An ensemble of mesoscale model simulations of the most severe tornadic outb
reak of the modern period, 24-15 June 1967, is examined. Results indicate t
hat the fields of convective available potential energy (CAPE), storm-relat
ive environmental helicity (SREH), and bulk Richardson number shear (BRNSHR
), are able to provide useful guidance on the region of tornadic supercell
thunderstorms for this outbreak. CARE is used to define the region in which
convection is possible, SREH is used to define the region in which thunder
storms are likely to be supercells, and BRNSHR is used to define the region
in which low-level mesocyclogenesis is more likely. These results highligh
t the potential value of analyzing various severe weather parameters in for
ecasting tornadic thunderstorms, and the value of mesoscale ensemble foreca
sts for predicting severe, life threatening weather events ill Europe.
The ensemble also clearly shows the sensitivity and uncertainty of the mode
l simulations to the physical process schemes used. Variations in all three
severe weather parameters are significant near regions of convection, whic
h unfortunately are where forecasters need these parameter values to he mos
t reliable. These sensitivities highlight the value of an ensemble system f
or short-range weather forecasting, since it is clear that if a single mode
l forecast of convective activity goes awry, then it provides little guidan
ce to forecasters concerned with threats to life and property from severe w
eather. Published by Elsevier Science B.V.