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Thread: higher summits forecast vs valley forecasts

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  1. #1
    Join Date
    Jul 2009
    Concord, NH
    Thanked 4 Times in 2 Posts

    Default higher summits forecast vs valley forecasts


    I've noticed that the weather forecast for the higher summits (thank you for this service!) Is only for today through tomorrow, where as the forecast for the valleys goes for several days.

    Why the discrepancy? Is it due to the unreliability of mountain weather? or something else?


  2. #2
    Join Date
    Mar 2010
    Taunton, Ma
    Thanked 112 Times in 72 Posts


    I'm sure one of the MWO Staff will chime in on this thread with greater detail. But, as far back as I can remember this is how the forecast has always been posted. Whatever the reason it works for me...

    Forecast period
    5 days - Valley
    36 hrs - Summit
    Club Member, Mt Washington Observatory
    ~ Everything happens in it's own time ~

  3. #3
    Join Date
    Aug 2007
    Mount Washington, NH
    Thanked 110 Times in 42 Posts


    Good afternoon David-

    You pretty much nailed the answer on the head. The summit weather compared to that of the valleys if much more variable and it was found through a statistical analysis 36 hours out on the higher summits was the most accurate window for forecasting with any sort of reliability. But a shorter time scale in general is far more accurate than any long term forecast. I could go on but I think referring you to a book would be a bit better. One book I like is the Essentials Of Meteorology: An Invitation to the Atmosphere by C Donald Ahrens which luckily is online. The pages you would be interested in are here: It is very informative and will give you a better idea why we limit our forecasting to the 36 hour window on the summit. If you have any further questions after reading the passage, please let us know and we will try and follow up.
    Ryan Knapp
    Staff Meteorologist/Night Observer, KMWN (Mt Washington Obs., NH)

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