Watching this wave run through today. The massive heating yesterday along with the moisture envelope drug up by the ULL caused some really nice t-storms last night.
Watching the ULL spin to our SE, it looked like some convection going on, likely the massive divergence aloft offered by the ULL, but just recently had a round of rain come through in a squall line. It was the outflow boundary layer spit out by the convection as it died and collapsed. This is quite visible on visible.
Could this ULL work down to the surface? Not out of the question.