Catawba Heights, North Carolina Weather Forecast Discussion

039
FXUS62 KGSP 191755
AFDGSP
Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
155 PM EDT Fri Sep 19 2025
.SYNOPSIS...
Pop up showers and thunderstorms are possible across the mountains
each day through the early part of next week. Dry conditions will
persist elsewhere with temperatures at or slightly above normal for
this time of year.
&&
.NEAR TERM /THROUGH SATURDAY/...
As of 1253 PM EDT Friday: Satellite imagery as of midday showed
a buildup of enhanced cu on the ridgetops, so it should only be a
short while before radar starts picking up some shower activity at
the high elevations. The 12Z run of the HREF showed a bit better
coverage across the mtns this afternoon than what we had in the
fcst, so the precip probs were nudged up a bit so more locations get
into the chance range. The latest RAP continues to support this with
some low level moisture pooled over the mtns/foothills resulting
in a breakable cap and modest amounts of sfc-based CAPE. The
latest SPC mesoanalysis shows 1500 J/kg of muCAPE which is more
than enough fuel. Not really expecting a chance of severe storms,
though. The same area that has the best CAPE has the poorest dCAPE,
though fcst soundings show an inverted-V so strong gusts are not
completely out of the realm of possibilities. Temp/dewpt trends
look ok, so no changes there.
Similar to yesterday, it is possible that an isolated shower or
storm could persist through the evening hours somewhere over the
western zones. Otherwise, the overnight should be quiet. It stands
to reason that without much change, another round of mtn valley
fog/low stratus is a good bet, given the time of year. Low temps
will be a few degrees on the warm side of normal.
For Saturday, it looks like the weak forcing and nondescript flow
brought about by the baggy upper pattern across the Carolinas
and Mid-Atlantic will come to an end. We should start to feel
more of an effect from a mid/upper trof over the nrn Plains and
upper Midwest that brings slightly better westerly flow aloft
by the afternoon. Some subtle air mass modification is shown by
some of the guidance, with better low level moisture spreading
east of the mtns resulting in better sfc-based CAPE across much
of the region in the afternoon. The model blend begs to differ,
however, and essentially keeps our chances limited to the same
places as this afternoon. The CAMs could be on the right track,
though, suggesting some isolated showers in the afternoon over
the Upstate and NC foothills, so don`t be too surprised if the
fcst trends in that direction. It should be another seasonally
hot day with high temps about ten degrees above normal, so keep
that in mind if you have outdoor plans.
&&
.SHORT TERM /SATURDAY NIGHT THROUGH SUNDAY NIGHT/...
As of 109 PM EDT Friday: Drier northeasterly surface winds will
filter in Saturday night as a surface high sets up shop over
New England in wedge-like fashion. The flow aloft becomes more
benign, without much of specific feature. Expect for sensible
weather conditions to be mostly dry, with the exception of an
upslope diurnal shower or thunderstorm in the southwest mountains
Sunday afternoon. Afternoon highs on Sunday will drop off a few
degrees compared to Saturday as a result. Surface high remains in
control Sunday night and Monday, but subtle height falls from the
west suggest a slight uptick in showers and thunderstorms in the
mountains via ridgetop convection by peak heating. Otherwise, dry
conditions will persist outside of the mountains, with afternoon
highs and overnight lows hovering near-normal.
&&
.LONG TERM /MONDAY THROUGH FRIDAY/...
As of 148 PM EDT Friday: Model guidance starting to build better
consensus for the overall synoptic pattern during the extended
period. A weak frontal boundary looks to approach the area from
the northwest Tuesday, allowing for another day of mountain
convection, but struggling to break containment outside of the
High Country as nothing aloft suggest the front will advance past
the mountains. Changes really take place by the middle of the week
as deterministic and ensemble guidance key in on the potential of
a cutoff low developing and moving across the central CONUS. In
this setup, deep layer southwesterly flow would commence as a
deeper moisture transport from the Gulf would filter in ahead of
a stronger frontal boundary. A nice slug of QPF response is shown
pulling into the area during the latter half of the extended, but
the question then becomes, will the cutoff low shift across and
out of the area quickly or somewhat stall? If the system stalls
then some form of hydro concerns could persist as QPF amounts
would begin to pile up. However, this is still too far out into
the future to speculate real-time impacts next week, especially as
guidance differ on the location of just about everything. Definitely
a pattern worth monitoring as we head into this weekend and early
next week. Temperatures will be at or slightly above normal through
the middle of next week before associated cloud cover and precip
enters the area in association with the potential cutoff low,
which would put us at or slightly below normal.
&&
.AVIATION /18Z FRIDAY THROUGH WEDNESDAY/...
At KCLT and elsewhere: VFR through the late evening across the
region, with the possible exception of brief restrictions around
scattered showers/storms that develop over the mtns. Will include a
VCTS at KAVL after 21Z based on the coverage shown on the 12Z HREF
model, but think it doesn`t warrant a PROB30 at this point. The
problem spot will be KAVL once again overnight. Fog/low stratus has
formed the past few nights in the mtn valleys and should develop
again in the pre-dawn hours Saturday. KAVL could easily fall down
to VLIFR temporarily, but the fcst stays optimistic with merely
low IFR in a TEMPO group. Wind should be light/variable. The fog
should mix out around 14Z. The rest of the period will be similar
to today, with scattered stratocu developing in the afternoon. Wind
may come around more to light NE.
Outlook: Dry weather returns to start the week. Rain chances may
return Tuesday thru midweek. Fog and stratus possible each morning
in the mountain valleys.
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...None.
NC...None.
SC...None.
&&
$$
SYNOPSIS...CAC
NEAR TERM...PM
SHORT TERM...CAC
LONG TERM...CAC
AVIATION...PM

NWS GSP Office Area Forecast Discussion