351
FXUS62 KGSP 130551
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
151 AM EDT Sat Jul 13 2024

.SYNOPSIS...
Drier conditions return this weekend, lingering into early next week
as high pressure builds across the area. This will allow hot weather
to return with afternoon highs climbing into the upper 90s and lower
100s east of the mountains. A pattern change is expected mid-week
into next weekend as a cold front stalls across the area and brings
above normal rain chances and cooler weather.

&&

.NEAR TERM /THROUGH TODAY/...
As of 145 am Saturday: A surface wave will continue lifting
northeast along a surface boundary stretched across the Coastal
Plain of the Carolinas, as the attendant mid/upper-level low becomes
absorbed within the general area of upper troughiness over the East.
A summertime regime will be in store for our area today as weak high
pressure sets up over the CWA, while the Bermuda High re-establishes
its position over the western Atlantic, and slowly turns surface
winds back out of the south-southwest by the end of the forecast
period. With 594-596 dm thicknesses in place, and dewpoints ranging
from the upper 60s to lower 70s, expect a few locations south and
east of I-85 to see heat indices climb into the low 100s this
afternoon. Highs should end up around 3-5 degrees above climo. CAMs
are not in good agreement regarding the overall coverage of showers
and thunderstorms this afternoon/early evening. Both the HRRR and
NAMNest show convection first developing over the mountains by
Saturday afternoon before pushing east the rest of the day. However,
the NAMNest depicts a broken line of isolated convection while the
HRRR depict widely scattered convection. Thus, PoPs are limited to
20-30% across much of the area for now.

&&

.SHORT TERM /TONIGHT THROUGH MONDAY/...
As of 224 PM Friday: Broad upper troughing will be draped from the
Northern Plains across the Great Lakes and into New England. Farther
west, a stout 600dam upper ridge will be parked over the Four
Corners region with broad ridging extending across the Southern
Plains and into the Lower Mississippi Valley. Ridging is forecast to
build east through the later half of the weekend and into the start
of the new week with heights rising across the Southern Appalachians
along with an uptick in low-level temperatures. This will support
rather hot temperatures with afternoon highs climbing into the low
to upper 90s on Sunday and mid 90s to low 100s on Monday. Any good
news, though, is that the frontal boundary that has been waffling
across the I-77 corridor is forecast to shift back east as flow
shifts to out of the west/northwest. This will shunt higher
dewpoints and richer moisture into the Coastal Plain with dewpoints
able to mix out more efficiently each afternoon. This will in turn
help keep heat indices in check with low 100s along and south of I-
85 on Sunday. While dewpoints will remain relatively low on Monday,
temperatures in the upper 90s to low 100s will be hot enough that
even lower end dewpoints could end up supporting heat indices near
advisory criteria (105 degrees) and a heat advisory may ultimately
be needed. Subsidence from the upper ridge and a lack of deeper
moisture will preclude diurnal convection across much of the area,
but an isolated shower and/or thunderstorm cannot be completely
ruled out across the mountains.

&&

.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
As of 232 PM Friday: The blowtorch will continue as we head into mid
week, especially on Tuesday, as the 850mb temperatures peak near 24
C. This will support at least one more day of hot weather with
afternoon highs once again peaking in the mid 90s to low 100s. A
potent upper trough is also progged to swing across the Northern
Plains and into the Great Lakes on Tuesday with an attendant surface
cold front dropping across the Midwest. Surface high pressure will
have also shifted offshore with low-level flow backing to out of the
south. This will allow for gradual moisture return into the area off
the Gulf of Mexico and eventually the Atlantic Ocean. PoPs slowly
return on Tuesday, but most of this activity may remain just south
of the area within the initial moisture return across the Deep South
into Georgia. A noticeable pattern change is still on tap for
Wednesday into next weekend as the upstream frontal boundary
approaches and then eventually stalls across the area as the upper
trough lifts across the Ohio Valley into New England. Lingering low-
level warmth may result in one last day of heat concerns on
Wednesday, but this will be conditional with PoPs quickly ramping
back up within the leading edge of moisture return. A more robust
afternoon cumulus field and an early start to diurnal pulse
convection may limit heating and preclude the need for heat
products, but this will have to be assessed closer to the day. By
Thursday into next weekend, guidance continues to depict the frontal
boundary stalling either across or near the forecast area as the
front becomes oriented parallel to upper westerlies with the parent
trough lifting out of New England. This will result in above average
PoPs each day in the likely to categorical range, which will
hopefully bring much needed rainfall and cooler temperatures to the
area.

&&

.AVIATION /06Z SATURDAY THROUGH WEDNESDAY/...
***AMD NOT SKED has been added to the KHKY TAF for this cycle due to
the ongoing ASOS comms outage and the potential for restrictions
this morning.***

At KCLT and elsewhere: The main concern for this period will be the
potential for visby and/or cig restrictions this morning at the NC
terminals. IFR/LIFR cigs are amassing just east of the Terminal
Forecast Area early this morning...and these look to ooze SW/ expand
into KCLT and perhaps KHKY prior to daybreak. Categorical IFR
conditions are forecast at KCLT, with a tempo for such at KHKY...and
can`[t rule out a period of LIFR. Visby restrictions are possible as
well, but low cigs appear more likely. Meanwhile, a wet ground
resulting from late evening heavy rain at KAVL will combine with
decreasing cloud cover to yield a strong chance for restrictions in
BR and LIFR stratocu there. Otherwise, VFR conditions are expected
to persist at the upstate SC terminals. Deep convection is expected
to develop this afternoon...esp across the mountains, but overall
coverage is expected to be rather spotty, and no mention appears
warranted in the TAFs at this time. General light NE winds...
becoming light & variable/calm or light NW later this morning. Winds
may return to the SW at the upstate SC terminals during the
afternoon...remaining light.

Outlook: Isolated/widely scattered diurnal showers and storms are
expected mainly over the mountains early next week. Shower and
thunderstorm are expected to increase during the latter half of the
week as a cold front pushes into the region. Morning fog/low stratus
will be possible each morning, especially across the mountain
valleys and for areas that received heavy rainfall the day prior.

&&

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

&&

$$

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