686
FXUS62 KGSP 121037
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
637 AM EDT Fri Jul 12 2024

.SYNOPSIS...
A weak tropical low will move inland over the eastern Carolinas on
Friday, increasing rainfall chances for areas along and east of
Interstate 77. Dry weather returns for the weekend and into the
beginning of next week, with a pattern change mid week possible.
Above normal temperatures through the middle of next week.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 625 am Friday: A weak disturbance near the Carolina Coast is
expected to retrograde a bit and become absorbed in the general
troughy upper pattern over the East this morning. This will result
in subtropical moisture...precipitable water values approaching
2"... surging into the eastern portion of our CWA through the
morning, resulting in thickening cloud cover and increasing
convective chances. In fact...a few showers are have already moved
into the I-77 corridor from the east...with even a couple of
thunderstorms ongoing just east of the CWA. Coverage and intensity
of convection should slowly increase throughout the day, as the
atmosphere destabilizes to the tune of ~1500 J/kg of sbCAPE across
the eastern half of the area by late afternoon. Additional shower
activity and perhaps a thunderstorm or two should also initiate over
the high terrain during mid/late afternoon. While much of the area
will see 20-40 PoPs, locations east of I-77 should see sufficient
afternoon coverage to warrant likely probabilities. Only the upper
Savannah River Valley/western Upstate are expected to be largely
void of convection today. Instability is expected to be a bit too
meager to support a severe storm threat, but locally heavy/perhaps
excessive rainfall will be possible across eastern areas in the very
moist conditions. Max temps will range from a little below normal
across the I-77 corridor and vicinity, to a little above normal west
of I-26. Convective chances dwindle this evening to little more than
token slight chances across the east after midnight. Min temps are
expected to be a couple of degrees above climo.

&&

.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
As of 155 AM Friday: Continuing the summertime pattern with more
heat and less rain. Synoptically, The majority of the CONUS remains
under high pressure, including the southeast. The Bermuda high off
the east coast churns and amplifies into Sunday as does the
persistent anti-cyclone over the southwest. Essentially, the CWA is
caught in the middle of two dominating areas of high pressure,
keeping the area relatively dry and hot. Saturday, a swath of 2 inch
plus PWATS remains centered just to the east of the CWA. Guidance
from the GFS signals around 1.5 inch PWATS on the eastern fringe,
upticking the moisture and heat index in this area. QPF response,
however, is dry. Modeled soundings indicate a strong mid-level
inversion and dry layer, hindering any notable rainfall. Even if
something could form, the boundary layer is also relatively dry
given the stout inverted-V shape. Sunday is a similar story, but
with less of a mid-level inversion present. This is driven by higher
moisture content east of the mountains due to the SW surface flow.
Modeled soundings also indicate better mid-level CAPE and a return,
but again, rain chances are minimal as QPF response is non-existent.
As for any heat index concerns, moisture return is slow and helps to
keep values around the low 100s for a few areas south of I-85 and
east of the I-77 corridor. Overall, hot and dry for the short term.

&&

.LONG TERM /MONDAY THROUGH THURSDAY/...
As of 200 AM Friday: The extended term starts off similar to how the
short term ended, with a pattern change possible by mid week. Monday
and Tuesday, high pressure continues to dominate the lower CONUS and
keeps the area dry for the most part. Long term guidance shows
little to no QPF response Monday and a small signal over the
mountains on Tuesday afternoon. Again, both days have similar
modeled soundings with abundant mid-level dry air and an inverted-V
in the boundary layer. Confidence for any rain during the beginning
of the week is very low. However, a pattern swing by mid-week could
be in the works. Long range guidance from the GFS/EURO signal a
developing upper low and trough across Canada, north of the Great
LAkes. This amplification could lead to height falls across the
eastern portion of the CONUS, and spilling into the CWA starting
Wednesday. At the surface, amplifying high pressure off the east
coast should setup a persistent SW flow and moisture advection into
the area. This could start the unsettled pattern with an increase in
PoPs, especially over the mountains, through the end of the period.
At this time, Thursday and Friday could be the wetter days, but will
likely change as the forecast nears. As for temperatures, Tuesday
looks to be the hottest day with actual temps reaching triple digits
across most of the CWA east of the mountains. Heat index could be a
concern, but with dewpoints mixing out during the day, confidence on
high heat indices over 105 is low at this time. After Tuesday, temps
look to decrease given the height falls aloft, which should provide
some heat relief to much of the area.

&&

.AVIATION /12Z FRIDAY THROUGH TUESDAY/...
At KCLT and elsewhere: VFR conditions are forecast at most sites
through at least this evening. The only exception will be at KCLT,
as sub-tropical moisture will continue to surge into the area
through the morning in association with a developing disturbance
near the coast. In fact, a few showers are already encroaching on
the KCLT area this morning, and there are a few TS just east of the
Terminal Forecast Area. While cigs are expected to lower to the
lower end of VFR, periods of MVFR are possible throughout the day.
Shower and thunderstorm chances will also increase in the KCLT area
from late morning through the afternoon, and a tempo for TSRA, along
with MVFR conditions have been introduced there from 15-19Z. Shower
and storm chances drop off sharply west of KCLT...a Prob30 for
-TSRA is carried at KHKY during the afternoon, but coverage near
KAVL and the upstate SC terminals is expected to be more isolated.
Stratus is possible, if not likely across mainly the NC portion of
the area late tonight/Sat morning...with IFR cigs possible. For now,
overnight restrictions are limited to the low end of MVFR, with SCT
IFR layers. Winds will generally favor light NE through the period.

Outlook: Convection and possible restrictions will linger into early
Saturday in eastern areas. Isolated/widely scattered diurnal showers
and thunderstorms are expected Sat through at least the first half
of next week...mainly over the mtns.

&&

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

&&

$$

SYNOPSIS...CP
NEAR TERM...JDL
SHORT TERM...CP
LONG TERM...CP
AVIATION...JDL