An unusually strong system will move slowly across the Mid-Atlantic late this week through the weekend. Persistent moist flow from the Atlantic will lead to prolonged moderate to heavy rainfall. Especially in favorable terrain and poorly drained urban areas, dangerous flooding will occur.
The latest model guidance and satellite trends indicate that this weekend’s storm won’t linger as long as previously thought. It will also move further south, sparing New York and Boston from the heaviest rains. However, the District of Columbia and Baltimore will still be in line to see major flooding.
Scattered storms will break out today across this region, becoming more generalized moderate to locally heavy rain tonight. Periods of rain will continue through Saturday before exiting the coast Saturday night. Here’s how our high-resolution model depicts the progress of the rain, starting Friday early afternoon and continuing through Saturday evening. Purples and whites represent the heaviest rainfall potential:
The heaviest amounts of 3-6 inches will occur from southern Pennsylvania into the DC-to-Baltimore stretch and southern New Jersey. Dangerous flooding can be expected in this corridor especially Friday night and Saturday morning. Look for 1-3 inch rain totals over a larger area of the Mid-Atlantic. Further south, expect the typical summertime pattern of localized flash flooding.
Prolonged heavy rainfall will lead to flash flooding and eventual river flooding as runoff flows into the system. Gusty winds will also be an issue, especially along the Mid-Atlantic and southern New England coasts. The combination of winds and rain-weakened soils will lead to downed trees and isolated power outages. Travel will be hazardous, especially near flooded creeks and ponds.
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