A cold front stalled over Southern New England on the 11th.  Low pressure from the Midwest then moved slowly east along the front. The weather system drew upon warm and very humid air to create showers with local downpours, resulting in rainfall amounts of two to five inches in Northern Massachusetts on August 11th and 12th.  An exceptionally powerful downpour left 8.15 inches in the city of Lynn.

Flash Flood in ESSEX, MASSACHUSETTS
From 12-AUG-18 09:16:00 to 12-AUG-18 13:00:00 (EST-5)
Location: LYNN
Flood cause: Heavy Rain
Property damage: 50.00K
Crop damage: 0.00K
Reported by: Amateur Radio

At 9:16 AM EST, cars on Monroe Street in Lynn were floating in the street. At 9:18 AM EST, water was rising in a building on Monroe Street, causing people to stand on chairs.  At 9:31 AM cars were trapped in flood waters on Chatham Street under a bridge; the road was impassable.  At 10:03 AM the basement door to a building on Union Street had collapsed due to the flooding, and water was pouring in.  At 10:18 AM, large sections of Boston Street in Lynn were flooded and impassable, and several cars were trapped in the floodwaters. At 10:32 AM state route 107 on the Lynn/Salem border was closed due to flooding. At 10:59 AM EST, manhole covers were reported coming off the road on Seymour Avenue.  A car was trapped in three feet of water on Wilfred Street; the road was impassable. At 11:42 AM EST, street flooding on Erie Street reached several feet.

Flash Flood in ESSEX, MASSACHUSETTS
From 12-AUG-18 09:18:00 to 12-AUG-18 13:00:00 (EST-5)
Location: SALEM MARITIME NHS
Flood cause: Heavy Rain
Property damage: 40.00K
Crop damage: 0.00K
Reported by: Amateur Radio

At 9:18 AM EST, Walnut Street in Peabody was closed due to flooding. At 9:36 AM EST, Spring Street was closed due to flooding. At 9:41 AM EST Oak Street was closed due to flooding; a car was trapped in the parking lot of the Elks Lodge on Oak Street.  At 9:42 AM train tracks were flooded near Howley Street and Proctor Brook; the water level was six inches below the bridge.  Also, Tremont Street and Foster Street were closed due to flooding with several cars trapped in the waters. By 9:48 AM nearly two feet of water was reported on Walnut Street with two cars trapped on the road. At 10:02 AM EST, Margin Street near Sheldon Road was flooded and closed.

Flash Flood in ESSEX, MASSACHUSETTS
From 12-AUG-18 10:33:00 to 12-AUG-18 13:00:00 (EST-5)
Location: WEST PEABODY
Flood cause: Heavy Rain
Property damage: 15.00K
Crop damage: 0.00K
Reported by: Amateur Radio

At 10:33 AM EST, Quail Road in South Peabody was closed due to flooding. At 10:52 AM EST, Lynnfield Street was closed due to flooding. At 11:07 AM EST, a car was reported trapped in floodwaters on Lynnfield Street.  At 11:14 AM a car was trapped in floodwaters on Lake Street near U.S. Route 1; Lake Street was reported closed soon after. At 11:33 AM EST, a house on Batchelder Avenue was reported to have 4 feet of water in the basement.

Flood in SUFFOLK, MASSACHUSETTS
From 12-AUG-18 06:30:00 to 12-AUG-18 09:30:00 (EST-5)
Location: CHARLESTOWN
Flood cause: Heavy Rain
Property damage: 10.00K
Crop damage: 0.00K
Reported by: Amateur Radio

At 6:30 AM EST, Storrow Drive near U.S. Route 1 was flooded and impassable, with a car trapped in the floodwaters. At 6:33 AM EST, Storrow Drive was also flooded and impassable in the Lagoon area along the Back Bay; cars were driving across the median to avoid the flooding.  At 6:40 AM a car was trapped in floodwaters under the Massachusetts Avenue bridge.  At 6:49 AM Heath Street was flooded and impassable.

Flood in MIDDLESEX, MASSACHUSETTS
From 12-AUG-18 06:38:00 to 12-AUG-18 09:00:00 (EST-5)
Location: EAST EVERETT
Flood cause: Heavy Rain
Property damage: 5.00K
Crop damage: 0.00K
Reported by: Amateur Radio

At 6:38 AM EST a car was trapped in floodwaters on Vale Street at Boston Street in Everett.

Flood in MIDDLESEX, MASSACHUSETTS
From 12-AUG-18 06:46:00 to 12-AUG-18 10:00:00 (EST-5)
Location: CAMBRIDGE
Flood cause: Heavy Rain
Property damage: 15.00K
Crop damage: 0.00K
Reported by: Amateur Radio

At 6:46 AM, Memorial Drive in Cambridge was flooded and impassable at Massachusetts Avenue.  Multiple cars were trapped in floodwaters.

Flood in MIDDLESEX, MASSACHUSETTS
From 12-AUG-18 07:20:00 to 12-AUG-18 10:15:00 (EST-5)
Location: WELLINGTON
Flood cause: Heavy Rain
Property damage: 5.00K
Crop damage: 0.00K
Reported by: Amateur Radio

At 7:20 AM EST, a car was trapped in floodwaters in the Mystic Avenue underpass of the McGrath Highway.

Flood in ESSEX, MASSACHUSETTS
From 12-AUG-18 07:52:00 to 12-AUG-18 10:00:00 (EST-5)
Location: DEVEREUX
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Amateur Radio

At 752 AM EST, West Shore Drive in Marblehead was flooded and impassable near the Tower School.

Flood in MIDDLESEX, MASSACHUSETTS
From 12-AUG-18 08:00:00 to 12-AUG-18 10:00:00 (EST-5)
Location: OAK GROVE
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Amateur Radio

At 8 AM EST, Woodland Road in Stoneham was flooded and impassable.

Flood in MIDDLESEX, MASSACHUSETTS
From 12-AUG-18 08:22:00 to 12-AUG-18 10:00:00 (EST-5)
Location: FARM HILL
Flood cause: Heavy Rain
Property damage: 5.00K
Crop damage: 0.00K
Reported by: Amateur Radio

At 8:22 AM EST, a car was trapped in floodwaters on Oak Street in Stoneham.

Flood in ESSEX, MASSACHUSETTS
From 11-AUG-18 13:55:00 to 11-AUG-18 16:00:00 (EST-5)
Location: LAWRENCE
Flood cause: Heavy Rain
Property damage: 10.00K
Crop damage: 0.00K
Reported by: Amateur Radio

At 1:55 PM EST, two cars were trapped in flooding at the intersection of Market Street and Parker Street in Lawrence.

Flood in WORCESTER, MASSACHUSETTS
From 11-AUG-18 18:03:00 to 11-AUG-18 21:00:00 (EST-5)
Location: WEST BOYLSTON
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Amateur Radio

At 6:03 PM EST, Crescent Street was flooded and impassable.

Flash Flood in ESSEX, MASSACHUSETTS
From 12-AUG-18 09:12:00 to 12-AUG-18 13:00:00 (EST-5)
Location: CARLETONVILLE
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Amateur Radio

At 9:12 AM EST, Highland Avenue in Salem near Walmart was impassable due to flooding.
At 9:22 AM EST, a portion of the O'Keefe Sports Complex parking lot at Salem State University was flooded and unusable. At 10:58 AM EST, the area in front of Salem Hospital was closed due to flooding. The hospital was not accessible and was placed on diversion until the flooding subsided.

Flash Flood in ESSEX, MASSACHUSETTS
From 12-AUG-18 09:50:00 to 12-AUG-18 12:00:00 (EST-5)
Location: NORTH SAUGUS
Flood cause: Heavy Rain
Property damage: 20.00K
Crop damage: 0.00K
Reported by: Amateur Radio

At 9:50 AM EST, several cars were trapped in floodwaters on U.S. Route 1 northbound in Lynnfield northwest of Walden Pond.