A series of thunderstorms with heavy rain from the late afternoon through the  evening on the 21st caused poor drainage and stream flash flooding in southern Monmouth County and northern Ocean County. Runoff from the heavy rain then caused some river flooding into the 23rd in central New Jersey  Event precipitation totals averaged two to five inches, highest in Monmouth and Ocean Counties.

The Millstone River at Griggstown was above its 10 foot flood stage from 402 a.m. EDT on the 22nd through 712 p.m. EDT on the 23rd. It crested at 11.83 feet at 715 p.m. EDT on the 22nd.
The Manasquan River at Squankum had moderate flooding and was above its 7.5 foot flood stage from 117 a.m. EDT through 536 p.m. EDT on the 22nd. It crested at 9.94 feet at 1030 a.m. EDT on the 28th.
The North Branch of the Metedeconk River at Lakewood.was above its 7 foot flood stage from 622 p.m. EDT on the 22nd through 900 a.m. EDT on the 23rd. It crested at 7.42 feet at 10 p.m. EDT on the 22nd.

Flood in OCEAN, NEW JERSEY
From 22-AUG-11 17:22:00 to 23-AUG-11 08:00:00 (EST-5)
Location: GREENVILLE
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: River/Stream Gage

The runoff from the heavy rain on the 21st caused flooding along the North Branch of the Metedeconk River.  Flooding occurred as far upstream as Aldrich Road (which was closed) in Jackson Township.  The North Branch of the Metedeconk River at  Lakewood was above its 7 foot flood stage from 622 p.m. EDT on the 22nd through 900 a.m. EDT on the 23rd. It crested at 7.42 feet at 10 p.m. EDT on the 22nd.

Flash Flood in OCEAN, NEW JERSEY
From 21-AUG-11 19:00:00 to 21-AUG-11 23:00:00 (EST-5)
Location: CASSVILLE
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Thunderstorms with torrential downpours caused small stream flash flooding as well as poor drainage flooding in the northwest part of Ocean County. The runoff also caused flooding along the North Branch of the Metedeconk River that lasted into the 23rd.  In Jackson Township, vehicles became trapped in flood waters on six roadways: Bennetts Mills Road, Cedar Swamp Road, Chandler Road, County Line Road, Fox Hollow Drive and Nottingham Way.  The most concentrated flooding occurred in the Four Seasons Development. Six Flags, Great Adventure even closed early. No serious injuries were reported. Event precipitation totals included 3.85 inches in Jackson Township and 2.58 inches in Point Pleasant Beach.

Flash Flood in MONMOUTH, NEW JERSEY
From 21-AUG-11 18:00:00 to 21-AUG-11 23:00:00 (EST-5)
Location: BRIELLE
Flood cause: Heavy Rain
Property damage: 1.00M
Crop damage: 0.00K
Reported by: Public

Thunderstorms with torrential downpours caused small stream flash flooding as well as poor drainage flooding in the southern half of Monmouth County. Howell, Ocean and Wall Townships were hardest hit with around a dozen homes damaged. The runoff also caused moderate flooding along the Manasquan River that lasted into the 22nd.
In Howell Township, the Mariner's Cove development near the Manasquan River was hard hit by flooding. Rescue boats were used to evacuate families as mud and water entered the first floor of homes. The U.S. Route 9 bridge over the Manasquan river was closed due to concern about its integrity. It was re-opened on the 22nd. Another bridge over the Manasuqan River on Allentown-Lakewood Road near Robert Brice Memorial Park was also flooded and closed.  In Ocean Township, flooding displaced residents of the Middlebrook at Monmouth Apartments on Deal Road. In Freehold, Post Road flooded by a creek and New Jersey State Route 33 was closed in both directions at Hills Mills Road. In Long Branch, 2nd Avenue was under three feet of water, the barricades were even floating away.   In Deal, New Jersey State Route 71 was closed in both directions. Streams were reported out of their banks in Millstone Township.
Event precipitation totals included 4.61 inches in Howell Township, 3.75 inches in Ocean Township, 3.16 inches in Asbury Park and 2.96 inches in Eatontown.

Flood in SOMERSET, NEW JERSEY
From 22-AUG-11 03:02:00 to 22-AUG-11 18:12:00 (EST-5)
Location: GRIGGSTOWN
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: River/Stream Gage

The Millstone River at Griggstown was above its 10 foot flood stage from 402 a.m. EDT on the 22nd through 712 p.m. EDT on the 23rd. It crested at 11.83 feet at 715 p.m. EDT on the 22nd.  Event precipitation totals included 2.91 inches in Princeton Township (Mercer County) and 1.48 inches in Montgomery Township.

Flood in MONMOUTH, NEW JERSEY
From 22-AUG-11 00:17:00 to 22-AUG-11 16:36:00 (EST-5)
Location: ALLENWOOD
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: River/Stream Gage

The runoff from the heavy rain on the 21st caused moderate flooding along the Manasquan River on the 22nd. The Manasquan River at Squankum had moderate flooding and was above its 7.5 foot flood stage from 117 a.m. EDT through 536 p.m. EDT on the 22nd. It crested at 9.94 feet at 1030 a.m. EDT.