026
FXUS62 KGSP 081731
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
131 PM EDT Sat Jun 8 2024

.SYNOPSIS...
Dry high pressure over the area today gives way to a a cold front
and returning shower and thunderstorm chances on Sunday. Forecast
confidence lowers starting next week as the overall pattern is
uncertain by the end of the seven day period, but trends are for a
dry start to the work week then increasing rain chances through
Friday.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 1205 PM EDT Saturday: Populated in the latest obs but no other
changes were needed this update thanks to the quiet wx pattern.
Otherwise, deep westerly flow will persist atop the CWA through the
near term, supporting a seasonably very warm and anomalously dry air
mass. As a result, instability is forecast to be virtually non-
existent once again through the period. A short wave trough/MCV is
forecast to approach the area this afternoon, but chances for
convection will be 10% at most owing to the lack of moisture and
instability. Additional MCVs...possibly accompanied by a decaying
MCS may approach the southern Appalachians late tonight/ early
Sunday. Nevertheless, a lack of buoyancy across and just upstream of
the CWA indicates convection will remain unlikely through 12Z
Sunday...although a slight chance for showers is carried along the
TN/NC border late in the period. Min temps are forecast right around
normal.

&&

.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
As of 145 AM EDT Saturday: Upper-level low centered over eastern
Canada and New England will send a trailing cold front into the
region and should be knocking on our door to the northwest at the
beginning portion of the forecast period. The front is expected to
sag across the CFWA during peak heating with PWATs quickly rising
to 1.50"+ and available instability (~750-1500 J/kg of sbCAPE)
to allow for showers and thunderstorms to develop. Lack of upper
forcing being confined north of the area will limit coverage, but
can`t completely rule out a strong to severe thunderstorm later in
the afternoon and evening as the embedded shortwave energy catches
up with the subtle height falls and better overall kinematics. The
HRRR and NAM produce a line of organized convection after 00Z
Monday and pushes them from north to south across the CFWA into
the early overnight period. Decided to prolong mentionable PoPs
into the overnight period Sunday due to these trends. Otherwise,
model guidance are in better agreement compared to this time last
night, with the frontal boundary completing a full fropa by mid-
morning Monday and allowing a continental surface high to filter in
from the Northern Plains under broad cyclonic flow aloft. Will point
out that some of the guidance are slower with the fropa and could
allow showers and storms to linger later into Monday, which would
lower afternoon highs. Temperatures on Sunday will run ~5 degrees
above normal as the CFWA is placed underneath the warm sector, ahead
of the front. With lingering cloud debris and slow push from the
front, overnight lows will also run ~5 degrees above normal Sunday
night. Temperatures lower a bit for Monday as values are up in the
air, as a west-northwesterly downslope component will be present as
values are forecasted to be at or slightly above normal, but may end
up slightly below normal if cloud debris and showers and
thunderstorms stick around longer than expected. Lower thicknesses
and dewpoints, with good radiational cooling conditions available
will lead to overnight lows Monday night to run slightly below
normal.

&&

.LONG TERM /TUESDAY THROUGH SATURDAY/...
As of 300 AM EDT Saturday: Broad cyclonic flow aloft will begin
to breakdown at the start of the forecast period as a shortwave
upper ridge builds in with weak high pressure remaining in
control going into the middle part of next week. The area of high
pressure shifts offshore by Thursday and brings a return flow
into the area. Hints of a surface low developing in the Gulf is
now present in the global models and shown lifting north into the
southeastern CONUS by the end of the period. Scattered diurnal
convection will be possible by the back half of the medium range,
but uncertainty amongst model guidance will keep PoPs at bay for
the moment as we continue to monitor the latest forecast for the
end of the extended period. Temperatures will start at or slightly
below normal Tuesday, while a slow warming trend will be present
through the end of the workweek.

&&

.AVIATION /18Z SATURDAY THROUGH THURSDAY/...
Key Messages:

1) Dry Conditions Linger into Tonight

2) Shower and Thunderstorm Chances Return Sunday

VFR through the 18Z TAF forecast period. Dry conditions should
linger through tonight with high pressure in place. The only caveat
is that an upper shortwave tracking overhead my allow some spotty
sprinkles or even -RA develop between 22Z and 01Z, mainly across
KAVL and KHKY. Confidence on this remains too low to add VCSH or
TEMPO into either TAF at this time, so maintained dry conditions.
Winds this afternoon will gradually turn WSW/SW across the
terminals. Coverage of upper-level cirrus will gradually increase
through the TAF period. Winds will turn back NW/WNW at KAVL
overnight into Sunday. Winds will remain WSW/SW east of the
mountains overnight, turning westerly ahead of an approaching cold
front on Sunday. This cold front will bring -SHRA (and possible
isolated TSRA in the afternoon) back to the area on Sunday. Went with
a PROB30 at KAVL as the activity will push across the mountains
towards the end of the 18Z TAF period. KCLT also gets a PROB30 since
the TAF goes out 30 hours. Timing on -SHRA/TSRA remains low as
timing differences remain between the high-res model guidance
sources.

Outlook: It`s looking more likely that dry weather will return the
first half of the next week.

&&

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

&&

$$

SYNOPSIS...CAC
NEAR TERM...AR/JDL
SHORT TERM...CAC
LONG TERM...CAC
AVIATION...AR