Mount Holly AFD on the heavy rain potential this week-
The pattern will quickly become more active heading into Wednesday night and Thursday. Expect a long southwesterly fetch generated by a broad dome of high pressure over the Western Atlantic and a deepening upper level trough that moves over the eastern CONUS. This will push a PWAT surge in over the region and between these features, we`ll have a slow moving/stagnant frontal system that be the trigger for fairly widespread shower activity heading into Thursday evening. We`ve opted to including mention of heavy rain at this time after collaborating with neighboring offices and with WPC. WPC`s Excessive Rainfall Outlook is carrying a D3 Marginal Risk and this is well supported over the PHI forecast area. From a synoptic point of view we`re looking at the potential for a Maddox Synoptic pattern to develop over the Mid Atlantic. Guidance at the surface has been a bit inconsistent, however aloft, the guidance looks to be in decent agreement. We`ll have a slow moving trough aloft with a deep moisture plume ahead. In the mid levels, BUFKit shows deep southwesterly moist flow from basically the surface up to 300mb with a slight veering profile. At the surface we`ll have a slow moving/stalled frontal system over the region. So when you add up those features, along with deep warm cloud depths, small MBE vectors, PWAT`s approaching 1.7-1.9" which would be in close to the 90th percentile should that verify, and storms that develop on the boundary rather than move off, the potential exists to see some localized flooding Thursday night. We`ll certainly need to keep an eye out for trends to see how things shake out over the next couple of guidance cycles but for at least the last 4 guidance cycles the potential has been there.