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903
FXUS62 KGSP 081937
AFDGSP

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

.SYNOPSIS...
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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.
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.NEAR TERM /THROUGH THURSDAY/...
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As of 245 PM EDT Wednesday: Very very busy forecast this afternoon
with ongoing convection and active warnings moving across the area
at forecast time, late AFD as a result. Upper ridge being pushed off
the Southeast Coast by strong low over the Central Plains with
shortwave pushing a front into the area. So for this afternoon,
we`re dealing with SBCAPEs of 2500J/kg+ across the Piedmont with
deep layer shear of 40+ kt, steep lapse rates. Plenty of upper
dynamic forcing with steep lapse rates and vort lobe embedded in the
upper flow. Ongoing convection with wind and hail threat across the
area. CAMs indicating we should see a lull for a period of time
later this evening, but then secondary round of convection
developing across the TN valley this evening will move across the
mountains late and CAMs have it 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.

Concern with main hazards remain large hail and damaging wind gusts,
as we have already seen baseball reports. Cannot rule out an
isolated tornado, but the limiting factor will be 0-1 km shear which
forecast soundings generally show <20 kts. SPC upgraded us to
Enhanced Risk (level 3 out of 5) which is climatologically
significant, but this is mainly for the wind threat.

Very warm highs today in the upper 80s (contributing to
instability), 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.
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.SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY/...
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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.
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.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 /20Z WEDNESDAY THROUGH MONDAY/...
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At KCLT and elsewhere: Convection across the area will impact TAFs
through the period. Have handled this with a period of VCTS, TEMPO,
and PROB30. Afternoon convection may periodically wane but then
expect overnight MCS to develop. Confidence on exact timing of TSRA
not particularly high, but high on occurrence. VFR cigs will drop to
MVFR but cannot rule out brief IFR as well as patchy fog. Gusty
conditions expected with any thunderstorms that develop. Winds
generally SW through the period.

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.
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&&

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

&&

$$

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