Fig. 3.

Evolution of the atmosphere until storm time over dry and wet soils. (A–F) Composite atmospheric fields in the 36 h ahead of the observed convective cores at 1700 UTC (t0), as a function of north–south distance, and zonally averaged 0 to 200 km upstream of cores, for (A and D) all convective cores, (B and E) convective cores over dry soils, and (C and F) convective cores over wet soils. A–C show anomalies of 925-hPa temperature (shading, K), 650- to 925-hPa zonal wind shear (contours, m$\cdot {\mathrm{s}}^{-1}$), and the ITD represented by the 0 line of 925-hPa meridional wind (thick black line). D–F depict anomalies of 925-hPa specific humidity (shading, g$\cdot {\mathrm{k}\mathrm{g}}^{-1}$) and 925-hPa equivalent potential temperature ${\mathrm{\Theta }}_e$ (contours, K). Black dot indicates 1200 UTC (sampling time in Fig. 1) and gray dot marks storm time. White bar in A–C denotes the average meridional extent of the −1.5% (ALL and DRY case) and 0.1% SMA contour and gray bars highlight daytime (0600 to 1800 UTC).