I'm pretty sure Patrick Marsh explain PDS watches as: Sig tor values over 70% are automatically PDS, anything 70% or lower is at forecaster discretion.
Yeah HRRR was dreadful predicting Del Rio area storms tonight. That in house model posted above actually did a pretty good job depicting those TX storms.
04 HRRR would be the start of a new trend, it's pretty different from even 03z. If 05,06,07,ect continue this, that's a bad look for north central MS/AL