Hail and Damaging Winds in South Carolina, May 2, 2025

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
1204 PM EDT Fri May 2 2025

.SYNOPSIS...
Coverage of showers and thunderstorms increases today, and increases
further Saturday, ahead of a slowly approaching cold front. Above
normal temperatures continue ahead of the front, falling back to
near normal Sunday and Monday.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 1146 AM EDT Friday: Now that we have passed the diurnal
minimum, we're starting to see some redevelopment of the deep
convection on the radar in the past 30 min or so. The area east of
the mtns has been able to destabilize nicely, courtesy of plenty
of sun, to the point where we have about 2000 J/kg of sfc-based
CAPE to work with. Expect more storms to form into the afternoon
along an old outflow from the convective remnants that crossed
the mtns earlier this morning. Temps look ok, now that the mtns
are starting to recover.

Otherwise...expect little forcing the first part of the day today,
as a robust upper trough digs into the Ohio Valley and pushes a
surface cold front eastward...though it'll remain well to our west
throughout the period.  Guidance is in good agreement on initiation
of convection along this boundary during the early afternoon, and
brings a mature MCS into the Tennessee Valley by Friday evening,
but the overall forecast for our area remains...mushy.  A few of
the CAMs depict some scattered convection over the area through
the afternoon, but most models prefer to keep things quiet until
the MCS arrives...and even then, they can't agree on how far
it'll make it into the Carolinas before faltering.  Critically,
it could be racing against diminishing daytime instability, but
should otherwise encounter a sheared environment conducive to
convective organization.  Though confidence isn't great on how
much convection will make it into the area, certainly can't rule
out a few strong to severe storms, especially into the evening
as mature QLCS activity arrives from the west.  Would expect the
primary threat to be straight-line wind, though large hail and
even localized heavy rainfall could pose secondary threats.

Just as it's unclear how quickly convection will begin, it's
unclear how quickly it'll wrap up, with some of the 06z CAMs
depicting showers and thunder persisting well into the overnight.
After midnight, should see things wane with the complete loss of
surface-based instability, giving way to a cloud, and possibly
foggy Sunday morning.

&&

.SHORT TERM /SATURDAY THROUGH SUNDAY/...
As of 200 AM Fri, key messages:

1. An upper low will develop in the mid-Mississippi Valley on
Saturday, leading to slow progression of a cold front across the
forecast area from then until late Sunday, bringing unsettled weather
through most of the weekend.

2. Clusters of storms could pose a threat of flash flooding and
strong to severe winds Saturday and Saturday night across most of the
area, and possibly into Sunday in our eastern zones.

3. Mild temperatures Saturday will trend a little below normal
Sunday.

At the start of the period Saturday morning a compact closed 500mb
low is expected to be centered near St Louis, with weak sfc low over
TN/KY/OH along the frontal zone. The upper low will deepen and wobble
generally southeast thru Sunday morning, part of an omega block which
will affect most of the CONUS through the weekend. Moisture flux will
continue across the forecast area ahead of these features; dewpoints
should rise into the 60s during the afternoon and SBCAPE of 1500-2000
J/kg result on the NAM, ECMWF and a significant portion of EC
Ensemble members. Synoptic lift may not be much of a factor during
peak heating--upper divergence and/or convectively generated vort
blobs will be mostly west of the Appalachians at that time, but will
shift east in the evening/overnight. The added boost of southerly
flow and/or earlier proximity to the dynamic features suggest
categorical PoPs by afternoon in the mountains near the TN border.
The best overall chance for the rest of the area will be Sat evening
and the very early morning hours Sunday, when model consensus seems
to be for the diurnal instability to be finally realized as elevated
convection.

0-6km shear is initially on the weak side, 20-30 kt in the afternoon,
but ramps up to near 40 kt with LLJ and tightening gradient
overnight. Profiles start out rather dry, perhaps dry enough to
curtail deep updrafts; sfc-midlevel delta-theta-e of 25 K is seen on
some prog profiles and any storms that do form may be able to produce
marginally damaging winds. The prefrontal moistening in the
evening/overnight brings PWATs above the 90th percentile of climo in
our east, and with boundary-parallel shear increasing, training cells
producing swaths of excessive rainfall and some wind threat could
result.

By Sunday morning the front will have pushed through part of the
area, at least. The LLJ and prefrontal forcing most likely will be
east of the area by late morning. Dry slot of the upper low will
bring low PWATs back to the CWA.  Preceding the front there remains
the possibility that small SBCAPE will develop during the day,
although the dry air aloft and/or limited forcing will be hindering
factors. That said, if convection develops it will have 0-6km shear
possibly exceeding 40 kt. Instability probably will not be enough to
support severe weather in that case.

&&

.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
As of 245 AM Fri, key messages:

1. Mild and mostly dry conditions are expected Monday and Tuesday as
omega-block pattern progresses enough that we fall more under the
influence of the associated ridge.

2. Warm frontal clouds and PoPs return to the forecast Wednesday, but
forecast confidence decreases from then onward as models diverge in
their handling of the second upper low and surface high pressure near
the East Coast.

3. The most likely high-impact weather in the Wed-Thu timeframe, if
at all, will be locally excessive rainfall.

Position of the upper low will have changed little from Sunday night
to Monday. Although most guidance depicts the front progressing
across the rest of the area by Monday morning, there remain some
timing differences among ensemble members. Plus, the ECMWF for
example shows low-level flow backing enough to promote slight
destabilization in the NW NC Piedmont that afternoon. For these
reasons small PoPs remain in the forecast in the eastern and northern
portions of the CWA. By Tuesday the low begins to merge with a trough
moving across Canada and progresses east, and shortwave ridging
shifts over the area between that low and the other low in the block,
then over the Four Corners region. Tuesday features the lowest PoPs
of the 7 day period beneath the ridge. The western low is the crux of
the remainder of the forecast. The northern stream remains
progressive, with a broad ridge developing across the US-Canada
border region. The low more or less remains under the ridge and forms
a Rex block, but models diverge in how they handle the Canadian
trough over the Appalachians and NE CONUS. It does look likely that a
warm front associated with the ridge will shift over the area by late
Wednesday. The GFS is developing a CAD-like pattern and stalling the
front just to our south, but the ECMWF and GDPS interact the front
and the diving Eastern trough. It appears fairly safe to say the
second half of next week will be unsettled, but specifics are
uncertain at this point. Temperatures most likely will trend slowly
warmer each day Monday through Thursday; if the front stalls we may
end up with a developing excessive rain threat, but otherwise not a
lot to hang one's hat on as far as impact weather.

&&

.AVIATION /16Z FRIDAY THROUGH TUESDAY/...
At KCLT and elsewhere: The latest round of model guidance hasn't
provided much clarity on how things will proceed over the next
24 hours.  Expect VFR cloud cover to continue through the night
tonight, with some valley fog and perhaps even isolated patchy
fog across the NC Piedmont before dawn.  Light SW winds will
persist through daybreak, then pick up again with low-end gusts on
Friday.  Afternoon cloud bases are expected in the 4-6 kft range,
and afternoon or evening convection appears...likely...though the
timing is still very tough to pin down.  Some guidance suggests
more of a typical afternoon/diurnal timing, while other guidance
favors more of a late afternoon/evening timing with showers and
isolated thunder continuing into Friday night.  For now...have
included PROB30s everywhere during the most-favored timing...but
confidence is low.

Outlook: Unsettled weather and associated restrictions are expected
to continue into Sunday. In the wake of a cold front on Sunday,
drier weather and predominately VFR conditions are expected to
return by early next week.

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...None.
NC...None.
SC...None.

&&

SYNOPSIS...Wimberley
NEAR TERM...MPR/PM
SHORT TERM...Wimberley
LONG TERM...Wimberley
AVIATION...MPR

Hazardous Weather Outlook
National Weather Service Greenville-Spartanburg SC
529 AM EDT Fri May 2 2025

GAZ010-017-018-026-028-029-NCZ033-035>037-048>053-056-058-059-
062>065-068>070-501>510-SCZ008-010>013-019-101>109-030930-
Rabun-Habersham-Stephens-Franklin-Hart-Elbert-Avery-Alexander-
Iredell-Davie-Madison-Yancey-Mitchell-Swain-Haywood-Buncombe-Catawba-
Graham-Northern Jackson-Macon-Southern Jackson-Transylvania-
Henderson-Cleveland-Lincoln-Gaston-Caldwell Mountains-
Greater Caldwell-Burke Mountains-Greater Burke-McDowell Mountains-
Eastern McDowell-Rutherford Mountains-Greater Rutherford-
Polk Mountains-Eastern Polk-Cherokee-Anderson-Abbeville-Laurens-
Union-Greenwood-Oconee Mountains-Pickens Mountains-
Greenville Mountains-Greater Oconee-Greater Pickens-
Central Greenville-Southern Greenville-Northern Spartanburg-
Southern Spartanburg-
529 AM EDT Fri May 2 2025

This Hazardous Weather Outlook is for northeast Georgia, Piedmont
North Carolina, western North Carolina and Upstate South Carolina.

.DAY ONE...Today and tonight.

Scattered thunderstorms may pose a risk of damaging wind gusts and
large hail, mainly this afternoon and evening.

.DAYS TWO THROUGH SEVEN...Saturday through Thursday.

Scattered thunderstorms may pose a risk of damaging wind gusts and
large hail again Saturday and Saturday night.

.SPOTTER INFORMATION STATEMENT...

Spotters are requested to forward any reports of large hail,
damaging winds, tornadoes, or flash flooding to our office.

NCZ057-071-072-082-SCZ009-014-030930-
Rowan-Mecklenburg-Cabarrus-Union-York-Chester-
529 AM EDT Fri May 2 2025

This Hazardous Weather Outlook is for Piedmont North Carolina and
part of South Carolina near the Catawba River.

.DAY ONE...Today and tonight.

Hazardous weather is not expected at this time.

.DAYS TWO THROUGH SEVEN...Saturday through Thursday.

Scattered thunderstorms may pose a risk of damaging wind gusts and
large hail Saturday and Saturday night.

.SPOTTER INFORMATION STATEMENT...

None.

Wimberley

Special Weather Statement
National Weather Service Greenville-Spartanburg SC
1200 PM EDT Fri May 2 2025

GAZ010-017-SCZ101-104-021630-
Rabun GA-Habersham GA-Greater Oconee SC-Oconee Mountains SC-
1200 PM EDT Fri May 2 2025

...A STRONG THUNDERSTORM WILL IMPACT NORTHERN HABERSHAM...SOUTHERN
RABUN AND CENTRAL OCONEE COUNTIES THROUGH 1230 PM EDT...

At 1159 AM EDT, Doppler radar was tracking a strong thunderstorm 7
miles south of Clayton, or near Tallulah Gorge State Park, moving
east at 35 mph.

HAZARD...Wind gusts up to 40 mph and pea size hail.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects. Minor hail damage to outdoor objects is
         possible.

Locations impacted include...
Lake Rabun, Mountain Rest, Long Creek, Tallulah Falls, Batesville,
Turnerville, Tiger, Hollywood, Lake Burton, and Walhalla.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

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 3482 8365 3488 8333 3492 8291 3472 8290
      3467 8332 3469 8334 3466 8337 3462 8364
      3465 8366 3466 8366 3467 8365 3471 8364
      3473 8362 3476 8363 3479 8367 3481 8367
TIME...MOT...LOC 1559Z 261DEG 31KT 3477 8336

MAX HAIL SIZE...0.25 IN
MAX WIND GUST...40 MPH

CP

Special Weather Statement
National Weather Service Greenville-Spartanburg SC
1244 PM EDT Fri May 2 2025

GAZ017-021715-
Habersham GA-
1244 PM EDT Fri May 2 2025

...A STRONG THUNDERSTORM WILL IMPACT CENTRAL HABERSHAM COUNTY THROUGH
115 PM EDT...

At 1244 PM EDT, Doppler radar was tracking a strong thunderstorm near
Clarkesville, moving east at 20 mph.

HAZARD...Wind gusts up to 40 mph and half inch hail.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects. Minor hail damage to outdoor objects is
         possible.

Locations impacted include...
Demorest, Hollywood, Turnerville, and Clarkesville.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

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.

&&

LAT...LON 3468 8361 3472 8341 3463 8339 3454 8343
      3457 8361
TIME...MOT...LOC 1644Z 272DEG 15KT 3463 8355

MAX HAIL SIZE...0.50 IN
MAX WIND GUST...40 MPH

MOORE