Medium Range Forecasting - HRES and ENS
This must be considered the normal state with the ENS giving the main indication of forecast conditions and importantly giving information on the uncertainty while the HRES augments this by giving information on possible finer scale detail. The HRES should be considered as part of the ensemble adding to the ENS but not dominating the forecast. The synoptic flow predictions from HRES and CTRL have almost the same skill and are usually very similar, and ideally the results of ENS and HRES should have similar characteristics. When HRES results are "jumpy", the ENS spread should ideally be larger than normal and reflect the difference between consecutive HRES. When the spread is small, the HRES should ideally develop along similar synoptic lines. The main problem for forecasters is how to react when the information from the ENS and HRES and/or other forecast guidance appears to diverge. What strategies should forecasters adopt? Some pointers into making the best use of HRES and ENS together are given in the sub-sections here.