Alert archive / Virginia / Flash Flood Warnings in 2012

Flash Flood Warning 50, NWS Blacksburg, VA

September 5, 2012Botetourt County, Roanoke County, Virginia

NWS Blacksburg, VA issued this flash flood warning at Sep 5, 2012, 7:19 PM EDT for Botetourt County, Roanoke County, Virginia. It was in force for 96 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 5, 2012, 7:19 PM EDT (23:19 UTC)
Expired
Sep 5, 2012, 8:55 PM EDT
In force
96 min
Issued by
NWS Blacksburg, VA
Area
Storm-based polygon
Flood severity
None

Counties Botetourt County, VA, Roanoke County, VA

The radar

The Roanoke radar (KFCX), 52 km from the middle of the area, began a volume at 23:21 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, 11.3 hours before the alert went out and 38 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 2012-09-05Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 608 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 2012-09-05The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 70 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
608 J/kg
Mixed-layer CIN
-5 J/kg
Mixed-layer LCL
540 m above ground
0-6 km bulk shear
18 kt
0-1 km storm-relative helicity
70 m²/s²
0-3 km storm-relative helicity
66 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

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

852 
WGUS51 KRNK 052319
FFWRNK
VAC023-161-060215-
/O.NEW.KRNK.FF.W.0050.120905T2319Z-120906T0215Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
FLASH FLOOD WARNING
NATIONAL WEATHER SERVICE BLACKSBURG VA
719 PM EDT WED SEP 5 2012

THE NATIONAL WEATHER SERVICE IN BLACKSBURG HAS ISSUED A

* FLASH FLOOD WARNING FOR...
  NORTHEASTERN ROANOKE COUNTY IN WEST CENTRAL VIRGINIA
  SOUTHWESTERN BOTETOURT COUNTY IN WEST CENTRAL VIRGINIA

* UNTIL 1015 PM EDT.

* AT 712 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED   
  VERY HEAVY RAIN FROM THUNDERSTORMS PERSISTING OVER THE WARNED AREA.
  DOPPLER RADAR INDICATES THAT RAINFALL OVER 2.0 INCHES MAY HAVE
  FALLEN IN PARTS OF NORTHEAST ROANOKE AND WESTERN BOTETOURT COUNTY
  DURING THE PAST HOUR...AND ADDITIONAL THUNDERSTORMS ARE DEVELOPING
  IN NORTHEAST ROANOKE COUNTY POISED TO MOVE INTO THE FLASH FLOOD
  WARNING AREA.

* LOCATIONS IN THE WARNING INCLUDE BUT ARE NOT LIMITED TO CATAWBA...
  TROUTVILLE...NACE...DALEVILLE AND BLUE RIDGE.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

EXCESSIVE RUNOFF FROM HEAVY RAINFALL WILL CAUSE FLOODING OF SMALL
CREEKS AND STREAMS...URBAN AREAS...HIGHWAYS...STREETS AND UNDERPASSES
AS WELL AS OTHER DRAINAGE AREAS AND LOW LYING SPOTS. FLOODING ALONG
INTERSTATE 81 BETWEEN MILE MARKERS 145 AND 155 IS LIKELY.

IN HILLY TERRAIN THERE ARE HUNDREDS OF LOW WATER CROSSINGS WHICH ARE
POTENTIALLY DANGEROUS IN HEAVY RAIN. DO NOT ATTEMPT TO TRAVEL ACROSS
FLOODED ROADS. FIND ALTERNATE ROUTES. IT TAKES ONLY A FEW INCHES OF
SWIFTLY FLOWING WATER TO CARRY VEHICLES AWAY.

A FLASH FLOOD WARNING MEANS THAT FLOODING IS IMMINENT OR OCCURRING.
IF YOU ARE IN THE WARNING AREA MOVE TO HIGHER GROUND IMMEDIATELY.
RESIDENTS LIVING ALONG STREAMS AND CREEKS SHOULD TAKE IMMEDIATE
PRECAUTIONS TO PROTECT LIFE AND PROPERTY. DO NOT ATTEMPT TO CROSS
SWIFTLY FLOWING WATERS OR WATERS OF UNKNOWN DEPTH BY FOOT OR BY
AUTOMOBILE.

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 3746 7974 3744 7973 3740 7981 3737 7978
      3732 7985 3727 7986 3728 7989 3731 7988
      3733 7997 3731 8001 3738 8017 3744 8002

$$



RAB
2 follow-up statements
603 
WGUS71 KRNK 060003
FFSRNK

FLASH FLOOD STATEMENT
NATIONAL WEATHER SERVICE BLACKSBURG VA
803 PM EDT WED SEP 5 2012

VAC023-161-060215-
/O.CON.KRNK.FF.W.0050.000000T0000Z-120906T0215Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
ROANOKE VA-BOTETOURT VA-
803 PM EDT WED SEP 5 2012

...A FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 1015 PM EDT FOR
NORTHEASTERN ROANOKE AND SOUTHWESTERN BOTETOURT COUNTIES...

AT 758 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED 
THAT THUNDERSTORMS HAD DIMINISHED WITHIN THE FLASH FLOOD WARNING 
AREA...BUT SCATTERED THUNDERSTORMS CONTINUED FROM NORTHERN ROANOKE 
COUNTY NEAR CATAWBA...TO NEAR THE ROANOKE AIRPORT...TO JUST SOUTH OF 
FINCASTLE. RAINFALL RATES HAVE DIMINISHED TO GENERALLY LESS THAN 0.5 
INCH PER HOUR WITHIN THE FLASH FLOOD WARNING AREA. 
HOWEVER...RAINFALL OF 2.0 TO 2.5 INCHES LIKELY FELL IN WESTERN 
BOTETOURT COUNTY JUST NORTH OF CLOVERDALE AND JUST NORTH OF THE 
ROANOKE AIRPORT IN NORTHEASTERN ROANOKE COUNTY.

LOCATIONS IN THE WARNING INCLUDE BUT ARE NOT LIMITED TO CATAWBA...
TROUTVILLE...NACE...LAYMANTOWN...DALEVILLE...CLOVERDALE AND BLUE
RIDGE

PRECAUTIONARY/PREPAREDNESS ACTIONS...

ADDITIONAL RAINFALL AMOUNTS OF 0.5 TO 1.0 INCH MAY OCCUR IN 
SCATTERED SPOTS THROUGHOUT THE FLASH FLOOD WARNING AREA.

BE ESPECIALLY CAUTIOUS AT NIGHT WHEN IT IS HARDER TO RECOGNIZE THE
DANGERS OF FLOODING. IF FLASH FLOODING IS OBSERVED ACT QUICKLY. MOVE
UP TO HIGHER GROUND TO ESCAPE FLOOD WATERS. DO NOT STAY IN AREAS
SUBJECT TO FLOODING WHEN WATER BEGINS RISING.

FLOODING IS OCCURRING OR IS IMMINENT. MOST FLOOD RELATED DEATHS OCCUR
IN AUTOMOBILES. DO NOT ATTEMPT TO CROSS WATER COVERED BRIDGES...
DIPS...OR LOW WATER CROSSINGS. NEVER TRY TO CROSS A FLOWING STREAM...
EVEN A SMALL ONE...ON FOOT. TO ESCAPE RISING WATER MOVE UP TO HIGHER
GROUND.

DO NOT UNDERESTIMATE THE POWER OF FLOOD WATERS. ONLY A FEW INCHES OF 
RAPIDLY FLOWING WATER CAN QUICKLY CARRY AWAY YOUR VEHICLE.

&&

LAT...LON 3743 7975 3740 7981 3737 7978 3732 7985
      3731 7988 3733 7997 3731 8001 3738 8017
      3744 8002 3746 7983

$$
846 
WGUS71 KRNK 060055
FFSRNK

FLASH FLOOD STATEMENT
NATIONAL WEATHER SERVICE BLACKSBURG VA
855 PM EDT WED SEP 5 2012

VAC023-161-060102-
/O.CAN.KRNK.FF.W.0050.000000T0000Z-120906T0215Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
ROANOKE VA-BOTETOURT VA-
855 PM EDT WED SEP 5 2012

...THE FLASH FLOOD WARNING HAS BEEN CANCELLED FOR NORTHEASTERN
ROANOKE AND SOUTHWESTERN BOTETOURT COUNTIES...

ONLY A FEW LIGHT SHOWERS REMAIN ACROSS THE FLASH FLOOD WARNING AREA. 
NO SIGNIFICANT RAINFALL HAS FALLEN SINCE 800 PM. SOME CREEKS AND 
SMALL STREAMS LIKELY REMAIN AT OR NEAR BANKFULL IN NORTHEAST ROANOKE 
AND WESTERN BOTETOURT COUNTIES FROM JUST NORTHEAST OF THE ROANOKE 
AIRPORT TO JUST SOUTH OF FINCASTLE. IN ADDITION...THE THREAT OF 
FLASH FLOODING ALONG INTERSTATE 81 BETWEEN MILE MARKERS 145 AND 55 
HAS ENDED. HOWEVER...SOME AREAS OF STANDING WATER MAY REMAIN IN THIS 
GENERAL AREA ALONG INTERSTATE 81 DURING THE NEXT COUPLE OF HOURS. 

FLOODING HAS ENDED OVER THE WARNED AREA...THUS THE FLASH FLOOD 
WARNING HAS BEEN CANCELLED. AN URBAN AND SMALL STREAM FLOOD ADVISORY 
REMAINS IN EFFECT FOR AREAS ALONG INTERSTATE 81 FROM MILE MARKERS 
145 TO 155 AND IMMEDIATE ADJACENT AREAS THROUGH 945 PM EDT.

LAT...LON 3743 7975 3740 7981 3737 7978 3732 7985
      3731 7988 3733 7997 3731 8001 3738 8017
      3744 8002 3746 7983

$$

RAB

The office that day

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

IssuedProductOfficeCountiesLasted
Sep 4, 8:37 PM EDTAreal Flood AdvisoryRNKPatrick3 hr
Sep 5, 11:21 AM EDTSpecial Weather StatementRNKSmyth54 min
Sep 5, 12:48 PM EDTSpecial Weather StatementRNKAlleghany, City of Covington27 min
Sep 5, 1:29 PM EDTSpecial Weather StatementRNKRockbridge, City of Lexington46 min
Sep 5, 1:59 PM EDTSpecial Weather StatementRNKBedford46 min
Sep 5, 2:23 PM EDTSpecial Weather StatementRNKRockbridge22 min
Sep 5, 4:30 PM EDTAreal Flood AdvisoryRNKAlleghany3 hr
Sep 5, 6:37 PM EDTSpecial Weather StatementRNKBotetourt53 min
Sep 5, 7:00 PM EDTAreal Flood AdvisoryRNKBotetourt, Roanoke3 hr

Nearby

Flash Flood Warnings in Virginia, 2012Every 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.