Alert archive / North Carolina / Special Weather Statements in 2021

Special Weather Statement, NWS Blacksburg, VA

July 11, 2021Caswell County, North Carolina

NWS Blacksburg, VA issued this special weather statement at Jul 11, 2021, 2:18 PM EDT for Caswell County, North Carolina. It was in force for 27 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
Jul 11, 2021, 2:18 PM EDT (18:18 UTC)
Expired
Jul 11, 2021, 2:45 PM EDT
In force
27 min
Issued by
NWS Blacksburg, VA

County Caswell County, NC

The radar

The Roanoke radar (KFCX), 107 km from the middle of the area, began a volume at 18:18 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, 6.3 hours before the alert went out and 47 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 12:00Z on 2021-07-11Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 536 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, Greensboro/Hi Pt, NC at 12:00Z on 2021-07-11The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 42 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
536 J/kg
Mixed-layer CIN
-25 J/kg
Mixed-layer LCL
923 m above ground
0-6 km bulk shear
14 kt
0-1 km storm-relative helicity
42 m²/s²
0-3 km storm-relative helicity
52 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

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What forecasters said that day

The local office's own words before this special weather statement 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 special weather statement went out at Jul 11, 2:09 PM EDT, 9 minutes earlier.

Area forecast discussion, Jul 11, 2:09 PM EDT, 9 minutes before
Area Forecast Discussion
National Weather Service Blacksburg VA
209 PM EDT Sun Jul 11 2021

.SYNOPSIS...
Scattered showers and thunderstorms will continue each afternoon
and evening. Ridging builds in from the east tomorrow and will
keep most precipitation and lightning over the western mountains.
The airmass will remain hot and humid overall.

&&

.NEAR TERM /THROUGH MONDAY/...

As of 130 PM EDT Sunday...

The Mid Atlantic region was in between strong ridging over the
western Atlantic and a digging closed low over the Midwest. This put
us in southwesterly flow aloft, with the jet stream and vorticity
maximums to our west. At the surface, the main surface low was back
in IL/IN with a wavy warm front extending through Ohio and the
Virginias. A cold front was over the southern Plains, making for a
broad warm sector.

We are on the eastern envelope of the stronger storms today, but we
have enough instability (MLCAPEs around 1500-2000 J/kg) and forcing
for ascent so that airmass thunderstorms are giving way to more
organized multicells. These more organized storm structures
will continue to feed off of existing outflow boundaries in the
region from previous or ongoing convection, and form broken
QLCS lines through this evening. Convection overall so far looks
similar to yesterday, and some areas will see more than one
round of rain/storms. Training along with deep warm cloud depths
and PWATs in excess of 1.50" will increase rain efficiency, and
heavy rainfall leading to flash flooding is possible. The added
downward momentum transfer of this mass will support damaging
winds in the strongest storms, especially in bowing segments.

Convection will begin to taper off tonight, similar to last night,
with the loss of heating. The warm frontal boundary will lift north
overnight. Expect another night of widespread fog and stratus late
tonight into the earlier morning hours Monday, in particular over
the river valleys. Overnight lows will be warm again and in the
lower to mid 60s along and west of the Blue Ridge, and in the upper
60s/lower 70s to the east.

On Monday ridging will push in from the southeast, especially
from 7H up. It will be another hot and humid day, with highs at
our slightly above climate norms. The ridge will limit our
thunderstorm activity somewhat west of the Blue Ridge. Still
expecting some showers and thunderstorms to form in the heat of
the day, especially over the mountains, but the severe threat
will be diminished.

&&

.SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY NIGHT/...

As of 130 PM EDT Sunday...

During this portion of the forecast, the region will remain between
high pressure off the coast of the Carolinas, and a trough/low
somewhere across the central portions of the country. The question
mark in this pattern remains how much capping influence will the
high/ridge have versus how close in proximity will the upper trough
and surface be to act as a focus for convection initiation. The
answer regarding at least the trough position will be an increasing
favorable position for convection initiation as the feature makes
gradual progress eastward Monday night through Wednesday. The trend
will make showers and storms more probable across the far western
sections of the region, especially during the afternoon and evening
hours. However, but Wednesday night, the trough both washes out and
continues its progression into parts of New England, allowing for
any surface front to also wash our, and/or retreat back to the north
by daybreak Thursday.

Temperatures during this portion of the forecast will average a few
degrees above normal, with Tuesday slightly warmer than Wednesday.

Confidence in the above weather scenario is moderate to high.

&&

.LONG TERM /THURSDAY THROUGH SUNDAY/...

As of 1145 AM EDT Sunday...

For the first half of this portion of the forecast, while we will
remain within a warm and moist atmosphere, any frontal boundary
north of the region is expected to remain well north of the region.
This will limit the focus for convection to weak orographical
convergence and areas of differential heating, all while
encountering some degree of capping from the western Atlantic high.
The result will be isolated to scattered coverage of showers and
storms that should dissipate quickly at sunset.

As we progress into and through the upcoming weekend, the upper
level low across the Upper Mississippi Valley is expected to open
into a more progressive wave, and head east to along the border of
southern Quebec and Ontario. Its associated cold front is expected
to approach, and possibly reach our area. This feature will bring
lifting mechanism needed (the front and better divergence aloft) to
support better coverage of showers and storms, and slightly cooler
high temperatures. Showers and storms will have a better chance of
continuing past sunset, along with the potential for redevelopment,
especially across western sections of the area, nearest the cold
front.

Temperatures during this portion of the forecast will be within a
couple of degrees plus or minus of normal conditions for this time
of year. However, high temperatures will trend slightly cooler
through the period while low temperatures may inch upward slightly.

Confidence in the above weather scenario is moderate to high.

&&

.AVIATION /18Z SUNDAY THROUGH FRIDAY/...

As of 200 PM EDT Sunday...

Showers and thunderstorms have developed and have already
affected a number of TAF sites, and expect widespread TSRA
through the evening. This will mean MVFR ceilings/visibilities
or perhaps lower if right under a thunderstorm with heavy rain.
The mean wind forecast is from 215 at 15 kts, so expect general
thunderstorm cell movement from the southwest to northeast this
afternoon. Away from any thunderstorm activity, expect VFR.

-TSRA diminished overnight, but low level moisture remains and
 there will be more fog and low stratus which will improve
 after 12-13Z Monday. Additional -TSRA is expected tomorrow but
 will mainly affect LWB and BLF with ridging building in over
 the east.

Extended Aviation Discussion...

Daily afternoon and evening showers and thunderstorms look to
continue for the Monday through Friday timeframe. Thunderstorm
activity will mainly be confined to the mountains Monday through
Wednesday as ridging and subsidence aloft starts to build from
the southeast. Better chances for storms arrive Thursday and
Friday as our next front nears the area.

&&

.RNK WATCHES/WARNINGS/ADVISORIES...
VA...None.
NC...None.
WV...None.

&&

SYNOPSIS...SH
NEAR TERM...SH
SHORT TERM...DS
LONG TERM...DS
AVIATION...SH
Hazardous weather outlook, Jul 11, 2:15 PM EDT, 3 minutes before
Hazardous Weather Outlook
National Weather Service Blacksburg VA
215 PM EDT Sun Jul 11 2021

NCZ001>006-018>020-VAZ007-009>020-022>024-032>035-043>047-058-059-
WVZ042>044-507-508-121815-
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-
Eastern Greenbrier-Western Greenbrier-
215 PM EDT Sun Jul 11 2021

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...This afternoon and tonight.

Strong thunderstorms will affect the area through this evening, and
may produce damaging winds and flash flooding due to heavy rainfall.

.DAYS TWO THROUGH SEVEN...Monday through Saturday.

There is a low probability for widespread hazardous weather.

.SPOTTER INFORMATION STATEMENT...

Weather spotters are encouraged to report significant weather
conditions according to Standard Operating Procedures.

In the hours before

Special weather statement, Jul 11, 12:24 PM EDT, 1 hour 54 minutes before
Special Weather Statement
National Weather Service BLACKSBURG VA
1224 PM EDT Sun Jul 11 2021

VAZ043-044-111700-
Henry-Pittsylvania-
1224 PM EDT Sun Jul 11 2021

...A STRONG THUNDERSTORM WILL AFFECT
SOUTHWESTERN PITTSYLVANIA AND EAST CENTRAL HENRY COUNTIES...

At 1224 PM EDT, a strong thunderstorm was located near Aiken Summit,
or near Axton, moving northeast at 20 mph.

Winds in excess of 30 mph are possible with this storm.

Frequent cloud to ground lightning is occurring with this storm.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.

This storm 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.

Locations impacted include...
Callands...
Axton...
Aiken Summit...
Sandy River...
Swansonville...
and Cascade.

LAT...LON 3656 7966 3662 7975 3683 7957 3667 7940
TIME...MOT...LOC 1624Z 225DEG 15KT 3663 7964

RR
Special weather statement, Jul 11, 12:42 PM EDT, 1 hour 36 minutes before
Special Weather Statement
National Weather Service BLACKSBURG VA
1242 PM EDT Sun Jul 11 2021

VAZ045-058-059-111715-
Halifax-Campbell-Charlotte-
1242 PM EDT Sun Jul 11 2021

...A LINE OF STRONG THUNDERSTORMS WILL AFFECT
CHARLOTTE...SOUTHEASTERN CAMPBELL AND NORTHEASTERN HALIFAX
COUNTIES...

At 1241 PM EDT, radar indicated strong thunderstorms were located
along a line extending from near Nathalie to near Mt Laurel to
Dryburg. Movement was northeast at 20 mph.

Winds in excess of 30 mph are possible with these storms.

Locations impacted include...
Brookneal...
Keysville...
Charlotte Court House...
Phenix...
Redoak...
Red House...
and Clover.

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 3689 7849 3675 7860 3669 7875 3687 7883
      3693 7904 3723 7891 3716 7862 3714 7859
      3715 7857 3714 7853 3699 7847
TIME...MOT...LOC 1641Z 222DEG 19KT 3697 7896 3692 7878 3675 7871

RR
Special weather statement, Jul 11, 12:46 PM EDT, 1 hour 32 minutes before
Special Weather Statement
National Weather Service BLACKSBURG VA
1246 PM EDT Sun Jul 11 2021

NCZ005-006-VAZ044-111730-
Rockingham-Caswell-Pittsylvania-
1246 PM EDT Sun Jul 11 2021

...A LINE OF STRONG THUNDERSTORMS WILL AFFECT
EASTERN ROCKINGHAM...WESTERN CASWELL AND WESTERN PITTSYLVANIA
COUNTIES AND THE CITY OF DANVILLE...

At 1245 PM EDT, radar indicated strong thunderstorms were located
along a line extending from near Swansonville to near Mayfield to
near McLeansville. Movement was northeast at 15 mph.

Winds in excess of 30 mph are possible with these storms.

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.

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.

Locations impacted include...
Danville...
Reidsville...
Bethel...
Chatham...
Gretna...
Providence...
and Mayfield.

LAT...LON 3625 7967 3644 7959 3676 7965 3706 7931
      3670 7924 3625 7944
TIME...MOT...LOC 1645Z 227DEG 14KT 3677 7958 3649 7953 3613 7969

RR
Special weather statement, Jul 11, 1:10 PM EDT, 1 hour 8 minutes before
Special Weather Statement
National Weather Service BLACKSBURG VA
110 PM EDT Sun Jul 11 2021

VAZ059-111745-
Charlotte-
110 PM EDT Sun Jul 11 2021

...A STRONG THUNDERSTORM WILL AFFECT
NORTHEASTERN CHARLOTTE COUNTY...

At 110 PM EDT, a strong thunderstorm was located over Drakes Branch,
or over Charlotte Court House, moving northeast at 20 mph.

Winds in excess of 40 mph and pea size hail are possible with this
storm.

Frequent cloud to ground lightning is occurring with this storm.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.

Locations impacted include...
Keysville...
Charlotte Court House...
Drakes Branch...
Abilene...
and Cullen.

LAT...LON 3693 7848 3690 7858 3705 7875 3720 7866
      3719 7864 3717 7864 3714 7859 3715 7855
      3714 7854 3714 7853 3713 7851 3711 7850
      3709 7848 3709 7846 3708 7844
TIME...MOT...LOC 1710Z 226DEG 19KT 3703 7859

RR
Special weather statement, Jul 11, 1:27 PM EDT, 51 minutes before
Special Weather Statement
National Weather Service BLACKSBURG VA
127 PM EDT Sun Jul 11 2021

NCZ006-VAZ044-045-058-111815-
Caswell-Halifax-Campbell-Pittsylvania-
127 PM EDT Sun Jul 11 2021

...A LINE OF STRONG THUNDERSTORMS WILL AFFECT
CENTRAL CASWELL...WESTERN CAMPBELL...EASTERN PITTSYLVANIA AND WESTERN
HALIFAX COUNTIES AND THE EASTERN CITY OF DANVILLE...

At 127 PM EDT, radar indicated strong thunderstorms were located
along a line extending from Leesville to near Keeling to near Camp
Springs. Movement was northeast at 25 mph.

Winds in excess of 40 mph are possible with these storms.

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.

Frequent cloud to ground lightning is occurring with these storms.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.

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.

Locations impacted include...
Danville...
Altavista...
Yanceyville...
Hurt...
Gretna...
Ingram...
and Mt Airy.

LAT...LON 3625 7951 3672 7935 3707 7944 3719 7936
      3736 7915 3700 7902 3638 7923 3625 7943
TIME...MOT...LOC 1727Z 222DEG 22KT 3710 7938 3677 7930 3629 7946

RR
Special weather statement, Jul 11, 2:18 PM EDT, 0 minutes before
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The office that day

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

IssuedProductOfficeCountiesLasted
Jul 10, 8:32 PM EDTSpecial Weather StatementRNKCarroll, Giles, Pulaski, City of Galax58 min
Jul 10, 10:07 PM EDTAreal Flood AdvisoryRNKCraig, Floyd, Giles, Montgomery, Pulaski, Roanoke and 1 more113 min
Jul 10, 10:22 PM EDTSpecial Weather StatementRNKPatrick23 min
Jul 10, 10:49 PM EDTSpecial Weather StatementRNKFloyd, Franklin, Henry, Patrick56 min
Jul 11, 12:20 AM EDTSpecial Weather StatementRNKCity of Roanoke, City of Salem55 min
Jul 11, 11:21 AM EDTSpecial Weather StatementRNKHalifax24 min
Jul 11, 11:43 AM EDTSevere Thunderstorm WarningRNKHalifax62 min
Jul 11, 11:53 AM EDTSpecial Weather StatementRNKCity of Martinsville37 min
Jul 11, 12:24 PM EDTSpecial Weather StatementRNKCity of Danville36 min
Jul 11, 12:42 PM EDTSpecial Weather StatementRNKCharlotte33 min
Jul 11, 12:46 PM EDTSpecial Weather StatementRNKPittsylvania, City of Danville44 min
Jul 11, 1:10 PM EDTSpecial Weather StatementRNKCharlotte35 min
Jul 11, 1:38 PM EDTSevere Thunderstorm WarningRNKCampbell, Halifax, Pittsylvania67 min
Jul 11, 2:34 PM EDTSpecial Weather StatementRNKCity of Lynchburg26 min
Jul 11, 2:43 PM EDTSpecial Weather StatementRNKCharlotte32 min
Jul 11, 2:56 PM EDTSpecial Weather StatementRNKCarroll34 min
Jul 11, 3:27 PM EDTSpecial Weather StatementRNKGrayson, Wythe48 min
Jul 11, 5:17 PM EDTFlash Flood WarningRNKGrayson, Smyth, Wythe3 hr
Jul 11, 5:38 PM EDTFlash Flood WarningRNKGrayson3 hr
Jul 11, 5:45 PM EDTSpecial Weather StatementRNKPulaski, City of Radford60 min
Jul 11, 6:02 PM EDTSpecial Weather StatementRNKCarroll, City of Galax58 min
Jul 11, 6:12 PM EDTFlash Flood WarningRNKCarroll, Grayson, City of Galax3 hr
Jul 11, 6:30 PM EDTSpecial Weather StatementRNKBath60 min
Jul 11, 6:47 PM EDTSevere Thunderstorm WarningRNKBath58 min
Jul 11, 1:27 PM EDTSpecial Weather StatementRNKCaswell48 min
Jul 11, 2:46 PM EDTSevere Thunderstorm WarningRNKCaswell, Rockingham31 min
Jul 11, 3:29 PM EDTAreal Flood AdvisoryRNKCaswell, Rockingham87 min
Jul 11, 5:55 PM EDTAreal Flood WarningRNKAshe3 hr
Jul 11, 6:22 PM EDTSpecial Weather StatementRNKStokes68 min
Jul 11, 7:11 PM EDTAreal Flood AdvisoryRNKRockingham, Stokes98 min
Jul 11, 6:00 PM EDTSpecial Weather StatementRNKMonroe45 min

Nearby

Special Weather Statements in North Carolina, 2021Every special weather statement 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.