Alert archive / Virginia / Areal Flood Advisories in 2021

Areal Flood Advisory 151, NWS Blacksburg, VA

September 1, 20217 counties in Virginia; Surry County, North Carolina

NWS Blacksburg, VA issued this areal flood advisory at Sep 1, 2021, 12:06 PM EDT for 7 counties in Virginia; Surry County, North Carolina. It was in force for 3 hr.

The area

The counties it named.

The facts

Issued
Sep 1, 2021, 12:06 PM EDT (16:06 UTC)
Expired
Sep 1, 2021, 3:00 PM EDT
In force
3 hr
Issued by
NWS Blacksburg, VA
Area
Storm-based polygon

Counties Surry County, NC, Carroll County, VA, City of Galax, VA, Floyd County, VA, Franklin County, VA, Montgomery County, VA, Patrick County, VA, Roanoke County, VA

The radar

The Roanoke radar (KFCX), 23 km from the middle of the area, began a volume at 16:08 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, 4.1 hours before the alert went out and 90 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 2021-09-01Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 44 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Roanoke, VA at 12:00Z on 2021-09-01The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 228 square meters per square second.193958Sfc1 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
44 J/kg
Mixed-layer CIN
-4 J/kg
Mixed-layer LCL
541 m above ground
0-6 km bulk shear
31 kt
0-1 km storm-relative helicity
228 m²/s²
0-3 km storm-relative helicity
316 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.4

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 Sep 1, 10:51 AM EDT, 1 hour 15 minutes earlier.

Area forecast discussion, Sep 1, 10:51 AM EDT, 1 hour 15 minutes before
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Hazardous weather outlook, Sep 1, 10:57 AM EDT, 1 hour 9 minutes before
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In the hours before

Local storm report, Sep 1, 8:50 AM EDT, 3 hours 16 minutes before
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Local storm report, Sep 1, 10:25 AM EDT, 1 hour 41 minutes before
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Local storm report, Sep 1, 10:26 AM EDT, 1 hour 40 minutes before
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE BLACKSBURG VA
1026 AM EDT WED SEP 1 2021

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0708 PM     TSTM WND DMG     2 ENE BLACKSBURG        37.25N 80.39W
08/31/2021                   MONTGOMERY         VA   911 CALL CENTER

            A LARGE TREE BLOCKS THE INTERSECTION OF
            HAPPY HOLLOW ROAD AND GOBBLERS KNOB ROAD.

&&

EST
Local storm report, Sep 1, 10:27 AM EDT, 1 hour 39 minutes before
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE BLACKSBURG VA
1027 AM EDT WED SEP 1 2021

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0759 PM     TSTM WND DMG     2 E MERRIMAC            37.19N 80.38W
08/31/2021                   MONTGOMERY         VA   911 CALL CENTER

            CORRECTS PREVIOUS TSTM WND DMG REPORT FROM 2
            E MERRIMAC. A LARGE TREE BLOCKING THE ROAD
            ALONG THE 936 BLOCK OF JENELLE ROAD.

&&

EST
Special weather statement, Sep 1, 11:38 AM EDT, 28 minutes before
Special Weather Statement
National Weather Service BLACKSBURG VA
1138 AM EDT Wed Sep 1 2021

VAZ014-017-022-023-033-011600-
Botetourt VA-Franklin VA-Floyd VA-Montgomery VA-Roanoke VA-
1138 AM EDT Wed Sep 1 2021

...A line of showers and thunderstorms will impact portions of
Roanoke, northeastern Floyd, southwestern Botetourt, western
Franklin and southeastern Montgomery Counties, the City of Salem and
the City of Roanoke through NOON EDT...

At 1135 AM EDT, Doppler radar was tracking a line of showers and
thunderstorms extending from near Catawba to near Floyd. Movement
was east at 30 mph. This line is indicating signs of intensification
and will be monitored closely over the next hour.

HAZARD...Winds in excess of 30 mph.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects.

Locations impacted include...
Roanoke...
Salem...
Vinton...
Troutville...
Floyd...
Boones Mill...
and Copper Hill.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Locally heavy rain will quickly reduce visibility and result in
ponding of water on roadways, standing water in low lying areas, and
minor flooding of creeks, streams, and areas of poor drainage.
Drivers are urged to slow down and use extra caution to avoid
hydroplaning.

&&

LAT...LON 3751 7978 3683 8007 3685 8009 3687 8023
      3686 8029 3687 8041 3738 8020 3738 8015
      3742 8008 3746 8004
TIME...MOT...LOC 1535Z 249DEG 25KT 3741 8008 3688 8035

MAX HAIL SIZE...0.00 IN
MAX WIND GUST...30 MPH

16
Special weather statement, Sep 1, 11:59 AM EDT, 7 minutes before
Special Weather Statement
National Weather Service BLACKSBURG VA
1159 AM EDT Wed Sep 1 2021

VAZ017-022-023-033-011645-
Botetourt VA-Franklin VA-Floyd VA-Roanoke VA-
1159 AM EDT Wed Sep 1 2021

...Strong showers will impact portions of Roanoke, northeastern
Floyd, southwestern Botetourt and western Franklin Counties, the
City of Salem and the City of Roanoke through 1245 PM EDT...

At 1157 AM EDT, Doppler radar was tracking a line of heavy showers
with occasional embedded thunderstorms extending from 6 miles
northeast of Catawba to near Floyd. Movement was northeast at 20
mph. This line is indicating signs of intensification and will be
monitored closely through 1 pm.

HAZARD...Winds in excess of 30 mph.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects.

Locations impacted include...
Roanoke...
Salem...
Vinton...
Troutville...
Boones Mill...
Copper Hill...
and Bent Mountain.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

These storms may intensify, so be certain to monitor local radio
stations and available television stations for additional information
and possible warnings from the National Weather Service.

&&

LAT...LON 3752 7978 3687 8005 3687 8030 3710 8021
      3711 8018 3717 8018 3742 8009 3747 8003
TIME...MOT...LOC 1557Z 241DEG 19KT 3744 8003 3688 8026

MAX HAIL SIZE...0.00 IN
MAX WIND GUST...30 MPH

16

The office that day

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

IssuedProductOfficeCountiesLasted
Aug 31, 8:00 PM EDTAreal Flood AdvisoryRNKCraig, Floyd, Giles, Montgomery, City of Radford5 hr
Aug 31, 8:26 PM EDTSpecial Weather StatementRNKCraig, Roanoke, City of Roanoke, City of Salem34 min
Aug 31, 8:40 PM EDTAreal Flood AdvisoryRNKBedford, Botetourt, Craig, Floyd, Franklin, Montgomery and 3 more3 hr
Aug 31, 8:43 PM EDTSpecial Weather StatementRNKCraig32 min
Aug 31, 9:12 PM EDTSpecial Weather StatementRNKBotetourt33 min
Aug 31, 9:18 PM EDTSpecial Weather StatementRNKAlleghany, City of Covington27 min
Aug 31, 9:35 PM EDTTornado WarningRNKBedford, Botetourt25 min
Aug 31, 9:44 PM EDTFlash Flood WarningRNKBotetourt, Craig, Roanoke5 hr
Aug 31, 9:47 PM EDTSpecial Weather StatementRNKAlleghany, Bath, City of Covington28 min
Aug 31, 9:58 PM EDTTornado WarningRNKBedford, Botetourt, Rockbridge32 min
Aug 31, 10:26 PM EDTSpecial Weather StatementRNKRockbridge, City of Buena Vista, City of Lexington34 min
Aug 31, 10:30 PM EDTSpecial Weather StatementRNKBotetourt30 min
Aug 31, 10:32 PM EDTAreal Flood AdvisoryRNKBedford, Botetourt, Rockbridge3 hr
Aug 31, 10:44 PM EDTTornado WarningRNKAmherst, Rockbridge, City of Buena Vista31 min
Aug 31, 11:10 PM EDTAreal Flood AdvisoryRNKAmherst, Rockbridge, City of Buena Vista, City of Lexington3 hr
Aug 31, 11:17 PM EDTSpecial Weather StatementRNKCity of Buena Vista28 min
Sep 1, 12:38 AM EDTSpecial Weather StatementRNKRockbridge22 min
Sep 1, 5:29 AM EDTAreal Flood AdvisoryRNKAlleghany, Botetourt, Craig, Roanoke3 hr
Sep 1, 7:27 AM EDTSpecial Weather StatementRNKCampbell, Pittsylvania, City of Danville, City of Lynchburg48 min
Sep 1, 7:54 AM EDTSpecial Weather StatementRNKAmherst, City of Lynchburg51 min
Sep 1, 8:43 AM EDTSpecial Weather StatementRNKAmherst32 min
Sep 1, 9:17 AM EDTAreal Flood AdvisoryRNKFranklin118 min
Sep 1, 11:38 AM EDTSpecial Weather StatementRNKFloyd, Roanoke, City of Roanoke, City of Salem22 min
Sep 1, 11:59 AM EDTSpecial Weather StatementRNKCity of Roanoke, City of Salem46 min
Sep 1, 3:47 PM EDTAreal Flood AdvisoryRNKPatrick2 hr
Sep 1, 4:35 AM EDTAreal Flood AdvisoryRNKAshe, Watauga3 hr
Sep 1, 2:47 PM EDTSpecial Weather StatementRNKStokes28 min
Sep 1, 3:20 PM EDTSpecial Weather StatementRNKStokes25 min
Sep 1, 3:27 PM EDTSpecial Weather StatementRNKWilkes33 min
Sep 1, 4:12 PM EDTSpecial Weather StatementRNKYadkin33 min

Nearby

Areal Flood Advisories in Virginia, 2021Areal Flood Advisories in North Carolina, 2021Every areal flood advisory in 2021

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.