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Note: The Ensemble Control Forecast is identical to Ensemble Control Forecast (ex-HRES) output in Cycle49 and HRES output in earlier cycles.  They have the same resolution and are scientifically, structurally and computationally identical.  Ensemble Control Forecast output, Ensemble Control Forecast (ex-HRES) output and HRES output are fully equivalent where shown in diagrams.  At the time of some older diagrams, HRES had resolution of 9km and ensemble members had a resolution of 18km.

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This product shows the 10-day evolution of three parameters: 850hPa temperature, 6h precipitation (up to the time shown) and 500hPa geopotential height for user-defined locations during the 10 days of the forecast.   Lines show the evolution of the medium range ensemble (dotted for each individual ensemble member, solid for Ensemble Control Forecast ).  Shading (for temperature and height only) denotes the probability that the value of the variable will fall in a particular range (see panel titles) at a given time.

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Fig8.1.6-5: An example of uncertainty.  850hPa temperature plumes for Reading, England from ensemble runs of 00UTC 31 Aug, 12UTC 1 Sep, 00UTC 3 Sep 2018 in association with uncertain forecasting of a cut-off low moving southeast across Britain.  Large and even multi-modal spread in the plume is evident on the forecast based on 00UTC 31 Jan, but the spread becomes much more narrow by the forecast from 00UTC 3 Sep.  Cut-offs tend to be difficult for models to forecast and consequently users should consider the consistency of the model evolution. The blue lines are for cross-referencing; they denote the same dates and values on each panel.

(FUG Associated associated with Cy50r1)