657
FXUS62 KGSP 090001
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
801 PM EDT Wed May 8 2024

.SYNOPSIS...
Showers and thunderstorm activity will be more numerous ahead of a
strong cold front tonight into Thursday, with severe storms
possible. The cold front pushes east early Friday morning but
another system approaching out of the south may bring shower and
thunderstorm chances back during the day on Friday. Drier conditions
and below normal temperatures return for the weekend.

&&

.NEAR TERM /THROUGH THURSDAY/...
As of 754 PM EDT Wednesday: With the first wave of strong to
severe storms east of the forecast area, our evening lull, that
most of the CAMs were suggesting, has taken hold. We will now turn
our attention to the west to see how the convection evolves over
middle to eastern TN. Of note across the western Carolinas is how
the afternoon convection has laid out an outflow boundary that runs
from roughly Andrews/Murphy NC down to Anderson and Greenwood. To
the north/east of the boundary, the atmosphere has become capped
and has lost most of its sfc-based instability. Unless there can be
some recovery of the air mass across that large part of the fcst
area, it will be difficult to get anything other than elevated
storms. Note this will still pose a threat for severe hail, but
would limit the potential for wind gusts and tornadoes, UNLESS we
can get storms rooted in the boundary layer once again. We will
be minding the evolution of the boundary layer over the next
few hours. Meanwhile, along and S and W of the aforementioned
boundary, all hazards remain in play. It is entirely possible that
later tonight some kind of organized deep convection will clip our
southwest NC/northeast GA/western SC zones, so stay tuned for that
possibility and maybe another watch for part of the region. So for
this update, we make some big changes to evening temps because of
rain-cooled air, and also some changes to sky condition and lower
precip probs. The precip probs ramp back up later this evening in
anticipation of storms coming in from the west over the mtns.

Some of the CAMs have convection marching across the mountains
and across the Piedmont overnight. Some guidance even indicating
multiple rounds of convection overnight. Hard to tell if the MCS
(or multiple MCSs) will be able to hold together and cross the
mountains. SPC has kept us in the Enhanced Risk (level 3 out of 5)
which is climatologically significant, but this is mainly for the
wind threat.

Otherwise...not quite as warm tomorrow but still mid 80s in the
Piedmont. Slight Risk in place on Thursday but that`s as the
convection slips south in the morning.

&&

.SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY/...
As of 100 PM EDT Wednesday: For the Thursday night period, the 12z
HREF and CAM consensus depicts just very limited and isolated deep
convection lingering from whatever daytime activity redevelops,
along with a smattering, but again limited response into the night
and mainly confined to the mountains.  Not unexpectedly, the pattern
atop the SE CONUS remains dynamic into Friday as energy rounding the
base of the upper trough will finally be again to shove lingering
sfc frontal zone downstream of the cwfa.  But before it does, we
will be wary for the threat for tstm encroachment and redevelopment,
along the front itself, and in addition, MCS/bowing cluster moving
in from Georgia.  Sensible weather will feature a shotgun mid-chance
pop for Friday with isolated svr storms possible mainly SE of I-85.
Will plan on overspreading the region with deep layered dry air
within the broad downward vertical motion behind the departing s/wv
axis Friday night.  Expecting to be under a well mixed and more
seasonable airmass within the deep cyclonic flow on Saturday
featuring maximum temperatures close to climo.

&&

.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
As of 315 am EDT Wednesday: A broad upper trough is expected to
progress across the East through the weekend, with dry air/pleasant
surface dewpoints supporting wide diurnal temp ranges...max temps
averaging around normal and min temps a category or so below climo.
By early in the work week, a split flow regime is expected to be in
place across the eastern Conus, with a short wave ridge developing
across the Southeast...downstream of a southern Great Plains upper
low. Global models are at odds regarding the evolution of this
feature, namely its interaction with the northern stream, and
eventual impacts on sensible weather across the Southeast. For now,
there`s enough of a signal to include chance PoPs across much of the
CWA by Mon night/Tue. Temperatures are forecast to be very close to
normal through the period.

&&

.AVIATION /00Z THURSDAY THROUGH MONDAY/...
At KCLT and elsewhere: VFR for the time being at all terminals, and
that should hold into the late evening, hopefully through the end of
busy operations. Most of the forecast area has rain-cooled air with
some sct-bkn low VFR debris clouds. We may see some brief MVFR at
KAND, but this is not likely and left out of the fcst. Wind will be
generally light and modulated by numerous outflow boundaries across
the region, so many places will have a variable direction for the
evening, until a southerly flow can be re-established. We look to
the west and await the next round of storms, which the HRRR brings
into the mtns at 04Z and then quickly east through the pre-dawn
hours. All terminals should see thunderstorms with this complex,
so a 4-hr TEMPO was employed for the initial round. There could be
a second round, or at least a trailing stratiform rain for several
hours into the middle part of the morning. There should be some
MVFR cloudiness lingering into the middle part of the day. Once we
scatter the low deck, expect deep enough mixing for some occasional
wind gusts from the SW thru the rest of the afternoon.

Outlook: A system lifting out of the south my increase shower
and thunderstorm chances again on Friday, but confidence on this
remains low. Drier conditions can be expected this weekend.

&&

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

&&

$$

SYNOPSIS...CSH
NEAR TERM...PM/TDP
SHORT TERM...CSH
LONG TERM...CSH
AVIATION...PM