An upper trough situated from the Great Lakes through the Tennessee Valley provided the instability to support very slow-moving showers and thunderstorms that drifted across the central Appalachians into the lower Mid-Atlantic.  During the afternoon of the 9th, a surface trough had developed from Surry County, NC northward through Montgomery County, VA into southeast West Virginia, providing the low level convergence needed to support prolonged thunderstorm activity. A southerly wind flow carried deep moisture northward from the Carolina coast during the afternoon, with precipitable water values observed in the 1.5 to 1.6 inch range across Montgomery County, while surface-based CAPE values were observed in the 1,000 to 1,200 J/Kg range.  Steering winds were less than 10 knots from the south, leading to slow storm movement.  Several personal weather stations indicated that the vast majority of rainfall occurred during a 2-hour period beginning around 1 PM EDT, with rainfall falling at rates of 4 to 6 inches per hour. CREST Unit Streamflow in the town of Blacksburg near the headwaters of Cedar Run peaked at 19Z at around 1,000 cfs/sec/mi^2, while the three-hour Average Recurrence Interval was nearing a 200-year event.

Heavy Rain in MONTGOMERY, VIRGINIA
From 09-SEP-23 07:00:00 to 10-SEP-23 07:00:00 (EST-5)
Location: BLACKSBURG VPI ARPT
Property damage: 0.00K
Crop damage: 0.00K
Reported by: CoCoRaHS

A CoCoRaHS Observer (VA-MN-13: Blacksburg 1.7 ESE) recorded a 24-hour rainfall amount of 5.23 inches caused by slow-moving thunderstorms.  This 24-hour total is roughly a 25-year ARI per NOAA Atlas 14 Point Precipitation Frequency estimates.

Heavy Rain in MONTGOMERY, VIRGINIA
From 09-SEP-23 07:00:00 to 10-SEP-23 07:00:00 (EST-5)
Location: BLACKSBURG VPI ARPT
Property damage: 0.00K
Crop damage: 0.00K
Reported by: CoCoRaHS

A CoCoRaHS Observer (VA-MN-51: Blacksburg 1.7 ESE) recorded a 24-hour rainfall amount of 4.73 inches caused by slow-moving thunderstorms. This 24-hour total is nearly a 25-year ARI per NOAA Atlas 14 Point Precipitation Frequency estimates.

Heavy Rain in MONTGOMERY, VIRGINIA
From 09-SEP-23 07:00:00 to 10-SEP-23 07:00:00 (EST-5)
Location: BLACKSBURG VPI ARPT
Property damage: 0.00K
Crop damage: 0.00K
Reported by: COOP Observer

The National Weather Service in Blacksburg recorded a 24-hour rainfall amount of 4.42 inches at the Weather Forecast Office, caused by slow-moving thunderstorms. This 24-hour total is roughly a 10-year ARI per NOAA Atlas 14 Point Precipitation Frequency estimates. This total is the 3rd highest recorded 24-hour total in the history of the Blacksburg COOP Observer records, which date back to 1893.

Heavy Rain in MONTGOMERY, VIRGINIA
From 09-SEP-23 12:04:00 to 09-SEP-23 15:04:00 (EST-5)
Location: BLACKSBURG VPI ARPT
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

A personal weather station (Weather Underground: KVABLACK128) recorded a 3-hour rainfall amount of 4.25 inches caused by slow-moving thunderstorms. This 3-hour total is nearly a 500-year ARI per NOAA Atlas 14 Point Precipitation Frequency estimates. Rainfall rates were observed reaching as high as 6 inches per hour at the beginning of the event.

Heavy Rain in MONTGOMERY, VIRGINIA
From 09-SEP-23 12:01:00 to 09-SEP-23 15:01:00 (EST-5)
Location: BLACKSBURG VPI ARPT
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

A personal weather station (Weather Underground: KVABLACK189) recorded a 3-hour rainfall amount of 4.67 inches caused by slow-moving thunderstorms. This 3-hour total is exceeded a 1,000-year ARI per NOAA Atlas 14 Point Precipitation Frequency estimates. Rainfall rates were observed reaching as high as 6.3 inches per hour at the beginning of the event.

Flash Flood in MONTGOMERY, VIRGINIA
From 09-SEP-23 14:00:00 to 09-SEP-23 16:15:00 (EST-5)
Location: BLACKSBURG VPI ARPT
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

A photo taken by a member of the public shows that Cedar Run flooded out of its banks up to a foot deep across Ellett Road at both locations where the road crosses over the Cedar Run.  The flooding was due to 4 to 5 inches of rainfall within a 2-hour period in the headwaters of the run.  No damage was reported to the road and it was reopened after flooding receded.

Flash Flood in MONTGOMERY, VIRGINIA
From 09-SEP-23 14:00:00 to 09-SEP-23 16:15:00 (EST-5)
Location: MERRIMAC
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: NWS Employee

A National Weather Service employee observed flood waters flowing across North Franklin Street up to 1 foot deep near the intersection with Red Oak Drive.  No damage was observed to the road, and it was reopened after the flooding receded.

Flood in GILES, VIRGINIA
From 09-SEP-23 12:50:00 to 09-SEP-23 14:00:00 (EST-5)
Location: RICH CREEK
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: 911 Call Center

The Giles County 911 Center reported that the intersection of Spruce Street and North Street in Rich Creek was flooded and briefly closed due to a blocked culvert.  No damage was reported, and the streets were reopened to traffic after the flooding receded.