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514
FXUS62 KGSP 082208
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
608 PM EDT Sat Jun 8 2024

.SYNOPSIS...
A cold front moves in on Sunday with returning shower and
thunderstorm chances. The front moves south of the area Monday and
Tuesday. Forecast confidence lowers through the rest of the week as
overall pattern is uncertain. For now, a chance of afternoon and
evening showers and thunderstorms is expected with above normal
temperatures.

&&

.NEAR TERM /THROUGH SUNDAY/...
-- Changed Discussion --
Key Messages:

1) Dry Conditions Linger into Tonight

2) Isolated Strong to Severe Storms are Possible on Sunday

As of 5:45 PM EDT Saturday: Cirrus with some patches of altocu
continue to make their way eastward across our fcst area early
this evening. CAMs appear to have backed off on producing any
showers over our area thru the evening except along the NC/TN
Border and over the northern NC mtns. Nonetheless, most of the
rain that does fall likely won`t reach the ground due to the dry
air currently in place. Lows tonight will end up about 3 to 5
degrees above climo thanks to lingering cirrus and SWLY flow.

Otherwise, cirrus will gradually increase in coverage Sunday morning
as a cold front approaches out of the west. The front will track over
the forecast area Sunday afternoon and evening, bringing shower and
thunderstorm chances back into the forecast. Have the highest PoPs
(high-end chance to low-end likely, 40%-60%) confined to the mountains
with lower PoPs (chance, 15%-35%) elsewhere. Mainly rain showers are
expected ahead of the front Sun morning, with thunderstorms expected
to develop during the afternoon and early evening hours. The SPC Day
2 Severe Wx Outlook has introduced a Marginal Risk for isolated severe
storms on Sun. This looks reasonable as 35-45 kts of deep shear will
be in place during peak heating along with SBCAPE up to 1200 J/kg
across portions of the fcst area. The main hazards with any severe
storm that develops will be large hail and damaging wind gusts.
Temperatures Sun afternoon will be much warmer (~5 degrees above
climo) due to increasing westerly flow ahead of the cold front.
Highs will climb into the upper 80s and lower 90s east of the mtns.
Some low-end wind gusts will be possible, mainly across the mtns,
Sun afternoon and early evening in association with the front.
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&&

.SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY/...
As of 145 PM EDT Saturday: Short waves carve a trough over the East
Coast Monday with the trough axis moving off shore Tuesday. At the
surface, a cold front crosses the area Sunday night, stalls near the
area Monday before pushing south on Tuesday. Expect ongoing
convection Sunday evening will taper off through the night, but
isolated showers may linger into Monday with lingering low level
moisture and weak forcing. Dry conditions expected on Tuesday as a
drier air mass moves in from the north. Breezy conditions Sunday
night and Monday will taper off Monday evening as the pressure
gradient relaxes. Lows near to slightly above normal Sunday night
drop around 5 degrees Monday night. Highs Sunday and Monday remain
nearly steady around normal.

&&

.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
As of 210 PM EDT Saturday: Guidance continues to show little run to
run consistency as they waffle back and front from a wetter to drier
pattern through the period. Have gone close to the model blend given
the low confidence in the forecast which results in isolated to
scattered mainly diurnal convection each day. The overall pattern
begins with a short wave ridge on Wednesday then a weak zonal flow
which weakens or becomes a ridge for Saturday. Weak high pressure
over the area Wednesday moves east as cyclogenesis takes place along
the Gulf Coast. The resulting low pressure center may remain nearly
stationary with a decent southerly fetch into the area. The low may
cross FL and move up the Atlantic Coast, which would also keep
moisture over the area. Or the low could remain suppressed as it
crosses FL and moves into the Atlantic, which would be a relatively
dry pattern. This is why confidence is low and forecast relies on
the model blend. This also results in temps bouncing around but
remaining above normal through the period.

&&

.AVIATION /22Z SATURDAY THROUGH THURSDAY/...
Key Messages:

1) Dry Conditions Linger into Tonight

2) Shower and Thunderstorm Chances Return Sunday

VFR through the 18Z TAF forecast period. Dry conditions should
linger through tonight with high pressure in place. The only caveat
is that an upper shortwave tracking overhead my allow some spotty
sprinkles or even -RA develop between 22Z and 01Z, mainly across
KAVL and KHKY. Confidence on this remains too low to add VCSH or
TEMPO into either TAF at this time, so maintained dry conditions.
Winds this afternoon will gradually turn WSW/SW across the
terminals. Coverage of upper-level cirrus will gradually increase
through the TAF period. Winds will turn back NW/WNW at KAVL
overnight into Sunday. Winds will remain WSW/SW east of the
mountains overnight, turning westerly ahead of an approaching cold
front on Sunday. This cold front will bring -SHRA (and possible
isolated TSRA in the afternoon) back to the area on Sunday. Went with
a PROB30 at KAVL as the activity will push across the mountains
towards the end of the 18Z TAF period. KCLT also gets a PROB30 since
the TAF goes out 30 hours. Timing on -SHRA/TSRA remains low as
timing differences remain between the high-res model guidance
sources.

Outlook: It`s looking more likely that dry weather will return the
first half of the next week.

&&

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

&&

$$

SYNOPSIS...RWH
NEAR TERM...AR/JPT
SHORT TERM...RWH
LONG TERM...RWH
AVIATION...AR/JPT