Our results show that over the recent period there are CAPE increases for the Midwest and Central regions particularly during the spring, along with sharp increases in Storm Relative Helicity (SRH) for all seasons. In contrast, the commonly applied 0-6km vertical wind shear parameter (S06) does not show a clear signal, while 0-1km vertical wind shear parameter (S01) shows positive trends in all seasons and regions (~1% per year). Seasonally, this analysis has identified a shift toward greater SRH, S06, and S01 through all percentiles towards the earlier parts of the year. When this shift coincides with higher values of CAPE which occur earlier in the year as well, this reflects a seasonal shift which extends the severe convective season in the last 17 years, increasing risk to the general public and consistent with the shifts seen in tornado observations. Shifts that are conditioned on already favorable environments reveal that generally, increases in the parameters have the largest slope at the extreme quantiles, suggesting that not only has the season shifted, but the shift is manifesting itself in the extremes, as has often been posited in warming climate scenarios for quantities such as temperature or precipitation. However, the strong increases identified to SRH and low-level wind shear go against the prevailing hypothesis for a warming climate. This suggests that in the current environment, changes to the low-layer shear may be having the strongest influence on severity or volatility, contrasting the projected increases to CAPE.