Spartanburg, South Carolina 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

841
FXUS62 KGSP 211409
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
909 AM EST Thu Nov 21 2024

.SYNOPSIS...
A cold front will drift off the Carolina coast today as cold high
pressure brings below normal temperatures and dry conditions through
the weekend. Light snow will fall mainly along the Tennessee border
tonight into Friday. There will be a warming trend beginning late
in the weekend through early next week.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 900 AM EST Thursday...No major changes were needed this
morning as the forecast remains on track. Dry conditions and clear
skies continue area-wide this morning with temps already in the
upper 30s to lower 40s in across the mountain valleys and east of
the mountains. Temps are much cooler along the NC/TN border and
across the higher elevations of the NC mountains, ranging from the
mid 20s to low 30s. Wind speeds will gradually increase through the
day with gusty winds returning east of the mountains. Already seeing
some gusts across the higher elevations of the NC mountains this
morning.

Still looks like our first taste of winter across the NC mountains
near the TN border starting this afternoon and continuing into the
overnight hours. An upper low over the Midwest is expected to wobble
in our direction as a powerful short wave/vort lobe rotates around
the low and dives southeast toward the srn Appalachians later this
morning. Guidance has the dpva associated with this feature reaching
the NC border between 18Z and 21Z this afternoon along a the slug of
moisture. Precip chances ramp up along the TN border from Avery down
toward the Smokies from mid-afternoon into the evening. Expect an
initial burst of precip, possibly beginning as a wintry mix which is
typical, but changing fairly quick to snow showers. Precip probs
along the border ramp up further into the likely and categorical
range this evening as the deeper moisture moves in after 00Z, deep
enough to reach into the dendritic growth zone anyway. The best
accum potential will probably be between midnight and daybreak
Friday. Thoughts about snow amounts haven`t changed appreciably so
we appear to be on the track to an Advisory. Note that isolated
locations above 5K feet will probably make it to warning criteria,
but overall the zone averages indicate snow accums in the Advisory
range. Temps tonight will feel wintry, especially with some residual
wind from the NW, and should bottom out 5-10 degrees below normal.
But...not cool enough to get anywhere close to an Advisory for the
cold temps.

&&

.SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
As of 221 AM EST Thursday: As drier air filters into the mountains
on Friday and warming aloft cuts off ice nucleation, snow should
taper off through most of the day.  There may be a resurgence
late in the day as a weak vort lobe rotates across the northern
zones and briefly cools the mid-levels...re-inciting activity
along the northern Blue Ridge.  The bigger story on Friday will
likely be winds, which will remain elevated through much of the
day.  Especially across the high terrain, both the HREF and the
comparatively-subdued NBM depict ~75% odds of advisory-criteria
winds through the first half of Friday.  Temperatures will only
climb into the low 50s, even across the low terrain.

Thereafter, forcing will be lost as the upper trough pulls
northeastward overnight, giving way to quasi-zonal flow aloft
and dry high pressure at the surface.  The sfc pressure gradient
will slacken across the mountains, allowing winds to die down.
Lows in the mid 30s can be expected just about everywhere overnight,
before they climb into the upper 50s on Saturday.  They`ll fall
into the mid- or even lower-30s again Saturday night, which looks
to be the best night for calm winds, clear skies, and excellent
radiative cooling.

&&

.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
As of 231 AM EST Thursday: Unperturbed flow aloft will continue
throughout most of the extended.  Ill-defined cyclogenesis looks to
take hold at some point mid-week, although the details are unclear.
The GFS and its ensembles tend to develop it around Wednesday over
the Ozarks, then have it track northeastward.  The GEPS ensembles
tend to take the same track, but depict its development later.
ENS members as well as the 00z deterministic ECMWF depict a cyclone
developing over the upper Midwest mid-week...such that any impacts
the Carolinas see will be through the passage of a cold front near
the end of the period, as opposed to any warm frontal activation
midweek.  So...initially-dry conditions will give way to warmer,
wetter conditions mid- to late-week, but there`s just not much
forecast confidence yet.

&&

.AVIATION /14Z THURSDAY THROUGH MONDAY/...
At KCLT and elsewhere: VFR at most terminals through the period,
with sky clear and no restrictions, but KAVL will be the exception
early Friday morning. Wind starting out light SW thanks to a
developing lee trof, but the speed picks up this morning as we
start to mix more deeply, followed by frequent gusts through
the afternoon and into the early evening. Wind should diminish
and we lose the gusts around sunset. Meanwhile, over the mtns,
moisture returns along with a strong short wave that arrives after
18Z. Precip production should begin in mid/late afternoon in the
NW flow upslope areas, and with cold air aloft, this should be
mostly light snow. Present indications are that precip will remain
confined close to the TN border, but the trend is toward more
cloudiness blowing up the French Broad R valley early Friday. Thus,
will introduce an MVFR bkn ceiling condition before the start of
operations, but will keep the precip mention to only a VCSH. Bear
in mind there will be a chance of snow showers, but this is too
uncertain to mention even as a PROB30 at this time.

Outlook: VFR outside of the mountains through Monday. Gusty W/NW
winds may linger through Friday. KAVL may see some low VFR or MVFR
cigs as moisture pushes up the valley through Friday night with
VFR returning through Monday.

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...None.
NC...Winter Weather Advisory from 1 PM this afternoon to 7 AM EST
     Saturday for NCZ033-048>052.
SC...None.

&&

$$

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