A southerly flow pumped in plenty of moisture from the Atlantic while a slow moving cold moved into the area. Copious amounts of moisture ahead of the boundary led to showers and thunderstorms. Torrential downpours combined with convection training over the same areas led to some flooding and flash flooding.  Some of the flooding lingered into the early morning hours of the 5th.

Flood in ANNE ARUNDEL, MARYLAND
From 04-AUG-18 07:52:00 to 05-AUG-18 01:31:00 (EST-5)
Location: RAYNOR HGTS
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: River/Stream Gage

The stream gage on the Patapsco River near Elkridge exceeded the 16 foot flood stage during the indicated period. The peak level of 21.38 feet occurred at 12:30pm August 4th. Numerous roads were flooded across and near the river.

Flood in BALTIMORE, MARYLAND
From 04-AUG-18 02:47:00 to 04-AUG-18 04:06:00 (EST-5)
Location: HOFFMANVILLE
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

The stream gauge at Gunpowder Falls near Hoffmanville crested at 6.14 feet, passing flood stage of 6 feet. Water entered buildings at River Valley Ranch.

Flash Flood in CARROLL, MARYLAND
From 04-AUG-18 01:55:00 to 04-AUG-18 04:29:00 (EST-5)
Location: FINKSBURG
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: River/Stream Gage

The USGS stream gage on Beaver Run near Finksburg rapidly went from falling stages to above flood stage. The stream was above flood stage during the indicated period, with three different peaks. The highest level was 5.48 feet at 3:00am EST. Hughes Road flooded during this event.

Flash Flood in CARROLL, MARYLAND
From 04-AUG-18 01:16:00 to 04-AUG-18 06:00:00 (EST-5)
Location: FINKSBURG
Flood cause: Heavy Rain
Property damage: 15.00K
Crop damage: 0.00K
Reported by: 911 Call Center

A basement wall collapsed due to flooding on Fawn Way.

Flash Flood in CARROLL, MARYLAND
From 04-AUG-18 01:30:00 to 04-AUG-18 01:30:00 (EST-5)
Location: MELROSE
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

A driveway was washed out. Seven inches of rain fell from 7:30 PM EST August, 3rd to 1:30 AM EST August, 4th.

Flood in FREDERICK, MARYLAND
From 04-AUG-18 00:00:00 to 04-AUG-18 02:00:00 (EST-5)
Location: NEW LONDON
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: 911 Call Center

Gas House Pike was closed due to flooding at Linganore Creek.

Flood in FREDERICK, MARYLAND
From 04-AUG-18 00:01:00 to 04-AUG-18 02:01:00 (EST-5)
Location: WALKERSVILLE
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: 911 Call Center

Water street road was closed due to flooding near Harp Road.

Flood in FREDERICK, MARYLAND
From 04-AUG-18 00:00:00 to 04-AUG-18 02:00:00 (EST-5)
Location: WALKERSVILLE
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: 911 Call Center

Stauffer Road was closed due to high water in Walkersville.

Flood in CARROLL, MARYLAND
From 04-AUG-18 00:58:00 to 04-AUG-18 02:58:00 (EST-5)
Location: SPRINGS MILL
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Department of Highways

MD-27 Ridge Road was closed due to flooding between Lone Tree Road and Kate Wagner Road.

Flood in CARROLL, MARYLAND
From 04-AUG-18 01:24:00 to 04-AUG-18 03:24:00 (EST-5)
Location: NEW WINDSOR
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Department of Highways

MD-31 New Windsor Road was closed due to flooding at Dickenson Run near Coe Drive.

Flood in FREDERICK, MARYLAND
From 04-AUG-18 03:05:00 to 04-AUG-18 05:05:00 (EST-5)
Location: JOHNSVILLE
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Department of Highways

MD-75 South Main Street was closed at Sams Creek south of Church Street due to flooding.

Flash Flood in CARROLL, MARYLAND
From 04-AUG-18 02:30:00 to 04-AUG-18 07:30:00 (EST-5)
Location: COVER
Flood cause: Heavy Rain
Property damage: 10.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Gillis Falls Road was washed out at Middle Run.

Flood in CARROLL, MARYLAND
From 04-AUG-18 01:28:00 to 04-AUG-18 13:27:00 (EST-5)
Location: KEYMAR
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: River/Stream Gage

The USGS stream gage on Big Pipe Creek near Bruceville exceeded the 8 foot flood stage during the indicated period. The peak level of 9.56 feet occurred at 10:45am EST. Keysville-Bruceville Road was flooded during this time.

Flood in BALTIMORE, MARYLAND
From 04-AUG-18 07:20:00 to 04-AUG-18 14:30:00 (EST-5)
Location: GLENCOE
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: River/Stream Gage

The stream gauge at Glencoe crested at 9.64 feet above the flood stage of 7 feet. Sparks Road was flood.

Flood in FREDERICK, MARYLAND
From 04-AUG-18 09:31:00 to 04-AUG-18 23:44:00 (EST-5)
Location: PEARL
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: River/Stream Gage

The stream gauge at Frederick along the Monocacy River crested at 15.74 feet, above the flood stage of 15 feet. Both banks of the river were flooded. Water flooded low-lying fields at Monocacy National Battlefield. Water reached the access road of the Frederick City Wastewater Treatment Plant.

Flash Flood in FREDERICK, MARYLAND
From 04-AUG-18 01:00:00 to 04-AUG-18 06:00:00 (EST-5)
Location: SAMS CREEK
Flood cause: Heavy Rain
Property damage: 10.00K
Crop damage: 0.00K
Reported by: Fire Department/Rescue

Sams creek rapidly exceeded its banks, causing flash flooding near the intersection of Oak Orchard Road and Sams Creek Road. The force of the water caused damage to the roadway, scouring out a portion of the road.