A developing area of lower pressure crossed the state on the night of July 29th.  Abundant moisture moved into the region ahead of this area of low pressure.  Rain began by late afternoon on July 29th across the Connecticut River Valley.  Rain continued to quickly spread east through the late afternoon hours across all of Central and Southern New Hampshire.  Moderate rain was steady with embedded areas of heavy rain that allowed rainfall rates to peak at 3 to 4��� per/hour at times.  The majority of the rain fell in a 3 to 4 hour window with a general 2 to 3��� south of the White Mountains.  A concentrated band of rainfall extended from Cheshire County across the state to Southern Carroll County where most of the flood damage occurred as localized rainfall amounts approached 5���.  Another localized maximum rainfall band was located across Southern Hillsborough County as a brief but intense band traveled across this area around 10 PM EDT.  The bands of rain ended from west to east with the rain clearing the state by midnight on July 30th. The heavy rain and well above normal soil saturation led to excessive run-off even after the rain ended through the night.

Flash Flood in CHESHIRE, NEW HAMPSHIRE
From 29-JUL-21 22:42:00 to 30-JUL-21 00:00:00 (EST-5)
Location: SURRY
Flood cause: Heavy Rain
Property damage: 10.00K
Crop damage: 0.00K
Reported by: Department of Highways

The Ashuelot River flooded Route 12A at Gilsum Road. The USGS gage at Gilsum reported a rise in stage from 3 feet to 9.5 feet between 7 PM on the 29th and 5 AM on the 30th. The streamflows rose likewise from 113 cfs to 2,280 cfs. The flows are comparable to those observed after Hurricane Irene in 2011.

Flash Flood in HILLSBOROUGH, NEW HAMPSHIRE
From 29-JUL-21 21:55:00 to 29-JUL-21 22:40:00 (EST-5)
Location: NOONE
Flood cause: Heavy Rain
Property damage: 10.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Heavy rain estimated around 1 to 3 inches washed out a portion of Old Jaffrey Road.

Flash Flood in HILLSBOROUGH, NEW HAMPSHIRE
From 29-JUL-21 22:30:00 to 29-JUL-21 23:30:00 (EST-5)
Location: HOLLIS
Flood cause: Heavy Rain
Property damage: 25.00K
Crop damage: 0.00K
Reported by: Law Enforcement

A few roads washed out in Hollis after 2.5 inches of rain fell in an hour and a half.

Flash Flood in MERRIMACK, NEW HAMPSHIRE
From 29-JUL-21 22:00:00 to 29-JUL-21 23:00:00 (EST-5)
Location: SHAKER VLG
Flood cause: Heavy Rain
Property damage: 20.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Hackleboro Rd and Merrill Rd washed out in Cantebury.

Flash Flood in BELKNAP, NEW HAMPSHIRE
From 29-JUL-21 22:00:00 to 29-JUL-21 23:00:00 (EST-5)
Location: GILMANTON IRONWORKS
Flood cause: Heavy Rain
Property damage: 10.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Washout reported on White Oak Drive in Barnstead.

Flash Flood in BELKNAP, NEW HAMPSHIRE
From 29-JUL-21 22:00:00 to 30-JUL-21 00:30:00 (EST-5)
Location: LILY POND
Flood cause: Heavy Rain
Property damage: 40.00K
Crop damage: 0.00K
Reported by: Fire Department/Rescue

Major road washout and undermining along Lake Shore Rd in Gilford.

Flash Flood in MERRIMACK, NEW HAMPSHIRE
From 29-JUL-21 22:30:00 to 30-JUL-21 00:00:00 (EST-5)
Location: WEST SALISBURY
Flood cause: Heavy Rain
Property damage: 20.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Buckhorn and Mill Rd sustained washouts from flash flooding.

Flash Flood in MERRIMACK, NEW HAMPSHIRE
From 29-JUL-21 22:30:00 to 30-JUL-21 00:00:00 (EST-5)
Location: NEWBURY
Flood cause: Heavy Rain
Property damage: 35.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Mountain Rd and Cheney Rd in Newbury sustained significant flooding and washouts.

Flash Flood in STRAFFORD, NEW HAMPSHIRE
From 29-JUL-21 22:30:00 to 30-JUL-21 00:00:00 (EST-5)
Location: MILTON
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Multiple washouts on local roads in Milton. Roads include Mason Rd, Teneriffe Rd, and Morgan Dr.

Flash Flood in HILLSBOROUGH, NEW HAMPSHIRE
From 29-JUL-21 20:50:00 to 30-JUL-21 01:00:00 (EST-5)
Location: HILLSBOROUGH
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Danforth Corners Road in Hillsboro flooded and impassable.

Flash Flood in SULLIVAN, NEW HAMPSHIRE
From 29-JUL-21 21:30:00 to 30-JUL-21 02:00:00 (EST-5)
Location: NEWPORT
Flood cause: Heavy Rain
Property damage: 150.00K
Crop damage: 0.00K
Reported by: Emergency Manager

The Town of Newport sustained significant flooding to properties and businesses along NH Route 103 in the area of 48 John Stark Highway. Flood waters were 1 to 2 feet deep throughout a business plaza which sustained significant damages. The confluence of the Sugar River and its South Branch occurs just west of the impacted areas.  The nearest river gage is located approximately 10 river miles to the west at an elevation of 500ft higher.  The river did not reach flood stage at Claremont, but did show a notable increase in discharge from about 350cfs in the afternoon of the 29th, to a crest over 5,000cfs in the early morning hours of the 30th.

Flash Flood in MERRIMACK, NEW HAMPSHIRE
From 29-JUL-21 21:50:00 to 29-JUL-21 23:00:00 (EST-5)
Location: LONDON CENTER
Flood cause: Heavy Rain
Property damage: 15.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Numerous roads washed out and flooded in and around Loudon. Washouts were reported on Bumfagon Rd, Storrs Dr, Hollow Route Rd, and Gilmanton Rd where significant damage occurred.

Flash Flood in HILLSBOROUGH, NEW HAMPSHIRE
From 29-JUL-21 21:55:00 to 29-JUL-21 22:30:00 (EST-5)
Location: WEST PETERBOROUGH
Flood cause: Heavy Rain
Property damage: 10.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Old Town Farm road washed out due to the heavy rain. A dozen homes were cut off from emergency access due to the road closure.

Flash Flood in HILLSBOROUGH, NEW HAMPSHIRE
From 29-JUL-21 23:24:00 to 30-JUL-21 00:00:00 (EST-5)
Location: ANTRIM CENTER
Flood cause: Heavy Rain
Property damage: 15.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Clinton Rd, NH 31, was washed out from the Great Brook due to the heavy rains.

Flash Flood in SULLIVAN, NEW HAMPSHIRE
From 29-JUL-21 20:35:00 to 30-JUL-21 00:00:00 (EST-5)
Location: ACWORTH
Flood cause: Heavy Rain
Property damage: 1.40M
Crop damage: 0.00K
Reported by: Fire Department/Rescue

Acworth was the hardest hit community during the flash flooding on July 29th. Localized rainfall amounts on July 29th approached or exceeded 4.5 inches in less than six hours. Reports from FEMA and State Officials list 75% of the town's 29 roads were damaged. Multiple bridges were damaged and destroyed. Reports on damages ranged from approximately 2 to 7 million dollars. Most damage was on Crane Brook Road and Charlestown Road at Luther Hill Road.  Local officials claim damage was the worst since the 2005 floods.

Flash Flood in BELKNAP, NEW HAMPSHIRE
From 30-JUL-21 00:22:00 to 30-JUL-21 01:00:00 (EST-5)
Location: ALTON
Flood cause: Heavy Rain
Property damage: 25.00K
Crop damage: 0.00K
Reported by: Department of Highways

RT-140 road washed out at Halls Hill Rd due to the heavy rain.

Flash Flood in CHESHIRE, NEW HAMPSHIRE
From 29-JUL-21 23:40:00 to 30-JUL-21 01:00:00 (EST-5)
Location: ALSTEAD
Flood cause: Heavy Rain
Property damage: 75.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Flash riverine flooding occurred on the evening of the 29th in Alstead.  Flood waters upstream in Acworth along the Cold River resulted in a washout of the Route 123A road near Kelley Road.  River levels from the USGS Cold River at Alstead gage reported an all time peak flow of 11.46 feet and a flow of 10,500cfs, cresting at 11 PM on the 29th. The period of record is relatively short dating back to 2009, but significant damage occurred in the Cold River basin with an estimated 50 to 75 year flood event based on USGS data.

Flash Flood in SULLIVAN, NEW HAMPSHIRE
From 29-JUL-21 21:45:00 to 30-JUL-21 00:00:00 (EST-5)
Location: LEMPSTER
Flood cause: Heavy Rain
Property damage: 125.00K
Crop damage: 0.00K
Reported by: Emergency Manager

In Lempster, the town lost access to 15 roads. 24 culverts were damaged or destroyed, and the recovery effort was further exacerbated by the closure of State Route 12 also caused by flash flooding.  Rainfall estimates were between 3 and 5 inches on the evening of the 29th.

Flash Flood in SULLIVAN, NEW HAMPSHIRE
From 29-JUL-21 21:50:00 to 30-JUL-21 00:30:00 (EST-5)
Location: LANGDON
Flood cause: Heavy Rain
Property damage: 34.00K
Crop damage: 0.00K
Reported by: Emergency Manager

The town of Langdon lost emergency access to 18 residents and closed three roads due to road washouts caused by the heavy rain.

Flash Flood in SULLIVAN, NEW HAMPSHIRE
From 29-JUL-21 21:56:00 to 29-JUL-21 23:00:00 (EST-5)
Location: GOSHEN FOUR CORNERS
Flood cause: Heavy Rain
Property damage: 155.00K
Crop damage: 0.00K
Reported by: Department of Highways

North Branch of the Sugar River caused flooding in Goshen. Route 10 closed from Route 31 to Grandview Road with water reported over the road. A campground had to evacuate 25 people due to rising flood waters.