Fall Moves In Quickly!

Someone in here today mentioned that the change in season (from warm and sunny) seems to be quite abrupt this year.  Specifically the last few days.  September was the 2nd warmest on record here in Portland; now the first few days of October have been below average (the daytime highs).  That’s quite a change.  Add to this is the fact October’s temperature changes more quickly than any other month.  We go from an average high of 70 the beginning of the month to upper 50s at the end.  Take a look at the temperature graph for this entire year here in Portland:

The delayed summer really stands out.  Notice the average high usually peaks in early August, but this year you can see the warmest days were from late August to mid-September.  Look closely and see the first few days of October; a sudden drop.  Picture this continuing over the next week and that chart will have a dramatic dip.   Speaking of dips, I like that drop during the brief arctic blast in late February.  Remember that was the beginning of the cool period that continued all the way through July.

So what about the next week or so?  We are obviously in a cool pattern.  Check out NCEP’s 6-10 500mb height anomaly forecast:

A significant trough over or just west of the west coast of North America.  I notice the tendency for troughs to drop in on us when looking at the daily maps of several different models.   Here’s a look at the ECMWF ensemble (51 of them!) forecast of 850mb temp:

The blue line is the forecast temperature at about 5,000′ (in Celsius) on the main “operational” ECMWF run.  The green line is climatology through the next 16 days (the upper-atmosphere cools in October, no big surprise).  All the black lines are the different ensemble members and the red is the average of all of them.  The big message is that both the operational run and ensemble average continue mainly at or below average through mid-October.  Cooler than average weather will be the result.  Notice the -2 deg temp on October 14th is coolest of all the ensemble members.

For now I don’t see any stormy weather ahead, in fact I have no idea why there is a high wind warning out for the Coast.  The gradient is too easterly and only the windiest exposed spots have any hope of making it to the 58 mph gust criteria.  The main energy with tonight’s system is slamming into California as well.

The newsies in here are somewhat excited about the possibility for snow in the Cascades the next 24 hours.  It appears it’ll be cold enough for sticking snow down to about 5,000′ or slightly under tonight and tomorrow morning.  That is mainly Timberline Lodge.  Precipitation looks a bit weak though.  Maybe just 2-3″ max at Timberline.  I like how the flow turns westerly late tonight through all of tomorrow (always better for snow than southerly flow). 

The saying, from a former co-worker, is that “October snow comes and goes, but November snow stays and grows” is usually correct.  Unless we have near-record cold weather the 2nd half of October, the atmosphere is just a bit too warm to give us a lasting snow base down below 6,000′ in October.

Chief Meteorologist Mark Nelsen

80 Responses to Fall Moves In Quickly!

  1. bgb41 says:

    10/6/2011 Oregon (All) Temperature Summary

    High:68 at CW5925 Coos Bay( 49 ft) & CW6568 Charlesto(38 ft) & KF7MWX Gold Beac(52 ft)
    Low: 54 at Clatsop Spit(30 ft)

    High:31 at FISH CREEK(7900 ft) & HOWARD Mt Howard(8150 ft)
    Low: 15 at Horse Ridge (US (4160 ft ) & CABIN LAKE (4560 ft )

    Largest Diurnal Change: 36 degrees
    Horse Ridge (US (51/15 ) (4160 ft )
    CABIN LAKE (51/15) (4560 ft)

    Heaviest Rainfall:
    1.20″ at EILERTSON MEADOW(5400ft)
    1.20″ at MOSS SPRINGS(5850ft)
    1.09″ at BLACK MTN RIDGE(4965ft)

  2. Muxpux says:

    Drizzly up here in Longview. Feels like the coast

  3. pappoose in scappoose says:

    Sure way to get a racing heartbeat:

    Lightning hits tractor driven by Molalla man

    By KGW Staff
    updated 10/6/2011 3:48:36 PM ET

    MOLALLA — A man suffered a racing heartbeat after the tractor he was riding on was struck by lightning early Wednesday evening.

    The lightning strike was near Toliver Road, west of Highway 213, according to the Molalla Fire Department.

    The man, whose identity was not available, drove himself to a fire station in another vehicle. After a check by firefighters, he drove himself to Willamette Falls hospital in Oregon City.

  4. bgb41 says:

    Low of 22 @ Sunriver Airport this morning. Yesterday ended up Partly Sunny breezy and 45 for a high. Today the clouds have wrapped around from the north and its a disappointing overcast day here in Bend with 50 degrees.

  5. Garron says:

    …and sometimes that November snow has to last well into February until we get a decent enough pattern of cool + wet, like the last few years. We had the best powder ever last year, that didn’t occur until nearly March! Early snows don’t guarantee a long stable season on the slopes around here.

  6. pappoose in scappoose says:

    Looks like we’ll need the thistle color (Brisk Wind Advisory) on the map come Monday:

    National Weather Service Portland or
    855 am PDT Thursday Oct 6 2011

    A stronger front will approach Sunday night and bring more substantial precipitation and breezy winds Monday.

  7. I’m at 1.01″ of rain for the first 6 days of the month. That’s pretty good. I’m done watering for the year, and I did turn on the heat for the first time this morning.

    At least my water bill will be going down because I know which way the gas bill is headed…

    Currently 49.1

  8. pappoose in scappoose says:

    Radar news. Forget about watering your garden:


  9. PaulB/Eugene says:

    High today in Redding CA was 58F…that is 26F below normal…there were severe thunderstorms with >1inch hail near Chico.

  10. PaulB/Eugene says:

    Models still indicating new trough establishing over region during day 6-10 time frame…although now with more onshore flow, moisture…less likely to get frost…Molson Light to stay N of border until at least after day 10.

  11. PaulB/Eugene says:

    Looking at 500mb GFS ensemble means…for the 12 hour forecast…the coldest/deepest 500mb anomaly in the entire northern hemisphere is right over Coos Bay at -333m.

    As for 850mb temps..the greatest departures from normal are actually over CA/NV….getting two feet of snow at Mammoth…they did not close last ski season until ? July. Short summer there too.

  12. My high today was 53.7…and that was at 12:05 this morning. This is my coldest high since May 29th.

  13. Timmy_Supercell (Klamath Falls @ 4200') says:

    I had a comment awaiting moderation for several hours, so for those just now checking in…. I posted below Ben J. Randall @ 3:26 PM. Lots of links to pictures 🙂

  14. runrain says:

    Unrelated but sad to hear of Steve Jobs death at 56.

    • MamaReen says:

      Funny how many of the comments below have iPhone mentioned in them…he was a trailblazer.

  15. thejory (Sandy) says:

    I notice that Barrow, Alaska is cooling down quickly. Quite cold up there already.

    436 PM PDT WED OCT 5 2011

    436 PM PDT WED OCT 5 2011






  17. Timmy_Supercell (Klamath Falls @ 4200') says:

    Okay how is it that this tiny cell on the KMAX radar…..

    Shows up as this??? (this looks more intense than most thunderstorms ive seen)

    http://oi51.tinypic.com/oielht.jpg (Intense graupel storm nearby)

    http://oi56.tinypic.com/1zqc1eh.jpg (Nothing like this shows up on radar!)

  18. ThunderCloud - North Plains says:

    It’s really dumping rain right now here in North Plains.

  19. well, it turned out pretty good. need to fiddle with my settings, took it with my Iphone 4, but the quality is poor. not sure if thats the program i recorded with or the compression in sending it to youtube.

  20. gnarly downpour rolling through Longview rightnow. timelapse is rolling, though im afraid rain on the window might blur it.

  21. Any suggestions for weather stations

  22. boringlarry says:

    …ripplebrook weather as long as I’m here, probably thru March:


  23. boringlarry says:

    …days on end of giant kptv/kpdx mugs of coffee..staring at the calendar with my autographed Stephanie picture above it…waiting…waiting…got to sell candy bars and coffee..cant close the store yet………but wait…where’s that giant pizza….axe??…axe??……..
    ,,,Here’s Larry………

  24. A decent amount of lightning is showing up off of the coast.

  25. Another dusting of snow at Timberline this morning:

  26. Timmy_Supercell (Klamath Falls @ 4200') says:

    Had lost power for nearly 45 minutes from 2:30 am to 3:00 something this morning…. Had wondered if it was weather related but found out it was just the homes here acting strange again. I began remembering that my house does this at least 2-3 times every week at this time of year. Typical and I better get used to it 🙂 we must have weak power here in Klamath

  27. PaulB/Eugene says:

    With things looking cool for the western USA…with cool anomalies extending well down in to California, for what may end up being a better part of the month of October, it does increase the odds of a mild November, before temps may return below normal later on in December.

    As Mark mentioned, even if snow falls down to pass elevation later this month, it more likely than not may not stick around for more than a few days.

    Even though there is optimism that we may have at least better than usual odds for periods of snow/cold weather at some point this winter, I am betting that ski areas may open later than usual. Timberline/Meadows may be fortunate to open by the last week of November, and am betting on them not opening until the first weekend of December. Ski Bowl may not open until 2nd weekend of December or later.

    After that, it will be a great ski season…I think…although at some point it may be just be too darn cold to ski……don’t think people will mind if that happens.

    Who knows…

    • Pete says:

      How does a cool October increase the odds of a mild November? I’m not arguing that it doesn’t, I just don’t understand the science.

    • PaulB/Eugene says:

      When you plug in the years with the coldest Octobers into the NCDC Climate Map generator


      and look at what the average Nov temps were, you will see that there is some correlation of colder Octobers with warmer Novembers in the western USA.

      I am not sure why that is, but if you imagine a month in October where the westerly jet is established over the PacNW early, then you lose those warm October days with 70s, etc for highs, so the average temps go down (although fall days with warm afternoons often have offsetting cool nights). The same pattern continuining into November may keep things relatively mild for that month. Remember that clear sunny days in November west of the Cascades are really just clear overhead with low clouds, fog, inversions, so temps down low may be lower than they would be in mixed atmosphere.

    • Pete says:

      Back from a couple of days away from the Internet…. Thanks for the reply, Paul. That makes some sense. Will be interesting to see how things unfold this year.

  28. Dave South Salem 500' says:

    nice heavy band of rain just arrived in the valley and is soaking us hard.

  29. boringlarry says:

    so….armed with a DIAL-UP connection, my reports and such this winter are originating from Ripplebrook Ranger Station, up the Clackamas, at an elevation of aprox. 1800ft…maybe, just maybe, i’ll have some nice snow reports and photos to share, along with my inspiring 🙂 haikus…it’s going to be a grand winter, i can just feel it…or is that grandpas rheumatism kicking up in this wet weather?..

  30. Ken (S. Salem 500ft) says:

    Great update Mark. Thank you for taking the time to post this. I will miss the 3 weeks of Summer we had this year.

  31. Mike near Clackamas Town Center says:

    It appears that Portland won’t reach 70F the rest of the fall…The pattern this month is definitely beginning to look like La Nina. Not seeing any blocking ridge over Greenland is also encouraging to see as well 🙂

  32. I just sent final approval for my calendars to the printer. I received a better price so instead of $15/each they will be $12 each! Yahoo! I know we are all in an economic downturn so buy a calendar so you know when that next unemployment check comes in!

    I’ll have a table at the October 29th OMSI “What Will The Winter Be Like?” AMS meeting so you can buy it there or e-mail me for more information!

    Here is the link to the calendar photos:


    Ok end of internet ad 😉

  33. PaulO says:

    Now that’s an update! 🙂

  34. Austin (Cornelius) says:

    FIRST!!!!!!!!!! 😀

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