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-- Discussion containing changed information from previous version are highlighted. --
000
FXUS62 KGSP 131504
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
1104 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/...
-- Changed Discussion --
As of 1040 AM: Forecast working out more or less as planned late
this morning. The main issue continues to be the wind, and we
continue to get frequent gust reports across the mtns, but not as
strong as yesterday, and mostly not advisory-level. The 850mb flow
was still fairly robust at daybreak, but model guidance shows it
tailing off steadily into the early afternoon, suggesting that at
some point this afternoon we probably won`t need the Advisory any
more. We shall keep it going for the time being as we continue
to get reports, but envision dropping it with the new forecast
package this afternoon. Speaking of the afternoon, we still expect
the dewpoint to mix out and bring the RH down to the 20-25 percent
range. See the Fire Wx Discussion below. Temps are in good shape.

Otherwise, quiet tonight. Min temps 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.
-- End Changed Discussion --

&&

.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 /15Z SATURDAY THROUGH WEDNESDAY/...
At KCLT and elsewhere: VFR into Sunday, largely SKC aside from
a few upslope clouds near KAVL this morning and a small area of
mountain wave cirrus developing tonight. 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, potentially
strongest soon after the onset of mixing and slacking off slightly
by afternoon. In general expect 15-25 kt gusts at times until nearly
sunset, with direction generally W to WSW early 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 is
as usual the exception, remaining solidly NW to NNW and having the
most gust potential, likely hitting 40 kt at times this morning,
and likely above 25 kt thru the afternoon. More typical nighttime
decoupling looks to occur after midnight tonight, with light SW
winds developing after sunrise Sunday.

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...
-- Changed Discussion --
GA...Increased Fire Danger until 8 PM EDT 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 until 8 PM EDT this evening for NCZ082.
SC...None.
-- End Changed Discussion --

&&

$$

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