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As a result of taking instantaneous cape and capes at discrete time steps the EFI can exhibit a stripy structure in the case of fast moving squall lines or very convective fronts as in the example in Fig. 2. This is an issue because the cold front is not jumping in reality, but is moving continuously from west to east. Replacing cape and capes with mxcape6 and mxcapes6 removes the stripy behaviour and provides a smoother and more realistic forecast field due to better sampling. Smaller scale discretization apparent on the top centre panel for HRES (attributable to the use of values at 1h intervals) is not manifested on the EFI because it will effectively be smoothed out by frontal-timing spread within the ensemble. The plot also provides one nice example of why we might expect to see more areally-extended regions of high EFI/SOT with the new formulation (and why these should be more realistic).
Fig. 2. EFI (and SOT) for CAPE-shear as well as the CAPE-shear high-resolution forecast for a case of a fast moving cold front. Stripy fields of instantaneous CAPE-shear and EFI/SOT (see black lines) are due to taking instantaneous CAPE-shear values at discrete time steps. The EFI forecast looks smoother when using the smoother fields of maximum CAPE-shear in 6-hour periods. The sequence of Air mass RGB imagery shows snapshots of the cold front approaching the south-western parts of the Iberian Peninsular.
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