The several-hour long downpour that drenched parts of Mercer and Middlesex County on the afternoon of July 30, 2016, represented an exceptionally rare event for the area. Afternoon and evening thunderstorms dropped 7.23” in West Windsor (Mercer County), with Plainsboro (Mercer) reporting 5.15”, South Brunswick (Middlesex) 5.03,” and North Brunswick (Middlesex) 4.90”. These rainfall totals were measured by volunteer weather observers in the Community Collaborative Rain, Hail, and Snow (CoCoRaHS) network, providing vital precipitation data that would otherwise be nonexistent. The bulk of the rainfall occurred during a roughly 3-hour period from 2:45 PM through 5:45 PM, with the most torrential rainfall occurring along and just south of Route 1 from Princeton Junction (West Windsor Twp.) east northeast to Monmouth Junction and Dayton (South Brunswick Twp.).