Area Forecast Discussion
Issued by NWS Greer, SC

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FXUS62 KGSP 240712
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
312 AM EDT Sun Mar 24 2024

.SYNOPSIS...
Dry high pressure will build in from the north through Monday,
before a rainy cold front crosses the area late Tuesday into
Thursday. Dry and warmer weather returns Friday into the weekend.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 306 AM EDT Sunday: A quiet night is in store with high
pressure over the Ohio Valley ridging down into the Carolinas.
Stout low-level CAA embedded within a ~3mb pressure gradient
across the NC mountains has kept winds breezy across the area.
This should continue through most of the night, before low-level
flow starts to turn northeast around daybreak and cuts off the
stronger CAA.  We`ll be clear through the period, as upper ridging
continues to build over the Southeast.  Some isolated areas of
patchy frost are possible across the NC Piedmont this morning,
but more widespread frost will be prevented by the elevated winds.
It`s possible that lows could even fall to freezing in sheltered
areas of the Piedmont (especially along the I-40 corridor) where
winds get light enough for the atmosphere to fully decouple.

Today will be a dry one.  Upstream soundings over the upper
Mid-Atlantic reveal a layer of incredibly dry air just above the
surface, which will advect into the Carolinas today.  With nothing
to hinder daytime heating from the moment the sun rises, ensemble
soundings depict the development of a mixed layer across the area
by mid-morning, and it won`t take long to start tapping into that
dry air aloft and mix it down to the surface.  Consequently, went
with the lower quartile of dewpoint guidance for this afternoon,
resulting in widespread critical RHs across most of the forecast
area.  The saving grace for fire weather will be the lack of
stronger winds; with flow getting increasingly anemic throughout
the day, afternoon RH minima will coincide with relatively weak
20ft winds, putting us below Fire Danger criteria for all zones.
High temperatures will climb into the mid/upper 50s across NC,
and may approach 60 in the Upstate and NE GA, especially along
the Savannah River.

Winds will slowly turn east before getting increasingly light this
evening and tonight.  Temperatures for much of the NC Piedmont
will fall to near or below freezing.  For zones with high enough
confidence in freezing temperatures, a Freeze Warning will be
issued; for those zones along the NC-SC border, where confidence
is lower, a Frost Advisory will be issued instead, as winds should
be light enough that at least patchy frost seems likely.

&&

.SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
As of 155 AM Sunday...An upper level ridge axis shifts across the
area Mon/Tue while stg high pressure ridges down the east coast
ahead of an incoming cold front. Model soundings still indicate a
lowering subsidence inversion, down to 2Kft, and a dry mixed layer
below that. This will lead to low RH values in the afternoon, but
likely not as dry as Sun. Cloud cover increases atop the sfc wedge
and the combination of llvl CAA and less heating will hold high
temps arnd 60 F east of the mtns and m50s mtn valleys. Thus, shallow
vertical mixing will not lower td/s greatly leading to RH values in
the u20s to arnd 30 percent range. Also with lower wind speeds, the
meteorological conds don`t support the need for fire-wx products
attm. An upstream h5 s/w brings an active cold front the east TN
Tues morning and this will interact with a sfc wedge leading to
widespread rainfall by the evening and overnight into Wed.
Instability is meager ahead of this system, yet added thunder across
the NC mtns Tue evening as upslope forcing could help produce a few
embedded tstms. Highs Tue will also hold around 8 degrees below
normal with a moist sfc wedge persisting. Mins will not drop off
each night in this environment as lows are held a few degrees abv
normal Mon night and 6-10 degrees abv normal Tue night.

&&

.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
As of 220 AM Sunday...A cold front continues to slowly push east of
the FA Wed and the atmos remains unsettled into the overnight as an
upper trof crosses from the west. The current timing consensus of
sfc convg favors the eastern zones for the best chance rain and have
kept PoPs in the mid chance range across the I-77 corridor thru the
evening. Rain chances go down to low early Thu across all areas as a
nrn stream sfc high builds in which may also bring enuf cold air for
a period of high elevation -snsh before the deeper moisture pushes
east. The synoptic setup Thu evening is still a little uncertain
tho, as the ECMWF and the CMC models produce a sfc wave on the coastal
front possibly bringing -shra back to the ern zones. The QPF trends
on this scenario have decreased however, so have not made sigfnt
adj/s to the grids. The pattern becomes dry with a large upstream
ridge developing across the central CONUS Fri, which will maintain
warming sfc hipres over the FA into Sat. High temps begin the period
arnd or a little below normal and by Sat expect max temps in the
m70s non/mtns and l70 mtn valleys. Mins will generally be held a few
degrees abv normal each morning with patchy/areas of frost possible
Thu night due to clearing skies and calm winds.

&&

.AVIATION /07Z SUNDAY THROUGH THURSDAY/...
At KCLT and elsewhere: VFR conditions expected through the TAF
period as high pressure rolls across the Carolinas.  What little
stratocu was left in the NC mountains has scattered out, and it`s
essentially SKC everywhere.  Breezy N winds still in place with
many ob sites still reporting low-end gusts...and this will continue
through much of tonight.  KAVL as well as many mountain sites will
continue to see some gusts through the night, while at other sites
gusts will likely vanish in the coming hours.  Winds will take on
an increasingly E component after daybreak Sunday, and will remain
breezy through the day, with some sites seeing afternoon gusts.
KAVL will see its flow channeled to SE, while the rest of the TAF
sites should remain N of E through the period.

Outlook: Dry high pressure and VFR conditions will continue into
Monday. Rain chances and possible restrictions return Tuesday
into Wednesday as a cold front moves in from the west. The front
could slow, keeping rain and restrictions on Thursday, but this
is uncertain.

&&

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

&&

$$

SYNOPSIS...SBK
NEAR TERM...MPR
SHORT TERM...SBK
LONG TERM...SBK
AVIATION...MPR


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