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000
FXUS62 KGSP 130734
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
334 AM EDT Sat Apr 13 2024

.SYNOPSIS...
Drier air will filter into the region today, with sunny skies
and still gusty winds. Temps return to around normal today and
trend still warmer Sunday, remaining well above normal through at
least Thursday.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 250 AM: A channeled vort max bisects our area, slowly
drifting east surrounding upper trough. The vort max extends all
the way upstream to Lake Michigan. This feature is the driver for
the spotty showers across the central Appalachians and some of
our northern CWA. Instability has diminished and so has shower
coverage over the last 90 minutes or so. Still can`t rule out a
few sprinkles across the northern mountains or foothills northeast
of I-26. Based on sfc temps and a couple of northern mtn webcams,
higher elevations may continue to see a rain-snow mix albeit not
likely with any additional accumulation. Coverage and intensity
should continue to wane thru daybreak, with clouds dissipating
soon after.

Heights will rise as upper trough axis swings further east and
offshore by midday. The upstream ridge will be quite dry and
skies look to remain virtually clear through the day. The gradient
won`t be nearly as strong as yesterday, and low level winds will
be comparatively tame. Nonetheless, with flow remaining moderate
through the boundary layer, frequent gusts of seasonable magnitude
will continue. Mixing will be a little deeper than usual, and
winds at the top of the mixed layer suggest low advisory-level
gusts remain possible beyond the original expiration of the wind
advisory. By mid-afternoon, say 18z, the stronger gusts probably
will be confined to high elevations. Given the difficulty in
messaging a switch from a full-zone to high-elevation wind product,
we have opted just to extend the advisory until 6 PM for the same
zones, given that an occasional 45 mph gust can`t be ruled out in
high elevations until mixing completely ceases diurnally. It is
possible some zones could be let go earlier in the afternoon.

Temps return to about normal today for most areas, perhaps a degree
or two above in the lower Piedmont. Dewpoints will mix diurnally
such that RH will dip below 25 percent in many areas. Fire Danger
Statements are being issued for Northeast Georgia and for Union
Co NC. See Fire Wx section below for details. Min temps tonight
also will return to about normal. Seeing a signal for a weak
mountain-wave cirrus event downstream of the Blue Ridge overnight
tonight, but with moisture spotty upstream, not certain those
clouds will be thick enough to impact temps.

&&

.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
As of 224 AM Saturday: Broad quasi-zonal flow is progged to be
draped from the Southern Plains to the southeast states Sunday
morning. Farther west, a powerful closed upper low will be diving
across the Great Basin and into the Four Corners region. At the same
time, a belt of northern stream flow is expected to extend along the
Canadian border with several troughs sliding across the northern
tier of the country. Guidance is in good agreement that the lead
trough will propagate across the Great Lakes region and Ohio Valley
with an attendant surface cold front oozing into northern Kentucky,
southern West Virginia and central Virginia. Southward progress of
the boundary will be slow and will likely stall as the front will be
oriented parallel to the upper flow as the parent wave lifts into
New England and southeast Canada. Heights will actually rise across
the Southern Appalachians as the pattern becomes amplified in
advance of the deepening western trough. This will result in a
warming trend through the period with highs on Sunday climbing into
the low to mid 60s across much of the area outside of the higher
mountain elevations. The trend will continue into Monday with mid to
upper 80s expected. An isolated shower or two may graze the
mountains Monday, but this will be the exception and not the rule.

&&

.LONG TERM /TUESDAY THROUGH FRIDAY/...
As of 251 AM Saturday: By Tuesday, attention shifts to a powerful
upstream closed upper low and associated trough that is forecast to
eject out of the southern Rockies and into the Southern Plains by
Tuesday morning. A tall and amplified ridge will slide into the
Appalachians ahead of the approaching wave, thus supporting a
continuation of warm temperatures in the 80s. Guidance continues to
depict strong agreement that the upper low will open into a
shortwave trough as it quickly lifts northeast into the Midwest on
Wednesday and becomes absorbed into a large longwave northern stream
trough dropping into the Canadian Prairies. This will result in a
rapid weakening of the wave with what waning forcing remains
displaced well north of the area. Weak height falls still seem
likely on Wednesday in advance of a cold front pushing across
Tennessee. Showers and a few thunderstorms will likely accompany the
front to our west, but a dearth of forcing should limit coverage as
the front approaches the mountains. Chance to slight chance PoPs
will be carried Wednesday into Wednesday night across the area, but
confidence is low as to how much of this activity will remain.
Thereafter, the large northern stream longwave trough will march
east and send a much stronger cold front through the area around
Friday. Guidance quickly diverges at this point, however, with
regards to the evolution of the trough and strength of the
front/forcing across the area. Nevertheless, an uptick in PoPs seems
reasonable by late week.

&&

.AVIATION /08Z SATURDAY THROUGH WEDNESDAY/...
At KCLT and elsewhere: VFR thru Sunday morning. A few sprinkles
are possible at KAVL and KHKY early in the period but likely with
minimal impact aside from possibly enhancing gusts; FEW-SCT clouds
in the 050-080 level may be seen there and at KCLT. Breezy winds
will be the story again this period, although not nearly as robust
as they were Friday. Gusts will return by mid-morning at all sites,
with 15-20 kt gusts at times until nearly sunset. KAVL`s gusts will
ramp up after daybreak, frequently reaching 30 kt from late morning
through mid-afternoon. Except at KAVL, winds generally will remain
W to WSW this morning, going N of W with onset of diurnal mixing,
and probably backing slightly S of W when the gradient relaxes
more significantly tonight. KAVL will remain solidly NW to NNW.

Outlook: VFR conditions will persist through early next week as
high pressure builds across the region.

&&

.FIRE WEATHER...
Most of the Piedmont and lower mountain valleys will see minimum
RH values below 25 percent this afternoon. Fuel moisture dipped
to 8-10 percent in NE Georgia yesterday, and likely will go lower
this afternoon. Together, these criteria alone meet Georgia state
criteria for a Fire Danger Statement, so we will issue one there
from noon to 8 PM.

Winds will be breezy and rather gusty through much of the day,
but in general will be just below the criterion for IFD in NC. NC
forestry officials previously recommended an Increased Fire Danger
Statement for Union County NC, and we are issuing the statement
for that county valid 10 AM to 8 PM in coordination with WFO
Raleigh. Other Piedmont zones of NC are perceived to have greened
up enough and/or received enough rainfall in the past couple of
days to preclude a Statement.

Fire Danger Statement not currently expected for SC due to ERC
criterion not being met, but further coordination is possible
sometime today.

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...Increased Fire Danger from noon EDT today through this evening
     for GAZ010-017-018-026-028-029.
NC...Wind Advisory until 6 PM EDT this evening for NCZ033-048>050-
     052-053-059-063>065-501-503-505-507-509.
     Increased Fire Danger from 10 AM EDT this morning through this
     evening for NCZ082.
SC...None.

&&

$$

SYNOPSIS...Wimberley
NEAR TERM...Wimberley
SHORT TERM...TW
LONG TERM...TW
AVIATION...Wimberley
FIRE WEATHER...Wimberley