Terrain Height v's forecast height

  • Hi - Clarification please on the effect of terrain height versus 'forecast' height. I would like to know with the forecast setting at 'surface' - is this ground surface regardless of terrain height or do I need to set the terrain height in the forecast height to get the correct reading?

    I hope this makes sense.

    Thank you

  • Moderator

    "surface" refers to weather model's lowest layer (orography).
    For locations over the sea or over plains (flat country)
    model's surface is the same with elevation.
    For locations over mountains (especialy for steep mountains) model's orography may differ from the actual elevation. The reason is that model's orography is the average elevation for each grid square.
    In general, the smallest the grid the gratest the accuracy.

    See also "Weather Model Accuracy"
    in http://www.onthesnow.com/news/a/584862/how-do-weather-models-work-
    and "Orographic adjustment of local weather forecasts"
    in http://www.metoffice.gov.uk/guide/weather/local-weather

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