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007
FXUS62 KGSP 161808
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
208 PM EDT Thu May 16 2024

.SYNOPSIS...
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Brief high pressure moves off the coast tonight as another low
pressure approaches from the west.  Showers and scattered
thunderstorms return Friday and continue into the weekend. Isolated
afternoon and evening showers and thunderstorms are expected early
next week.
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&&

.NEAR TERM /THROUGH FRIDAY/...
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As of 200 pm EDT Thursday: Visible satellite imagery indicates
widespread cumulus...some of it quite agitated across the forecast
area this afternoon. Further vertical development will continue to
be limited by rather weak CAPE (sbCAPE < 1000 J/kg) and a capping
stable layer in the 5-10kft layer. Nevertheless, some CAMs still
allow some spotty showers to develop later this afternoon, so can`t
rule out a couple of the cumulus developing into a shallow SHRA or
sprinkles-producer.

Otherwise, heights will fall across the region tonight as a short
wave ridge progresses east of the area late tonight and a
low-amplitude short wave trough approaches from the southwest late
Friday morning. Moisture and lift will increase across the CWA by
afternoon, increasing shower chances, with precip chances becoming
likely across western areas by 00Z Saturday. Mid/high level cloud
cover overspreading the area during the morning will limit the
destabilization potential tomorrow afternoon, while mid-level lapse
rates are expected to be very poor. As such, sbCAPE is expected to
generally be limited to the 500-1000 J/kg range. Thus, while shear
parameters (esp deep layer shear) will be improving throughout the
day, the expected shear/buoyancy combination should preclude a
notable severe storm threat. Indeed, SPC has removed our CWA from
the Day 2 Marginal Risk. With precipitable waters expected to surge
above 1.5", There may be a slightly higher potential for locally
excessive rainfall, but again...limited instability and modest
forcing should act to tame rainfall rates. Min temps tonight will
again above normal, while maxes Friday should be right around
climo.
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&&

.SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY/...
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As of 1245 PM EDT Thursday: Short Term Key Messages

1) Widespread Showers and thunderstorms are expected off and on
throughout the weekend.

2) Areas of heavy rainfall may lead to isolated flooding issues
this weekend.

3) Isolated strong to severe storms are possible through the weekend
but confidence remains low at this time.

Showers and thunderstorms will be ongoing across the western
Carolinas and northeast Georgia Friday evening into Friday night as
a low pressure system approaches out of the west. There may be a
lull in activity the first half of Saturday before another round of
showers and thunderstorms returns Saturday afternoon into Saturday
night as the low pressure system tracks into the forecast area. Have
likely to categorical PoPs (70% to 80%) in place during this
timeframe as global models and high-res models agree that there will
be multiple rounds of convection. All global models continue to
agree that the low will stall over the area on Sunday, thus
monotoned likely PoPs (60 to 70%) across the forecast area. With
PWATs expected to climb near or above 90th percentile, locally heavy
rainfall will be a concern, especially with wet antecedent
conditions already in place. The WPC Day 3 Excessive Rainfall
Outlook has a Marginal risk across the Carolinas as isolated flash
flooding will be possible, especially for areas that saw heavy
rainfall the day prior. The flooding threat will steadily increase
throughout the weekend as rainfall totals pile up. Currently 0.50-
1.50 inches of rain is expected to fall Friday night through Sunday,
with the highest amounts expected to fall across the western and
southern zones. Isolated strong to severe storms continue to look
possible thoughout the weekend but confidence on this is low as
thick cloud cover may limit destabilization. GEFS plumes show less
than 1,000 J/kg of SBCAPE through the weekend, with ~35-45 kts of
deep shear on Saturday and only ~15-20 kts of deep shear on Sunday.
Thus, Saturday still looks to have the better severe potential, and
this matches up with the Day 3 SPC Severe Weather Outlook which has
a Marginal risk in place east of the mountains. The main potential
hazards with any severe storms that develop are damaging wind gusts
and large hail. High temperatures have trended down slightly for the
weekend and are now expected to be a few to several degrees below
climo. Low temperatures will remain several degrees above climo
thanks to both cloud cover and precip.
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&&

.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
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As of 100 PM EDT Thursday: The low pressure system will linger over
the eastern Carolinas through Monday before gradually pushing
offshore Monday evening into Monday night. Thus, maintained chance
PoPs (15% to 30%) across much of the forecast area Sunday night into
Monday. Upper ridging and sfc high pressure will build into the
southeast Monday night into Tuesday night, leading to drier
conditions, while the low pressure system lingers just off the
Southeast Coast. A cold front will approach out of the west on
Wednesday before tracking across the forecast area Wednesday night
into early Thursday morning. This will allow shower and thunderstorm
chances to return towards the end of the forecast period. High
temperatures will remain a few to several degrees below climo on
Monday, becoming near climo to a few degrees above climo on Tuesday.
Highs are then expected to become a few to several degrees above
climo Wednesday into Thursday. Low temperatures will generally
remain a few to several degrees above climo through the period, with
the exception Monday night as lows east of the mtns will be near or
just below climo.
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&&

.AVIATION /18Z THURSDAY THROUGH TUESDAY/...
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At KCLT and elsewhere: SCT-to-occasionally BKN VFR cumulus will
continue across the area this afternoon. A couple of these could
produce sprinkles or brief -RA, but chances are very low at any TAF
site. Otherwise, mid/high level clouds will begin increasing from
the west tonight. The latest guidance is backing off of the
potential for late night/early Friday restrictions across the area,
but still can`t rule out a brief restriction at KAVL...or at KCLT,
where the mid/high clouds won`t arrive until around sunrise. Even
so, restrictions are hardly a slam dunk, and have limited any
restrictions to MVFR at this point. Otherwise, winds will generally
favor light N or NW, becoming light/variable tonight, before
becoming southerly at around 5 kts late in the period.

Outlook: Showers and a few thunderstorms and associated restrictions
are expected to overspread the area from the west Fri afternoon.
Periods of convection, which could be widespread at times, are
expected through the weekend. Late night/early morning restrictions
in low stratus and/or fog will also be possible. Drier weather is
expected to return early in the next work week.
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&&

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

&&

$$

SYNOPSIS...DEO
NEAR TERM...JDL
SHORT TERM...AR
LONG TERM...AR
AVIATION...JDL