Alert archive / Virginia / Flash Flood Watches in 2011

Flash Flood Watch 6, NWS Blacksburg, VA

May 17, 201125 counties in Virginia; Rockingham County, Stokes County, Surry County, North Carolina

NWS Blacksburg, VA issued this flash flood watch at May 17, 2011, 4:03 AM EDT for 25 counties in Virginia; Rockingham County, Stokes County, Surry County, North Carolina. It was in force for 24 hr.

The area

The counties it named.

The facts

Issued: May 17, 2011, 4:03 AM EDT (08:03 UTC)
Expired: May 18, 2011, 4:00 AM EDT
In force: 24 hr
Issued by: NWS Blacksburg, VA
Flood severity: None

All 28 counties

Rockingham County, NC, Stokes County, NC, Surry County, NC, Alleghany County, VA, Amherst County, VA, Bath County, VA, Bedford County, VA, Botetourt County, VA, Campbell County, VA, Carroll County, VA, City of Buena Vista, VA, City of Covington, VA, City of Danville, VA, City of Galax, VA, City of Lexington, VA, City of Lynchburg, VA, City of Martinsville, VA, City of Roanoke, VA, City of Salem, VA, Craig County, VA, Floyd County, VA, Franklin County, VA, Henry County, VA, Montgomery County, VA, Patrick County, VA, Pittsylvania County, VA, Roanoke County, VA, Rockbridge County, VA

The radar

The Roanoke radar (KFCX), 37 km from the middle of the area, began a volume at 08:06 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, 8.1 hours before the alert went out and 35 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: 1 J/kg
Mixed-layer CIN: No buoyant parcel
Mixed-layer LCL: 1175 m above ground
0-6 km bulk shear: 25 kt
0-1 km storm-relative helicity: -8 m²/s²
0-3 km storm-relative helicity: 118 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

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 May 16, 7:30 PM EDT, 8 hours 33 minutes earlier.

Area forecast discussion, May 16, 7:30 PM EDT, 8 hours 33 minutes before

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Hazardous weather outlook, May 16, 4:15 AM EDT, 23 hours 48 minutes before

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE BLACKSBURG VA
415 AM EDT MON MAY 16 2011

NCZ001>003-018-019-VAZ007-009>020-022>024-032>035-WVZ042>045-170815-
ASHE-ALLEGHANY NC-SURRY-WATAUGA-WILKES-TAZEWELL-SMYTH-BLAND-GILES-
WYTHE-PULASKI-MONTGOMERY-GRAYSON-CARROLL-FLOYD-CRAIG-ALLEGHANY VA-
BATH-ROANOKE-BOTETOURT-ROCKBRIDGE-PATRICK-FRANKLIN-BEDFORD-AMHERST-
MERCER-SUMMERS-MONROE-GREENBRIER-
415 AM EDT MON MAY 16 2011

THIS HAZARDOUS WEATHER OUTLOOK IS FOR NORTH CENTRAL NORTH
CAROLINA...NORTHWEST NORTH CAROLINA...CENTRAL VIRGINIA...SOUTH
CENTRAL VIRGINIA...SOUTHWEST VIRGINIA...WEST CENTRAL VIRGINIA AND
SOUTHEAST WEST VIRGINIA.

.DAY ONE...TODAY AND TONIGHT.

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY.

PERIODS OF HEAVY RAIN ARE EXPECTED BEGINNING EARLY TUESDAY MORNING
AS A STRONG UPPER LEVEL DISTURBANCE PUSHES ACROSS OUR REGION. THE
SLOW MOVEMENT OR THE REPEATED DEVELOPMENT OF THUNDERSTORMS OVER
THE SAME LOCATIONS MAY LEAD TO LOCALIZED FLASH FLOODING...ESPECIALLY
IN AREAS WHERE THE GROUND IS ALREADY SATURATED DUE TO RECENT HEAVY
RAIN. IN ADDITION TO HEAVY RAIN...A FEW THUNDERSTORMS MAY BECOME
STRONG AND PRODUCE HAIL AND FREQUENT LIGHTNING.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION IS NOT EXPECTED AT THIS TIME.

NCZ004>006-020-VAZ043>047-058-059-170815-
STOKES-ROCKINGHAM-CASWELL-YADKIN-HENRY-PITTSYLVANIA-CAMPBELL-
APPOMATTOX-BUCKINGHAM-HALIFAX-CHARLOTTE-
415 AM EDT MON MAY 16 2011

THIS HAZARDOUS WEATHER OUTLOOK IS FOR NORTH CENTRAL NORTH
CAROLINA...NORTHWEST NORTH CAROLINA...CENTRAL VIRGINIA AND SOUTH
CENTRAL VIRGINIA.

.DAY ONE...TODAY AND TONIGHT.

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY.

PERIODS OF HEAVY RAIN ARE EXPECTED BEGINNING EARLY TUESDAY MORNING
AS A STRONG UPPER LEVEL DISTURBANCE PUSHES ACROSS OUR REGION. THE
SLOW MOVEMENT OR THE REPEATED DEVELOPMENT OF THUNDERSTORMS OVER
THE SAME LOCATIONS MAY LEAD TO LOCALIZED FLASH FLOODING. IN
ADDITION TO HEAVY RAIN...A FEW THUNDERSTORMS MAY BECOME STRONG AND
PRODUCE HAIL AND FREQUENT LIGHTNING.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION IS NOT EXPECTED AT THIS TIME.

The office that day

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

Issued	Product	Office	Counties	Lasted
May 16, 9:48 PM EDT	Flash Flood Warning	RNK	Patrick	6 hr
May 16, 11:22 PM EDT	Special Weather Statement	RNK	Henry, City of Martinsville	53 min
May 17, 12:49 AM EDT	Special Weather Statement	RNK	City of Roanoke	56 min
May 17, 12:53 AM EDT	Special Weather Statement	RNK	Franklin	67 min
May 17, 2:07 AM EDT	Special Weather Statement	RNK	Roanoke, City of Roanoke, City of Salem	53 min
May 17, 11:03 AM EDT	Special Weather Statement	RNK	Floyd, Franklin	57 min
May 17, 1:20 PM EDT	Special Weather Statement	RNK	City of Roanoke, City of Salem	40 min
May 17, 2:24 PM EDT	Special Weather Statement	RNK	Charlotte	51 min
May 17, 3:51 PM EDT	Special Weather Statement	RNK	Patrick	24 min
May 17, 4:55 PM EDT	Special Weather Statement	RNK	Alleghany, City of Covington	50 min
May 17, 5:53 PM EDT	Special Weather Statement	RNK	Greenbrier	52 min

Nearby

Flash Flood Watches in Virginia, 2011 Flash Flood Watches in North Carolina, 2011 Flash Flood Watches in West Virginia, 2011 Every flash flood watch in 2011

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.