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An ensemble of NWP model runs starting from different data times is known as a lagged ensemble.   Combining the A combination of current and recent ensembles into a larger ensemble (as in Fig6.1.1.2-1) can show possible consistency or divergence in forecasts and identify any different evolution..  They can also show alternative solutions.  Nevertheless, there can be some agreement between the spread and jumpiness. 

It is inappropriate to rely on the results of any individual ensemble member or ensemble run itselfalone.  But if  If there is some any indication of extreme or hazardous weather in the ensembles then that threat should be passed on to users, but with a very low probability.  Nevertheless, there can be some agreement between the spread and jumpiness.   

Fig6.1.1.2-1: Schematic illustration of the relation between the latest ensemble forecasts (green lines) and two previous Ensemble Control Forecast (ex-HRES) solutions (red lines)the :

• several lagged previous ensemble forecasts (blue lines).  

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• Some solutions show a

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• large variation between regimes

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• .
• the latest

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• ensemble forecasts (green

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• lines) show less extreme variability.
• two previous Ensemble Control Forecast (ex-HRES) solutions (red lines)

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• show less extreme variability..

The  The latest solutions are rather more likely. This is because they benefit from up-to-date information and observations, but the more variable or extreme .  However, any solutions from earlier runs (blue) that show greater variability or are more extreme should not be ignored and the results .  These results may be retained as a small probability.