207
FXUS62 KGSP 041840
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
240 PM EDT Tue Jun 4 2024

.SYNOPSIS...
Scattered showers and thunderstorms are on tap with afternoon
storms persisting into Thursday. Dry air will mix in Friday and
persist into the weekend with a small chance of mainly
mountain thunderstorms returning for Sunday afternoon.

&&

.NEAR TERM /THROUGH WEDNESDAY/...
As of 202 PM EDT Tuesday: GSP finds itself beneath a weak upper
ridge this afternoon, with convection just firing up across the
area.  The synoptic setup will remain largely unchanged through
the duration of the near term, with the Carolinas ensconced
in a strengthening warm advective regime.  Heights will fall
ever-so-gently aloft in response to a deepening upper low over
Manitoba and peripheral shortwave trough sliding up the central
Ohio Valley.  As the localized ridge axis drifts east of the area,
high pressure over the west Atlantic will intensify and drive ever
more moisture into the forecast area.

All the action today will come from mesoscale elements.
This afternoon, basically all the CAMs depict some flavor of
1200-1600 J/kg sbCAPE across the region, in advance of a remnant MCV
drifting out of TN.  So that will manifest as continuing scattered
convection, triggering especially over the NC mountains, during
the early/mid afternoon, followed by the arrival of a somewhat more
organized line picking up out of Georgia in the late afternoon and
evening hours.  Generally speaking, lapse rates will be poor and
deep layer shear minimal, but where there`s organization associated
with the MCV, a some strong storms - perhaps even a severe -
can`t be ruled out.  Isolated heavy rain will also be a concern,
with RAP profiles indicating 1.6-1.9" PWs...but flow aloft will
be strong enough to keep storms moving, so only in locations where
multiple cells train will there be problems.

Tonight, another round of fog is expected, for the mountain valleys
and for any locations that receive appreciable rainfall this
afternoon and evening.  Some light sprinkles may linger well into
the overnight, but should become less in coverage and intensity
as the night progresses.  Kind of like this morning, a few early
morning showers can be expected over the Upstate and southern
NC mountains Wednesday, but impacts are expected to be minimal.
The bulk of CAMs then depict another round of scattered showers
and thunderstorms tomorrow afternoon, in an environment of better
instability and synoptic support than today`s, but similarly
paltry shear.  Severe risk looks overall a little higher on
Wednesday compared to today, owing to the stronger forcing and
better instability.

&&

.SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY/...
As of 2:25 PM Tuesday...the short-term fcst picks up at 00z on
Thursday with a fairly robust upper shortwave approaching the
Western Carolinas from the west. Over the next 24 to 48 hours,
the shortwave will move thru our area and then offshore as broader
upper level trofing morphs into a large, closed h5 low centered
over the Great Lakes. At the sfc, another moist cold front will
be moving into our fcst area from the west as the period begins.
The front will move thru early Thursday and is expected to be
moving off the coast by late Thursday. It will likely produce
sct to numerous showers and thunderstorms on Thursday across
our CWA, however most of the model guidance continues to depict
weak low to mid-level lapse rates. Thus, the severe potential
appears to minimal at best. In its wake, broad but fairly weak
high pressure will gradually spread over our area on Friday and
linger into the weekend keeping us dry for the latter half of the
period.

&&

.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
As of 2:15 PM Tuesday...the extended forecast picks up at 00z on
Saturday with a broad upper trof having morphed into an h5 low
centered over the eastern Great Lakes. Over the next few days,
the upper low will get reinforced from the NW with additional
upper level energy and become larger. By early next week, the
low begins to open back up to the mean flow as the western peri-
phery of the low dives southward. This will allow the upper low/
trof axis to translate over our area by the end of the period
next Tuesday. At the sfc, broad but fairly weak high pressure
will be spreading over the Southeast as the period begins late
Friday. The is expected to be transitory and weaken/move off the
Atlantic Coast on Saturday. On Sunday, low pressure well to our
north will move a weak/moist cold front to our doorstep from the
NW. This boundary is expected to linger over our area into early
next week. As it does, most of the long-range guidance has multiple
weak lows trying to spin up over our area along what`s left of the
boundary. As for the sensible wx, I expect mostly dry conditions
for Saturday with a return to more diurnally-driven climo PoPs
for the rest of the period.

&&

.AVIATION /19Z TUESDAY THROUGH SUNDAY/...
At KCLT and elsewhere: A complex aviation forecast sets up for this
afternoon and tonight as multiple rounds of convection hit the area.
Already, scattered cells are popping up over the NC mountains
near KAVL and surrounding sites.  Most hi-res guidance agrees
that scattered to numerous shower and thunderstorm coverage will
expand across the entire terminal forecast area.  Some guidance
suggests a well-defined line will lift up out of Georgia late
this evening...such that at least for the Upstate terminals,
convection will last well past sundown.  Overnight, areas which
received ample rainfall can expect MVFR to IFR vis restrictions...as
well as widespread IFR ceilings.  More recent runs of the HRRR now
support some additional predawn showers, mainly across the Upstate
terminals and KAVL.  Diurnal convection is expected once again on
Wednesday, possibly a little delayed compared to today.

Outlook: Coverage of diurnal convection is expected to
increase Wednesday evening as a frontal boundary moves into the
region. Morning low clouds and fog will also be possible Thursday
morning. Drier air will filter into the area Thursday afternoon and
Friday morning, reducing chances for convection and restrictions,
with relatively dry conditions continuing into the weekend.

&&

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

&&

$$

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