Page History

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• comparing analyses of temperature, dewpoint dew point and soil moisture with observed data
• assessing future "background" conditions and the potential impacts thereof (e.g. snowfall or cloud cover that might be different from atmospheric model predictions).

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• comparing analyses of temperature, dewpoint dew point and soil moisture with observed data
• assessing future "background" conditions and the potential impacts thereof (e.g. snowfall or cloud cover that might be different from atmospheric model predictions).

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• too little snow-cover and/or too much cloud is analysed then there is a risk forecast temperatures may be too high and humidity too low.
• too extensive snow-cover and/or too little cloud is analysed then there is a risk forecast temperatures may be too low and humidity too high.
• in light winds, humidity over snow and water surfaces is likely to be rather higher than shown in background or forecast fields, particularly where flooding or with melting snowfields.
• the boundary layer structure is not successfully analysed then there is a risk forecast temperatures may correspondingly be in error.
• winds are too strong or too weak then forecast temperatures may have larger errors (particularly at high latitudes in winter where the role of insolation in offsetting radiative cooling is minimal.

Other errors in near surface Temperature and

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dew point

Errors associated with thick fog.

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The right panel shows that on this occasion the magnitude of the dewpoint dew point errors was even larger overall.   Again there are many possible reasons, but one candidate would be mishandling of moisture fluxes to/from the surface.  In turn these could relate to soil moisture errors, or errors in handling the biology of evapotranspiration.  

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 Fig9.2-5: Soil moisture 00Z 11 June 2017.  It is possible that there was too much moisture in the soil (yellow) when more arid conditions (brown) would have been more appropriate as suggested by the observed lower dew points during the day on 12th June  in Fig9.2-4.  Dew point errors are more likely to be indicative of soil moisture errors during the day, because there is much more convective overturning then. Conversely night-time dewpoint dew point errors could be much more a function of very local effects - e.g. proximity of a lake or river.

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• comparing analyses of temperature, dewpoint dew point and soil moisture with observed data
• assessing future "background" conditions and the potential impacts thereof (e.g. snowfall or cloud cover that might be different from atmospheric model predictions).

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