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 Fig9.2.1-10: 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.  This is suggested by the observed lower dew points during the day on 12th June in Fig9.2-9.  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 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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Fig9.2-11: An example of possible connection between IFS forecast 2m temperature (here using forecast EFI as a proxy) and forecast soil moisture content.  EFIs lower than -0.8 suggest extreme low temperatures compared to the model M-Climate and appear to be associated with high soil moisture content.  During the period, surface ground moisture appears to limit the amount of diurnal surface warming.  As the soil is forecast to dry out during the period, the 2m temperature is forecast to become unexceptional.  The reasons IFS are showing the temperature and moisture differences and uncertainties in analysis and forecasts are not clear.  Possible causes: 

• Surface ground moisture limits the amount of diurnal surface warming. As the soil is forecast to dry out, the 2m temperature is forecast to become unexceptional.
• Vegetation could be greener and more lush after previous wet period, leading to lower 2m temperature and higher 2m relative humidity being observed and forecast.
• The observed temperature could be colder than the first guess and thus in the analysis cause wetting of the model soil (despite no precipitation) and a higher relative humidity.
• Evapotranspiration could be mis-represented.
• Diurnal influxes of moist sea air may not be well forecast either in depth or penetration.
• Insufficient information on atmospheric structure due to the lack of radiosonde . 

Users should assess the analysis of temperature and moisture in the area against observations, and modify forecasts accordingly.

Summary of Soil temperature errors:

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