When Will It Rain?

I’ve heard the quote today that the dryness outdoors right now is a “once in a lifetime” experience for this time of year.  That’s not too far off.  Take a look at the driest 3 month periods on record at PDX:

This July-September IS the driest 3 month period ever.  Now we are seeing no rain through at least the first 10 days of October (next Wednesday) and possibly longer.  In 1952, it was drier in May & June.  Remember this year we saw our 2nd wettest June.  In 1967, the autumn rains hit and hit hard the last couple days of September.  October was a soaker.  1991 is quite a good match to this year’s weather with wet May and June, then extremely dry the rest of the warm season.  So we’ve only seen such a combination of dry late summer and a total lack of early Fall rain in 1991 and 1952.  Twice in 70 years; that’s very rare. 

In every other year we see SOME sort of wetting rain at SOME point between late August and early October.  That didn’t happen in those two years and now this year.

So what happened in some of those extremely dry late summers?

1952:  It remained generally dry all the way through November!  BUT, some light rains arrived starting around October 20th.  That would have been the end of any fire danger.

1967:  Already mentioned this above, but after a scorching hot summer and 71 day dry spell (Portland’s longest) it started raining the last few days of September.  October was a big soaker through the whole month, memories of the summer heat and dry weather disappeared quickly.

1991:  Mainly dry until the first cold and wet weather system arrived around the 20th.  I remember this year since I was fresh out of college and it was my first Fall/Winter to forecast.  Snow levels dropped down around 2,000′ the last few days of the month and there was even sticking snow on Halloween up around Boring, Sandy, and the foothills of the Cascades.  Most of the rest of the winter was boring, but that’s another story.

So most likely we’ll see some sort of rain show up during the 2nd half of the month.

Chief Meteorologist Mark Nelsen




So what happened in those other dry

51 Responses to When Will It Rain?

  1. East wind is ripping along pretty good now. I’m gusting to 33-38mph now and Larch Mtn(Washington) is gusting over 50mph.

  2. Steve Pierce says:

    ** Update: Columbus Day Storm Commemoration **

    One week and counting! Are you ready to “relive the storm” next Saturday (October 13th) at 10 AM at OMSI? How about being the lucky raffle winner of a $300 Davis home weather station? Spread the word and get there early if you want a seat. Max capacity is 300. For complete details on this great public meeting along with a list of expert guest speakers and presentations, please see: http://www.ametsoc.org/chapters/oregon/.

    See you all there!

    Steve Pierce
    Oregon AMS President

  3. W7ENK says:

    Highly unlikely, I know, but I wonder if it isn’t possible that we make the switch from a warming “summer”-like East wind with highs in the mid/upper-70s to the frigid “winter”-like East winds with highs in the low-30s (or even upper 20s) — without any precip, or even clouds for that matter. Wouldn’t that be strange?

    I get the feeling we’re almost on the edge of that now…

  4. runrain says:

    Pretty cool out at PDX this morning during my jog. 14 fighter jets took off eastbound within a half an hour. Six were our own F-16s and the other eight must’ve been visiting aircraft. Not much wind out there. As I understand it the east wind diffuses quite a bit out there and doesn’t seem to affect PDX that much.

  5. W7ENK says:

    1117 AM PDT FRI OCT 5 2012


  6. Joshua in Lake Oswego says:

    12Z GFS brings the pattern change back next weekend with some decent rainfall. Please let it be!

    • W7ENK says:

      Flip-flop, flip-flop, flip…

      Welcome to the Lala Land Rollercoaster, the Winter 2012 Wishcasting Train is now boarding! 😆

      The 00z Operational will show 0.00″ precip again by tonight’s run, just watch.

  7. I had dropped down to almost 54.0, but now back up to 56.8 ^rising as east winds have developed again.

  8. Latest CFS forecast for Nino3.4

    We’re now roughly around a +0.3 anomaly, so a very weak El Nino at this point. We only are projected to peak around +0.5 November through December before diminishing again throughout the Winter months to a flat Neutral reading. Also worth nothing Jan-Feb several Ensemble members now dip into the Nina range. Hmmm…

  9. W7ENK says:

    In looking back at the last several months, I see that I’ve only had 0.08″ of rain in the last 93 days. Chances are I’ll make it to 100 days before I see my next measurable rainfall.

    My grass is crunchy under foot.

  10. I’d do the analysis if I I had the tools… But I bet analogs of bone dry October + cold PDO + neutralist ENSO will be of interest

    • David B. says:

      I do not believe if this October will be “bone dry” (no precip), just “dry” (below normal precip, the normal fall/winter rains not really kicking in until some time next month). No rain for a whole month would be very unusual for this time of year, perhaps unprecedented. Even the previous years that match this year’s ENSO-PDO configuration had _some_ rain in October, I believe.

    • David B. says:

      BTW, the preponderance of previous neutral-to-weak-El-Niño/cold-PDO winters had drier-than-average falls with rainy seasons that started late, but which had ample and vigorous rainfall once they finally began. That’s what I’m basing my expectations for this year on.

  11. bgb41 says:

    Incoming ‎00z GFS – Just took away all the precip for the next 16 days .. Bone dry!!
    This could be an unprecedented situation developing.

  12. http://io9.com/5948859/weve-finally-figured-out-what-these-strange-breast+shaped-clouds-mean

    anyone else know that Mammatus clouds mean “breast clouds” and they only form when a T-storm is weakening?

  13. bgb41 says:

    10/4/2012 Oregon (All) Temperature Summary

    High:88 at ILLINOIS VALLEY(1389 ft) & MERLIN SEED ORCH(1064 ft)
    Low: 58 at ROSLDG Rose Lodg(236 ft) & SQUAW PEAK(4964 ft)

    High:35 at HOWARD Mt Howard(8150 ft)
    Low: 12 at FOSTER FLAT (5000 ft )

    Largest Diurnal Change: 59 degrees
    Beatty (74/15 ) (4320 ft )
    KLAMATH NWR (74/15) (4531 ft)

  14. paulbeugene says:

    Already 42F in Shelton. Should be a frosty Friday morning for them , low perhaps a few degrees colder, ? 26F
    Still 55F here at my house in Eugene. Still looking for mid 30s.

    As for fall/winter weather…..it could well happen that we will get more rain in 3 days then we have gotten in the last three months. Question is when are those three days going to happen. Euro model showing renewed ridging over western US toward day 10.

    Sea surface temp positive anomalies have shifted toward NW Pacific off Japan, while the persistent positive anomaly blob N of Hawaii has noticeably weakened…..perhaps that portends a break through of strong westerlies across the Pacific later on as we get to last week of Oct/first week of Nov, perhaps more than what we saw last fall/first half of winter.

    There should be a cinnamon roll before Thanksgiving, hopefully not just in Starbucks.

  15. Saw frost in a few places the last couple mornings with temps down to 36 in a few spots west of Corvallis. Can we call this Indian Summer yet?

  16. W7ENK says:

    When will it rain?

    NEVER AGAIN!!! Muhuhwahahahahahaaaaaaa!!! 👿

    Milwaukie’s anti-weather glass dome has grown and strengthened, it now encompasses ALL of the PNW, and has pushed out ALL forms of precipitation… FOREVER!!! :manaical laughter:

    No, seriously though, as I said earlier, I (wish) what we’re experiencing is unprecedented.

    • W7ENK says:

      Or maybe this is another one of those
      “after October 20th” years?

    • David B. says:

      _Some_ rains starting by the end of the month are a good bet, though as I wrote on an earlier thread I think it will be some time in November before the rains kick in in earnest.

  17. I’m loving the lack of rain – haven’t had to mow the lawn yet. I have noticed, however, that the leaves on the oak in the backyard are still all green. Mark, perhaps a follow-up on “how late the leaves turned” by year? 🙂

    • Mark Nelsen says:

      You’d have to talk to botanists on that one. Although it seems to me that generally it’s about the same time each year regardless of the weather conditions.

    • W7ENK says:

      I think Larry’s asking you to foot the research, Mark…?

    • Timmy_Supercell (Hillsboro, OR) says:

      Mark I thought you knew “everything!” O_O

    • i work for a landscaping company, and while its nice to not have to mow right now, it hurts business, very few people around here run irrigation (surprise!) so a LOT of yards are “dead”. leaves are starting to be a problem, but i believe that has more to do with the lack of sunlight this time of year. though early frosts and other factors can quicken the changeover.

  18. Timmy_Supercell (Hillsboro, OR) says:

    When will it rain? When Fall begins.

    Its still Summer…. (tsk, tsk, tsk)

    • Timmy_Supercell (Hillsboro, OR) says:

      I bet Karl has been running around having all sorts of fun lately! 😛

  19. IceCold says:

    Snowstorm on Dec.17th……take it to the bank!

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