112
FXUS62 KGSP 120237
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
1037 PM EDT Thu Jul 11 2024

.SYNOPSIS...
A weak tropical low will move inland over the eastern Carolinas on
Friday then further north over the weekend.  This will enhance
rainfall for areas along and east of Interstate 77 mainly Friday and
Friday night.  Above normal temperatures and daily isolated to
scattered afternoon and evening showers and storms are expected
from Sunday through the middle of next week.

&&

.NEAR TERM /THROUGH FRIDAY NIGHT/...
As of 10:15 PM EDT Thursday: A coastal baroclinic zone continues
to slide westward late this evening as a sfc wave slides north
along it. More dense cirrus already creeping in from the east
will steadily thicken overnight. The increasing cloud cover will
help keep temperatures warmer than last night, with lows expected
to bottom-out slightly above climatology outside the mtns and
slightly below climo over the mtns. Winds have gone light to
calm at most sites and should remain that way into the morning.

Otherwise, we will remain sandwiched between broad upper ridging
to our east and to our west, while lower amplitude upper trofing
lingers to our north over the Great Lakes. At the sfc, weak and
poorly organized low pressure will linger over the SE Coast thru
the day on Friday. It will eventually get absorbed in the broader
SLY low-lvl flow courtesy of the much larger Bermuda High as the
period ends early Saturday. This will result in deeper moisture
spreading further westward and into our eastern zones overnight
and Fri morning. Profiles should be moist enough that lower and
thicker clouds develop over the I-77 corridor along with increasing
rainfall chances by late morning. The latest CAM guidance continues
to depict isolated to sct convection over the I-77 corridor during
the afternoon hrs, however the better coverage and the more robust
cells appear to remain just to our east and over RAH`s fcst area.
Nonetheless, most of the latest model profiles still produce about
500 to 1000 J/kg of sfc-based CAPE over roughly the eastern third
of our CWA for Friday aftn/evening. This CAPE does appear to be
fairly "tall and skinny" which makes strong to severe thunderstorms
less likely. As such, the svr potential still looks minimal across
our CWA thru the period. With PWs of 2+" or higher over our eastern
zones on Friday, the bigger potential threat may be locally heavy
rainfall. Having said that, WPC`s Day 2 Slight Risk for excessive
rainfall remains to our east.

&&

.SHORT TERM /SATURDAY THROUGH SUNDAY/...
As of 211 PM Thursday...The short term forecast period starts off
tomorrow night with a sharp upper shortwave trough over the eastern
Great Lakes and stout upper ridging over the Atlantic. A weak
surface low is also progged to have moved inland over southeast
Georgia with a subtle inverted trough extending across the Coastal
Plain. Persistent onshore flow will have pushed the previously
stalled frontal boundary west back into the I-77 corridor. Afternoon
showers and thunderstorms on the moist side of the boundary may
linger into the early evening hours, but will dissipate shortly
after sunset with loss of daytime heating. Heading into Saturday,
the surface pattern becomes more nebulous as the upper trough axis
passes by to the north. This will in turn allow low-level flow to
shift to out of the west/northwest with the boundary sliding back
east again. This will shunt the deeper moisture plume back east as
well with PWATs falling to around 1.5" or less. A lack of deep
moisture will greatly preclude coverage of diurnal convection
through the weekend with any cumulus/weak updrafts struggling to
deepen in the face of substantial dry air entrainment. A couple
isolated showers and storms cannot be discounted, but this will be
the exception and not the rule. Temperatures will continue to warm
through the period with highs climbing into the mid to upper 90s.
Deep mixing within the drier airmass will mix out dewpoints, thus
while several readings with heat indices in the low 100s are
possible, heat advisory criteria (105 degrees) isn`t expected to be
reached through the weekend.

&&

.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
As of 237 PM Thursday...Unfortunately, next week doesn`t start off
with any good news. A perturbed belt of westerlies will extend from
the Great Lakes into New England. The Southern Appalachians will be
situated south of the base of broad troughing with upper ridging
building into the region from the Southern Plains. Heights will rise
through the beginning of the week with warming low-level
temperatures. Low to upper 90s will be common on Monday with a
couple readings touching the century mark. Tuesday appears to be the
hottest day of the period with widespread mid to upper 90s and
numerous low 100s possible. The good news, however, is that
dewpoints should mix out into the low to upper 60s each afternoon
which will keep heat indices in check. Low 100s to near 105 will
still be possible though and heat advisories may ultimately be
needed. Subsidence and a lack of moisture will limit diurnal
convection with below average PoPs and only isolated coverage
expected.

A pattern change will be on the horizon by mid week as a potent
longwave trough becomes established from the Hudson Bay into the
Ohio Valley. An attendant surface cold front will be dropping across
the Midwest on Wednesday and encroaching on the Appalachians by late
week. Ridging will also slide to the east which will allow for
return flow off the Gulf and Atlantic to advect rich moisture back
into the region. The net result will be a noticeable uptick in PoPs
Wednesday through Friday, especially as the front stalls just west
of the area. One more day of heat and humidity may continue into
Wednesday, but will be conditional on timing and coverage of showers
and thunderstorms. Should this wetter pattern change hold, most of
the area should hopefully see some much needed rainfall mid to late
next week.

&&

.AVIATION /03Z FRIDAY THROUGH TUESDAY/...
At KCLT and elsewhere: Expect VFR conditions to continue at all
taf sites thru the 00z period. The only exceptions will be at
KCLT where there is a decent chance that MVFR cigs will spread
over the terminal late tomorrow (Friday) morning. Expect the
lower cigs to lift to low-end VFR by the early afternoon. In
addition, a weak coastal low will spread showers and thunder-
storms westward tomorrow with KCLT the most likely to see pre-
cip from this system. For the time being, I have a combination
of VCSH and a PROB30 for TSRA for KCLT and KHKY. The other ter-
minals are less likely to see showers and/or thunderstorms so
I just have VCSH and VCTS for them. Otherwise, thickening cirrus
will persist over the area well into the overnight hrs as winds
become light and most sites. Outside the mtns, winds will remain
N to NELY thru tomorrow aftn and veer to more ELY by tomorrow
evening. At KAVL, winds will go light and vrb later tonight and
remain light thru the rest of the period, generally favoring an
ELY to NELY direction thru the day tomorrow.

Outlook: Rain and possible restrictions will linger into early
Saturday. Sct diurnal showers and thunderstorms will be possible
over the weekend and into the first part of next week.

&&

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

&&

$$

SYNOPSIS...DEO
NEAR TERM...JPT
SHORT TERM...TW
LONG TERM...TW
AVIATION...JPT