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The web site includes cluster products equivalent to Fig8.1.3.2 for each of the four predefined lead-time windows.  For additional information, the 1000hPa geopotential fields are also provided for each ensemble scenario to show the corresponding near-surface evolution.  Users should note that for these the clustering has been made on the 500hPa fields, not the 1000hPa fields.  Whilst the user should not treat the most representative members as deterministic solutions, it can nonetheless be helpful to examine the details of the evolution in such members, to see how a particular scenario can plausibly arise and evolve.  One good way to do this is to use the cyclone database products presented by the extratropical cyclone diagrams, specifically the animations, at 12 hour intervals, of synoptic patterns for individual members.

Weather Regimes

It After day10, it is desirable to place the daily clustering in the context of the large-scale flow and to allow the investigation of regime changes.  Use of weather regimes indicates differences between most representative members (MRMs or Cluster scenarios) in terms of the large-scale flow and provides information about the possible transitions between regimes during the forecast.  

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