How accurate is NOAA, really?

Discussion in 'All Things Boats & Boating' started by science abuse, Sep 2, 2011.

  1. science abuse
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    science abuse Junior Member

    So I've been watching their forecasting "tool" for a bit, and its eems like the kind of "round up", biasing the more dangerous side of their margin of error.

    Those of you who have been at this a while; how accurate does NOAA tend to be in their forcats?

    I've got a sailing trip that begins tomorrow, and they're calling for light variables. What are the chances that they'll be wrong in a way that helps me? :)
     
  2. jehardiman
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    jehardiman Senior Member

  3. science abuse
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    science abuse Junior Member

  4. CatBuilder

    CatBuilder Previous Member

    Mostly, I find the "round up" to be true as well, since their forecasts tend to be for maximum expected winds.

    I find them to be quite accurate though, once you have spent enough time looking at various NOAA pages, then actually getting out on the water.

    It's all about seeing the general patterns, rather than a snapshot of, say, 3PM, even though they do set up their forecasts with times such as 3PM. The NOAA information is just a guideline, IMO. You use it to figure out what is most likely to happen. Anything and everything can change the local conditions though - for instance - a set of mountains or hills funneling wind down to the sea when you are just offshore can take a moderate breeze and make it into a wind tunnel area where you have to reef or at least ease a sheet.

    It's best to use NOAA as a general idea (small craft warning is usually accurate, as are 5-10MPH wind days). Then, get used to the area you are sailing in and get a feel for the weather. Read the clouds. Know if the wind kicks up every evening as an onshore breeze. Watch the water and see gusts of wind coming.

    It's far more accurate to observe your local conditions yourself than to rely on a wide swath of a NOAA zone for your immediate weather.
     
  5. science abuse
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    science abuse Junior Member

    Couldn't agree more, unfortunately I'm at their mercy this time; I don't live anywhere near where I'm going.
     
  6. science abuse
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    science abuse Junior Member

    After this weekend, it appears the best solution is not bother checking the weather before your trip. Just ask the Harbormaster when you get there. He'll tell you someting different than the forecasting tools, and he'll be right.
     
  7. hoytedow
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    hoytedow Bananas

    If you are not checking the weather, please name me in your will before you go. :)
     
  8. science abuse
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    science abuse Junior Member

    I'll be sure to go into huge debt on a nice boat before I do. ;)
     
  9. jehardiman
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    jehardiman Senior Member

    Climate is what you expect, weather is what you get...And if you don't like the weather; wait 5 minutes.

    No forecast is ever correct, just like calling ahead doesn't work that well either.
     
  10. Poida
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    Poida Senior Member

    What you need is weather forecasting like we have in Western Australia.
    Typical Forecast:

    Fine with a chance of a shower.

    Winds 10 - 20 knots with possible gusts to 50 knots
    East to South East swing West to South West to West during the day.

    Temperatures Mid Twentys to Thirtys

    They are seldom wrong!:D
     
    Last edited: Sep 8, 2011
  11. Quatsino Boater
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    Quatsino Boater Junior Member

    I don't know if this helps, but I have a barometer on board my boat. i found this chart somewhere , I still can't rember where though. here goes:

    Barametric change in pressure

    1mb/hr----- strong wind force 6 to 7 -----22-33 knots
    2mb/hr----- gale force 8 to 9-----34-47 knots
    3mb/hr----- storm force 10to 11-----48-63 knots
    4mb/hr-----hurricane force 12 ------> 64 knots
    5mb/hr----- weather bomb

    So typically here the sea state is around 1 to 2 meters on any given day. I check the barometer every 45 to 60 min to see a trend. Usually around 1 pm local the wind will pick up fast and the sea state will go to capping 2 to 3 meters. I have a planing boat at the moment with a 20 + mile run back to my marina so I can get into our inlet and get out of a large fetch so choppy 1 meter will be the worst of it.

    I like the fact that I am getting local barametric readings around my boat and not some fixed location that can be far away and drastically different conditions.

    i hope this might help :)
     
  12. michael pierzga
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    michael pierzga Senior Member

    Met office or Noaa forecasts for oceanic sailing are very accurate. Inshore in areas with many geographic influences ineveitably cause discrepancies in computer models. For inshore work local forecasts are best.
     
  13. powerabout
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    powerabout Senior Member

    where do they get the data for offshore?

    Re barometer here close to the equator...they never work because the needles have all seized up
     
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  14. jehardiman
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    jehardiman Senior Member

    There is a whole range of data buoys, and then there are the ship reports, NAVMET flights, the EOS satellites with SAR, etc.

    Go here for the tip of the iceberg...

    http://www.ndbc.noaa.gov/
     

  15. powerabout
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    powerabout Senior Member

    nice link , thanks
    a bit thin in Indian ocean and around Asia
    I have been using the NOAA Gribs and wondered where the data comes from as they show many small pressure patterns and hence winds
    Maybe its commercial ship reporting data out here?
     
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