Alert archive / North Carolina / Special Weather Statements in 2021

Special Weather Statement, NWS Raleigh, NC

July 14, 2021Alamance County, Guilford County, North Carolina

NWS Raleigh, NC issued this special weather statement at Jul 14, 2021, 4:41 PM EDT for Alamance County, Guilford County, North Carolina. It was in force for 64 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 14, 2021, 4:41 PM EDT (20:41 UTC)
Expired
Jul 14, 2021, 5:45 PM EDT
In force
64 min
Issued by
NWS Raleigh, NC

Counties Alamance County, NC, Guilford County, NC

The radar

The Raleigh/Durham radar (KRAX), 106 km from the middle of the area, began a volume at 20:44 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, 8.7 hours before the alert went out and 31 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 2021-07-14Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 95 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 2021-07-14The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 7 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
95 J/kg
Mixed-layer CIN
-116 J/kg
Mixed-layer LCL
1024 m above ground
0-6 km bulk shear
17 kt
0-1 km storm-relative helicity
7 m²/s²
0-3 km storm-relative helicity
10 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 Raleigh, NC wrote its last area forecast discussion before this special weather statement went out at Jul 14, 3:43 PM EDT, 58 minutes earlier.

Area forecast discussion, Jul 14, 3:43 PM EDT, 58 minutes before
AREA FORECAST DISCUSSION
National Weather Service Raleigh NC
343 PM EDT Wed Jul 14 2021

.SYNOPSIS...
Bermuda high pressure will maintain seasonably hot and humid
conditions, with afternoon and evening showers and thunderstorms
each day through this weekend.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 115 PM Wednesday...

High pressure, both aloft and at the surface, will sit along/just
off the Carolina coast through tonight. An upper level disturbance
crossing the Appalachians this afternoon will move over central NC
this evening into early tonight. Aside from the diurnal airmass
thunderstorms developing this afternoon, this disturbance combined
with a strengthening Piedmont trough will enhance convective
activity and provide a focused area over which it will occur. These
storms will move through the Triad between 4 PM and 8 PM this
evening, and are expected to dissipate given the loss of daytime
heating/nocturnal stabilization as they approach the Triangle. Most,
if not all, showers should abate by midnight, with the remainder of
the night expected to be dry and mild. Lows will bottom out in the
upper 60s to mid 70s.

&&

.SHORT TERM /THURSDAY AND THURSDAY NIGHT/...
As of 120 PM Wednesday...

Persistence. The surface high will remain off the Carolina coast
through Thursday night as the upper level high weakens slightly but
remains in place. A Piedmont trough will again set up over the area
on Thursday. The only change from the previous day will be a much
weaker/more subtle disturbance aloft clipping the NC/VA border
during the aft/eve, which could enhance convection briefly.
Otherwise, expect the diurnal showers/storms with highs in the upper
80s to low 90s and lows in the low to mid 70s to persist.

&&

.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
As of 335 PM Wednesday...

The models indicate the flow aloft will undergo amplification across
the CONUS this period, highlighted by another ridge forecast to near
600 dam (~+3 sigma) over the Rockies. Downstream, a positive tilt
longwave trough will amplify and become reinforced by subsequent
shortwaves from ern Canada swwd across the ern US, lwr MS Valley,
and srn Plains. That trough will be preceded by the strong sub-
tropical ridge that has been situated off the middle Atlantic coast
in recent days, which will gradually weaken and lose influence as
the aforementioned trough and accompanying slow-moving surface cold
front approach. That front will likely overtake, by Mon, a preceding
Appalachian-lee trough that will sharpen across the middle Atlantic
and Carolinas Fri-Sat. The front should subsequently settle across
the Carolinas through the middle of next week.

The sensible weather related to the pattern described above will
feature another couple of seasonably hot days Fri-Sat, with
generally climatological probabilities (~30%) of diurnally-driven
and weakly-forced convection, initiated by the lee trough, sea
breeze, and outflow. Well above average chances of convection will
follow and maximize Sun afternoon-Mon night, as forcing for ascent
accompanying the trough and front coincide with precipitable water
values at or above 2 inches. Those precipitation chances would
decrease if the front completely clears cntl NC by the middle of
next week, but given both the time of year and the orientation of
front-parallel, swly flow aloft, it is more likely that above
average chances persist throughout the forecast period. With that
convection and cloudiness, temperatures will trend cooler Sun
onward.

&&

.AVIATION /18Z WEDNESDAY THROUGH MONDAY/...
As of 105 PM Wednesday...

24 hour TAF period: Showers and thunderstorms will move into the
area from the NW, impacting KINT and KGSO most adversely. Some
isolated to widely scattered showers and storms are expected
elsewhere and could impact KRDU and KFAY this aft/eve, but
confidence on exactly when and how badly is uncertain. The strongest
storms will result in LIFR vsbys and strong gusty winds where they
occur. Otherwise through this evening, expect primarily VFR
conditions with scattered to broken cigs around 3500 ft and
southwesterly winds around 5-10 kts expected. MVFR stratus will
again be possible around daybreak Thursday, especially at KFAY but
cannot completely rule it out at the remaining terminals.

Looking ahead: Generally a persistence forecast expected through the
weekend. Southwesterly winds, light overnight and 5-10 kts during
the day, diurnal chances for showers and storms and morning stratus
are all expected to continue.

&&

.RAH WATCHES/WARNINGS/ADVISORIES...
None.

&&

SYNOPSIS...CBL
NEAR TERM...KC
SHORT TERM...KC
LONG TERM...MWS
AVIATION...KC
Hazardous weather outlook, Jul 14, 3:37 AM EDT, 13 hours 4 minutes before
Hazardous Weather Outlook
National Weather Service Raleigh NC
337 AM EDT Wed Jul 14 2021

NCZ007>011-021>028-038>043-073>078-083>086-088-089-150745-
Person-Granville-Vance-Warren-Halifax-Forsyth-Guilford-Alamance-
Orange-Durham-Franklin-Nash-Edgecombe-Davidson-Randolph-Chatham-Wake-
Johnston-Wilson-Stanly-Montgomery-Moore-Lee-Harnett-Wayne-Anson-
Richmond-Scotland-Hoke-Cumberland-Sampson-
337 AM EDT Wed Jul 14 2021

This Hazardous Weather Outlook is for central North Carolina.

.DAY ONE...Today and tonight.

No hazardous weather is expected at this time.

.DAYS TWO THROUGH SEVEN...Thursday through Tuesday.

No hazardous weather is expected at this time.

.SPOTTER INFORMATION STATEMENT...

Spotter activation is not expected at this time.

In the hours before

Special weather statement, Jul 14, 2:49 PM EDT, 1 hour 52 minutes before
Special Weather Statement
National Weather Service Raleigh NC
249 PM EDT Wed Jul 14 2021

NCZ007-008-141945-
Person NC-Granville NC-
249 PM EDT Wed Jul 14 2021

...A STRONG THUNDERSTORM WILL AFFECT CENTRAL PERSON AND NORTHWESTERN
GRANVILLE COUNTIES UNTIL 345 PM EDT...

At 249 PM EDT, Doppler radar was tracking a strong thunderstorm over
Roxboro, moving northeast at 15 mph.

Wind gusts up to 40 mph will be possible with this storm.

Locations impacted include...
Roxboro, Concord, Bethel Hill, Mayo Reservoir, Surl and Hyco Lake.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Seek shelter in a nearby building or vehicle. Wind gusts as high as
40 mph are capable of knocking down tree limbs and blowing around
trash cans, potted plants, lawn furniture and other light outdoor
objects.

&&

LAT...LON 3640 7857 3628 7903 3644 7913 3654 7892
      3654 7865
TIME...MOT...LOC 1849Z 245DEG 13KT 3640 7900

Leins
Special weather statement, Jul 14, 2:57 PM EDT, 1 hour 44 minutes before
Special Weather Statement
National Weather Service Raleigh NC
257 PM EDT Wed Jul 14 2021

NCZ007-023-024-142000-
Alamance NC-Person NC-Orange NC-
257 PM EDT Wed Jul 14 2021

...A STRONG THUNDERSTORM WILL AFFECT NORTHERN ALAMANCE...SOUTHWESTERN
PERSON AND NORTHERN ORANGE COUNTIES UNTIL 400 PM EDT...

At 256 PM EDT, Doppler radar was tracking a strong thunderstorm near
Burlington, moving east at 15 mph.

Wind gusts up to 40 mph will be possible with this storm.

Locations impacted include...
Burlington, Graham, Mebane, Haw River, Lake Cammack Park & Marina,
Carr, Altamahaw-Ossipee, Bushy Fork, Glen Raven and Union Ridge.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Seek shelter in a nearby building or vehicle. Wind gusts as high as
40 mph are capable of knocking down tree limbs and blowing around
trash cans, potted plants, lawn furniture and other light outdoor
objects.

&&

LAT...LON 3619 7897 3606 7945 3619 7954 3623 7953
      3625 7950 3624 7915 3643 7914 3644 7913
TIME...MOT...LOC 1856Z 255DEG 12KT 3617 7943

Leins
Special weather statement, Jul 14, 4:41 PM EDT, 0 minutes before
Special Weather Statement
National Weather Service Raleigh NC
441 PM EDT Wed Jul 14 2021

NCZ022>024-039-142145-
Guilford NC-Alamance NC-Randolph NC-Orange NC-
441 PM EDT Wed Jul 14 2021

...THUNDERSTORMS WITH FREQUENT LIGHTNING AND HEAVY RAIN WILL AFFECT
CENTRAL GUILFORD COUNTY EAST ACROSS ALAMANCE...NORTHERN ORANGE...
COUNTIES UNTIL 545 PM EDT...

At 438 PM EDT, Doppler radar was tracking a strong thunderstorm over
Greensboro, moving east at 20 mph. Other strong thunderstorms were
located over Mebane and near Trinity, also moving east at 20 mph.

Locations impacted include...
Greensboro, Burlington, Graham, Hillsborough, Mebane, Elon,
McLeansville, Archdale, Climax, and Gibsonville.

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, especially in urban areas where prolonged heavy rain
can quickly lead to flooding.

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.

&&

LAT...LON 3624 7895 3611 7897 3582 8005 3584 8005
      3601 7987 3613 7992 3625 7965
TIME...MOT...LOC 2038Z 248DEG 15KT 3608 7980

PWB

The office that day

Everything else NWS Raleigh, NC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Jul 14, 2:49 PM EDTSpecial Weather StatementRAHPerson56 min
Jul 14, 2:57 PM EDTSpecial Weather StatementRAHCaswell63 min
Jul 14, 3:51 PM EDTAreal Flood AdvisoryRAHAlamance, Guilford, Orange3 hr
Jul 14, 4:46 PM EDTSpecial Weather StatementRAHForsyth59 min
Jul 14, 5:11 PM EDTAreal Flood AdvisoryRAHDavidson, Guilford, Randolph64 min
Jul 14, 5:29 PM EDTSpecial Weather StatementRAHDavidson, Randolph61 min
Jul 14, 5:49 PM EDTAreal Flood AdvisoryRAHDavidson, Guilford, Randolph116 min
Jul 14, 6:21 PM EDTSpecial Weather StatementRAHRandolph54 min
Jul 14, 6:50 PM EDTFlash Flood Warning Considerable damage threatRAHRandolph115 min
Jul 14, 7:23 PM EDTSpecial Weather StatementRAHWake52 min
Jul 14, 7:32 PM EDTSpecial Weather StatementRAHMontgomery, Moore, Stanly58 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.