A cold front arriving from the west late in the day on the 2nd moved into a warm and moist air mass, which resulted in thunderstorms across the area with torrential rainfall. Hunterdon County reported the worst damage. Flooding occurred from Mercer and Hunterdon Counties northeast through Morris and Middlesex Counties. Doppler Radar storm total estimates average 1.5 to 3.0 inches across the region, most of which fell within one hour.

Flash Flood in MERCER, NEW JERSEY
From 02-AUG-09 11:20:00 to 02-AUG-09 19:01:00 (EST-5)
Location: LAWRENCEVILLE
Flood cause: Heavy Rain
Property damage: 250.00K
Crop damage: 0.00K
Reported by: River/Stream Gage

Thunderstorms with torrential downpours damaged a home in Hamilton Township, flooded and closed U.S. Route 206 in Lawrence Township and caused flooding along the Assunpink Creek. In Hamilton Township, a home on Evergreen Avenue became structurally unsound after its basement foundation collapsed. Several other homes in the area also had flooded basements. In Lawrence Township, U.S. Route 206 was flooded near Notre Dame High School. The Assunpink Creek at Trenton was above its 8.5 foot flood stage from 312 p.m. EDT through 801 p.m. EDT on the 2nd. It crested at 8.96 feet at 630 p.m. EDT. Event totals included 3.54 inches in Lawrence Township, 2.51 inches in Hamilton Township and 2.15 inches in Hightstown.

Flash Flood in SOMERSET, NEW JERSEY
From 02-AUG-09 11:30:00 to 02-AUG-09 19:00:00 (EST-5)
Location: PLUCKEMIN
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Thunderstorms with torrential downpours caused flash flooding of smaller streams and led to flooding along the North Branch of the Raritan River as well as parts of the Millstone River. Several roads were flooded and closed. In Bridgewater Township, Chambers Brook flooded. Several roads in the township were closed and a few water rescues were performed. Roads were also flooded and closed in Manville, Bedminster and Bound Brook.  Event precipitation totals included 3.52 inches in Pottersville, 1.92 inches in Bridgewater, 1.90 inches in Bound Brook, 1.71 inches in Bridgewater, 1.68 inches in Somerville and 1.48 inches in Bernards Township.

Flash Flood in MORRIS, NEW JERSEY
From 02-AUG-09 12:00:00 to 02-AUG-09 14:00:00 (EST-5)
Location: PARSIPPANY
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Broadcast Media

Thunderstorms with torrential downpours caused considerable poor drainage flooding as well as flooding of some of the smaller streams in eastern Morris County. Roadways had as much as five feet of water on them from Morris Plains northeast through Parsippany. One motorist was trapped in their car. Storm totals included 2.48 inches in Morris Township, 2.37 inches in Mendham Township, 2.26 inches in Parsippany and 1.90 inches in Boonton.

Flash Flood in HUNTERDON, NEW JERSEY
From 02-AUG-09 11:00:00 to 02-AUG-09 19:00:00 (EST-5)
Location: CALIFON
Flood cause: Heavy Rain
Property damage: 5.00M
Crop damage: 0.00K
Reported by: Newspaper

Thunderstorms with torrential downpours caused considerable flash flooding of smaller streams and led to flooding along the South Branch of the Raritan River. Numerous roads were flooded and three bridges had to be closed. Hardest hit were Clinton and Tewksbury Township.
In Clinton, the Beaver Brook flooded for the second time this summer. It flooded Main Street, East Main Street, Lehigh Street and Old Highway 22. Some stores and their basements were flooded. The flooding brook carried benches, newspaper bins, garbage dumpsters and even a couple of cars. More than two dozen basements were flooded. In Clinton Township, Camp Carr was evacuated. In Tewksbury Township, the Rockaway Creek (which exceeded its banks by 100 feet) flooded basements on Water Street.  In Califon Borough, basement flooding as flooding along Main Street and Old Califon Road occurred. In Readington Township, along the South Branch of the Raraitan River, flooding was reported in the Stanton area.
The biggest public property toll occurred to three bridges in the northern part of the county. In Tewksbury Township, the Water Street Bridge between Longview Road and County Route 639 was expected to be closed for repairs for up to five months. The Guinea Hollow Road Bridge was expected to be closed for up to 10 weeks after a wall collapsed. In Lebanon Tonwship, the Buffalo Hollow Road Bridge between Poplar Road and New Jersey State Route 31 was also closed for about three weeks.
Event precipitation totals included 4.35 inches in Califon, 3.62 inches in Annandale, 3.51 inches in High Bridge, 3.45 inches in Clinton and 2.48 inches in Flemington.

Flood in SOMERSET, NEW JERSEY
From 02-AUG-09 15:44:00 to 04-AUG-09 00:15:00 (EST-5)
Location: GRIGGSTOWN
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: River/Stream Gage

Runoff from the torrential downpours, especially in Mercer and Hunterdon Counties caused river flooding that lasted into August 4th. The Millstone River at Griggstown was above its 10 foot flood stage from 550 p.m. EDT on the 2nd through 115 a.m. EDT on the 4th. It crested at 11.96 feet at 745 a.m. EDT on the 3rd. The North Branch of the Raritan River at North Branch was above its 12.3 foot flood stage from 653 p.m. EDT through 1108 p.m. EDT on the 2nd. It crested at 13.04 feet at 915 p.m. EDT. Farther downstream at its confluence point, the North Branch of the Raritan River at the village of South Branch was above its 7 foot flood stage from 444 p.m. EDT on the 2nd through 610 a.m. EDT on the 3rd. It crested at 8.77 feet at 2 a.m. EDT on the 3rd.

Flood in HUNTERDON, NEW JERSEY
From 02-AUG-09 12:53:00 to 03-AUG-09 13:11:00 (EST-5)
Location: SUNNYSIDE
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: River/Stream Gage

Runoff from the heavy rain in Hunterdon County led to flooding along the sections of the South Branch of the Raritan River. The South Branch of the Raritan River at Stanton was above its 8 foot flood stage from 153 p.m. EDT on the 2nd through 211 p.m. EDT on the 3rd. It crested at 11.17 feet at 5 p.m. EDT on the 2nd.

Flash Flood in MIDDLESEX, NEW JERSEY
From 02-AUG-09 12:00:00 to 02-AUG-09 14:00:00 (EST-5)
Location: EAST BRUNSWICK
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Newspaper

Thunderstorms with heavy rain caused Daily's Pond to overflow into streets in South River. Flooding was also reported along New Jersey State Route 18 in East Brunswick. A Skywarn spotter reported 1.38 inches of rain that fell within 20 minutes in Edison. Storm totals included 1.59 inches in New Brunswick, 1.52 inches in Middlesex and 1.46 inches in New Brunswick.