-- Discussion containing changed information from previous version are highlighted. --
883
FXUS62 KGSP 091757
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
157 PM EDT Sun Jun 9 2024

.SYNOPSIS...
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A cold front moves south of our area becoming stationary through
mid week with dry conditions under weak high pressure for Monday
through Thursday.  Isolated to widely scattered showers and
thunderstorms are expected by next weekend as a weak cold front
approaches from the north.  Temperatures are expected to be well
above normal at end of the week.
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&&

.NEAR TERM /THROUGH TONIGHT/...
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Key Messages...

1) Lingering Cloud Cover and Light Rain May Limit Both the Severe
Weather Potential and High Temperatures this Afternoon

2) Another Round of Rain is Expected to Develop Overnight

As of 1125 am EDT Sunday: Cloud cover across the forecast area has
allow temps to stay much cooler than forecast so far so lowered
temps a few degrees through the morning hours to factor in the
limited insolation. No other changes were needed this update.
Otherwise, light rain continues tracking eastward across the central
portion of the CWA this morning but it continues to gradually fall
apart the farther east it goes.

Large scale height falls will carve out a broad trough across the
East by end of the period, with a series of embedded MCVs expected
to ripple across our region, esp this afternoon and evening. A cold
front is forecast to move into the forecast area this afternoon, and
move steadily east throughout the afternoon/evening. This will
provide the primary focus for initiation of deep convection.
Uncertainty persists regarding the magnitude of destabilization this
afternoon, owing primarily to uncertainty re: the extent, longevity,
and thickness of this morning`s debris cloud cover and attendant
impacts on insolation. Our best guess based upon a consensus of
deterministic and probabilistic guidance is that sbCAPE will peak at
around 1500 J/kg across much of the area this afternoon. With deep
layer shear expected to range from 30-40 kts, instability is
expected to be just enough to yield a marginal severe storm threat.
Shear values may support a couple of rotating cells, but forecast
low level shear and SRH values are such that the tornado threat is
minimal, and isolated damaging wind gusts and large hail will be the
main threats.

Max temps are forecast to be about a category above normal, with
temps likely reaching or exceeding the 90 degree mark across the
southeast quadrant of the CWA. However, cloud cover from this
morning may limit highs somewhat this afternoon. Convective chances
linger into the overnight hours, especially across the southern half
of the CWA, as the front takes its time clearing the area of
moisture. However, overnight convection is expected to be
tame...likely more showery than anything...as instability quickly
weakens owing to very poor mid-level lapse rates. Min temps are
expected to be close to normal.
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&&

.SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
As of 145 AM EDT Sunday: The aforementioned cold front will be in
the vicinity of the southern portion of the CFWA and may keep a few
lingering showers across the Upstate and northeast Georgia through
mid-morning Monday. Otherwise, drier air filters in by Monday
afternoon thanks to a continental surface high building in from
the northwest and the front continuing to push southward. Cyclonic
flow aloft will remain in place as the area of high pressure sets
up shop across the southern/central Appalachians by the end of
the forecast period. A shortwave will carve out of the base of the
cyclonic flow and shift the axis offshore by 12Z Wednesday. Either
way, the sensible weather will remain dry after Monday morning
with temperatures at or slightly below normal for max/min through
the short term.

&&

.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
As of 300 AM EDT Sunday: Run to run consistency is still out of
whack amongst the guidance, especially for the second half of the
medium range. One thing that seems evident is the airmass will
moderate, with hot and muggy conditions returning by the extended
forecast period. Model guidance continue to develop a surface low
over the eastern Gulf, but becomes nearly stationary due to very
weak steering flow. The GFS and ECMWF keeps the CFWA dry for a good
portion of next week, with some resemblance of a rex blocking
pattern developing. Going to stick with the NBM due to the low
confidence in the forecast, but will need to monitor the position of
this low as a heavy rainfall threat will occur if it lifts north
into the region at any point due to the plume of deep tropical
moisture associated with this system. Temperatures will be slightly
above normal for much of the period.

&&

.AVIATION /18Z SUNDAY THROUGH FRIDAY/...
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Key Messages...

1) Thunderstorms Expected this Afternoon Ahead of a Cold Front

2) Widespread Rain expected Overnight into early Monday Morning

3) Cigs and Vsbys should generally range from MVFR to VFR through
the period

At KCLT and elsewhere: Light rain continues pushing east this
afternoon, with only isolated activity lingering along/near I-77.
Low-end gusts are noted at KAVL and KAND as of 18Z and KGSP and KGMU
could see gusts develop this afternoon as well. Gusts should
diminish by the early evening hours. Cloud cover is starting to
clear across portions of the terminals this afternoon which should
allow the atmosphere to become unstable. However, cloud cover will
gradually increase from west to east again, becoming BKN to OVC,
later this afternoon ahead of a cold front. The cold front will lead
to -SHRA/-TSRA late this afternoon into early this evening as it
tracks overhead. Have TEMPOs at all terminals, with the exception of
KAND which is expected to remain dry, to account for the convective
potential. Cigs should generally remain VFR outside of TSRA. Wind
direction remains W`ly east of the mtns this afternoon. Winds will
remain NW at KAVL through the TAF period, while winds east of the
mtns will turn N/NW behind the front this evening into tonight.
Brief drying is expected before a round of widespread showers tracks
across the terminals overnight into early Monday morning. Handled
this potential with PROB30s across all terminals. -SHRA should start
between 07Z and 09Z and push out between ~11Z and 13Z and should
allow cigs to fall to high-end MVFR levels, mainly across the SC
Upstate terminals. High pressure will build into the region
throughout Monday leading to much drier conditions and allowing VFR
cigs to gradually return. Cloud cover will gradually decrease
throughout Monday becoming FEW to SCT. Winds east of the mtns should
become more variable around daybreak Monday before turning WSW/SW
Monday afternoon.

Outlook: Dry sfc high pressure will linger through mid-week leading
to quieter weather.
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&&

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

&&

$$

SYNOPSIS...DEO
NEAR TERM...AR/JDL
SHORT TERM...CAC
LONG TERM...CAC
AVIATION...AR