Alert archive / Virginia / Flash Flood Watches in 2021

Flash Flood Watch 8, NWS Blacksburg, VA

August 19, 2021Buckingham County, Virginia

NWS Blacksburg, VA issued this flash flood watch at Aug 19, 2021, 2:40 PM EDT for Buckingham County, Virginia. It took effect at Aug 20, 2021, 2:00 AM EDT. It was in force for 115 min.

The area

The counties it named.

The facts

Issued
Aug 19, 2021, 2:40 PM EDT (18:40 UTC)
In effect from
Aug 20, 2021, 2:00 AM EDT
Expired
Aug 20, 2021, 3:55 AM EDT
In force
115 min
Issued by
NWS Blacksburg, VA
Flood severity
None

County Buckingham County, VA

The radar

The Norfolk radar (KAKQ), 150 km from the middle of the area, began a volume at 18:44 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 12:00Z, 6.7 hours before the alert went out and 95 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-pSkew-T log-p diagram, Roanoke, VA at 12:00Z on 2021-08-19Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 17 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Roanoke, VA at 12:00Z on 2021-08-19The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -22 square meters per square second.1939Sfc1 km3 km6 km9 kmRMLM
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
17 J/kg
Mixed-layer CIN
-143 J/kg
Mixed-layer LCL
1038 m above ground
0-6 km bulk shear
23 kt
0-1 km storm-relative helicity
-22 m²/s²
0-3 km storm-relative helicity
9 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

194 
WGUS61 KRNK 191840
FFARNK

URGENT - IMMEDIATE BROADCAST REQUESTED
Flood Watch
National Weather Service Blacksburg VA
240 PM EDT Thu Aug 19 2021

VAZ047-200945-
/O.NEW.KRNK.FF.A.0008.210820T0600Z-210820T2200Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Buckingham-
240 PM EDT Thu Aug 19 2021

...FLASH FLOOD WATCH IN EFFECT FROM 2 AM EDT FRIDAY THROUGH FRIDAY 
AFTERNOON...

The National Weather Service in Blacksburg has issued a

* Flash Flood Watch for a portion of central Virginia, including the 
  following area, Buckingham.

* From 2 AM EDT Friday through Friday afternoon.

* Incoming rainfall this afternoon and evening, combined with recent 
  rainfall from the last week, will make for saturated soil 
  conditions in the watch area. This, combined with heavy rainfall 
  rates of 1 to 3 inches per hour tonight into tomorrow, could 
  result in flash flooding.

* Heavy rainfall may result in rapid rises on streams, creeks, and 
  in urban and poor drainage areas. This will especially be the case 
  where repetitive or persistent thunderstorm activity occurs.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

You should monitor later forecasts and be prepared to take action 
should Flash Flood Warnings be issued.

&&

$$

RR
1 follow-up statement
667 
WGUS61 KRNK 200755
FFARNK

Flood Watch
National Weather Service Blacksburg VA
355 AM EDT Fri Aug 20 2021

VAZ047-200900-
/O.CAN.KRNK.FF.A.0008.000000T0000Z-210820T2200Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Buckingham-
355 AM EDT Fri Aug 20 2021

...FLASH FLOOD WATCH IS CANCELLED...

The Flash Flood Watch for a portion of central Virginia, including 
Buckingham, has been cancelled.

The Flood Watch is cancelled. Flooding is no longer expected to pose 
a threat. Please continue to heed remaining road closures.

$$

SH

The office that day

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

IssuedProductOfficeCountiesLasted
Aug 19, 6:40 PM EDTSpecial Weather StatementRNKFloyd35 min
Aug 19, 6:42 PM EDTSpecial Weather StatementRNKHenry, City of Martinsville48 min
Aug 19, 7:45 PM EDTAreal Flood AdvisoryRNKCity of Roanoke3 hr

Nearby

Flash Flood Watches in Virginia, 2021Every flash 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.