While thunderstorms are possible the next couple of afternoons thanks to the unstable airmass in place over us, a cold front approaches the region on Sunday and will bring a better chance for thunderstorms to the Delaware Valley. In fact, we're already seeing the Storm Prediction Center highlight the potential for severe weather on Sunday as we're in a slight risk across the entire region.
Odds are higher to our northwest (30% as of now) then along I-95 and southeast as the timing of the front of us is closer to late Sunday night and that the axis of better dynamics and instability will reside across Central Pennsylvania on Sunday during the afternoon hours.
Computer modeling shows the front's approach to our region on Sunday afternoon, with thunderstorms firing up across Western, Central, and Northeast Pennsylvania. These storms will spread east and northeast through Sunday evening and night as the front crosses the state, with Philly's "best" chance for storms associated with the front probably occurring overnight Sunday into Monday.
Even though the front may not cross the region until Sunday night, the possibility of storms firing up around the region during the course of the day exists...and they certainly can and some of which probably do become severe. However, the highest chances of severe weather appear to be setting up for Central Pennsylvania on north into Upstate New York.