Alert archive / Virginia / Flash Flood Warnings in 2012

Flash Flood Warning 49, NWS Blacksburg, VA

September 1, 20125 counties in Virginia

NWS Blacksburg, VA issued this flash flood warning at Sep 1, 2012, 6:35 PM EDT for 5 counties in Virginia. It was in force for 64 min. No storm report in the archive falls inside the area while it was in force.

The area

The outline as issued.

The facts

Issued: Sep 1, 2012, 6:35 PM EDT (22:35 UTC)
Expired: Sep 1, 2012, 7:39 PM EDT
In force: 64 min
Issued by: NWS Blacksburg, VA
Area: Storm-based polygon
Flood severity: None

Counties City of Roanoke, VA, City of Salem, VA, Franklin County, VA, Montgomery County, VA, Roanoke County, VA

The radar

The Roanoke radar (KFCX), 29 km from the middle of the area, began a volume at 22:36 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, 10.6 hours before the alert went out and 50 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: 472 J/kg
Mixed-layer CIN: -66 J/kg
Mixed-layer LCL: 1024 m above ground
0-6 km bulk shear: 23 kt
0-1 km storm-relative helicity: -16 m²/s²
0-3 km storm-relative helicity: 18 m²/s²
Significant tornado parameter: 0.0
Supercell composite: -0.4

Open this sounding in Storm Lab

The text

As transmitted, in the capitals the NWS used until 2016.

660 
WGUS51 KRNK 012235
FFWRNK
VAC067-121-161-770-775-020430-
/O.NEW.KRNK.FF.W.0049.120901T2235Z-120902T0430Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
FLASH FLOOD WARNING
NATIONAL WEATHER SERVICE BLACKSBURG VA
635 PM EDT SAT SEP 1 2012

THE NATIONAL WEATHER SERVICE IN BLACKSBURG HAS ISSUED A

* FLASH FLOOD WARNING FOR...
  ROANOKE COUNTY IN WEST CENTRAL VIRGINIA
  CITY OF ROANOKE IN WEST CENTRAL VIRGINIA
  CITY OF SALEM IN WEST CENTRAL VIRGINIA
  NORTHWESTERN FRANKLIN COUNTY IN WEST CENTRAL VIRGINIA
  EASTERN MONTGOMERY COUNTY IN SOUTHWEST VIRGINIA

* UNTIL 1230 AM EDT.

* AT 632 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED
  VERY HEAVY RAIN FROM A THUNDERSTORM OVER THE WARNED AREA.

* LOCATIONS IN THE WARNING INCLUDE BUT ARE NOT LIMITED TO ROANOKE
  MOUNTAIN...HOLLINS...VINTON...ROANOKE AIRPORT...POAGES MILL...
  GLENVAR...CAVE SPRING...CATAWBA...BRADSHAW...SHAWSVILLE...
  MERRIMAC...MC DONALDS MILL...ELLISTON-LAFAYETTE...ELLISTON...
  BLACKSBURG...ROANOKE AND SALEM CITY.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

EXCESSIVE RUNOFF FROM HEAVY RAINFALL WILL CAUSE FLOODING OF SMALL
CREEKS AND STREAMS...HIGHWAYS AND UNDERPASSES. ADDITIONALLY...COUNTRY
ROADS AND FARMLANDS ALONG THE BANKS OF CREEKS...STREAMS AND OTHER LOW
LYING AREAS ARE SUBJECT TO FLOODING.

DO NOT DRIVE YOUR VEHICLE INTO AREAS WHERE THE WATER COVERS THE
ROADWAY. THE WATER DEPTH MAY BE TOO GREAT TO ALLOW YOUR CAR TO CROSS
SAFELY. MOVE TO HIGHER GROUND.

PLEASE RELAY ANY REPORTS OF FLOODING INCLUDING MUDSLIDES...OR ROAD
CLOSURES TO THE NATIONAL WEATHER SERVICE IN BLACKSBURG BY CALLING
TOLL FREE...1...8 6 6...2 1 5...4 3 2 4. DELAYED REPORTS ARE WELCOME.

&&

LAT...LON 3734 7989 3727 7985 3722 7985 3721 7982
      3712 8012 3712 8014 3709 8026 3705 8032
      3723 8047 3741 8006

$$

KK

1 follow-up statement

175 
WGUS71 KRNK 012339
FFSRNK

FLASH FLOOD STATEMENT
NATIONAL WEATHER SERVICE BLACKSBURG VA
739 PM EDT SAT SEP 1 2012

VAC067-121-161-770-775-012347-
/O.CAN.KRNK.FF.W.0049.000000T0000Z-120902T0430Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
ROANOKE VA-CITY OF ROANOKE VA-CITY OF SALEM VA-FRANKLIN VA-
MONTGOMERY VA-
739 PM EDT SAT SEP 1 2012

...THE FLASH FLOOD WARNING HAS BEEN CANCELLED FOR THE CITY OF
ROANOKE...THE CITY OF SALEM... ROANOKE...NORTHWESTERN FRANKLIN AND
EASTERN MONTGOMERY COUNTIES...

THE STORM HAS WEAKEN AND THE HEAVIEST RAIN HAS MOVED NORTHEAST OF 
THE AREA. NO FLOODING HAS BEEN REPORTED TO THE NATIONAL WEATHER
SERVICE. THUS THE FLASH FLOOD WARNING HAS BEEN CANCELLED.
ADDITIONAL SHOWERS AND THUNDERSTORMS MAY FORM UNTIL MIDNIGHT. 


LAT...LON 3734 7989 3727 7985 3722 7985 3721 7982
      3712 8012 3712 8014 3709 8026 3705 8032
      3723 8047 3741 8006

$$

KK

The office that day

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

Issued	Product	Office	Counties	Lasted
Sep 1, 4:57 PM EDT	Special Weather Statement	RNK	Floyd, Patrick	78 min
Sep 1, 5:00 PM EDT	Special Weather Statement	RNK	Pulaski, Wythe	60 min
Sep 1, 5:53 PM EDT	Special Weather Statement	RNK	Montgomery, Pulaski, City of Radford	67 min
Sep 1, 6:10 PM EDT	Severe Thunderstorm Warning	RNK	Floyd, Franklin, Montgomery, Roanoke	65 min
Sep 1, 6:26 PM EDT	Severe Thunderstorm Warning	RNK	Montgomery, Roanoke, City of Radford, City of Roanoke, City of Salem	55 min
Sep 1, 7:47 PM EDT	Special Weather Statement	RNK	Botetourt	58 min

Nearby

Flash Flood Warnings in Virginia, 2012 Every flash flood warning in 2012

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.