Special Weather Statement, NWS Raleigh, NC

Area Forecast Discussion
National Weather Service Raleigh NC
300 PM EDT Wed Aug 23 2017

.SYNOPSIS...
A cold front will continue to cross the area this afternoon and
linger across the east this evening. High pressure for the end of
the week will bring cooler and drier weather to the area.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 300 PM Wednesday...

Showers and thunderstorms associated with a cold front are
continuing to fill in along a line from just south and east of the
Triad northeastward to north and west of the Triangle area. This
increase in activity is expected to continue this afternoon as
storms move into a more favorable airmass for development and are
accompanied by an increase in dynamical forcing. ML CAPE values of
1500-2000 J/kg will be common and effective shear values will reach
upwards of 30 knots across the north which will most likely lead to
a broken line of multicellular development with damaging winds the
most likely threat for severe weather. The best DCAPE values however
are expected to remain out ahead of the advancing convection and
will continue push eastward through the evening which could mitigate
somewhat the potential for downbursts. Although there is the
potential for some rotation aloft in storms, LCL values are very
high and low-level helicity values are near non-existent.

A secondary threat from these storms would be localized flooding,
especially in the south and east where high resolution models
indicate a slowing down of the system over the southeastern counties
into the evening and early overnight areas which could extend the
amount of time that areas could potentially see heavy rainfall. As
far as timing is concerned, the Triad will see the most activity
from now through mid-afternoon, with the Triangle seeing the best
coverage from 19-23Z and the Fayetteville area closer to 00z
potentially through 6z if enough slowing occurs.

After frontal passage expect locations to see a switch to
northwesterly and then northerly winds with dewpoints eventually
dropping about 10 degrees or so into the 60s in the Triad with
locations to the southeast maintaining upper 60s to low 70s
dewpoints into Thursday. Lows overnight in the mid 60s NW to lower
70s in the southeast.

&&

.SHORT TERM /THURSDAY AND THURSDAY NIGHT/...
As of 300 PM Wednesday...

For Thursday expect the frontal zone to hang up either in far
southeastern areas of the state or just offshore. With the exception
of a lingering afternoon shower in the far southeastern portion of
the forecast area, much of the CWA should remain dry and
significantly cooler than the past week or so. Expect high
temperatures only in the low to mid 80s with north winds at 5-10
kts. Skies will continue to clear as the day progresses with the
Triad seeing the most sun. Lows in the low to mid 60s across the
area.

&&

.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
As of 210 PM Wednesday...

An extended period of mostly dry and cooler-than-normal weather
appears likely. Cool Canadian high pressure will build in strongly
from the north through the period, as its center drifts from N
Ontario early Fri to New England early Mon, then weakens just off
the Northeast and Mid Atlantic coast Tue/Wed. The only significant
rain chance through the period appears to be in the far SE, closer
to the old frontal zone where PW will be higher. The far NW
including the Triad will see a smaller chance of light precip,
driven largely by moist upglide and shallow instability, mainly Fri
night into Sat, with overrunning clouds dominating there through
Sun. Will start to edge pops up closer to climatology for early next
week, given the uncertainty with a potential tropical-type low off
the SE coast, along with the weakening of the surface high and
resultant increase in onshore-directed low level flow drawing in
Atlantic moisture. Expect high temps in the low-mid 80s Fri, before
trending down to the mid 70s to near 80 by Tue as the stable wedge
noses down through central NC. Some rebounding back to highs in the
low-mid 80s is expected by Wed as low level thicknesses begin to
inch back up toward normal. -GIH

&&

.AVIATION /18Z WEDNESDAY THROUGH MONDAY/...
As of 225 PM Wednesday...

Showers and thunderstorms are expected to move through the area this
afternoon and evening in association with a cold front. Current
radar shows convection in the vicinity of KINT and KGSO but pushing
eastward with a few showers near eastern airports as well. Coverage
will continue to increase this afternoon for eastern sites whereas
the Triad terminals should see decreasing trends as the front moves
past. Winds will be light and variable outside of gusts within
thunderstorms which could reach 20-30 kts. Overnight expect
potential visibility restrictions as well as some possible IFR
ceilings at eastern locations, especially where rain lingers into
the overnight hours. Winds will switch to northerly after frontal
passage and conditions are expected to return to VFR after 15z
Thursday. Cant rule out a shower in the east tomorrow afternoon but
confidence is low at this time.

Long Term: High pressure over the area should yield an extended
period of VFR conditions.

&&

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

&&

$$ SYNOPSIS...Ellis
NEAR TERM...Ellis
SHORT TERM...Ellis
LONG TERM...Hartfield
AVIATION...Ellis

Hazardous Weather Outlook
National Weather Service Raleigh NC
416 AM EDT Wed Aug 23 2017

NCZ007>011-021>028-038>043-073>078-083>086-088-089-240830-
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-
416 AM EDT Wed Aug 23 2017

This Hazardous Weather Outlook is for central North Carolina.

.DAY ONE...Today and Tonight.

Scattered thunderstorms are expected to develop this afternoon and
evening, ahead of a strong cold front moving into the region. Some
storms could become severe, with the greatest threat coming from
damaging thunderstorm gusts. Frequent cloud to ground lightning
will also pose a threat.

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

No hazardous weather is expected at this time.

.SPOTTER INFORMATION STATEMENT...

Spotter activation may be needed this afternoon and evening.

Special Weather Statement
National Weather Service Raleigh NC
215 PM EDT WED AUG 23 2017

NCZ024-231900-
Orange NC-
215 PM EDT WED AUG 23 2017

...A STRONG THUNDERSTORM WILL AFFECT SOUTHERN ORANGE COUNTY UNTIL 300
PM EDT...

At 214 PM EDT, Doppler radar was tracking a strong thunderstorm 8
miles southeast of Mebane, or 8 miles southwest of Hillsborough,
moving east at 20 mph.

Wind gusts up to 40 mph are possible with this storm.

Locations impacted include...
Chapel Hill, Hillsborough, Carrboro, Efland, Cane Creek Reservoir and
Eno River State Park.

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. Move indoors at the first sound of thunder.

&&

LAT...LON 3607 7898 3587 7901 3586 7902 3594 7926
      3602 7926 3610 7920
TIME...MOT...LOC 1814Z 283DEG 16KT 3598 7921

GIH

Special Weather Statement
National Weather Service Raleigh NC
341 PM EDT WED AUG 23 2017

NCZ022-039-232045-
Guilford NC-Randolph NC-
341 PM EDT WED AUG 23 2017

...A STRONG THUNDERSTORM WILL AFFECT NORTHEASTERN RANDOLPH AND
SOUTHEASTERN GUILFORD COUNTIES UNTIL 445 PM EDT...

At 340 PM EDT, Doppler radar was tracking a strong thunderstorm over
Randleman, moving northeast at 10 mph.

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

Heavy rain and minor flooding and deadly cloud to ground lightning
will also be possible with this storm.

Locations impacted include...
Asheboro, Randleman, Liberty, Franklinville, Staley, Climax, Lake
Guilford Mackintosh Marina, Randleman Regional Reservior Marina and
Forest Oaks.

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.

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.

&&

LAT...LON 3609 7954 3578 7954 3571 7977 3586 7989
TIME...MOT...LOC 1940Z 236DEG 9KT 3583 7975

KDS

Special Weather Statement
National Weather Service Raleigh NC
349 PM EDT WED AUG 23 2017

NCZ026-027-041-232045-
Nash NC-Franklin NC-Wake NC-
349 PM EDT WED AUG 23 2017

...A STRONG THUNDERSTORM WILL AFFECT WEST CENTRAL NASH...NORTHEASTERN
WAKE AND SOUTH CENTRAL FRANKLIN COUNTIES UNTIL 445 PM EDT...

At 349 PM EDT, Doppler radar was tracking a strong thunderstorm near
Wake Forest, or 12 miles northeast of Raleigh, moving east at 15 mph.

Nickel size hail will be possible with this storm.

Deadly cloud to ground lightning will also be possible with this
storm.

Locations impacted include...
Zebulon, Bunn, Rolesville, Spring Hope and Pilot.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

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 3598 7809 3577 7824 3577 7825 3579 7824
      3582 7826 3578 7833 3586 7851 3600 7839
TIME...MOT...LOC 1949Z 292DEG 11KT 3590 7845

Ellis

Special Weather Statement
National Weather Service Raleigh NC
433 PM EDT WED AUG 23 2017

NCZ074-075-232130-
Moore NC-Montgomery NC-
433 PM EDT WED AUG 23 2017

...A STRONG THUNDERSTORM WILL AFFECT NORTHERN MOORE AND EASTERN
MONTGOMERY COUNTIES UNTIL 530 PM EDT...

At 431 PM EDT, Doppler radar was tracking a strong thunderstorm
extending from near Star and Biscoe east to Robbins, moving east at
35 mph.

Frequent lightning, heavy rain and wind gusts up to 50 mph will be
possible with this storm.

Locations impacted include...
Southern Pines, Carthage, Pinehurst, Aberdeen, Biscoe, Whispering
Pines, Pinebluff, Robbins, Foxfire and Star.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

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 3506 7950 3507 7957 3508 7958 3512 7957
      3517 7962 3516 7964 3518 7986 3551 7985
      3552 7935 3550 7934 3548 7936 3543 7933
      3540 7929 3535 7927 3531 7919 3527 7922
      3526 7921 3521 7924 3516 7933 3504 7946
TIME...MOT...LOC 2031Z 267DEG 29KT 3539 7973

Badgett

Special Weather Statement
National Weather Service Raleigh NC
448 PM EDT WED AUG 23 2017

NCZ011-232145-
Halifax NC-
448 PM EDT WED AUG 23 2017

...A CLUSTER OF STRONG THUNDERSTORMS WILL AFFECT SOUTHEASTERN
HALIFAX COUNTY UNTIL 545 PM EDT...

At 448 PM EDT, Doppler radar was tracking a cluster of strong
thunderstorms along a line extending from 7 miles west of Rich
Square to 11 miles southwest of Halifax. Movement was east at 20 mph.

Pea size hail and wind gusts up to 50 mph will be possible with these
storms.

Locations impacted include...
Scotland Neck, Enfield and Tillery.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Seek shelter in a nearby building or vehicle. Wind gusts of this
magnitude are capable of producing tree damage, including isolated
instances of knocking down small or weakened trees. Unsecured, light
outdoor objects may also blow around, or away.

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.

&&

LAT...LON 3606 7735 3606 7754 3607 7753 3609 7753
      3610 7754 3610 7760 3615 7768 3615 7771
      3613 7772 3615 7774 3615 7776 3616 7776
      3614 7782 3631 7743 3629 7741 3626 7741
      3624 7738 3621 7738 3616 7728 3612 7725
TIME...MOT...LOC 2048Z 268DEG 19KT 3629 7742 3617 7768

26

Special Weather Statement
National Weather Service Raleigh NC
504 PM EDT WED AUG 23 2017

NCZ041-042-077-232200-
Johnston NC-Harnett NC-Wake NC-
504 PM EDT WED AUG 23 2017

...A CLUSTER OF DEVELOPING STRONG THUNDERSTORMS WILL AFFECT
NORTHEASTERN HARNETT... SOUTHWESTERN WAKE AND JOHNSTON COUNTIES
UNTIL 600 PM EDT...

At 503 PM EDT, Doppler radar was tracking a cluster of strong
thunderstorms along a line extending from 9 miles east of Clayton to
6 miles west of Smithfield to Angier. Movement was east at 25 mph.

Locations impacted include...
Smithfield, Garner, Fuquay-Varina, Clayton, Angier, Benson, Holly
Springs, Micro, Selma and Coats.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Seek shelter in a nearby building or vehicle. Wind gusts of this
magnitude are capable of producing tree damage, including isolated
instances of knocking down small or weakened trees.

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.

&&

LAT...LON 3542 7816 3539 7814 3537 7816 3535 7815
      3534 7822 3532 7824 3540 7872 3543 7884
      3560 7887 3566 7886 3571 7847 3573 7841
      3573 7819 3571 7816 3561 7813 3558 7807
TIME...MOT...LOC 2103Z 292DEG 23KT 3564 7829 3551 7846 3552 7876

26