Severe weather events this week in the Midwest, Plains, and South will be presented by a storm system that is organizing in Colorado and Nebraska, moving slowly east and northeast over the balance of the week. This system is poised to impact our region on Friday evening through Friday night before exiting early Saturday. Timing between the GFS and Euro regarding the frontal passage is pretty consistent and in solid agreement at this point -- the models both suggest the front moves through the region on Friday night and that rain and thunder accompany the front.
As of now, it appears that the bulk of Friday should be dry -- there could be a shower or two in Central through Northeast Pennsylvania, but the lion's share of precipitation holds off until after dinner before approaching the region from the west.
Right now, the timing of the front (nighttime) suggests the prospect of severe weather is limited around Philadelphia. It's possible gusty winds and perhaps a couple of severe thunderstorms could occur along the front but the odds favor more of a heavy rain threat at this point given a strong southerly flow of moisture and the front's timing overnight. That situation may be different for Central and Western Pennsylvania, as the front is poised to work through their region a bit earlier and thunderstorms will have the energy from daytime heating to enhance them out there.
Both the GFS and Euro suggest the prospect of an inch of rain for portions of the region with the front as it works through on Friday night. Widespread flooding does not look likely as of now but some portions of the region could see ponding of water on roads and some localized stream flooding, depending on how quickly those rains fall.
It doesn't appear that Saturday is in danger of being a washout although the start could be damp or perhaps showery (best chances of the showery start is in New Jersey).