be from an upper-level trough passing overhead.  Then not much happening Wednesday as high pressure builds over and north of us at the surface.

Thursday is by far the nicest day of the week with offshore flow (really, it should happen this time!) and sunshine.

What about Friday and beyond?  We get into an increasingly zonal (west to east) flow or “troughiness” over and west of the West Coast.  This is a wet weather pattern in general and it appears it’s going to stick around awhile.  Take a look at Week1 of the ECMWF ensemble maps:


A huge negative anomaly over us and to the west for next week.  The pattern is more like October than September.  Look at the 850mb ensemble chart from the 12z ECMWF and you see the below average temps (except for Thursday and Friday) through the period.


Pretty decent agreement through at least the middle of next week too.  The following 3 weeks show a similar, although less amplified troughing setup in the Eastern Pacific.  I get these maps on Monday and Thursday afternoons from the previous 00z ECMWF run:



At least we’ll be able to shut off the sprinklers and irrigation much earlier this year!

How about snow in the mountains?  At this point there isn’t a cold enough trough forecast in the next week or so to bring it much below about 6,000′.  The earliest measurable snowfall at Government Camp (4,000′) is September 23rd.  That was in 1984.

Not looking forward to the report card tonight.  I totally missed Thursday and Friday.  The only saving grace for Saturday is that I didn’t forecast that day since I had a day off Friday.  Otherwise I would have screwed that one up too!

Chief Meteorologist Mark Nelsen

39 Responses to Fall Is Here

  1. WEATHERDAN says:

    Every year the snow lovers come out and most years they go away unhappy. They really shouldn’t expect much anyway. Mark himself has shown the graph that shows how our average snow has decreased every decade sine the 1860,s. Back then Portland averaged some incredible numbers. Something like 40 inches a year. Now it is down to around 5 inches per year. And these last few years we have had almost nothing. This summer was so warm especially at night it set records.. So if our nighttime lows are warmer in the winter then they used to be why should we be surprised. Don’t get me wrong, I want to see snow. I miss a good snowstorm like I used to have growing up. I just don’t expect to see much of them anymore. The reason for those epic snowstorms back East is I think because of the fact that instead of the snow falling at 20 degrees it falls at 30 degrees. The warmer atmosphere holds more moisture. Now maybe this will be one of those rare years when we see a good old Arctic outbreak and a big honker of a snowstorm. But the odds are that we will see another mild Winter. Portland had 44 nights so far with the low staying above 60 degrees. Salem has had 29 such nights. Expect that number to only climb over the next few years. Whether the cause is global warming or uhi effect or some naturally occurring effect that we don’t know about yet, I think we should expect more hot Summers and mild Winters. At least in the near term. Here is a interesting stat, since June 22nd 88 of 89 nights in Salem have been 50 degrees or warmer. Only a low of 48 degrees on July 28 spoiled what would have been a record 89 nights in a row above 50. That record is still in reach however. Our low this morning was 56 degrees. This was the 51st night in row above 50. The record is 57 nights in a row. We might still make it. Peace.

    • Aloha Rainshadow says:

      Weatherdan, nothing personal but your reasoning here is very skewed. The big reason for the warm nights this summer is simply a southerly flow with all of the cutoff lows we experienced, which is warmer and moister…that in turn, holds the temps up…it’s not a simple fact of the weather in the PNW being warmer these days. Don’t be such a debbie downer and keep your head up. Enso is PERFECT right now for an on and off active winter, I say embrace the possibilities rather than dwell on the recent past!
      Did you see the ensemble analogs yesterday based on a late September large scale west coast trough???
      1955= Massive Snow in PDX
      1995, think about it.
      1962, BOOM.
      1968, motherload.
      2008…remember this one???
      All of these were analogs…pretty good group if you ask me 😉

    • JJ 78259 says:

      The will it snow or won’t it snow has started my the best man over 1000 ft win!

    • JJ 78259 says:

      May the best man win!

    • WEATHERDAN says:

      All well and fine. Except our winter weather is changing. It is not being a Debbie Downer to face the facts. Just being realistic. Also many warm nights this summer had a Northerly flow. Yes the Southerly flow helps but that explains only a part of it. I don’t know why our weather is warming up but it is. For example in the 1960,s it was very rare to have a nightly low stay above 50 degrees. Now it happens several times every winter. Ok so maybe it happens with a Southerly flow. But what is causing the increased Southerly flow. Look at the last few winters in Salem/Portland.

      2003-2004 Big Snowstorm
      2004-2005 Very little snow
      2005-2006 Almost no snow
      2006-2007 Small coldsnap/snowstorm
      2007-2008 Lots of snow above 1000 feet/almost none below
      2008-2009 Big Snowstorm
      2009-2010 Very little snow
      2010-2011 Almost no snow
      2011-2012 Very little snow
      2012-2013 Almost no snow
      2013-2014 ?

      Now take a visit back to about 50 years ago
      1961-1962 Cold winter with multiple snow storms
      1962-1963 Cold winter with multiple snow storms
      1963-1964 Mild winter with little snow
      1964-1965 Major Arctic outbreak with big snowstorm then major flood then more snow
      1965-1966 One major snowstorm with major cold push + 2 minor snowstorms
      1966-1967 Very mild winter with no snow
      1967-1968 One major snowstorm with Arctic outbreak + 2 additional minor snow events
      1968-1969 The snowiest and coldest winter in my life, multiple major snowstorms and multiple Arctic outbreak with many minor snowstorms
      1969-1970 one minor snowstorm
      1970-1971 2 major snowstorms and 3 major Arctic outbreaks
      1971-1972 1 major and 1 minor snowstorm
      1972-1973 -12 in Salem, very major snowstorm and Arctic outbreak that lasted almost two weeks

      Those are the facts or as Casey Stengel once said (please don’t ask me who he is ) you could look it up. So I want to see a cold Winter here I just don’t expect it. Peace

    • WEATHERDAN says:

      Ooops that should read it was rare in the 1960,s to have a wintertime low above degrees. Sorry

  2. BoringOregon says:

    Tornado at Island Park, Idaho!

  3. W7ENK says:

    It’s funny. It’s been so warm overnight until now, last night felt cold despite a typically warm low of 55. Relative to the rest of this month (and summer) though, that’s darn near freezing! 😆 Made for a chilly ride in this morning. I can smell fall in the air.

  4. Brrrrr. It cooled down to just 3 degrees above normal on the low lol

    51 here in Battle Ground with fog.

    Coldest low since August 21st.

  5. 27 and snowing lightly in Barrow, AK.

  6. paulbeugene says:

    Summit Guard Station data going back to 1895, not a complete historical data set, has earliest snow fall in Gov Camp vicinity 9/19 4.5 inches in 1895. There was trace on 9/11/1921.

    Glad to see fall arrive. Also nice to see that perhaps we won’t be dealing with much of a split flow pattern for a while.

  7. schmit44 says:

    9/16/2013 Oregon (All) Temperature Summary

    High:89 at LAKE OWHEE AND O(2400 ft)
    Low: 66 at JUNIPR(359 ft)

    High:47 at Timberline Lodge(7001 ft)
    Low: 27 at DIMLKE (4726 ft )

    Largest Diurnal Change: 45 degrees
    Lakeview, Lake C (79/34 ) (4734 ft )

    Heaviest Rainfall:
    0.55″ at HEBOWX Mt. Hebo(3160ft)
    0.52″ at CEDAR(2220ft)

  8. Greg Carstens says:

    Interesting Mark and thank you.

    It is looking like I will have to do some tree transplanting early perhaps this year. Last year I transplanted 8 small Western Red Cedars and 4 Douglas Fir trees. Every tree survived the transplant and I was so pleased with that. Having been a ranger at Mount Rainier in the past, I really love the old growth trees in the park especially in the Grove of the Patriarchs. Last year my planting was done in October per advice from the greenhouse supervisor and revegetation planting foreman at Mount Rainier. I waited till your forecasts showed more rain coming for the PNW and then the mass planting commenced.

    This year I only have 3 Douglas Firs, 2 Western Red Cedars and 1 pine tree to replant. I’m not sure exactly where I will plant them in the yard just yet but I will find some good spots I think. We definitely need more tall trees in the backyard for more privacy and to block out at least some of the hot summer sun around the backyard and especially on the back deck.

    I think the reason I am so successful in replanting is because I also mange to get almost all the root systems with the tree out when I dig them up.

    Something for everyone to keep in mind here if you plan on planting or even replanting these kind of trees. Western Red Cedar roots go deep and Douglas Fir fans out. That is why many large Douglas Firs uproot in windstorms. It is because most of their root system is on the surface. I once say half of a front yard pulled up when 3 large Douglas Firs toppled over from the wind. The last thing to keep in mind is also plant the trees so that they wont some day fall on your house from normally prevailing southwest winds.

    • pappoose in scappoose says:

      I have had a couple cedar trees go over in super saturated soil, but they usually snap off.

    • Greg Carstens says:

      Just about any large tree can go over in soil that is well saturated. With that in mind though, Cedars still demand more water than most trees and do best near creek and river drainage areas. I have never seen Cedars do well in soil that is to dry and even rocky. Douglas Fir can stand a lot of rain but it prefers less water on it’s roots than Cedar does and on top of that it at least needs partial sunshine when the sun is available. Western Red Cedars especially when they are young enjoy shade from larger plants and trees.

      I think the worst trees to have in any yard are probably Lodgepole pine trees because the roots are so short and small. Not many know it but when I worked in Yellowstone National Park back in the mid 1980’s the number one cause of death to hikers was from falling Lodgepole pine trees because of their very shallow root systems. As most of you know the wind can really get going in the afternoons in the Rocky Mountains. I have seen winds at Old Faithful on a typical July afternoon gust up to 50 mph with sustained winds well over 20 mph. Yes watch for bears if you hike but also keep your eye open above you for what might end up on top of your head.

  9. W7ENK says:

    I’m sad to see summer go, but it was a good run — the best in years! I guess it’s time to transition back into cloudy skies, rain, wind, browner beers, falling leaves, squash, dark mornings, early sunsets… Oh yeah, and cooler temperatures. Before you know it, we’ll be waiting patiently for snow that will never come and watching arctic blasts stall North of the Columbia! 😆

    All good things come to an end.

  10. pappoose in scappoose says:

    I really like what you really like Mark (Pendleton severe thunderstorm). Are you in, runrain?

    As long as I’m on the subject of what I really like, how about this! “Could be some real good downpours or hail/thunder”
    I like this statement quite a bit.
    NWS has a comment as well.

    National Weather Service Portland or
    845 PM PDT Monday Sep 16 2013

    The GFS and European model (ecmwf) show some pretty good quantitative precipitation forecast Tuesday morning across the southern part of our forecast area as it moves through. Model soundings show some cape up to around 20k feet. It is a bit marginal with the minus 20 degree c cold pool moving through…but added a slight chance of thunder for Tuesday.

  11. umpire says:

    Driving back from the westside around 8:00, it poured from Cornelius to about the fairgrounds in Hillsboro. Nada on the east side.

  12. pappoose in scappoose says:

    Won’t have to get much below 6,000′ to put snow at Timberline!

    Have you skied all your life, Henry?

    “Not yet.”


  13. Mark, you read my mind and my comment on your previous post. Does look “fallish” for sure.
    Time to go fishing for salmon in the bay!
    Ahhh…grilled salmon covered with a fresh picked chantrelle mushroom-butter sauce…mmmm 🙂

    • gidrons says:

      I’ve been out in the coast range bow hunting the last few weekends and I’ve never seen so many Chantrelles. That early heavy rain really got the fungus growing.

  14. pappoose in scappoose says:

    Looks like the last chance saloon, to spray/kill some blackberry bushes on Wednesday/Thursday!

  15. oldwxwatcher says:

    I’m on the east side and did hear thunder yesterday, just before noon. At about the same time it poured but it was a quick on/off event and amounted to only 0.04″.

    Hopefully the pattern will change by this time next month, when the leaves begin falling in earnest. Just one season I’d like to have dry leaves to rake instead of the soggy masses I’m usually faced with.

  16. PhilinForestGrove says:

    Pouring rain in Forest Grove right now.

  17. BoringOregon says:

    First again !!!

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