Alert archive / North Carolina / Flash Flood Watches in 2012

Flash Flood Watch 13, NWS Blacksburg, VA

August 6, 2012Grayson County, Virginia; Ashe County, Watauga County, North Carolina

NWS Blacksburg, VA issued this flash flood watch at Aug 6, 2012, 4:17 AM EDT for Grayson County, Virginia; Ashe County, Watauga County, North Carolina. It took effect at Aug 6, 2012, 8:00 AM EDT. It was in force for 7 hr.

The area

The counties it named.

The facts

Issued
Aug 6, 2012, 4:17 AM EDT (08:17 UTC)
In effect from
Aug 6, 2012, 8:00 AM EDT
Expired
Aug 6, 2012, 3:26 PM EDT
In force
7 hr
Issued by
NWS Blacksburg, VA
Flood severity
None

Counties Ashe County, NC, Watauga County, NC, Grayson County, VA

The radar

The Roanoke radar (KFCX), 125 km from the middle of the area, began a volume at 08:17 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

Greensboro/Hi Pt, NC (KGSO), launched 00:00Z, 8.3 hours before the alert went out and 147 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, Greensboro/Hi Pt, NC at 00:00Z on 2012-08-06Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 286 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, Greensboro/Hi Pt, NC at 00:00Z on 2012-08-06The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 34 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
286 J/kg
Mixed-layer CIN
-88 J/kg
Mixed-layer LCL
1128 m above ground
0-6 km bulk shear
14 kt
0-1 km storm-relative helicity
34 m²/s²
0-3 km storm-relative helicity
38 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.

335 
WGUS61 KRNK 060817
FFARNK

URGENT - IMMEDIATE BROADCAST REQUESTED
FLOOD WATCH
NATIONAL WEATHER SERVICE BLACKSBURG VA
417 AM EDT MON AUG 6 2012

...SHOWERS AND THUNDERSTORMS WITH VERY HEAVY RAIN EXPECTED AGAIN
TODAY...

.A COOL FRONT WILL DRIFT SOUTHEAST THROUGH THE MID APPALACHIAN AND
MID ATLANTIC STATES TODAY INTO TONIGHT BEFORE STALLING AND
DISSIPATING OVER NORTH CAROLINA ON TUESDAY. SHOWERS AND
THUNDERSTORMS WITH VERY HEAVY RAIN ARE EXPECTED TO PRECEDE AND
ACCOMPANY THE PASSAGE OF THIS FRONT.

NCZ001-018-061630-
/O.NEW.KRNK.FF.A.0013.120806T1200Z-120807T0000Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
ASHE-WATAUGA-
INCLUDING THE CITIES OF...WEST JEFFERSON...BOONE
417 AM EDT MON AUG 6 2012

...FLASH FLOOD WATCH IN EFFECT FROM 8 AM EDT THIS MORNING THROUGH
THIS EVENING...

THE NATIONAL WEATHER SERVICE IN BLACKSBURG HAS ISSUED A

* FLASH FLOOD WATCH FOR A PORTION OF NORTHWEST NORTH CAROLINA... 
  INCLUDING THE FOLLOWING AREAS...ASHE AND WATAUGA. 

* FROM 8 AM EDT THIS MORNING THROUGH THIS EVENING

* A TROPICAL AIRMASS WILL COMBINE WITH AN APPROACHING COOL FRONT
  TO PRODUCE NUMEROUS TO WIDESPREAD SHOWERS AND THUNDERSTORMS OVER
  THE MOUNTAINS OF NORTH CAROLINA TODAY...IMPACTING THE SAME AREAS
  THAT RECEIVED SIGNIFICANT RAINFALL ON SUNDAY. RUNOFF FROM ADDITIONAL
  RAIN WILL BE SIGNIFICANT AND IMMEDIATE...INCREASING THE THREAT
  FOR FLASH FLOODING IN BOTH ASHE AND WATAUGA COUNTY.

* POTENTIAL LOCALIZED ROAD WASHOUTS AND MUDSLIDES.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A FLASH FLOOD WATCH MEANS THAT CONDITIONS MAY DEVELOP THAT LEAD
TO FLASH FLOODING. FLASH FLOODING IS A VERY DANGEROUS SITUATION.
YOU SHOULD MONITOR LATER FORECASTS AND BE PREPARED TO TAKE ACTION
SHOULD FLASH FLOOD WARNINGS BE ISSUED.

&&

$$

WERT
2 follow-up statements
612 
WGUS61 KRNK 061456
FFARNK

URGENT - IMMEDIATE BROADCAST REQUESTED
FLOOD WATCH
NATIONAL WEATHER SERVICE BLACKSBURG VA
1056 AM EDT MON AUG 6 2012

...SHOWERS AND THUNDERSTORMS WITH HEAVY RAIN EXPECTED AGAIN
TODAY...

.A COOL FRONT WILL DRIFT SOUTHEAST THROUGH THE MID APPALACHIAN
AND MID ATLANTIC STATES TODAY INTO TONIGHT BEFORE STALLING AND
DISSIPATING OVER NORTH CAROLINA ON TUESDAY. SHOWERS AND
THUNDERSTORMS WITH VERY HEAVY RAIN ARE EXPECTED TO PRECEDE AND
ACCOMPANY THE PASSAGE OF THIS FRONT.

VAZ015-062300-
/O.EXB.KRNK.FF.A.0013.000000T0000Z-120807T0400Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
GRAYSON-
INCLUDING THE CITIES OF...INDEPENDENCE...WHITETOP...TROUTDALE...
VOLNEY
1056 AM EDT MON AUG 6 2012

...FLASH FLOOD WATCH IN EFFECT THROUGH THIS EVENING...

THE NATIONAL WEATHER SERVICE IN BLACKSBURG HAS EXPANDED THE

* FLASH FLOOD WATCH TO INCLUDE A PORTION OF SOUTHWEST VIRGINIA...
   INCLUDING THE FOLLOWING AREA...GRAYSON. 

* THROUGH THIS EVENING

* A TROPICAL AIRMASS WILL COMBINE WITH AN APPROACHING COOL FRONT
  TO PRODUCE NUMEROUS SHOWERS AND THUNDERSTORMS OVER THE MOUNTAINS
  OF NORTH CAROLINA TODAY...IMPACTING THE SAME AREAS THAT RECEIVED
  SIGNIFICANT RAINFALL ON SUNDAY. RUNOFF FROM ADDITIONAL RAIN WILL
  INCREASE THE THREAT FOR FLASH FLOODING ESPECIALLY IN URBANIZED
  OR HILLY TERRAIN.

* POTENTIAL ROAD WASHOUTS AND MUDSLIDES.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A FLASH FLOOD WATCH MEANS THAT CONDITIONS MAY DEVELOP THAT LEAD
TO FLASH FLOODING. FLASH FLOODING IS A VERY DANGEROUS SITUATION.
YOU SHOULD MONITOR LATER FORECASTS AND BE PREPARED TO TAKE ACTION
SHOULD FLASH FLOOD WARNINGS BE ISSUED.

&&

$$

NCZ001-018-062300-
/O.EXT.KRNK.FF.A.0013.000000T0000Z-120807T0400Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
ASHE-WATAUGA-
INCLUDING THE CITIES OF...WEST JEFFERSON...BOONE
1056 AM EDT MON AUG 6 2012

...FLASH FLOOD WATCH NOW IN EFFECT THROUGH THIS EVENING...

THE FLASH FLOOD WATCH IS NOW IN EFFECT FOR

* A PORTION OF NORTHWEST NORTH CAROLINA...INCLUDING THE 
  FOLLOWING AREAS...ASHE AND WATAUGA. 

* THROUGH THIS EVENING

* A TROPICAL AIRMASS WILL COMBINE WITH AN APPROACHING COOL FRONT
  TO PRODUCE NUMEROUS SHOWERS AND THUNDERSTORMS OVER THE MOUNTAINS
  OF NORTH CAROLINA TODAY...IMPACTING THE SAME AREAS THAT RECEIVED
  SIGNIFICANT RAINFALL ON SUNDAY. RUNOFF FROM ADDITIONAL RAIN WILL
  INCREASE THE THREAT FOR FLASH FLOODING ESPECIALLY IN URBANIZED
  OR HILLY TERRAIN.

* POTENTIAL ROAD WASHOUTS AND MUDSLIDES.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A FLASH FLOOD WATCH MEANS THAT CONDITIONS MAY DEVELOP THAT LEAD
TO FLASH FLOODING. FLASH FLOODING IS A VERY DANGEROUS SITUATION.
YOU SHOULD MONITOR LATER FORECASTS AND BE PREPARED TO TAKE ACTION
SHOULD FLASH FLOOD WARNINGS BE ISSUED.

&&

$$
125 
WGUS61 KRNK 061926
FFARNK

FLOOD WATCH
NATIONAL WEATHER SERVICE BLACKSBURG VA
326 PM EDT MON AUG 6 2012

NCZ001-018-VAZ015-062030-
/O.CAN.KRNK.FF.A.0013.000000T0000Z-120807T0400Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
ASHE-WATAUGA-GRAYSON-
INCLUDING THE CITIES OF...WEST JEFFERSON...BOONE...INDEPENDENCE...
WHITETOP...TROUTDALE...VOLNEY
326 PM EDT MON AUG 6 2012

...FLASH FLOOD WATCH IS CANCELLED...

THE FLASH FLOOD WATCH FOR PORTIONS OF NORTHWEST NORTH CAROLINA
AND SOUTHWEST VIRGINIA HAS BEEN CANCELLED. HOWEVER SHOWERS WILL
REMAIN IN THE REGION INTO THE EVENING ALTHOUGH NONE ARE EXPECTED
TO CAUSE WIDESPREAD FLOODING.

$$

The office that day

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

IssuedProductOfficeCountiesLasted
Aug 5, 8:08 PM EDTSpecial Weather StatementRNKAlleghany, Amherst, Bath, Rockbridge, City of Buena Vista, City of Covington and 1 more52 min
Aug 5, 9:00 PM EDTAreal Flood AdvisoryRNKBotetourt, Craig, Floyd, Montgomery, Pulaski, Roanoke and 4 more107 min
Aug 5, 9:11 PM EDTSpecial Weather StatementRNKCarroll, Grayson, City of Galax64 min
Aug 6, 2:47 PM EDTSpecial Weather StatementRNKHalifax58 min
Aug 6, 3:03 PM EDTSpecial Weather StatementRNKAppomattox57 min
Aug 6, 5:42 PM EDTSpecial Weather StatementRNKHenry, City of Martinsville63 min
Aug 6, 6:16 PM EDTSpecial Weather StatementRNKCharlotte59 min
Aug 6, 6:59 PM EDTSpecial Weather StatementRNKHenry, City of Martinsville61 min
Aug 6, 7:14 PM EDTAreal Flood AdvisoryRNKHenry, Pittsylvania, City of Martinsville109 min
Aug 6, 7:36 PM EDTSpecial Weather StatementRNKStokes54 min

Nearby

Flash Flood Watches in North Carolina, 2012Flash Flood Watches in Virginia, 2012Every flash flood watch 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.