Episodic Analyses. For each high P&I mortality episode, we calculated the duration (in days), the summed total mortality over the entire episode, and the average daily episode mortality ( Table 2 ). These quantities served as dependent variables in a linear regression analysis vs. the independent (weather) variables (1200 and 1900 UTC T and T d and the deseasoned SSC frequencies). We used a 17-day lag in which the mean for each variable was calculated across the days in the episode and the preceding 17 days. This lag was selected based upon prior research that examined absolute humidity [6] and the results of other studies [28] , [43] .