Alert archive / Virginia / Flood Watches in 2021

Flood Watch 4, NWS Blacksburg, VA

September 21, 20215 counties in North Carolina; 28 counties in Virginia

NWS Blacksburg, VA issued this flood watch at Sep 21, 2021, 4:11 AM EDT for 5 counties in North Carolina; 28 counties in Virginia. It took effect at Sep 21, 2021, 2:00 PM EDT. It was in force for .

The area

The counties it named.

The facts

Issued: Sep 21, 2021, 4:11 AM EDT (08:11 UTC)
In effect from: Sep 21, 2021, 2:00 PM EDT
Expired: Sep 21, 2021, 5:53 AM EDT
In force
Issued by: NWS Blacksburg, VA
Flood severity: None

All 33 counties

Alleghany County, NC, Ashe County, NC, Surry County, NC, Watauga County, NC, Wilkes County, NC, Alleghany County, VA, Amherst County, VA, Bath County, VA, Bedford County, VA, Bland County, VA, Botetourt County, VA, Carroll County, VA, City of Buena Vista, VA, City of Covington, VA, City of Galax, VA, City of Lexington, VA, City of Martinsville, VA, City of Radford, VA, City of Roanoke, VA, City of Salem, VA, Craig County, VA, Floyd County, VA, Franklin County, VA, Giles County, VA, Grayson County, VA, Henry County, VA, Montgomery County, VA, Patrick County, VA, Pulaski County, VA, Roanoke County, VA, Rockbridge County, VA, Smyth County, VA, Wythe County, VA

The radar

The Roanoke radar (KFCX), 12 km from the middle of the area, began a volume at 08:15 UTC, the scan nearest the moment this went out.

Open the radar archive at this moment

The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.

The nearest sounding before it

Roanoke, VA (KRNK), launched 00:00Z, 8.2 hours before the alert went out and 78 km from the middle of its area. This is the routine balloon launch nearest before it, the air the forecaster had in hand, not a measurement taken for the alert.

Skew-T log-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km.

Mixed-layer CAPE: 56 J/kg
Mixed-layer CIN: -4 J/kg
Mixed-layer LCL: 828 m above ground
0-6 km bulk shear: 22 kt
0-1 km storm-relative helicity: 96 m²/s²
0-3 km storm-relative helicity: 136 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

358 
WGUS61 KRNK 210811
FFARNK

URGENT - IMMEDIATE BROADCAST REQUESTED
Flood Watch
National Weather Service Blacksburg VA
411 AM EDT Tue Sep 21 2021

NCZ001>003-018-019-VAZ009>020-022>024-032>035-043-211615-
/O.NEW.KRNK.FA.A.0004.210921T1800Z-210922T1500Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Ashe-Alleghany NC-Surry-Watauga-Wilkes-Smyth-Bland-Giles-Wythe-
Pulaski-Montgomery-Grayson-Carroll-Floyd-Craig-Alleghany VA-Bath-
Roanoke-Botetourt-Rockbridge-Patrick-Franklin-Bedford-Amherst-Henry-
Including the cities of Roanoke, Wilkesboro, Sparta, Pulaski, 
Covington, Independence, Fincastle, Buena Vista, Floyd, Hot Springs, 
Clifton Forge, Wytheville, Whitetop, Bedford, Volney, Martinsville, 
Pearisburg, Blacksburg, West Jefferson, Lexington, Radford, Boone, 
Stuart, New Castle, Dobson, Rocky Mount, Galax, Salem, Marion, 
Amherst, Bland, and Troutdale
411 AM EDT Tue Sep 21 2021

...FLOOD WATCH IN EFFECT FROM 2 PM EDT THIS AFTERNOON THROUGH 
WEDNESDAY MORNING...

The National Weather Service in Blacksburg has issued a

* Flood Watch for portions of North Carolina and Virginia, including 
  the following areas, in North Carolina, Alleghany NC, Ashe, Surry, 
  Watauga and Wilkes. In Virginia, Alleghany VA, Amherst, Bath, 
  Bedford, Bland, Botetourt, Carroll, Craig, Floyd, Franklin, Giles, 
  Grayson, Henry, Montgomery, Patrick, Pulaski, Roanoke, Rockbridge, 
  Smyth and Wythe.

* From 2 PM EDT this afternoon through Wednesday morning.

* Deep tropical moisture will move across the central Appalachians 
  this afternoon through tonight, supporting the potential for 
  prolonged periods of heavy rain. Rainfall amounts will be highest 
  along and near the crest of the Blue Ridge, where the terrain will 
  enhance rainfall intensity in the southeasterly windflow.

* Where high rainfall rates occur, or where bands of rain pass 
  repeatedly over the same locations, rapid rises on smaller creeks 
  and streams is expected.  Some of these waterways may flood outside 
  of their banks, and flow across roads and into low-lying areas. 
  Depending on where the heaviest rain occurs, minor flooding of the 
  larger main-stem rivers may be possible.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

You should monitor later forecasts and be alert for possible Flood 
Warnings. Those living in areas prone to flooding should be prepared 
to take action should flooding develop.

&&

$$

16

1 follow-up statement

243 
WGUS61 KRNK 210953
FFARNK

Flood Watch
National Weather Service Blacksburg VA
553 AM EDT Tue Sep 21 2021

NCZ001>003-018-019-VAZ009>020-022>024-032>035-043-211100-
/O.CAN.KRNK.FA.A.0004.210921T1800Z-210922T1500Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Ashe-Alleghany NC-Surry-Watauga-Wilkes-Smyth-Bland-Giles-Wythe-
Pulaski-Montgomery-Grayson-Carroll-Floyd-Craig-Alleghany VA-Bath-
Roanoke-Botetourt-Rockbridge-Patrick-Franklin-Bedford-Amherst-Henry-
Including the cities of Roanoke, Wilkesboro, Sparta, Pulaski, 
Covington, Independence, Fincastle, Buena Vista, Floyd, Hot Springs, 
Clifton Forge, Wytheville, Whitetop, Bedford, Volney, Martinsville, 
Pearisburg, Blacksburg, West Jefferson, Lexington, Radford, Boone, 
Stuart, New Castle, Dobson, Rocky Mount, Galax, Salem, Marion, 
Amherst, Bland, and Troutdale
553 AM EDT Tue Sep 21 2021

...FLOOD WATCH TO BE REPLACED WITH A FLASH FLOOD WATCH...

The Flood Watch for portions of North Carolina and Virginia, 
including the following areas, in North Carolina, Alleghany NC, 
Ashe, Surry, Watauga and Wilkes. In Virginia, Alleghany VA, Amherst, 
Bath, Bedford, Bland, Botetourt, Carroll, Craig, Floyd, Franklin, 
Giles, Grayson, Henry, Montgomery, Patrick, Pulaski, Roanoke, 
Rockbridge, Smyth and Wythe has been cancelled.

The Flood Watch is replaced with a Flash Flood Watch.

$$

16

The office that day

Everything else NWS Blacksburg, VA issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Sep 21, 5:59 AM EDT	Flash Flood Watch	RNK	Alleghany, Ashe, Rockingham, Stokes, Surry, Watauga and 1 more	41 hr
Sep 21, 4:15 PM EDT	Special Weather Statement	RNK	Charlotte, Halifax	45 min
Sep 21, 4:53 PM EDT	Special Weather Statement	RNK	Charlotte	37 min
Sep 21, 7:19 PM EDT	Areal Flood Advisory	RNK	Floyd, Patrick	3 hr
Sep 21, 7:41 PM EDT	Special Weather Statement	RNK	Botetourt, Rockbridge, City of Lexington	34 min

Nearby

Flood Watches in Virginia, 2021 Flood Watches in North Carolina, 2021 Every flood watch in 2021

Sources

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.