Flash Flooding in New Jersey, July 24 to 26, 1997

Heavy rain, associated with weak low pressure systems riding along a nearly stationary frontal boundary in the southern Delmarva Peninsula, caused flooding on some of the river and streams in Morris and Somerset Counties and flooding of some of the smaller creeks and streams in Mercer and Hunterdon Counties. Although it was southeast of this frontal boundary, some of the moisture from Tropical Storm Danny was ingested into this boundary and exacerbated the heavy rain. The recent unseasonably dry weather prevented much damage from flooding to occur in spite of storm totals that in some locations exceeded eight inches. The heaviest rain fell during the afternoon and evening of the 24th. The rain started early on the 24th. Three injuries occurred at 610 a.m. EDT in Hunterdon County when a passenger train was hit by a fallen oak tree near Old Mountain Road north of the Round Valley Recreational Area. Another tree came down about half a mile farther down on the tracks. Three crew members were injured. The recent severe weather and the rain apparently loosened the dirt enough to cause the trees to fall. Later that day in Hunterdon County, significant road flooding was reported along New Jersey State Route 29. The route was closed as were many adjacent side streets. Flooding was also reported around the Lambertvillle School. In Somerset County, the heavy rain caused a roof to collapse in Franklin Township. The heavy rain also forced the Stony and Green Brooks from their banks just after midnight EDT on the 25th. In Mercer County, most of the urban and stream flooding occurred in the northern half of the county. A SKYWARN spotter reported over 5 inches of rain fell by 6 p.m. EDT in Hopewell Township.Storm totals included 8.34 inches in West Amwell, 8.28 inches in Chatham, 8.19 inches in Franklin Township, 7.62 inches in Wertsville, 7.29 inches in Lambertville, 6.82 inches in Blackwell Mills, 4.43 inches in Somerville, 4.09 inches in Pottersville and 4.04 inches in Princeton.The heavy rain did cause some minor flooding along sections of the Passaic River in Morris County and the Millstone and Raritan Rivers in Somerset County. In Morris County, the Passaic River at Chatham exceeded its 6 foot flood stage from 1 a.m. EDT to 7 a.m. EDT on the 25th. It crested at 6.6 feet at 4 a.m. EDT on the 25th. In Somerset County, the Millstone River at Blackwell Mills was above its 9 foot flood stage from 3 a.m. EDT on the 25th to 3 a.m. EDT on the 26th. It crested at 11.1 feet at 1 p.m. EDT on the 25th. The Raritan River at Bound Brook also was above flood stage (26 feet) from 10 a.m. EDT to 3 p.m. EDT on the 25th. It crested at 26.5 feet at 130 pm. EDT on the 25th.