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In total, each set of re-forecasts consists of 20 years x 9 runs x 11 ensemble members = 1980 re-forecast values.  These are available for each forecast parameter, forecast lead-time, calendar start date, location, at forecast intervals of 6 hours. 

A lhigher higher number of re-forecasts than for evaluating SUBS-M-climate  is justified because the tails are rather more important and it is preferable to have a larger sample size.

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• Day1 M-climate is used with T+12h to 36h forecasts from the 12UTC run and T+0h to 24h forecasts from the 00UTC run.
• Day2 M-climate is used with T+36h to 60h forecasts from the 12UTC run and T+24h to 48h forecasts from the 00UTC run.

Updates to M-climate

In Cy49 and later, re-forecasts are made every four days during each month on 1/5/9/13/17/21/25/29 (excluding 29 February).  There remain problems using each newly updated M-climate, particularly in spring and autumn when mean temperatures change most rapidly day by day. 

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