852
FXUS62 KGSP 061801
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
201 PM EDT Mon May 6 2024

.SYNOPSIS...
A summerlike weather pattern remains through mid week with mainly
afternoon and early evening showers and thunderstorms. Temperatures
will be well above normal Tuesday through Thursday. Showers and
thunderstorms will be more numerous ahead of a strong cold front
which will cross our region Thursday night and Friday.  Expect drier
and cooler weather for the weekend.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 1005 am EDT Monday: Bands of sct showers continue to make their
way NE across our area with a cluster of more intense showers and
some embedded thunder moving into our far western NC counties. Over
the next few hrs, areas just to our west are still expected to become
dry-slotted allowing a combination of strong insolation and a plume
of relatively steep mid-level lapse rates to allow for strong desta-
bilization, just as height falls are overspreading the region. Con-
vection will fire in this regime, with some terrain induced initiation
also likely across the southern Appalachians by the early afternoon
and likely overspreading NE Georgia and the western Carolinas thru
the afternoon and into the evening. Thus, likely PoPs appear warranted
across much of the CWA during this time frame.

Convection could arrive in western areas with a bit of robustness
this afternoon. However, the environment is expected to be less
hospitable to convection over our area owing to morning clouds/
precip and relatively modest instability. While shear parameters
are improved over recent days...deep layer shear of 25-30 kts (as
opposed to < 20 kts the past couple of days)...this won`t be enough
to allow for anything more than a very isolated severe storm threat,
with the upper Savannah River Valley being the most likely area to
see a stray downburst and/or large hail event. As flow turns NW aloft
this evening, convection-allowing guidance suggests additional waves
of scattered showers and storms could drop into western NC from east
TN through at least the evening hours, so PoPs remain elevated in
the 40 to 60% range near the TN/NC border during that time, while
steadily diminishing elsewhere. Max temps will be slightly above
normal, while tonight`s lows will again be around 10 degrees above
climo.

&&

.SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
As of 230 AM EDT Monday: Weak upper ridging will build across the
Southeast on Tuesday before flattening out on Wednesday. This along
with W/SW`ly 850 mb flow will lead to well above normal temps
through the short term, with the mid to upper 80s expected east of
the mountains and the mid 80s across the mountain valleys. Highs
should end up ~8-12 above climo, with lows ~13-15 degrees above
climo. Diurnal convection can be expected each afternoon and evening
so have chance to likely PoPs in place each day. 0-6 km bulk shear
should range from 25-35 kts each day, with SBCAPE values from 1500-
2000 J/kg on Tuesday afternoon and 2000-2500 J/kg on Wednesday
afternoon. NAM and NAMnest model forecast soundings show DCAPE
values from ~900-1200 J/kg each afternoon as well. Thus, strong to
severe storms will be possible each day, especially on Wednesday
thanks to higher SBCAPE values. The SPC Day 2 Severe Weather Outlook
(Tuesday) shows a Marginal Risk for isolated severe storms across
western North Carolina which makes sense considering CAMs are mainly
producing convection across the NC zones on Tuesday. The SPC Day 3
Severe Weather Outlook (Wednesday) shows a Slight Risk for scattered
severe storms across most of the mountain zones with a Marginal Risk
for isolated severe storms across the rest of the forecast area.
This looks plausible as coverage of convection should be higher on
Wednesday. Damaging wind gusts will be the primary hazard with any
severe storms that develop. Some concern will still exist for
locally heavy rainfall through the short term, especially for areas
that received heavy rain in the days prior.

&&

.LONG TERM /THURSDAY THROUGH MONDAY/...
As of 300 AM EDT Monday: An upper trough will approach out of the
west on Thursday before swinging across the Carolinas on Friday. At
the sfc, a strong cold front will track east over the TN Valley on
Thursday before pushing across northeast Georgia and the western
Carolinas Thursday night into Friday morning. Convection is expected
to develop well ahead of the main FROPA on Thursday so have likely
to categorical PoPs in place. The global models have sped up the
timing of the cold front compared to the last few runs, with some
solutions depicting much more stable air and drier conditions for
Friday. The exception is the 00Z GFS which has convection lingering
through Friday afternoon. Thus, lowered PoPs to chance on Friday but
PoPs may need to be lowered further in future updates if this faster
trend holds. Thursday continues to look like one of the more active
day of the week in regards to the severe weather potential. The
approaching cold front will allow 0-6 km bulk shear values to climb
to 35-45 kts, with up to 2,000 J/kg of SBCAPE in place Thursday
afternoon. Forecast soundings from the GFS depict ~1,000 J/kg of
DCAPE as well on Thursday afternoon, so damaging winds will be the
main concern with severe storms. The locally heavy rainfall threat
will return once again on Thursday thanks to 90th percentile (or
greater) PWATs expected ahead of the FROPA. However, faster storm
motion help offset this potential somewhat. The only kink in the
severe potential at this time is that widespread cloud cover is
expected to be in place on Thursday, which may limit destabilization
a bit. However, with a 40 kt 850 mb jet tracking over the western
Carolinas on Thursday (per the GFS), upper support should make up
for the lack of insolation. Temps will remain above climo Thursday
into Thursday night, but will be slightly cooler compared to
Wednesday/Wednesday night thanks to convection and cloud cover.

Global models show dry high pressure building into the region out of
the west behind the departing front Friday night into Saturday. The
00Z ECMWF and Canadian show another system impacting the forecast
area on Sunday, but the 00Z GFS does not have this system impacting
the area until after the forecast period. Thus, confidence on PoPs
will be low towards the end of the forecast period. Cooler temps are
expected to return this weekend, trending a few degrees below climo
for both highs and lows.

&&

.AVIATION /18Z MONDAY THROUGH SATURDAY/...
At KCLT and elsewhere: Another challenging fcst all-around for
the terminals. Still expect mostly VFR conditions this afternoon
and evening (outside of any showers and/or thunderstorms). We`ve
seen a lull in shower activity since late this morning, however
another round of sct convection is expected to move thru our area
later this aftn and into the evening. This is mostly handled with
VCSH and TEMPOs for TSRA at KCLT, KHKY, and KAVL. Per the latest
CAM runs, the convective coverage looks more sparse for the Upstate
terminals, so I just have VCSH with PROB30s for TSRA. Activity could
linger well into the overnight and early morning across our area,
but thinking it will be mostly showers after about 06z overnight
and most likely impact KAVL. Visby and cig restrictions return to
the area just before daybreak on Tuesday, with predominately MVFR
visby and IFR cigs expected at most sites. Expect visby to improve
and cigs to sct out by roughly 14z tomorrow with VFR for the rest
of the taf period.

Outlook: Moist profiles will combine with a weak/stalled front thru
the mid-week, resulting in a period of active, mainly diurnal convec-
tive weather each day. There is potential for restrictions associated
with widespread fog and/or low clouds each morning. A cold front moves
in later in the week with continued chances of diurnal convection.

&&

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

&&

$$

SYNOPSIS...AR
NEAR TERM...JDL/JPT
SHORT TERM...AR
LONG TERM...AR
AVIATION...JPT