Page History

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• 15-day medium-range plot at 6hr intervals for:
  • weather (total cloud cover, 10m wind strength, 6hr rainfall total, 2m temperature).
  • waves (significant wave height, mean wave direction, mean wave period, and strength and distribution of direction of the 10m wind).  If no sea grid point nearby, only wind data is plotted from the nearest land grid point and the wave diagrams are empty. 
• 15-day extended-range plot at 24hr intervals for:
  • weather only (mean total cloud cover, 24hr rainfall total, mean strength and distribution of direction of the 10m wind, max and min 2m temperature).
  • weather only (as above) but also showing M-climate.

Note:

• The Ensemble Control Forecast  values are shown as a blue line on the 10-day ensemble meteogram. 
• The 15-day ensemble meteogram displays the probability distribution for each calendar day from 00UTC to 00UTC.  For forecasts with data time of 12UTC the first and last 12 hours in the forecast period are excluded and only 14 (instead of 15) daily distributions are generated. 

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Fig8.1.4-4: 10-day medium-range meteogram for Athens data time 00UTC 12 May 2017.  Solid blue lines are Ensemble Control Forecast .  The red numbers above the precipitation panel are the greatest precipitation value reached by any ensemble member.  Ensemble extreme values cannot be ignored as the evolution of every ensemble member is considered to be equally probable.  Note: Forecast temperatures at 00UTC, 06UTC, 12UTC, 18UTC are shown. 15-day meteograms show forecast maximum and minimum temperatures.  UTC is used exclusively in the meteograms. 

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Fig8.1.4-7: Illustration of the relationship between 10day ensemble presentation and 15day presentation (truncated to 10days for ease of comparison).

Note: HRES and Ensemble Control Forecast are scientifically, structurally and computationally identical.  With effect from Cy49r1, Ensemble Control Forecast output is equivalent to HRES output where shown in the diagrams.   At the time of the diagrams, HRES had resolution of 9km and ensemble members had a resolution of 18km.

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Data at the selected ensemble point is calculated using HTESSEL and FLake according to the proportions of land and sea cover within the surrounding grid point box (see examples below, or the Land-Sea Mask section for details).

Some influences of the adjacent sea areas or mountains may be over- or under-represented by the ensemble meteograms.  This can significantly affect the forecast parameter on the meteogram (temperature, wind, etc).    Users should assess differences in meteograms for coastal, island or mountainous regions.   In particular consider:

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Note: the so-called land-sea mask processing (where the land or sea nature of the source and target points was used to adjust the interpolation weights) used by the old ECMWF interpolation software scheme (called EMOSLIB) is not used by default in the new MIR interpolation package that was introduced early in 2019.

(FUG Associated associated with Cy50r1)