NBM v4.1 probabilities of >2" over the 24 hours ending 12Z Sunday
continue to increase, now showing a widespread 40-50% across most of
the forecast region, up from about 30-40% last night. Probabilities
of >1" in any 6 hours has nudged up some for Saturday AM into early
afternoon, and this is the window of greatest concern for locally
heavy downpours. Overall, global ensembles paint a widespread 1" to
2.5" Saturday into early Monday for the area, with still some spread
amongst members. RFC 3 hr flash flood guidance is over 2" for much
of the region, with the exception of parts of NE NJ, where values
fall to around 1.5". This would be the area of greatest concern for
any flash flood potential, though certainly cannot be ruled out
elsewhere. More likely, nuisance flooding with the long duration
rainfall is likely with ponding and poor runoff areas. WPC has
maintained a slight risk for excessive rainfall, indicating the
potential for isolated to scattered areas of flash flooding.