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An illustration of the effect of resolution upon forecast rainfall distribution and intensity. 

Fig2.1.51.2-1: Rainfall forecasts run for the same period (24hr rainfall to T+69 verifying at 06UTC 6 Dec 2015) at several resolutions.    Resolutions: 80km , 36 km (used by the extended range and seasonal (SEAS5) ensembles), 18km, 9km (used by medium range ensemble), 5km (a possible future resolution).

Fig2.1.1.62-2: Magnification of rainfall forecasts as in Fig2.1.1.52-1. The bottom right plot shows the observed rainfall for comparison.  Higher resolution gives better representation of the rain shadow effect but it still is underestimated (e.g. northeast Northeast England).

Fig2.1.1.5 2-1 and Fig2.1.1.6 2-2 illustrate the impact of resolution on rainfall, particularly orographic enhancement and the rain shadow effect.  The effect of increased model resolution on:

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Note:   An estimate of the range of totals likely within each gridbox is made by the Point Rainfall products.