Snow pack data points to better than expected

Discussion in 'Fly Fishing Forum' started by Lex Story, Apr 6, 2013.

  1. Lex Story

    Lex Story Angler, Gastronomist, Artist, Jarhead, Geek

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  2. Golden Trout

    Golden Trout Active Member

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  3. Lex Story

    Lex Story Angler, Gastronomist, Artist, Jarhead, Geek

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    Please resend link. It doesn't work for me in its current format
     
  4. Richard Olmstead

    Richard Olmstead BigDog

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    There is an interesting caveat to this report that isn't mentioned, but affects one's perspective, if this is something you have followed over the years.

    Every 10 years NOAA recalculates what is 'normal' to the most recent 30 years of records. So, the 2011-12 winter was the first calculated under the 1980-2010 snowpack data. Throughout much of the west, including the PNW, the 2000-2010 snowpack was substantially lower than the 1970-1980 data. This means that the 112% of 'normal' snowpack this year, might have been closer to 100% of normal 2 years ago, because 'normal' has shifted to a lower baseline.

    With global warming, that baseline is likely to continue to shift downward. So, when old timers (I guess I'm getting pretty close to this myself) say that this ain't nuthin' compared to what it used to be, even though the snowpack reports are saying greater than average snowfall, there's an explanation that isn't just foggy memory.

    Dick
     
  5. Old Man

    Old Man Just an Old Man

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    As I look around the mountains here in Dillon I don't see much in the way of any snow left. Only the high peaks have some snow left. The ones about 9,000'.

    Don't look for the rivers to have much left running down hill in the late summer.
     
  6. Brookie_Hunter

    Brookie_Hunter aka Dave Hoover

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    Very interesting Dick, thanks for providing that important subtlety. I guess it's similar to how the national unemployment figure continues to shrink....because the denominator (e.g. number of people in the work force) keeps getting smaller.
     
  7. Lex Story

    Lex Story Angler, Gastronomist, Artist, Jarhead, Geek

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    My mistake Golden trout. I was trying to access the link you posted via my Kindle Fire and the OS it could not process the PDF document. I am able to see it now on my PC.
     
  8. freestoneangler

    freestoneangler Not to be confused with Freestone

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    Why would NOAA do that?
     
  9. Golden Trout

    Golden Trout Active Member

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    Thank you Dick. Very well put. We must be ever vigilant when it comes to "average", "normal", "natural", etc.
     
  10. cabezon

    cabezon Sculpin Enterprises

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    How far back would you like the baseline to go? If you go back 20,000 years ago, then this year's snowfall is way below normal because all of Puget Sound was under a mile of ice.....

    I am surprised that NOAA does not use a running average of the previous 30 years: drop the oldest year and add in the last year. That would produce a smoother comparison. Also, one needs to consider long-term weather forcers, such as the frequency and intensity of El Nino / La Nina events as well as longer-term cyclic phenomena.

    Steve
     
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  11. Richard Olmstead

    Richard Olmstead BigDog

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    I don't know why NOAA doesn't do a running average; one would think that would be easy enough.

    Here's a link to a short piece on this subject from the High Country News a few issues back. This may be behind a paywall; sorry if that's the case (but you all should be reading the High Country News, anyway).
    http://www.hcn.org/issues/45.2/a-new-normal-for-snow

    Let me see if I can copy/paste the graphic into this reply.

    image.jpg
     
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  12. cabezon

    cabezon Sculpin Enterprises

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    Hi Richard,
    Thank you for sharing that article and especially the graph. That highlights the issue very nicely. The "new normal" peaks about 5 inches (85%) lower than the "old normal".

    Steve
     
  13. freestoneangler

    freestoneangler Not to be confused with Freestone

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    Well, excluding that data (Puget Sound under a mile of ice) sorta skews the facts a bit don't you think? Seems a bit odd to call something the "new normal" and selectively decide what parts of history we use to compare to the old normal.
     
  14. cabezon

    cabezon Sculpin Enterprises

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    I don't know enough about meterological history to know why 30 years should be the magic number. From a purely statistical sense, 30 years does give one enough data points to smooth out typical year-to-year variation (such as an El Nino year or two). Do you have a recommendation for a better standard? Five years?, Two years? 100 years? Of course, an alternative is to ignore the comparison totally and just use the raw numbers for snowpack (e.g., cm or inches during the season). But those are less valuable for the general public without any context, hence the standard for "normal snowpack". "Oh, last year we were 125% of normal and the high lakes weren't accessible until August." Or "Oh, last year we were 75% of normal and the rivers dropped into shape very early."

    Steve
     
  15. Richard Olmstead

    Richard Olmstead BigDog

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    In addition to Cabezon's reply, I suspect that there are some changes to the number and placement of snowpack measurement stations from time to time, so while estimates of snowpack from individual stations could be kept (and no doubt are) over longer periods of time, estimates of river basin snowpack might change as the location and number of stations change, giving rise to some discontinuity in such aggregate estimates.

    Dick