A strong cold front associated with a negatively tilted shortwave upper trough approached the region on October 23rd. Precipitable water rose to near excessive levels for the time of year with 1.44��� on the 12z (8 AM EDT)/23 RNK (Blacksburg) and 1.57��� on the 12z (8 AM EDT) GSO (Greensboro) soundings, with sea-level values of 1.75��� to 2���. These are roughly three standard deviations above the late October climatology and near all-time maxima for the date. Enhanced rainfall rates due to decent instability (for late October) were also expected to develop.  Moderate rainfall of 1 to 2 inches had already fall ahead of a cold front that approached in the mid-afternoon. Flood impacts began to occur quickly as the higher rate rainfall moved into the area. The IFLOWS rain gage at Sandy Flats (SDRN7) just southwest of Boone had 2.73��� in a 2-hour period ending at 400 PM, close to a 10-year (0.1 AEP) annual recurrence interval. Flooding was described as 'historic' by some observers ranking close to that seen in Hurricane Hugo in 1989.

Flood in WATAUGA, NORTH CAROLINA
From 23-OCT-17 10:00:00 to 24-OCT-17 00:00:00 (EST-5)
Location: SUGAR GROVE
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: River/Stream Gage

Persistent rainfall caused flooding on numerous streams and rivers across Watauga County. The Watauga River at Sugar Grove (SGWN7) crested at 11.72 feet (Moderate flood stage - 10 feet) and the highest reading since July of 2013.  The flood peak discharge of 7040 cfs fell midway between a 2- and 5-year recurrence interval (0.5 to 0.2 annual exceedance probability) according to USGS reports. The Watauga River IFLOWS gauge at Foscoe (FOSN7) crested at 8.86 feet, the highest since January 2013. Several roads and low water bridges were flooded by the Watauga River.  The Middle Fork of the New River at Boone IFLOWS gauge (NERN7) crested at 12.58 feet (Minor flood stage is 12 feet), which was the highest on record but over a fairly short period of data (2010-2017).

Flash Flood in ASHE, NORTH CAROLINA
From 23-OCT-17 16:00:00 to 23-OCT-17 18:00:00 (EST-5)
Location: WEST JEFFERSON
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: 911 Call Center

Numerous reports of roads flooded in the Jefferson and West Jefferson area between 5 PM and 7 PM local time.

Flash Flood in ASHE, NORTH CAROLINA
From 23-OCT-17 17:40:00 to 23-OCT-17 19:40:00 (EST-5)
Location: CRUMPLER
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: 911 Call Center

Several roads were flooded in the Crumpler area. The South Fork of the New River at Jefferson (JFRN7) crested at 8.22 feet early on the 24th just above the Minor flood stage of 8 feet.

Heavy Rain in WATAUGA, NORTH CAROLINA
From 23-OCT-17 08:00:00 to 24-OCT-17 08:00:00 (EST-5)
Location: BOONE BLWNG RCK ARPT
Property damage: 0.00K
Crop damage: 0.00K
Reported by: COOP Observer

Boone 1 SE COOP observer measured 5.95 in 24-hour period ending 8 AM on the 24th. This is the highest ever 24-hour October rainfall at this location since 1980 and at any Boone COOP site dating back to 1929. It was also the 3rd highest 24-hour rainfall for any day at both sites. The annual recurrence interval for this rainfall (per NOAA Atlas 14) was between a 5 and 10-year event (0.2 and 0.1 Annual exceedance probability).

Heavy Rain in ASHE, NORTH CAROLINA
From 23-OCT-17 08:00:00 to 24-OCT-17 08:00:00 (EST-5)
Location: JEFFERSON
Property damage: 0.00K
Crop damage: 0.00K
Reported by: COOP Observer

At the Jefferson 2 E COOP (JFRN7) 4.25 fell in 24 hours ending 12z on the 24th for the 4th highest October daily rainfall, with records dating back to 1896. Most of the rain fell in about a 12-hour period ending near midnight on the 24th.

Flash Flood in WATAUGA, NORTH CAROLINA
From 23-OCT-17 16:00:00 to 23-OCT-17 19:00:00 (EST-5)
Location: BOONE
Flood cause: Heavy Rain
Property damage: 800.00K
Crop damage: 0.00K
Reported by: Newspaper

Severe flash flooding was reported in various locations in and around Boone. Rainfall of 1 to 2 inches earlier in the day was followed by rainfall rates that increased sharply toward late afternoon reaching 2 to 3  inches per hour for about a one-hour period and this led to flash flooding. Boone Creek, which runs from the Appalachian State University campus southeast through (and under) the town, caused some of the worst damage.  At least a dozen water rescues were reported across Boone and numerous cars were flooded and abandoned. A later report said that 13 commercial properties and 53 residential units suffered some flood damage, with 7 commercial and 36 residential sustaining major damage (water above the electrical outlets). Repairs to damaged roadways, both secondary and primary, were approximately $100,000 according to the NC Department of Transportation.

Debris Flow in WATAUGA, NORTH CAROLINA
From 23-OCT-17 15:45:00 to 23-OCT-17 16:30:00 (EST-5)
Location: AHO
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Broadcast Media

The intense rainfall in the late afternoon over a short period cause at least two mudslides along NC Route 321 south of Boone near the communities of Tweetsie and Mystery Hill.

Debris Flow in ASHE, NORTH CAROLINA
From 23-OCT-17 17:46:00 to 23-OCT-17 18:00:00 (EST-5)
Location: SCOTTVILLE
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: 911 Call Center

A mudslide caused by heavy rain blocked a road in the Laurel Springs area.

Debris Flow in ASHE, NORTH CAROLINA
From 23-OCT-17 17:40:00 to 23-OCT-17 18:00:00 (EST-5)
Location: WARRENSVILLE
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: 911 Call Center

A mudslide blocked a road in the Warrensville area.