018
FXUS62 KGSP 031350
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
950 AM EDT Thu Apr 3 2025

.SYNOPSIS...
Warmer temperatures are expected today, even as clouds and spotty
rain chances continue.  Fair afternoon skies and exceptionally
warm weather end the week. A cold front brings rain and possibly
thunderstorms on Sunday and Monday, followed by dry and cool
conditions Tuesday and Wednesday.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 950 AM EDT Thursday: Starting to see minor breaks in the cloud
filter in from the southwestern fringe of the CFWA. Continued
southerly upslope showers over the Escarpment should break
containment outside of the escarpment by noon, but confidence has
gotten lower with the lack of reflectivity on radar. Tweaked PoPs as
a result, but most of the forecast remains on track.

Otherwise...Despite an expected break in precip, guidance may be
too bullish on the erosion, and stubborn stratus may result in
temps not quite making it to the expected forecast highs where
the last of the wedge breaks. Most of the area should be in the
warm sector air mass with clouds breaking up by early aftn. Dewpts
surging into the mid 60s combined with temps in the lower 80s will
likely result in around 1000 J/kg of sbCAPE by mid-aftn. There may
be enough isentropic lift and differential heating boundaries to
trigger isolated to scattered showers. Most of the guidance shows
this, but disagree on exact locations of the best coverage. So
will keep PoPs in the slight chc to low-end chc range, favoring
the south flow upslope areas. With forcing and instability expected
to be weaker than yesterday, think thunder chances will be lower,
but isolated general storms will be possible.

Tonight...whatever convection develops should wane with loss of
daytime heating, except for some spotty southerly upslope light
rain near the Escarpment. Low cloud cover is expected to redevelop,
and persistent warm southerly flow will combine to keep low temps
well above normal. In fact, Charlotte is forecast to break its
daily high minimum temp by several deg today with temps still in
the 70s thru this evening.

&&

.SHORT TERM /FRIDAY THROUGH SATURDAY/...
As of 200 AM Thu: Anomalously deep upper ridge east of Florida will
remain almost stationary Friday and Saturday, drifting slightly
eastward in response to gradually advancing troughs in the central
CONUS. A nocturnal stratus deck is likely to have to burn off during
the morning, which could be a limiting factor in max temps if it
lasts longer than anticipated, but otherwise daily max temp records
at CLT/GSP are in jeopardy both days, arguably more likely Friday
simply on account of the records being slightly cooler that day. High
min records appear likely to be broken also.

Sfc low pressure will develop in the lower MS Valley early in the
period. A quasi-stationary front will extend from that low to the
Mid-Atlantic Coast on the northern periphery of the ridge; a weak but
persistent sfc trough is seen on model MSLP progs near the VA/NC
border Fri, lifting slightly further north Sat as low tracks further
north. The upper pattern should provide a net southwesterly flow over
the CWA.  Models are split as to whether the strong ridge will
provide a capping inversion over our area. Several synoptic models
plus the HiRes Windows (ARW and FV3) respond with widely scattered
diurnal convection across the mountain ridges and the southern
Piedmont. Wondering if differential heating may be playing a role in
these model depictions, between the area that will have seen rain
Wed-Thu and the area that saw little to nothing. The NAM and HRRR
however are devoid of any QPF response during the day, although the
NAM shows some light response Fri night with the sea breeze front.

Models are more in agreement on capping Saturday, despite falling
700mb and 500mb heights. Dewpoints are expected to be a little lower
which will also play a role in limiting instability. GFS and EC still
develop a few showers over the SW NC mountains and Escarpment.

&&

.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
As of 300 AM Thu: Well defined shortwave, if not partially cutoff
low, will move across the western Ozarks Saturday night, activating
the longstanding frontal boundary as a cold front which will cross
the Deep South and TN during the day Sunday. Over our CWA, SW flow
continues in low levels into Sunday morning, increasing to 30-40
kt over the mountains preceding the front. High elevations may
experience near-Wind Advisory level gusts early Sunday. A line of
thunderstorms could cross the Deep South overnight into morning,
but looks to be running out of instability by the time the line
reaches eastern AL or GA. PoPs will ramp up in the early morning
hours in that part of the CWA with the SW upslope flow and perhaps
the arrival of decaying storms. Severe threat more likely to stay
to our west and we are not currently included in any SPC Day 3
outlook risk area.

The front itself looks to be timed to reach our west by late morning
and progress across most of the area by late afternoon. Instability
is still relatively low, with ensembles suggesting less than 30%
chance of 500 J/kg of SBCAPE in our area thru Sun afternoon. This
is presumably due to warm midlevels and low 850-700mb lapse
rates owing to the strength of the preceding ridge. 0-6km bulk
shear of as much as 70 kt may be in play during peak heating, but
given the weak instability the 0-1km and 0-3km values may be more
telling for high-shear low-CAPE severe threat, and those are not as
impressive but confidence remains limited with only low-resolution
guidance to evaluate. Upper divergence associated with right-rear
quad of jet streak still looks to be the main dynamic forcing,
as the aforementioned shortwave will be absorbed into a broader
northern-stream trough, and the base of the new trough does not
actually cross the area until Monday. The frontal zone appears to
pivot in response and flow becomes more parallel to it. A band
of categorical PoPs cross the CWA during the day Sunday; with
the slowing front these decline only slowly through Sun night
and Monday.  PWATs still are progged to peak near or above daily
record values, and as the front slows an excessive rain threat
could evolve or expand in scope, if not already as a result of
convection during the day Sunday. We remain in WPC Marginal ERO.

Cold advection behind the front will bring temps back near or even
slightly below normal Monday. High elevations presently look to
fall near or below freezing Monday night. Precip probably will
end before temps get that cold, although some guidance depicts a
shallow moist layer persisting into Tue in the NW flow upslope zone,
so light snow or rime icing can`t be completely ruled out there. Dry
and cool conditions Tue and Wed, with sfc high centering over the
area Tue night and allowing good radiation and widespread temps
in the 20s across the mountains and 30s Piedmont. Frost-freeze
program is in effect for some lower elevation areas so headlines
could be warranted, although it may be too dry for frost.

&&

.AVIATION /14Z THURSDAY THROUGH MONDAY/...
At KCLT and elsewhere: The wedge has mostly eroded completely with
all TAF sites outside of the wedge at this point. IFR cigs and MVFR
vsbys are continuing at the Upstate terminals and KHKY that should
start to lift later this morning. The other TAF sites are MVFR, and
confidence is increasing they will not go IFR this morning. There is
still expected to be an uptick in showers across the area this
morning, but should be mainly isolated to widely scattered and
therefore, will not be included in the TAFs except at KAVL and KHKY.
Cigs should gradually lift and scatter out to VFR by late aftn, but
confidence on how quickly that happens is low. Guidance still in
good agreement on IFR to MVFR stratus forming across the Midlands
and expanding north into the area late tonight, lingering into
Friday.  Winds will be out of the south at all sites, once the wedge
fully erodes, picking up with some low-end gusts by late morning or
midday, then weakening again late aftn into this evening.

Outlook: IFR to MVFR cigs may linger thru Friday morning. Drier
conditions return Friday night into Saturday night before another
cold front brings shower and thunderstorm chances, and associated
flight restrictions, back on Sunday.

&&

.CLIMATE...
RECORDS FOR 04-03

               MAX TEMPERATURE         MIN TEMPERATURE
  STATION      HIGH        LOW         HIGH        LOW
  -------  ----------  ----------  ----------  ----------
   KAVL      88 1963     31 1936     64 1946     23 1936
   KCLT      90 1946     42 1915     62 1986     26 2021
                                        1946
   KGSP      87 1967     44 1901     62 2014     27 2021
                1963                                1993
                1946                                1902



RECORDS FOR 04-04

               MAX TEMPERATURE         MIN TEMPERATURE
  STATION      HIGH        LOW         HIGH        LOW
  -------  ----------  ----------  ----------  ----------
   KAVL      83 1999     33 1891     61 1893     22 1936
                1978
   KCLT      87 1999     43 1911     63 1986     29 1936
                            1899        1945
                                        1934
   KGSP      88 1963     44 1936     62 1999     25 1975
                1934



RECORDS FOR 04-05

               MAX TEMPERATURE         MIN TEMPERATURE
  STATION      HIGH        LOW         HIGH        LOW
  -------  ----------  ----------  ----------  ----------
   KAVL      86 1909     30 1891     60 2023     20 1944
                                        1910
   KCLT      88 1942     38 1891     62 1910     26 1891
   KGSP      90 1934     43 1899     60 2023     25 1904
                                        1888



RECORDS FOR 04-06

               MAX TEMPERATURE         MIN TEMPERATURE
  STATION      HIGH        LOW         HIGH        LOW
  -------  ----------  ----------  ----------  ----------
   KAVL      88 1967     36 1950     64 2023     22 1898
   KCLT      90 2010     43 1931     67 2023     28 1891
                1929
   KGSP      88 2010     47 1950     65 2023     26 1904
                            1945

&&

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

&&

$$

SYNOPSIS...Wimberley
NEAR TERM...ARK/CAC
SHORT TERM...Wimberley
LONG TERM...Wimberley
AVIATION...ARK/CAC
CLIMATE...