Severe Thunderstorm Warning 47, NWS Greenville-Spartanburg, SC

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

.SYNOPSIS...
Showers and thunderstorms today and Saturday ahead of a slowly
approaching cold front. Above normal temperatures continue ahead of
the front, falling back to near normal Sunday and Monday. Unsettled
pattern possible by midweek.

&&

.NEAR TERM /THROUGH SATURDAY/...
As of 241 AM EDT Friday: Thunderstorms continue to make the most
of the remnant outflow boundary that runs W-E from Habersham County
GA to south of GSP metro, with several large hail producers having
developed early this afternoon. Meanwhile, additional strong/severe
storms were present in north central GA. The area along and south
of I-85 to the west of I-26 look to be the most active over the
next 2-3 hours. The environment over that area has 2000-2500 J/kg
of sfc-based CAPE, but shear was meager. The dCAPE was a bit better
farther to the south over the Lakelands, so the possibility of wind
damage may increase into the late afternoon over that area. Storms
will be more isolated elsewhere, but still with a severe threat. As
for temps, they will be modulated by the locations of storms and
outflows. Expect the storms to wane in the early evening as we
start to lose daytime heating, after which our attention will be
turning to our west.

Some of the CAMs, in particular the HRRR, continue to develop some
organized convection in the late afternoon and early evening over
the TN valley. This activity may pose a severe threat as it arrives
over the wrn mountains around 02Z, but should gradually diminish as
it moves eastward over the mtns thru late evening. By that time,
it will be more stable east of the mtns so it will be unlikely
to maintain severe threats in that area. Will have to maintain
some precip chances for the entire overnight. Low temps will be
seasonally mild, so roughly 5-8 degrees above climo.

Meanwhile, overnight, a mid/upper trof will continue to dig over
the MS Valley region, closing off an upper low over IL by daybreak
Saturday. After a lull in the action during the diurnal minimum,
strong forcing rotating around the deepening upper low will move
in from the west as we start to destabilize in the late morning
into the early afternoon. The addition of this forcing from the
west will provide a trigger/focus for new storms across much of the
fcst area for the afternoon. Thermodynamically, the buoyancy won't
be quite as good as this afternoon, but the western Piedmont and
northern Upstate should be able to develop CAPE upwards of 2000
J/kg. Combined with about 30kt of deep layer shear, expect some
strong/severe storms over the eastern half in the afternoon. The
Marginal risk on the Day 2 Severe Outlook is a good call. Precip
probs will be mainly good chance/likely. High temps will be a bit
lower than today, but still above normal.

&&

.SHORT TERM /SATURDAY NIGHT THROUGH MONDAY/...
Key Messages:

1) Showers and thunderstorms continue Saturday night and Sunday. A
few could be strong with an isolated severe chance

2) Cold front should pass through the area Sunday

3) Cooler temperatures for the end of the weekend into Monday

As of 140 PM Friday: Continuing on Saturday night, an emerging omega
blocking pattern sets up over the CONUS. The cut-off low to the NW
of the CWA slowly drags a weak cold front across the area by Sunday.
This has been a steady slowdown in guidance and prolonging the
passage. What it means in terms of weather is a longer unsettled
pattern now extending into Sunday. Current trends in guidance keeps
showers and thunderstorms Saturday night into Sunday, and the
illusive front crossing by Sunday night. PoPs Saturday night remain
higher (>80%) before tapering off through Sunday. The better chance
for showers is east of the mountains as the front comes through. As
for rainfall, the QPF response remains has increased a bit from
previous guidance and has a range of 0.25-1" of additional rain
Saturday night through Sunday night. The higher amounts are expected
to be east of the mountains, but could change as we get closer to
the event. No hydro concerns at this time. However, not everywhere
will receive this amount and is highly dependent on where a shower
or storm goes over. Temperatures have trended slightly cooler for
the weekend, but remain close to normal.

&&

.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
Key Messages

1) Drier pattern Sunday night through midweek

2) Unsettled pattern could increase rain chances toward the end of
next week

3) Temperatures start off cooler and gradually warm through Wednesday

As of 100 PM Friday: The extended part of the forecast is more on
the uncertain side as an unusual pattern emerges across the entire
CONUS. Synoptically, the omega blocking pattern sticks around Monday
before the eastern cutoff low starts to get kicked out of the flow
by Tuesday night into Wednesday. Quasi higher pressure attempts to
push into the area, keeping the weather dry. By mid-week, guidance
gets wonkier and tries to develop a semi-rex block, with the
southeast caught in the middle. This has the potential for a
relatively unsettled pattern. Depending on how this pattern emerges,
could generate some showers toward the end of the period. Given the
uncertainty and general strange pattern, there is not a lot of
confidence in the extended period. Will continue to monitor over the
next few days. Overall, the pattern has trended drier, especially
for the beginning of the week. For the lower confidence in this
messy pattern, will keep PoPs at slight chance for various portions
of the area through most of the period. Either way, expect
temperatures to remain closer to normal and slowly warm with another
small dip possible by the end of the week.

&&

.AVIATION /19Z FRIDAY THROUGH WEDNESDAY/...
At KCLT and elsewhere: Thunderstorms developing along an old outflow
boundary may affect the Upstate terminals through the mid/late
afternoon, with a large hail threat at KGMU/KGSP. If the storms
hold together, they would possibly affect KCLT around 21Z or so,
but confidence was sketchy as to them making it that far east. We
will continue to evaluate and look for an amend to handle that if
needed. Otherwise, most of the convection will affect northeast GA
and the Upstate through the afternoon. Outside of storms...VFR. Most
of the storms will weaken with the loss of heating. We shall look
to the west this evening for the possible development of a line or
band of showers and storms. The HRRR has this arriving from the
west around 02Z then affecting the terminals west to east in the
late evening or early morning hours. It is not clear that it will
make it across the entire forecast area, so PROB30s were used. In
its wake, a low cloud MVFR ceiling can be expected, lasting well
into the morning given the higher low level moisture. More storms
will develop overhead by midday Saturday. Outside of storms,
winds will be generally SW.

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...CP
NEAR TERM...PM
SHORT TERM...CP
LONG TERM...CP
AVIATION...PM

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

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