834
FXUS62 KGSP 031353
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
953 AM EDT Wed Jul 3 2024

.SYNOPSIS...
Hot and humid conditions will become established once again for the
second half of the week.  Afternoon showers and thunderstorms will
be possible each afternoon starting Thursday, especially over the
mountains.  A cold front may enhance thunder chances on Saturday.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 935 AM: Temps appear on track for today but based on obs
so far this morning, dewpoints may have been a hair too low,
so adjusted them upward through early aftn when mixing is still
expected to have some effect. Touched up sky cover also, to reflect
latest extent of low clouds scattered across the Piedmont. Cloud
streets are forming which suggests cloud cover will last longer
than originally expected, but still think skies will trend clearer
with the aforementioned mixing.

The upper pattern should slowly evolve over the next 24 hours,
with the axis of a mid/upper ridge over the Appalachians to start
the day getting tilted over positively and pushed to the East Coast
by a nrn stream short wave that trails off across the OH Valley
region. Altho the sfc high centered over New England this morning
gets steadily pushed offshore as a result, it should still be able
to ridge back and control our weather thru tonight. The movement
of the sfc high should allow for some moisture to trickle back
in from the Atlantic this afternoon, thus beginning our return
to more typical humidity. Won`t rule out a few ridgetop showers
during peak heating if the moisture makes it far enough west. High
temps will creep back up above normal this afternoon and mild low
temps can be expected as well.

&&

.SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
As of 218 AM EDT Wednesday: The western Carolinas should be
ensconced in a SW flow regime by Thursday, although at the
low-levels the positioning of an axis of high pressure over the
western Atlantic will result in trajectories mostly off the Atlantic
coast, not the Gulf of Mexico as is typical of SW flow patterns.
That might serve to hold our dewpoints in the lower 70s, although
with afternoon temps in the mid 90s in the upper 90s to low 100s
outside the mountains.  Some afternoon showers and thunderstorms
will be possible, with 1000-1500 J/kg sbCAPE expected across
the area...but still think triggering will only occur over the
NC mountains.

On Friday, temps will get even higher, and much of the area will
see afternoon heat index values above 100 degrees.  In keeping
with the past few forecasts...trended toward raw model output for
dewpoints...which keeps most of the forecast area clear of any heat
advisory criteria for Friday afternoon.  Will monitor going forward.
Once again, diurnally-driven showers and thunderstorms will be
likely on Friday, and with the approach of a frontal boundary
from the Ohio Valley and better instability (1500+ J/kg virtually
everywhere) it`s possible we could see some cells pop up outside
the mountains.

&&

.LONG TERM /SATURDAY THROUGH TUESDAY/...
As of 227 AM EDT Wednesday: Long-range guidance has doubled down
on the idea of a cold front arriving Saturday, and now points to
a somewhat faster and more aggressive push into the forecast area.
This`ll enhance coverage of showers and thunderstorms on Saturday,
amid what should be a very moist and unstable environment.

There`s less agreement on how the second half of the weekend will
evolve...with some ensemble solutions pushing the deteriorating
front all the way through the area, and others allowing it to
stall and even surge back north as a sfc wave works its way up
from the Deep South.  Seems likely that some kind of unsettled
weather will be possible through the end of the forecast period,
as even the drier solutions have a return to S/SE flow driven by
the Bermuda high by the start of the new workweek...meaning hot,
humid weather and diurnal showers and thunderstorms.

&&

.AVIATION /14Z WEDNESDAY THROUGH SUNDAY/...
At KCLT and elsewhere: The patchy stratus/stratocu which developed
around daybreak have thinned, although in the same areas low cumulus
are forming, which will prolong the duration of SCT-BKN clouds
below 030 perhaps until 15-16z. Outside of northeast GA these clouds
should then mix out or scatter and lift to VFR level. Thereafter,
confidence still highest for VFR at all sites, with only sct low
clouds. Wind will be light SE to S and SW through the daytime. Any
remaining low clouds should dissipate with sunset. Wind will
probably go light/variable again.

Outlook: A return of more typical mid-summer humidity and diurnal
convection returns Thursday into the weekend leading to possible
restrictions each afternoon/early evening. Fog and/or low stratus
may develop each morning, especially for areas that received rain
the previous day.

&&

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

&&

$$

SYNOPSIS...MPR
NEAR TERM...PM/Wimberley
SHORT TERM...MPR
LONG TERM...MPR
AVIATION...PM/Wimberley