Prior to the IFS cycle 47r1, the EFI for both CAPE and CAPE-shear has used instantaneous CAPE (ShortName=cape; parameter ID=59) and CAPE-shear (ShortName=capes; parameter ID=228044) in 6-hour steps from which 24-hour maximum values have been computed. For example for T+24-48h EFI forecast, four CAPE values at T+30h, T+36h, T+42h and T+48h have been used to compute the maximum for this forecast period. With the IFS cycle 45r1 two new model output parameters, maximum CAPE in the last 6 hours (ShortName=mxcape6; parameter ID=228035) and maximum CAPE-shear in the last 6 hours (ShortName=mxcapes6; parameter ID=228036), have been introduced (see details here). In the IFS cycle 47r1 mxcape6 and mxcapes6 are replacing cape and capes respectively. This change is aiming for a better sampling in the computation of 24-hour maximum values necessary for the EFI. The impacts of this change are described in detail below.
Firstly this changes has a neutral impact in terms of the EFI skill measured by the area under the Relative Operating Characteristic (ROC).
The EFI fields using mxcape6 and mxcapes6 generally look smoother and in this case of a tornadic outbreak in the USA earlier in March 2020 shown in Fig. 1 they even fit better to the severe weather reports. Please note that the EFI shows a wide area where the environment favours convective hazards whilst the actual severe thunderstorms develop along relatively narrow bands where sufficient lift is present to initiate deep, moist convection, e.g. along cold fronts or dry lines.
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