Hail and Damaging Winds in South Carolina, May 4 to 5, 2020

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
529 PM EDT Mon May 4 2020

.SYNOPSIS...
A series of weak disturbances will cross the area early this week,
with showers and a few thunderstorms expected. Temperatures will
fall to below normal by Thursday, cooling off even more by the
weekend.

&&

.NEAR TERM /THROUGH TUESDAY/...
As of 510 PM Monday: The RADAR remains clear across our fcst area
as a weak cap persists around 10kft. If the cap gets eroded over
the next few hours, then we could see some showers and possibly a
few thunderstorms as moisture increases across the area.

The main concern going forward, however, is an impressive-looking
MCS currently well to our west, that is looking more likely to make
a run at our CWFA overnight (say midnight to 4 am). Guidance is
pretty all over the board to where this might occur, but thinking
if a decaying MCS makes it into our area, it would be most likely
to follow the instability gradient or roughly the I-26 corridor.
The potential for damaging wind would be the main threat with small
hail and maybe a weak and brief tornado as secondary threats
(mainly southwest of I-26). Warm front activation late tonight
will support mainly showers racing northeastward into the early
morning morning hours Tuesday.

After a lull in activity Tuesday morning, increasing instability and
a nearby shortwave energy to our north will support another round of
showers and thunderstorms focused across the mountains. An elevated
mixed layer with decent instability aloft may support some strong to
severe thunderstorms focused across the mountains with wind followed
by hail as the primary threats. Modest moisture transport from the
west and decent instability may support localized excessive rain
across the mountains Tuesday afternoon, especially if training of
cells develops. A hybrid wedge across the North Carolina Piedmont
will likely limit convection for the area especially through mid
afternoon. Rain and wedge cooled air should support lows into the
50s tonight with highs struggling to break 60 for the I-40 corridor
(thanks to the wedge) with 70s and 80s elsewhere.

&&

.SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY/...
As of 230 PM Monday: With broad, low amplitude troughing aloft, sfc
low pressure along a once stationary front will be in the process of
moving through the Carolinas Tuesday night as it's associated cold
front brings showers and thunderstorms to the area. Do expect
convection to be ongoing at the beginning of the fcst period,
especially with a majority of the area situated within the warm
sector. Upper s/w impulses within troughing will aid with upper
dynamic support and notable shear looks to be in place. The amount
of available instability continues to be the fly in the ointment and
will depend on the timing of the system to push through the area.
For now, have kept with the trend of showers and thunderstorms, with
a few thunderstorms possibly becoming strong to severe Tuesday
night. The primary threat with any stronger storm would be hail and
damaging winds. With the latest update, SPC Day 2 convective outlook
has the western portions of the area under a marginal risk and the
rest of the area under a general thunder, where the atmosphere looks
to be slightly more stable. Do not anticipate any hydro threats attm.

Behind the exiting system, light showers may linger into Wednesday
late morning across the area, possibly later along the TN border
with NW flow. Otherwise, expect a drying trend for the remainder of
the fcst period into Thursday as sfc high pressure builds into the
area. Max temperatures through the period will remain below normal,
with min temperatures Wednesday morning above normal and below
normal Thursday morning.

&&

.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
As of 255 PM Monday: The aforementioned drying trend will be a brief
one as latest guidance continues to prog s/w energy within broad
upper troughing to usher in another cold front later in the day on
Friday. Conditions are trending more towards showers with this
system versus thunderstorms/severe weather, especially given limited
instability and upper dynamic support. Anticipate pre-frontal
showers across the westernmost portions of the area Friday morning,
with activity spreading east-southeastward throughout the day. As
precipitation tapers off across much of the area, with a cooler
airmass infiltrating in behind the front, could not entirely rule
out isolated snow showers at the higher elevations late Friday night
into Saturday morning with upper trough swinging through overhead.

Otherwise, Saturday and Sunday will be dry as sfc high pressure
builds in with amplified trough over the eastern CONUS. Guidance
continues to prog temperatures below normal through the forecast
period. As a result, frost/freeze concerns could arise in some
locations, as noted the past few days.

&&

.AVIATION /22Z MONDAY THROUGH SATURDAY/...
At KCLT and Elsewhere: A lee convergence zone and lingering boundary
will support isolated thunderstorms mainly between 21Z and 03Z and
southwest of I-26. A decaying MCS may support a later round of
thunderstorms between 02Z and 08Z (low confidence on this timing)
focused across this area although showers may extend as far north as
I-40 including KCLT. A lull in activity is expected between 12Z and
18Z. The combination of rainfall south and a hybrid wedge setting up
to the north will support IFR or lower cigs developing across many
areas between 08Z and 13Z with gradual improvement likely after 13Z.

Outlook: A period of unsettled weather and flight restrictions
continues through midweek. Dry high pressure builds in for the end
of the workweek.

Confidence Table...

            00-06Z        06-12Z        12-18Z        18-00Z
KCLT       High 100%     High 100%     High 100%     High 100%
KGSP       High 100%     High 100%     High 100%     High 100%
KAVL       High 100%     High  80%     High  89%     High 100%
KHKY       High 100%     High 100%     High 100%     High 100%
KGMU       High 100%     High 100%     High 100%     High 100%
KAND       High 100%     High 100%     High 100%     High 100%

The percentage reflects the number of guidance members agreeing
with the scheduled TAF issuance flight rule category. Complete hourly
experimental aviation forecast consistency tables are available at
the following link:

www.weather.gov/gsp/aviation

&&

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

&&

SYNOPSIS...17
NEAR TERM...JPT/65
SHORT TERM...12
LONG TERM...12
AVIATION...JPT/65

Hazardous Weather Outlook
National Weather Service Greenville-Spartanburg SC
611 PM EDT Mon May 4 2020

GAZ010-017-018-026-028-029-NCZ048-051>053-058-059-062>065-507-509-
510-SCZ001>007-010>013-019-052215-
Rabun-Habersham-Stephens-Franklin-Hart-Elbert-Madison-Swain-Haywood-
Buncombe-Graham-Northern Jackson-Macon-Southern Jackson-Transylvania-
Henderson-Rutherford Mountains-Polk Mountains-Eastern Polk-
Oconee Mountains-Pickens Mountains-Greenville Mountains-
Greater Oconee-Greater Pickens-Greater Greenville-Spartanburg-
Anderson-Abbeville-Laurens-Union SC-Greenwood-
611 PM EDT Mon May 4 2020

This Hazardous Weather Outlook is for northeast Georgia, southwestern
North Carolina and upstate South Carolina.

.DAY ONE...Tonight.

A line or area of strong to severe thunderstorms is expected to move
east across Tennessee this evening and reach western North Carolina
late in the evening. If the storms hold together, strong to severe
thunderstorms may move across the central and southern mountains of
North Carolina, northeast Georgia, and Upstate South Carolina through
the early morning hours. Strong and damaging wind gusts are the main
threat, but sporadic large hail or a brief tornado cannot be ruled
out. Lightning, gusty winds, and brief, heavy rainfall can be
expected with any storm. The storms would weaken as they move east
across the Upstate before dawn.

.DAYS TWO THROUGH SEVEN...Tuesday through Sunday.

Hazardous weather is not expected at this time.

.SPOTTER INFORMATION STATEMENT...

None.

NCZ033-049-050-068>072-082-501-503-505-506-508-SCZ008-009-014-052215-
Avery-Yancey-Mitchell-Cleveland-Lincoln-Gaston-Mecklenburg-Cabarrus-
Union NC-Caldwell Mountains-Burke Mountains-McDowell Mountains-
Eastern McDowell-Greater Rutherford-Cherokee-York-Chester-
611 PM EDT Mon May 4 2020

This Hazardous Weather Outlook is for piedmont North Carolina,
western North Carolina and upstate South Carolina.

.DAY ONE...Tonight.

Showers and a few thunderstorms will move into the area tonight.
Lightning, gusty winds, and brief, heavy rainfall can be expected
with any storm.

.DAYS TWO THROUGH SEVEN...Tuesday through Sunday.

Hazardous weather is not expected at this time.

.SPOTTER INFORMATION STATEMENT...

None.

NCZ035>037-056-057-502-504-052215-
Alexander-Iredell-Davie-Catawba-Rowan-Greater Caldwell-Greater Burke-
611 PM EDT Mon May 4 2020

This Hazardous Weather Outlook is for piedmont North Carolina and
western North Carolina.

.DAY ONE...Tonight.

No hazardous weather is expected at this time.

.DAYS TWO THROUGH SEVEN...Tuesday through Sunday.

No hazardous weather is expected at this time.

.SPOTTER INFORMATION STATEMENT...

None.

PM