Thunderstorm Environments over the Northeastern Pacific Ocean and Gulf of Alaska

Thunderstorm environments over the northeastern Pacific Ocean and Gulf of Alaska were analyzed from the summer of 2014 through the early spring of 2016.Thermodynamic parameters investigated in this study highlight processes supporting charge separation in the 0 to -20°C (32 to -4°F) layer (CRTZ; charge reversal temperature zone), similar to the study carried out by Bright et al. (2005).Results from the present study show that environments from May-October (warm season) that were "lapse rate starved" yielded shallower and weaker updrafts that were not supportive of lightning.In contrast, updraft depth and CAPE were sufficient for vigorous convection from November-April (cool season).However, cool season lightning was mainly confined to environments that possessed warmer boundary layer temperatures, which favored supercooled liquid water and graupel within the CRTZ.In addition, lightning was most probable, during both the warm and cool seasons, when favorable thermodynamic conditions were collocated with the most active portion of the synoptic flow regime.