336
FXUS62 KGSP 232307
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
707 PM EDT Sun Jun 23 2024

.SYNOPSIS...
A cold front will cross the area tonight and bring a chance of
showers with isolated thunderstorms. Drier conditions return through
Wednesday, before another active cold front moves in from the
northwest Wednesday night into Thursday.

&&

.NEAR TERM /THROUGH MONDAY/...
As of 546 PM Sunday: No major changes to the forecast this evening.
Radar is now clear, althought the latest HRRR depicts some limited
redevelopment of remnants from upstream Cumberland Plateau
activity as they move along the I-40 corridor over the next
1-2 hours.  Mesoanalysis depicts some 1500+ J/kg sbCAPE in that
area, and retains the ~1000 J/kg DCAPE observed earlier today.
Lapse rates are still a little meager as to producing taller,
icy cores...but it`s not out of the question, and if it happens,
the environment would support a possible weak downburst.  So, will
keep mention in the HWO through the evening.  We`re also past the
peak in temperatures...which, as expected, got toasty...but will
begin to fall in the coming hours.

Otherwise...recent model trends for tonight and Monday continue in
the latest forecast guidance. The main concern, albeit minor, is the
thunderstorm chances over the mtns tonight. Models continue to show
a vort lobe dropping in from the WNW tonight, digging a broad upper
trof axis over the Mid-Atlantic region. The forcing should help
to develop and bring a broken band of showers and thunderstorms
into the area after dark, with some timing differences between
the various CAMs. The expectations for any strong to severe storms
are low as the timing is poor. A few of the showers might survive
east of the mtns into the pre-dawn hours on Monday, especially
over the NC foothills and NW Piedmont, but altogether no big deal
and most places will stay dry. Low temps will be mild as the weak
sfc reflection of this short wave will not cross the region until
the hours around daybreak. In reality, this isn`t so much a cold
front as it is more of a dry front, which is typical for this
area at this time of year. Behind the boundary, a sfc high will
build in thru Monday afternoon from the NW on the strength of an
upstream ridge. The upshot is that temps Monday afternoon might
ultimately be similar to Sunday afternoon, but the RH should
be noticeably less (and less than we expected a few days ago),
such that apparent temps should stay well below the Heat Index
criteria. Precip chances will also be limited to a slight chance
over the eastern-most zones in the middle part of the day before
the boundary moves off toward the Coastal Plain in the afternoon.

&&

.SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY/...
As of 1230 PM Sunday...Upper heights will begin to rise early Tue
which will support a Canadian sfc high to the north. This high will
dominate the weather into Wed as it becomes reinforced and ridges
down the east coast. Relatively dry and cool air will mix in, but
still expect deep subs to allow for temps in the l90s east of the
mtns and u80s across the mtn valleys. Soundings show mixing into the
drier air aloft which will help keep sfc dwpts in the u50s to l60s
and HI values below adv criteria. The atmos becomes more dynamic
early Wed as a pos tilted h5 s/w pushes in from the west. This wave
will likely produce sct showers and a few general to strong tstms
across the NC mtns with isol activity east thru the day. Rainfall
amts will be modest and wont make much of a dent in the below normal
precip amounts received this month. Surface dewps will bump up in
this environ ahead of the front and along with temps reaching the
mid to upper 90s east of the mtns, heat index values could rise into
advisory levels across the Lakelands. Overnight temps will remain
rather warm with mins held abt 5-7 degrees abv normal.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
As of 205 PM Sunday...An upper trof axis continues to cross the area
Wed night which will likely maintain chance thunder across the NC
mtns and isolated storms east. With high pressure pushing a llvl
convg zone into the area during the afternoon, expect another round
of tstms across the NC mtns. Meanwhile, heights will rise as a
subTrop ridge builds in from the west. This neg forcing will help
keep tstm strength in the general category Thu afternoon and again
Fri afternoon when the llvl flow brings in an upslope e/ly se/ly
flow. The building ridge dominates the pattern into the weekend and
makes for a summertime pattern with PoPs a little below climo and
temps remaining above normal. Expect highs in the m90s each
afternoon and lows likely held a couple cats abv normal. Heat
indices look to remain below adv level Thu and Fri, yet may reach
criteria Sat as dewpts surge ahead of a sfc front approaching from
the northwest Sat night.

&&

.AVIATION /23Z SUNDAY THROUGH FRIDAY/...
At KCLT and elsewhere: Cu field is diminishing at this point
with the sun on its way down.  Isolated showers over the I-40
corridor are possible over the next 1-2 hours as a weak frontal
circulation pushes into the area...but coverage will be sparse and
shouldn`t impact any of the TAF sites.  Another, better-defined
band of showers is expected to arrive in the NC mountains a little
before midnight, and slip across the terminal forecast area through
daybreak.  Some embedded thunder is possible, particularly for the
NC zones; coverage over the Upstate terminals will be too paltry
for a mention in the TAFs.  Admittedly, the 21z HRRR has come in
more aggressive than past runs, with a better-defined band of
showers and storms affecting all the TAF sites...but not ready
to make a sweeping change to the forecast based only on this.
Anyway, winds will come around to NW after daybreak, leading into
another day of shallow VFR cumulus.  Conditions behind the front
should be suppressed enough to inhibit any shower chances on Monday.

Outlook: Drying trend now expected to continue into Tuesday,
with little to no diurnal convection.  Summertime humidity will
returns by midweek, with SHRA/TSRA chances also returning.

&&

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

&&

$$

SYNOPSIS...SBK
NEAR TERM...MPR/PM
SHORT TERM...AR/SBK
LONG TERM...SBK
AVIATION...MPR