Latest Forecast

A potent cold front traversing the Commonwealth from west-to-east will trigger widespread, strong-to-severe thunderstorms across northern MD, southeastern PA and the Lower Susquehanna Valley between 1-8 PM. The primary threats will be torrential downpours, significant flash flooding, locally heavy rainfall amounts of 2-3", frequent lightning, small hail and locally damaging wind gusts of 55-65 mph. The atmosphere is sufficiently moist and unstable for rapid thunderstorm development and growth, and rainfall rates may exceed 2" per hour in the most intense storms. Parts of Lancaster and Lebanon Counties received 3-6" of rain on Monday. An additional 0.75-1.50" of rain in 6 hours will cause flash flooding, and that much (or more) may fall in just 1 hour or less this afternoon. Avoid roadways next to smaller streams and creeks, and never drive through floodwaters! Instead, always turn around and seek an alternate route. Reduce speed and turn on your vehicle's hazard lights in blinding downpours, as well. The locally strong wind gusts will cause downed trees and powerlines in spots, along with isolated power outages. Lighter showers will linger during the mid-to-late evening hours but should taper off overnight. Behind the cold front, winds will turn northwesterly and usher drier and slightly less humid air into the region on Wednesday. Skies should gradually clear throughout the day, and a light breeze of 5-10 mph will accompany highs in the mid 80s and dewpoints in the upper 60s Wednesday afternoon. An upper-level disturbance will then swing through the Northeast on Thursday, but the Lower Susquehanna Valley will be on its southern periphery. A stray shower or thunderstorm cannot be ruled out Thursday afternoon, especially north of the Turnpike, but most of the day should turn out mostly sunny, warm and dry with highs in the mid 80s to perhaps 90°F.