Water Year Ends Slightly Wet

Thursday should be the warmest day in 3+ weeks here in the Metro area with temps at least in the mid 80s, possibly upper 80s in a few spots too.  The 00z Salem sounding was up to +18 deg. C. at 850mb and models forecast a +20 to +22 by tomorrow afternoon/evening.  Then we add a good 4-5 millibars easterly gradient (it was flat today) through the Columbia Gorge and over the Cascades.  That should give us far better surface heating, all the way out to the North Coast.  We’re going for 84 degrees at PDX, but I think anywhere between 83 and 88 is possible.  88 IS the record for the day at PDX too.  A nice, warm (and dry!) end to a strange month.

So what is a “Water Year”? 

Quite a foreign concept to any normal person, but let me attempt to explain…

Here in the Pacific Northwest a vast majority of our yearly precipitation (rain and snow) comes from Pacific frontal systems that move in regularly during the cool season; that would be October through March.  In other parts of the country (especially east of the Rockies) it’s the opposite; most rainfall comes from summertime thunderstorms or active frontal boundaries in the warm season.  Generally winters are the dry season in those areas.

So if you want to measure how much precipitation fell each “rainy season” , it doesn’t do you much good to measure the calendar year rainfall.  It makes more sense to start the “Water Year” at the beginning of each rainy season.  Most meteorologists in our area use October 1st as the start of that year.   Sometimes September 1st is used instead.

Tomorrow will be the end of the 2009-2010 water year.  Now this year is a bit strange because we had such a huge amount of rain in May and June, plus September to a lesser extent.  It was actually a pretty dry “wet season” due to the El Nino conditions last winter, but our water year number was salvaged by the wet Spring and early Fall.  So we ended up slightly above average.   Most of the Pacific Northwest was above average as well.  Notice that only 3 of the last 10 years have been at/above average…seems as if the first decade of the century has been a bit drier than normal.

Chief Meteorologist Mark Nelsen

57 Responses to Water Year Ends Slightly Wet

  1. W7ENK says:

    September’s over, the water year’s over… FWIW

    September 2010 ~ Rainfall Summary
    Date Daily”

    09/01 0.04
    09/02 –
    09/03 –
    09/04 –
    09/05 –
    09/06 –
    09/07 0.54
    09/08 Trace
    09/09 –
    09/10 –
    09/11 –
    09/12 –
    09/13 –
    09/14 Trace
    09/15 0.12
    09/16 0.25
    09/17 0.21
    09/18 0.70
    09/19 0.08
    09/20 0.04
    09/21 –
    09/22 –
    09/23 0.05
    09/24 –
    09/25 –
    09/26 0.08
    09/27 –
    09/28 –
    09/29 –
    09/30 –

    Monthly Total: 2.11″

  2. W7ENK says:

    [Milwaukie] 9/30/2010
    87.6°F High
    53.2°F Low
    NE 14.5 mph at 2:52p

  3. Crazy thermal trend at Red Mound last 24 hours


    Low of 82 last night, then temp dropped to 68 at 10:30am this morning, then it jumped up to 86 again at 2:30pm, and then finally plummeted to 60 at 5:20pm with strong south winds 23mph. Now its foggy and 55 at 9:30pm with gusty south winds at 23mph. What a roller coaster.

  4. Tyler in Hazel Dell says:

    A wide variety of temps and dewpoints right now.

    68/60 here, while some areas are still in the upper 70s with dewpoints in the low 50s.


  5. HIO Phil (Punxsutawney) elevation 189' says:

    There’s some really nice high altitiude cumulus around town right now. Maybe some true cirrocumulus. Sunset may be quite nice here in a few minutes

  6. Kyle says:

    Sorry for double posting. It said “Your posting comments too quickly” on my very FIRST and I mean F-I-R-ST post. 😦

  7. W7ENK says:

    Oooh! Anyone headed to Gliese 581g? I need a ride.

    ‘100 percent’ chance for life on newly found planet?

    I’ve had enough of this whole “Earth” thing… 😛

    • Garron near washington square says:

      How’s the weather doing there this time of year? I’ve got a whole bunch of vacation time saved up and a bunch of frequent flyer miles to use, so ready when you are…lol.

    • Kyle says:

      They better have lots and LOTS of snowy places!

    • Kyle says:

      It better have lots and LOTS of snowy places!

    • W7ENK says:

      I guess the planet’s orbit is tidally locked, meaning it’s rotational period and it’s orbital period are equal. This means that one side is ALWAYS facing the star, and the other side is always facing away (like the Moon). So, I’d imagine there’s a TON of snow and ice on the “dark side”. 🙂

  8. W7ENK says:

    ‘Tis a beautiful day in Clackamas, light east winds indicated by the way my Doug Flag is pointed due west. No idea on the temperature, I’ll have to check that when I get home, but I’m guessing it’s probably about 83-ish right now.

    Lovin’ this weather! 🙂

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

    Figured we are close enough to the season for this one :):

    • Josh "The Snowman" From Everett, WA says:

      This video always makes me do this:

    • The Salmon Killer says:

      Josh, yes the killer is back. Were not quite close enough for that yet though I dont think. Give it two more months coaster

    • pappoose in scappoose says:

      Hahaah! Preview of coming attractions?

    • W7ENK says:

      Gah! This video always p!$$3$ me off… That driver kept punching the gas, all that damage was totally deliberate. I hope they lost their licence! >_<

      Honestly, had he hit my car, I'd probably own his house by now. What a dumb@$$.

    • Garron near washington square says:

      I’d love to see that video in an insurance commercial. I think people might actually watch this one…

  10. muxpux says:

    first to clear out yesterday, last one today. so much for sunshine and 80+ degrees today here in Longview…

  11. Punxsutawney (aka HIOPHIL) at work by Sunset High elev ~280' says:

    12z GFS

    Has 0 degree 850mb temps early next week, and < 540dm thicknesses for the first time this fall. Looks like fall Sunday through Tuesday. The extended long term has no temps above 70.


  12. Only 63.2 here at 11:45am and yet its 80 at Larch Mtn.

    Hope the easterlies break through soon here.

  13. WEATHERDAN says:

    What a nice reprieve we have early this fall. I thought we were going to have an early start to the rainy season. Now even going to the first half of October the weather pattern looks reasonably nice. I’m not in a giant hurry for this nasty La~Nina Winter to get here. The cold rain and snow will be here before long so I’m going to enjoy the nice weather while it’s here. By the way our first reasonable chance at snow down low is only about 5 weeks away. Let’s see what happens this year. See you at OMSI for the Winter weather forum on 10-16-2010 at 10 AM.

  14. …i think i have a problem…i was walking thru a field of perfectly green tomatoes when…i don’t know, they must be rotting or something, because there’s this odd red color starting to show up…..

    • Aleta-West Gresham says:

      Isn’t that wonderful!! 😉 Got my first decent pick of cherry tomatoes yesterday.

    • Runrain says:

      I’m getting that too, now, mostly on the larger tomatoes. The cherry tomatoes are doing ok though.

    • Garron near washington square says:

      Yeah, and that funny yellow orb…in the sky? Every time it hits my garden for a day or two, the same thing seems to be happening to me too…IT MUST BE A SUNSPIRACY???? Me so happy toooooo! Ripe veggies better late than thrown away. Note to Santa….GREENHOUSE PLEASE.

    • Boydo3 500' North Albany says:

      the bad news it’s about done. over. fini!
      I’ve got tomatoes rotting before the turn red.BUT! My broccoli looks great and the brussel sprouts are coming along just fine.

  15. RobWaltemate says:

    3 Mile N Long Beach WA
    6:30 low out side temp since mid night 48.0 DP 46.4
    pressure has dropped about 0.1 since 00:00 to now
    and what little breaze we got was NE, which I think is a bit odd for this time of year.

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

    Offshore gradients have increased nicely over the past 6 hours.

    Pressure Gradients
    As of 6 AM
    PDX-DLS: -3.0mb
    TTD-DLS: -3.7mb
    OTH-GEG: -7.2mb

    Easterlies should develop at Troutdale/Gresham before 7:00 AM.

  17. Karl Bonner says:

    I posted a question in the “Amazing Dewpoints” thread that never got answered in any way. It’s not usually a good idea to post it a second time, so I’d like to draw attention to the first time. It’s the newest of the comments. I’d appreciate if someone took a look at that post and provide whatever knowledge they may have.

    • Rob "Wrath" S.E. Portland says:

      Karl, I just read your post. Definitely logical and reasonable to suggest we could have been warmer perhaps upper 80’s? ….

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

    Anyone see tonight’s 00z EURO? 😀

  19. I just crunched all the precip numbers for BG Lake. Here are my water year totals from Oct 1 2006 to Present.

    Water Year = Oct 1 to Sept 30 each year

    2006-07—> 60.58″
    2007-08—> 49.29″
    2008-09—> 44.42″
    2009-10—> 52.43″

    4 Year Average —> 51.68″

  20. W7ENK says:

    Interesting pattern. Also notice that the overall trend is gradually leaning toward wetter… I wonder if that will continue over the next decade?

    [Milwaukie] 9/29/2010
    76.7°F High
    58.5°F Low
    NE 8.3 mph at 3:12p

  21. Curry County Map at 11:45pm

    I have circled 2 stations which are at 86 degrees right now on this map.

  22. Kyle says:

    No Duh Mark. I have been telling that on this blog for quite some time that we have had the false hope “weather curse”.

  23. Derek Hodges says:

    This will be our more than overdue 40 inch water year. Calling it now.

  24. Mback says:

    Interesting to see every 4 years since 2002, just going off that graph, have been average or above. Interesting little pattern there.

  25. SilentReader says:

    seems like a defined pattern on that graph. Odd.

    • Rob "Wrath" S.E. Portland says:

      It does, doesn’t it? I’m sure the rises and drops correlate heavily with La Nina/El Ninos years too. Maybe someone can research that? Ummm Justin, Steve P., Jesse?

    • RobWaltemate says:

      I should calculate the standard devation before we get to excited about it, or at least the RMS. But to ignore it would be wrong too. How about a graph that goes back further?

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

    Yes, I do realize how unnecessary that was.

    Mark, thanks for the update.

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


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