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000
FXUS62 KGSP 170505
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
105 AM EDT Wed Apr 17 2024

.SYNOPSIS...
Very warm and relatively humid weather will continue through
Friday. Small chances of showers and storms through Wednesday over
the mountains. More widespread showers and thunderstorms are
expected with a front reaching the area Friday, with unsettled but
cooler weather continuing through the weekend as the front slowly
moves to the Carolina coast and north Florida by late Sunday.

&&

.NEAR TERM /THROUGH TODAY/...
As of 102 AM Wednesday: Temperatures have dropped faster than
forecast tonight ahead of much thicker upper clouds encroaching from
the west. Once these clouds arrive, the rate of cooling will slow
down and some locations may actually see a slight rise in
temperatures. Regardless, nudged low temperatures down a degree or
two to account for current trends before clouds move in and take
control.

Otherwise, high clouds will continue to thicken as moisture
increases amid falling heights in advance of an impressive short
wave trough rotating around a stacked cyclone located over the Upper
Midwest. Ahead of this feature, regional radar imagery depicts an
area of somewhat spotty/weak radar returns extending from the TN
into the OH Valley. Most of this is falling from mid-level clouds,
while the sub-cloud layer is relatively dry. Therefore, measurable
rainfall is expected to be difficult to come by as these returns
move into our CWA overnight, and PoPs are limited to the 10-20%
range...although a mention of sprinkles was added to the forecast.
Lows will dip into the lower 60s for most of the area...as thick
cloud cover inhibits better cooling.

On Wednesday, increasingly strong SW winds will usher in better
moisture as a cold front moves into the Ohio Valley...making a run
at our area by the end of the day. Sprinkles or light showers will
become increasingly likely through the day as profiles saturate,
with an outside chance of significant thunderstorms if updrafts
overcome the less-than-impressive synoptic forcing and weak
subsidence, and tap into ~500 J/kg sbCAPE and modest deep
shear...but the main band of frontally-forced showers won`t arrive
in the NC mountains until late Wednesday afternoon.

&&

.SHORT TERM /TONIGHT THROUGH FRIDAY NIGHT/...
As of 210 PM Tuesday: Starting off the short term with quasi-zonal
flow aloft, which is quickly replaced with height rises by Thursday
as an area of high pressure over the Gulf amplifies. An upper low
situated across Canada extends a weak front over the midwest. This
feature causes a ripple effect toward the south, with a shortwave
developing west of the CWA and traversing toward the region. By
Friday, it`s possible the weak cold front could extend into the CWA
and at least bring a slight dip in temps and low-end gusts.
Meanwhile, the weak ridge axis slides off shore by Thursday night as
the shortwave crosses the area. Guidance from the GFS and EURO
diverge a bit on the QPF response and keeps the majority of precip
potential confined to the mountains. The Euro has a wetter response,
while the GFS keeps it drier. Looking at modeled soundings, an
extremely dry profile exists from the sfc to 700mb, despite minimal
muCAPE available. Unless moisture can get into the area ahead of
this shortwave, any precip that does form will likely evaporate
before reaching the ground. For this, QPF response is near zero
across the western NC mountains through Friday. Confidence is very
low that the area will see much in any measurable rainfall during
this period. As far as convection, the NAM shows better instability
but with a stronger cap in place near 800mb. There also looks to be
minimal forcing available with better DPVA well off to the north.
Can`t rule out an isolated storm, but it will be difficult to
overcome the capping inversion and little forcing. Winds should be
relatively light through the period and SW/W, and at times VRB. If
the FROPA can cross the area, expect low end gusts that quickly
diminish into the beginning of the next period. Thursday high temps
are expected to be the warmest with most of the area topping out in
the high 80s. High temperatures on Thursday could make a run for the
record high at GSP, but not appearing at this time to top other
climate sites in the area.

&&

.LONG TERM /SATURDAY THROUGH TUESDAY/...
As of 225 PM Tuesday: Picking up on Friday night, any remnant precip
or weak convection that might develop will be on the downward trend.
By Saturday morning, any rain chances should be gone as flow aloft
turns quasi-zonal. Out west, an amplifying ridge builds in and keeps
the weekend dry. A strong sfc high develops over the central CONUS
Saturday night in the wake of the low moving off the NE. Winds will
turn N/NE as the high progresses eastward. The more N/NE winds will
draw in cooler air from the north, not quite a CAD event, but keep
temps mild Sunday and Monday. By the start of the work week, a low
attempts to develop over the central plains. Guidance from the long
range models show the potential low weakening before even fully
developing, leaving behind a modest trough axis that could swing
through the region. This would increase rain chances for Sunday
night into Monday, but again the timing and amounts are too far out
to pinpoint. At this time, GFS shows little to no sbCAPE on Monday,
which keeps TS out of the running for now. Overall, the pattern
looks mild and tame by spring standards. Winds will veer from W to
the N/NE through the weekend and should become more SW once again by
the end of the period. The warmest day looks to be Saturday with
highs reaching the 80s. Temperatures drop for Sunday and Monday into
the upper 60s from the N/NE sfc flow. Lows appear to remain above
freezing through the period, with Monday night dipping into the low
40s across the Piedmont, so no frost/freeze concerns at this time.

&&

.AVIATION /05Z WEDNESDAY THROUGH SUNDAY/...
At KCLT and elsewhere: VFR conditions will continue through much of
the period as high clouds stream across the region overnight. A band
of showers will approach the area from the west during the afternoon
to early evening hours. A brief period of light rain will be
possible at any given terminal as these showers move through.
Confidence is highest at KAVL/KGSP/KGMU/KAND where brief MVFR
visibilities will be possible with any moderate rainfall rates.
Elsewhere, coverage and anticipated lighter precipitation rates
should allow for VFR visibility. Light winds overnight will become
gusty out of the southwest this afternoon before becoming light
again tonight.

Outlook: VFR generally will persist through midweek. An unsettled
pattern with precip chances and periodic restrictions may develop
from Thu night into the early part of the weekend, but confidence
remains low.

&&

.CLIMATE...
RECORDS FOR 04-18

               MAX TEMPERATURE         MIN TEMPERATURE
  STATION      HIGH        LOW         HIGH        LOW
  -------  ----------  ----------  ----------  ----------
   KAVL      90 1896     44 1921     60 1927     28 1905
                                        1891
   KCLT      93 1896     45 1983     66 1896     32 2001
   KGSP      89 2002     51 1983     66 1927     28 1905
                1967

&&

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

&&

$$

SYNOPSIS...DEO
NEAR TERM...JDL/MPR/TW
SHORT TERM...CP
LONG TERM...CP
AVIATION...TW
CLIMATE...GSP