924
FXUS62 KGSP 040516
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
116 AM EDT Tue Jun 4 2024

.SYNOPSIS...
Scattered afternoon showers and thunderstorms are expected
again on Tuesday with temperatures warming back into the mid to
upper 80s. Showers and thunderstorms will increase in coverage
Wednesday into Thursday morning as a cold front crosses our area.
Drier weather is expected to return by the end of the week and
persist into the weekend, although a few isolated mountain showers
will remain possible.

&&

.NEAR TERM /THROUGH TODAY/...
As of 113 AM Tuesday: Scattered showers and a few isolated lightning
strikes continue to fester across the Upstate mainly along and north
of I-85. This activity is expected to persist through much of the
overnight within a moist environment. Patchy fog has also already
developed across the mountains with widespread fog, some possibly
dense, across the favorable valleys. The ongoing forecast captures
this well and only a few minor adjustments were needed.

Otherwise, a weak short wave ridge will progress steadily across the
forecast area over the next 18-24 hours. Meanwhile, persistent SW
low level flow is supporting quite moist conditions, with 12Z
regional Raobs indicating precipitable water values at around the
75th percentile in terms of climatology. Strong insolation has
resulted in moderate destabilization across the forecast area this
afternoon, with sbCAPE of 1500-2000 J/kg analyzed across much of the
CWA. Isolated convection is developing in the favored high terrain
locations this afternoon, and coverage is expected to expand to at
least widely scattered territory across the mtns, with more like
isolated activity elsewhere, as the presence of the upper ridge
should act to somewhat limit the overall coverage. Locally heavy
rainfall will be the main threat, but mean cloud-bearing winds of
around 15 kts should result in relatively progressive cell movement,
keeping the excessive rainfall threat muted. Absence of robust
instability will also limit the severe storm threat, but can`t rule
out a stray pulse storm producing a microburst. While activity will
diminish in coverage this evening, weak height falls and continued
enhanced moisture is expected to result in some degree of coverage
persisting across western areas into the overnight, with a continued
threat of locally heavy rainfall. Min temps should be 2-4 degrees
above climo.


The upper ridge is forecast to have pushed east of the CWA by Tue
afternoon, with the upper flow becoming increasingly cyclonic/open
to passing vorticity lobes downstream of an upper low over the
western Ohio Valley. If anything, moisture is forecast to increase
further, while a consensus of guidance indicates another afternoon
of moderate destabilization. These factors should support scattered
to numerous coverage of diurnal convection...with PoPs ranging from
40-60% across much of the CWA. Although shear parameters will remain
meager and cell movement rather progressive, the increase in
"targets of opportunity" should yield an uptick in the threat for a
couple of pulse severe storms and isolated excessive rainfall. Max
temps will be a degree or two warmer than today.

&&

.SHORT TERM /TONIGHT THROUGH THURSDAY/...
As of 1245 PM Monday: The coverage of diurnally enhanced deep
convection has the potential to remain numerous, especially acrs the
mountains, into the evening hours on Tuesday, as synoptic scale
forcing, in the form of subtle s/wv energy. lifts into the Tenn
Valley.  Regionally, the potential for strong tstms Tuesday night is
mainly west of the mtns, within the zone of better flow and
instability.  The mean flow atop the cwfa through Wednesday is
progged to be moderately fast with a subtle cyclonic curvature.
Within a plume of developing instability and PWAT values nearing 2
inches, diurnally enhanced tstms should become widespread within
this favorable pattern.  Since there is the potential for storms to
be blossoming and/or ongoing during the morning hours, it remains to
be seen on just how unstable the atmosphere becomes.  Select 12z
short range model solutions depict moderate destabilization and
given the progged shear, clusters of severe tstms are possible.

A less than common June cool frontal passage is slated for Thursday.
Sensible wx could wind up being limited to just morning showers
along the front itself in the mountains, and then within the veered
llvl flow and falling dwpts, deep convective redevelopment could
hold off until the bndry translates to the coastal plain, we`ll see.
Fcst sndgs continue to advertise developing deep mixing coincident
and in the wake of the frontal passage, along with downslope
warming. We will have to monitor for the possibility of max temps
nearing 90 in parts of the piedmont.

&&

.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
As of 130 PM Monday: The SE CONUS is progged to be under the broad
cyclonic flow within the southern periphery of closed upper low
rotating toward the mid-atlantic at the start of the period.  A dry
continental airmass is progged to be in place, maintained by
moderately deep mixing.  Seasonably warm conditions are on tap for
Friday, but accompanied by much lower than climo sfc dwpts.  Closed
upper low will wobble into the NE CONUS and eventually offshore over
the weekend maintaining the seasonably warm and mostly dry
conditions acrs the southern Appalachians within the NW and
cyclonically curved flow limiting any daily small shower chances to
just the nc mtns thanks to wrap around moisture or upslope.

&&

.AVIATION /05Z TUESDAY THROUGH SATURDAY/...
At KCLT and elsewhere: A busy TAF period is expected with
restrictions expected at all terminals. Scattered showers and an
isolated thunderstorm continue to fester early this morning with
SHRA possible across the Upstate at KAND, KGMU and KGSP through the
remainder of the overnight. Elsewhere, fog and low stratus has
already developed at KAVL and will be possible at any given terminal
through sunrise. Temporary visiblity and ceiling restrictions as low
as LIFR will be possible. Fog will mix out after sunrise with any
low stratus also scattering and lifting. VFR conditions will return
area wide by mid morning, if not sooner. Thereafter, attention
shifts to what is forecast to be a busy convective day with numerous
afternoon showers and thunderstorms across the area. Temporary
restrictions will once again be possible with any of this activity
followed by another night of patchy fog and low stratus.

Outlook: Coverage of diurnal convection is expected to increase
Wednesday as a frontal boundary moves into the region. Morning low
clouds and fog will also be possible Wednesday morning and Thursday
mornings. Drier air will filter into the area Thursday afternoon and
Friday morning, reducing chances for convection and restrictions,
with relatively dry conditions continuing into the weekend.

&&

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

&&

$$

SYNOPSIS...DEO
NEAR TERM...JDL/TW
SHORT TERM...CSH
LONG TERM...CSH/TW
AVIATION...TW