Depicted soundings from the 12z Euro are actually spookily similar to Sept 2019. One of the weird characteristics of that event was that convective initiation occurred while the main axis of the trough was sliding overhead. Usually our convective outbreaks are well ahead of the main trough and exist as an ancillary feature.
Another eerie similarity is the incredibly deep marine layer in place. Sept 2019 was completely invisible until powerful downdrafts punched holes through low level stratus. The depth of that marine layer was so intense, the midlevel moist layer and the top of the marine layer actually melded into one cohesive unit. One could argue we were simply convecting the top of the marine layer. That would explain why parcels that day were so voluminous, as the viable parcel depth neared 50mb deep beneath the top of the overall moist mid levels, and why convection occurred so close to the center of the trough.
September 7th 2019 happened under nearly due SW flow.... And ended up as one of the best lightning shows in the city's history. I still have fond memories of that storm... If we want another storytime with Aidan tonight...
It's more about the differential flow aloft and getting midlevel moisture in early enough before the steep lapse rates associated with existing ridging make way for moister, warmer westerlies above 700mb. SE flow is the most common way we get that but it's feasible with other flow directions under the right conditions.