Alert archive / North Carolina / Areal Flood Advisories in 2012

Areal Flood Advisory 49, NWS Blacksburg, VA

July 21, 2012Caswell County, North Carolina

NWS Blacksburg, VA issued this areal flood advisory at Jul 21, 2012, 2:06 PM EDT for Caswell County, North Carolina. It was in force for 3 hr.

The area

The counties it named.

The facts

Issued: Jul 21, 2012, 2:06 PM EDT (18:06 UTC)
Expired: Jul 21, 2012, 5:00 PM EDT
In force: 3 hr
Issued by: NWS Blacksburg, VA
Area: Storm-based polygon

County Caswell County, NC

The radar

The Roanoke radar (KFCX), 109 km from the middle of the area, began a volume at 18:06 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

Greensboro/Hi Pt, NC (KGSO), launched 12:00Z, 6.1 hours before the alert went out and 62 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: 679 J/kg
Mixed-layer CIN: -73 J/kg
Mixed-layer LCL: 870 m above ground
0-6 km bulk shear: 16 kt
0-1 km storm-relative helicity: 49 m²/s²
0-3 km storm-relative helicity: 69 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 areal flood advisory 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 areal flood advisory went out at Jul 21, 12:38 PM EDT, 1 hour 28 minutes earlier.

Area forecast discussion, Jul 21, 12:38 PM EDT, 1 hour 28 minutes before

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Hazardous weather outlook, Jul 21, 6:31 AM EDT, 7 hours 35 minutes before

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE BLACKSBURG VA
631 AM EDT SAT JUL 21 2012

NCZ001>006-018>020-VAZ007-009>020-022>024-032>035-043>047-058-059-
WVZ042>045-221045-
ASHE-ALLEGHANY NC-SURRY-STOKES-ROCKINGHAM-CASWELL-WATAUGA-WILKES-
YADKIN-TAZEWELL-SMYTH-BLAND-GILES-WYTHE-PULASKI-MONTGOMERY-GRAYSON-
CARROLL-FLOYD-CRAIG-ALLEGHANY VA-BATH-ROANOKE-BOTETOURT-ROCKBRIDGE-
PATRICK-FRANKLIN-BEDFORD-AMHERST-HENRY-PITTSYLVANIA-CAMPBELL-
APPOMATTOX-BUCKINGHAM-HALIFAX-CHARLOTTE-MERCER-SUMMERS-MONROE-
GREENBRIER-
631 AM EDT SAT JUL 21 2012

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.

THE PROBABILITY FOR WIDESPREAD HAZARDOUS WEATHER IS LOW.

.DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY.

THE PROBABILITY FOR WIDESPREAD HAZARDOUS WEATHER IS LOW.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION IS NOT EXPECTED AT THIS TIME.

In the hours before

Special weather statement, Jul 21, 1:47 PM EDT, 19 minutes before

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE BLACKSBURG VA
147 PM EDT SAT JUL 21 2012

NCZ006-VAZ058-211830-
CASWELL NC-HALIFAX VA-
147 PM EDT SAT JUL 21 2012

...A STRONG THUNDERSTORM WILL AFFECT PORTIONS OF CASWELL AND HALIFAX
COUNTIES...

AT 142 PM EDT...A STRONG THUNDERSTORM WAS LOCATED 10 MILES EAST OF
PROVIDENCE...MOVING EAST AT 10 MPH.

WIND GUSTS TO 40 MPH AND SMALL HAIL ARE POSSIBLE WITH THIS STORM.
VERY HEAVY RAIN WILL FALL FROM THIS STORM...AND WILL CAUSE WATER TO
POND ON ROADS AND QUICKLY FILL ROADSIDE DITCHES AND SMALL STREAMS.
EXPECT FREQUENT CLOUD TO GROUND LIGHTNING FROM THIS STORM. DO NOT
STAY IN THE OPEN OR SEEK SHELTER UNDER TREES WHEN LIGHTNING
THREATENS...MOVE INDOORS WHEN A THUNDERSTORM APPROACHES.

THIS STORM WILL BE NEAR ALTON AROUND 230 PM.

LAT...LON 3641 7926 3654 7928 3654 7922 3655 7921
      3662 7888 3654 7887 3654 7913 3640 7914

WP

The office that day

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

Issued	Product	Office	Counties	Lasted
Jul 21, 4:37 PM EDT	Areal Flood Advisory	RNK	Charlotte, Halifax	3 hr
Jul 21, 5:04 PM EDT	Severe Thunderstorm Warning	RNK	Pittsylvania	56 min
Jul 21, 5:15 PM EDT	Severe Thunderstorm Warning	RNK	Franklin, Henry, Pittsylvania	34 min
Jul 21, 5:47 PM EDT	Special Weather Statement	RNK	Franklin	58 min
Jul 21, 1:47 PM EDT	Special Weather Statement	RNK	Person	43 min
Jul 21, 3:33 PM EDT	Special Weather Statement	RNK	Caswell	57 min
Jul 21, 4:40 PM EDT	Special Weather Statement	RNK	Rockingham	65 min
Jul 21, 5:15 PM EDT	Severe Thunderstorm Warning	RNK	Caswell	60 min
Jul 21, 5:37 PM EDT	Flash Flood Warning	RNK	Caswell	4 hr
Jul 21, 5:40 PM EDT	Severe Thunderstorm Warning	RNK	Caswell, Rockingham	65 min
Jul 21, 1:47 AM EDT	Special Weather Statement	RNK	Mercer	58 min

Nearby

Areal Flood Advisories in North Carolina, 2012 Every areal flood advisory 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.