Special Weather Statement, NWS Raleigh, NC

AREA FORECAST DISCUSSION
National Weather Service Raleigh NC
435 AM EDT Fri May 27 2022

.SYNOPSIS...
A warm front and increasingly humid air will retreat north across
the southern Mid Atlantic this morning. A pre-frontal trough will
then become quasi-stationary over the Piedmont today, followed by
the passage of a cold front across the region tonight. High
pressure, and associated much drier and warm conditions, will build
across the region this weekend.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 435 AM Friday...

A mid/upper-level cyclone centered over srn IL/IN this morning will
move ene to PA through 12Z Sat. A preceding, 50-55 kt sly jet streak
extending from the srn Appalachians through the OH Valley in 500 mb
upr air data last evening will strengthen to around 70 kts while
lifting northeast and across the Mid Atlantic today.

At the surface, a quasi-stationary wedge front and broad triple point
low over wrn NC, diabatically-reinforced from multiple rounds of
convection there during the past 12-18 hours, will continue to mix
and pivot north across VA this morning and up the Mid Atlantic coast
through the afternoon. An outflow boundary and confluence axis was
evident in surface observational data from the broad triple point
ssewd across the Upstate of SC and through the Savannah Basin, with
backed/ssely flow and richer maritime Tropical moisture
characterized by surface dewpoints in the lwr 70s to its east. That
boundary, beneath a plume of deeper moisture with PWs of 1.6-1.8",
will likely serve as a focus for bands of convection and multi-layer
overcast that will move slowly ne across the cntl and ern Carolinas
through midday-early afternoon. To the west of that moisture plume
and early day convection, a pre-frontal trough will develop and
strengthen swd across the Piedmont of the Carolinas and VA,
including over the srn and wrn Piedmont of cntl NC, this afternoon.
Stronger heating/deeper mixing in the drier air along and west of
the trough axis, where more sunshine will result, will serve to
sharpen a moisture and instability gradient over the Piedmont.
Additional convection will likely develop and move off this boundary
through the afternoon. Lastly, a cold front will move east and
across cntl NC tonight. While an additional band of showers and
isolated storms will likely accompany the front, the severe threat
will have ended by that time.

Regarding that severe threat, strengthening deep layer flow will
result in 35-50 kts of effective shear, characterized by generally
straight forecast hodographs. While these shear profiles will favor
bowing cells/segments capable of wind damage, the combination of
backed surface flow and the presence of a 35-45 kt low level jet
over the srn Mid Atlantic will maintain elongated and cyclonically-
curved hodographs through 1 km, with an associated mini-
supercell/tornado risk, both in discrete cells and embedded QLCS
segments.

In addition to that severe risk, a flash flooding threat will result
from training cells embedded in slowly-ewd progressing convective
bands and amidst the anomalously high PWs. This threat would be
greatest in urban areas from RDU to FAY.

Temperatures today will be modulated by convection and clouds, with
the highest temperatures in the lwr 80s likely over the srn and wrn
Piedmont this afternoon, and perhaps also in the Coastal Plain
before convection arrives, with upr 70s in between. Cooler and
drier/less humid air will filter across the region overnight-Sat
morning, with lows ranging from upr 50s to mid 60s.

&&

.SHORT TERM /SATURDAY AND SATURDAY NIGHT/...
As of 210 AM Friday...

The upper trough will progress through the region Sat, with the sub-
tropical ridge shifting eastward into the region Sat night. At the
surface, the cold front/surface trough will sit over the Coastal
Plain Sat, then continue eastward to along the NC coast Sat night,
with relatively cool high pressure settling over the Appalachians
and into the mid-Atlantic through Sat night. Some showers and storms
are possible along the lingering front/trough Sat, but should
largely be east of central NC. Otherwise, dry weather is expected
across the area through Sat night. Highs in the low to mid 80s, with
lows in the upper 50s NW to mid 60s SE expected.

&&

.LONG TERM /SUNDAY THROUGH THURSDAY/...
As of 225 AM Friday...

The sub-tropical ridge will remain over the Southeast and mid-
Atlantic through mid-week, with the center of the high generally
over the OH Valley/northern mid-Atlantic. An area of low pressure
off the Southeast US coast Mon/Tue, should move westward and inland
over the Southeast by mid week. While rain cannot be completely
ruled out, the high just to the north should keep it suppressed to
the south. High pressure will dominate at the surface Mon, with a
Piedmont trough possible Tue and Wed. A northern stream wave will
move through the northern Plains and upper MS Valley through Wed and
into the Great Lakes/OH Valley Wed night/Thu, pushing the ridge
south and east. The best chance for rain in the extended forecast
will be with this wave and associated cold front and pre-frontal
trough, as they move into the mid-Atlantic/Northeast US Thu/Thu
night. Temperatures will remain above average, gradually moderating
with time, through at least mid-week.

&&

.AVIATION /06Z FRIDAY THROUGH TUESDAY/...
As of 220 AM Friday...

Occasionally gusty sly low level flow will transport increasingly
moist and humid air across cntl NC this morning. This regime will
favor both widespread IFR to MVFR ceilings this morning and also the
development and maintenance of multiple bands of showers and storms
ahead of a cold front and following drier and more stable air
that will not move east across the region until tonight.

Outlook: Warm and dry high pressure, and associated VFR conditions,
will extend across the region this weekend through early next week.

&&

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

&&

SYNOPSIS...MWS
NEAR TERM...MWS
SHORT TERM...KC
LONG TERM...KC
AVIATION...MWS

Hazardous Weather Outlook
National Weather Service Raleigh NC
1045 PM EDT Thu May 26 2022

NCZ007>011-024>028-041>043-076>078-088-089-280245-
Person-Granville-Vance-Warren-Halifax-Orange-Durham-Franklin-Nash-
Edgecombe-Wake-Johnston-Wilson-Lee-Harnett-Wayne-Cumberland-Sampson-
1045 PM EDT Thu May 26 2022

This Hazardous Weather Outlook is for central North Carolina.

.DAY ONE...Tonight.

Hazardous weather is not expected at this time.

.DAYS TWO THROUGH SEVEN...Friday through Wednesday.

Scattered to locally numerous thunderstorms on Friday will be capable
of producing damaging wind gusts, hail, and an isolated tornado.
Heavy rain and flash flooding may also result.

.SPOTTER INFORMATION STATEMENT...

Spotter activation is not expected at this time.

NCZ021>023-038>040-073>075-083>086-280245-
Forsyth-Guilford-Alamance-Davidson-Randolph-Chatham-Stanly-
Montgomery-Moore-Anson-Richmond-Scotland-Hoke-
1045 PM EDT Thu May 26 2022

This Hazardous Weather Outlook is for central North Carolina.

.DAY ONE...Tonight.

Isolated to widely scattered thunderstorms are expected to redevelop
late tonight. Strong winds and localized heavy rainfall will be
possible.

.DAYS TWO THROUGH SEVEN...Friday through Wednesday.

Scattered to locally numerous thunderstorms on Friday will be capable
of producing damaging wind gusts, hail, and an isolated tornado.
Heavy rain and flash flooding may also result.

.SPOTTER INFORMATION STATEMENT...

Spotter activation is not expected at this time.

Special Weather Statement
National Weather Service Raleigh NC
450 AM EDT Fri May 27 2022

NCZ021-270945-
Forsyth NC-
450 AM EDT Fri May 27 2022

...A strong thunderstorm will impact portions of western Forsyth
County through 545 AM EDT...

At 450 AM EDT, Doppler radar was tracking a strong thunderstorm near
Bermuda Run, or near Mocksville, moving northeast at 35 mph.

HAZARD...Winds in excess of 40 mph.

SOURCE...Radar indicated.

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

Locations impacted include...
Winston-Salem, Clemmons, Bermuda Run, Huntsville, Lewisville, Rural
Hall, Pfafftown, Stanleyville and Donnaha.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

Doppler radar has indicated weak rotation with this storm. If the
storm intensifies and rotation strengthens, a warning may need to be
issued.

&&

LAT...LON 3611 8051 3612 8046 3614 8044 3621 8045
      3622 8043 3624 8045 3626 8045 3626 8012
      3597 8038 3597 8040 3599 8042 3601 8042
      3603 8045 3606 8046 3604 8049 3605 8051
      3609 8052
TIME...MOT...LOC 0850Z 212DEG 30KT 3598 8050

MAX HAIL SIZE...0.00 IN
MAX WIND GUST...40 MPH

10

Special Weather Statement
National Weather Service Raleigh NC
621 AM EDT Fri May 27 2022

NCZ021-022-038-271045-
Guilford NC-Forsyth NC-Davidson NC-
621 AM EDT Fri May 27 2022

...A strong thunderstorm will impact portions of Forsyth,
northeastern Davidson and northwestern Guilford Counties through 645
AM EDT...

At 621 AM EDT, Doppler radar was tracking multiple strong
thunderstorms over Winston-Salem and Midway, moving northeast at 40
mph.

HAZARD...Wind gusts up to 50 mph.

SOURCE...Radar indicated.

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

Locations impacted include...
Greensboro, Winston-Salem, High Point, Thomasville, Kernersville,
Clemmons, Lewisville, Summerfield, Stokesdale and Walkertown.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

Doppler radar has indicated weak rotation with this storm. If the
storm intensifies and rotation strengthens, a warning may need to be
issued.

A Tornado Watch remains in effect until 200 PM EDT for central North
Carolina.

&&

LAT...LON 3614 8044 3621 8045 3622 8043 3624 8045
      3626 8045 3625 7982 3592 8005 3593 8037
      3596 8038 3599 8042 3601 8041 3603 8044
      3612 8046
TIME...MOT...LOC 1021Z 222DEG 35KT 3610 8028

MAX HAIL SIZE...0.00 IN
MAX WIND GUST...50 MPH

10