Widespread Flash Flooding and Severe Storms Threaten Large Swaths of Eastern U.S.

Overview

• Forecasters at the NWS Weather Prediction Center and Storm Prediction Center warned Tuesday that clusters of training storms could produce multiple‑inch‑per‑hour rainfall and widespread flash flooding from southeastern New York into western New England and across parts of the Mid‑Atlantic and southern Appalachians.
• The SPC issued mesoscale discussions that put the probability of watch issuance at about 80 percent for two regions including eastern Kentucky through western North Carolina and the Mid‑Atlantic from southern Pennsylvania into New Jersey, with primary risks of damaging wind, large hail, and a few tornadoes.
• WPC highlighted specific heavy‑rain axes: cores capable of 3 inches per hour in southeastern Pennsylvania into northern New Jersey, 1–2 inches per hour with 2–4 inch storm totals in the upper Ohio Valley and central Appalachians, and 3–5 inch storm totals possible in parts of southeastern Nebraska into northeastern Kansas.
• Forecasters say mesoscale drivers — mesoscale convective systems, mid‑level vortices, a warm‑front corridor, and a strong low‑level jet feeding anomalously high precipitable‑water values — are organizing repeat waves of convection as high‑resolution models show backbuilding and training that will prolong impacts this afternoon.
• Saturated soils and low flash‑flood guidance make short bursts of heavy rain more dangerous for urban areas, small streams, and terrain‑fed waterways, so local watches and warnings are likely and residents should avoid flooded roads and follow guidance from local NWS offices and river forecast centers.