Page History

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• on 200hPa and 925hPa.
• on synoptic scale evolution.
• on 2m temperature and 2m specific humidity (SPPT tended to focus its perturbations above the boundary layer).
• increases spread of near surface fields and precipitation (increases capture of extremes).
• decreases spread of mid/upper troposphere fields (users should asses important features).
• increased spread in tropical cyclones (beneficial for strong systems).
• positive impact in MJO at week 3-4 in monthly forecasts.  

Occasionally the ensemble may show a very small risk of extreme weather beyond what is synoptically reasonable (e.g. winter maritime convective heating may be dampened and some members may be unrealistically cold).

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