Alert archive / Virginia / Flash Flood Watches in 2020

Flash Flood Watch 8, NWS Blacksburg, VA

August 2, 202034 counties in Virginia; 9 counties in North Carolina; Mercer County, West Virginia

NWS Blacksburg, VA issued this flash flood watch at Aug 2, 2020, 4:55 AM EDT for 34 counties in Virginia; 9 counties in North Carolina; Mercer County, West Virginia. It took effect at Aug 3, 2020, 8:00 AM EDT. It was in force for 23 hr.

The area

The counties it named.

The facts

Issued: Aug 2, 2020, 4:55 AM EDT (08:55 UTC)
In effect from: Aug 3, 2020, 8:00 AM EDT
Expired: Aug 4, 2020, 6:43 AM EDT
In force: 23 hr
Issued by: NWS Blacksburg, VA
Flood severity: None

All 44 counties

Alleghany County, NC, Ashe County, NC, Caswell County, NC, Rockingham County, NC, Stokes County, NC, Surry County, NC, Watauga County, NC, Wilkes County, NC, Yadkin County, NC, Amherst County, VA, Appomattox County, VA, Bedford County, VA, Bland County, VA, Botetourt County, VA, Buckingham County, VA, Campbell County, VA, Carroll County, VA, Charlotte County, VA, City of Buena Vista, VA, City of Danville, VA, City of Galax, VA, City of Lexington, VA, City of Lynchburg, 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, Halifax County, VA, Henry County, VA, Montgomery County, VA, Patrick County, VA, Pittsylvania County, VA, Pulaski County, VA, Roanoke County, VA, Rockbridge County, VA, Smyth County, VA, Tazewell County, VA, Wythe County, VA, Mercer County, WV

The radar

The Roanoke radar (KFCX), 11 km from the middle of the area, began a volume at 08:57 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, 8.9 hours before the alert went out and 64 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: 784 J/kg
Mixed-layer CIN: -4 J/kg
Mixed-layer LCL: 1219 m above ground
0-6 km bulk shear: 33 kt
0-1 km storm-relative helicity: 95 m²/s²
0-3 km storm-relative helicity: 119 m²/s²
Significant tornado parameter: 0.2
Supercell composite: 2.9

Open this sounding in Storm Lab

What forecasters said that day

The local office's own words before this flash flood watch went out, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.

NWS Blacksburg, VA wrote its last area forecast discussion before this flash flood watch went out at Aug 2, 1:55 AM EDT, 3 hours earlier.

Area forecast discussion, Aug 2, 1:55 AM EDT, 3 hours before

<!doctype html>
<html lang="en">
<head>
  <meta charset="utf-8">
  <meta name="viewport" content="width=device-width, initial-scale=1">
  <title>Service Notice</title>
  <link rel="stylesheet" href="index.css">
</head>
<body>
  <main class="wrap">
    <section class="card" role="status" aria-live="polite">
      <div class="status" id="status">Temporary Notice</div>
      <h1 id="headline">This service is currently unavailable.</h1>
      <p id="message1">
        The site you requested is temporarily down for maintenance or an unexpected outage.
      </p>
      <p id="message2">
        Please try again in a few minutes.
      </p>
      <p class="small" id="detail">
        If you are an administrator, restore upstream service and remove the redirect/fallback rule when normal operations resume.
      </p>
    </section>
  </main>
  <script src="index.js"></script>
</body>
</html>

Hazardous weather outlook, Aug 1, 10:48 PM EDT, 6 hours 7 minutes before

<!doctype html>
<html lang="en">
<head>
  <meta charset="utf-8">
  <meta name="viewport" content="width=device-width, initial-scale=1">
  <title>Service Notice</title>
  <link rel="stylesheet" href="index.css">
</head>
<body>
  <main class="wrap">
    <section class="card" role="status" aria-live="polite">
      <div class="status" id="status">Temporary Notice</div>
      <h1 id="headline">This service is currently unavailable.</h1>
      <p id="message1">
        The site you requested is temporarily down for maintenance or an unexpected outage.
      </p>
      <p id="message2">
        Please try again in a few minutes.
      </p>
      <p class="small" id="detail">
        If you are an administrator, restore upstream service and remove the redirect/fallback rule when normal operations resume.
      </p>
    </section>
  </main>
  <script src="index.js"></script>
</body>
</html>

The office that day

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

Issued	Product	Office	Counties	Lasted
Aug 1, 8:02 PM EDT	Special Weather Statement	RNK	Charlotte	28 min
Aug 1, 8:05 PM EDT	Special Weather Statement	RNK	Rockbridge, City of Lexington	25 min
Aug 1, 8:11 PM EDT	Severe Thunderstorm Warning	RNK	Charlotte, Halifax	35 min
Aug 2, 1:40 PM EDT	Special Weather Statement	RNK	City of Lynchburg	35 min
Aug 2, 2:08 PM EDT	Special Weather Statement	RNK	Appomattox	37 min
Aug 2, 2:10 PM EDT	Special Weather Statement	RNK	Franklin	35 min
Aug 2, 2:25 PM EDT	Severe Thunderstorm Warning	RNK	Franklin	35 min
Aug 2, 2:38 PM EDT	Special Weather Statement	RNK	Buckingham	22 min
Aug 2, 2:42 PM EDT	Severe Thunderstorm Warning	RNK	Buckingham	22 min
Aug 2, 4:19 PM EDT	Special Weather Statement	RNK	Patrick	26 min
Aug 2, 4:48 PM EDT	Special Weather Statement	RNK	City of Martinsville	27 min
Aug 2, 5:24 PM EDT	Special Weather Statement	RNK	Campbell	36 min
Aug 2, 6:24 PM EDT	Special Weather Statement	RNK	Charlotte	51 min
Aug 2, 6:59 PM EDT	Areal Flood Advisory	RNK	Montgomery, Pulaski	63 min
Aug 2, 7:24 PM EDT	Special Weather Statement	RNK	Charlotte	36 min
Aug 2, 2:53 PM EDT	Special Weather Statement	RNK	Wilkes	37 min
Aug 2, 3:33 PM EDT	Special Weather Statement	RNK	Surry	27 min
Aug 2, 4:04 PM EDT	Special Weather Statement	RNK	Surry	26 min
Aug 2, 5:21 PM EDT	Special Weather Statement	RNK	Ashe, Watauga	39 min
Aug 1, 8:20 PM EDT	Special Weather Statement	RNK	Greenbrier	25 min
Aug 1, 8:42 PM EDT	Special Weather Statement	RNK	Greenbrier	48 min

Nearby

Flash Flood Watches in Virginia, 2020 Flash Flood Watches in North Carolina, 2020 Flash Flood Watches in West Virginia, 2020 Every flash flood watch in 2020

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.