807
FXUS62 KGSP 141409
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
1009 AM EDT Tue May 14 2024

.SYNOPSIS...
Low pressure brings rain and scattered thunderstorms to our region
today through Wednesday. Brief high pressure brings a mainly dry day
on Thursday. Showers and scattered thunderstorms return Friday and
into the weekend.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 1000 AM EDT Tuesday: Latest water vapor imagery and surface
analysis indicates occluding cyclone over central Missouri, with
effective warm frontal zone extending from there through the Ohio
Valley into the Carolinas. Warm conveyor belt precip is currently
lifting northeast away from our CWA, with more in the way of
scattered shower activity left behind, mainly near the I-85
corridor. Light precip has established an in-situ cool pool across
the area, with NE surface winds noted across the heart of the CWA.
It doesn`t appear that there will be much of a mechanism to dislodge
the cool pool this afternoon. However, as the area becomes dry-
slotted, increased insolation is expected to allow for some
destabilization where the stable layer is most shallow... i.e.,
around the western and southern periphery of the CWA. However, even
in these areas, a consensus of the latest model guidance suggests
sbCAPE will maximize only in the 500-1000 J/kg range late this
afternoon. With deep layer shear in the 40-45kt range expected,
ingredients are expected to become adequate for a marginal severe
storm risk.

Convective initiation remains a bit of a question mark this
afternoon, as the region will be devoid of much synoptic forcing or
any other organized source of lift.  And indeed, a consensus of the
latest CAM runs depict a pronounced lull in activity during the
afternoon hours, so much so that only chance to low-end likely PoPs
are featured for much of that time (and may still be overdone).
Nonetheless, the environment will support some severe storm risk,
especially going into the evening, as mid-level lapse rates steepen
and low-level SRH becomes enhanced in response to surface low
entering the Ohio Valley. Within this environment, CAMs generally
depict an uptick in activity this evening...primarily due to cells
moving into western areas from TN/GA. This will be the time frame in
which an isolated severe storm will be most possible, with damaging
wind gusts being the primary threat...although mini-supercell modes
will yield a threat of marginally severe hail and perhaps a brief
tornado. Highs today will be 5-10 degrees below normal, while lows
tonight will again be around 5 degrees above climo.

&&

.SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
As of 250 AM EDT Tuesday: An upper trough crosses the area
Wednesday as short waves rotate through the trough and across the
area as well. A surface low pressure center crosses the area as
well. Guidance showing moderate instability developing during the
day. The forcing and instability will lead to numerous to widespread
showers and scattered thunderstorms. Bulk shear may reach moderate
levels which could lead to some multicellular organization and a few
severe storms. Large hail and damaging winds are the main threats.
Isolated heavy rainfall is also possible. Convection should taper
off quickly during the evening as forcing moves east and instability
wanes. Highs will be near normal and lows around 5 degrees above
normal.

A short wave ridge moves in Thursday along with a drier air mass.
This should help limit convective chances to the northern mountains
where a weak trough and lingering low level moisture could lead to
isolated or scattered diurnal showers. Highs and lows will be around
5 degrees above normal.

&&

.LONG TERM /FRIDAY THROUGH MONDAY/...
As of 315 AM EDT Tuesday: Convective chances ramp back up on Friday
as an upper low/trough and the associated surface low pressure
approach from the west. The trough and surface low continue to
slowly move into the area Saturday. Guidance has slowed and now
shows the system only slowly crossing the area on Sunday. Therefore,
have likely convective coverage Friday, solid chance Saturday, and
now, low end scattered coverage on Sunday. A short wave ridge builds
in on Monday, but lingering moisture and an approaching cold front
could keep scattered diurnal convection in the area. The magnitude
of instability and shear is uncertain through the period making
severe probability uncertain as well. Isolated heavy rainfall is
possible Friday given the amount of moisture, forcing, and
convective coverage. It`s more uncertain the rest of the period.
Temps look to be around normal Friday then rise above normal through
the rest of the period.

&&

.AVIATION /14Z TUESDAY THROUGH SATURDAY/...
At KCLT and elsewhere: Widespread IFR and even LIFR ceilings this
morning beneath a potent isentropic ascent regime.  Rain hasn`t
quite performed the way the models said it would, but still it`s
been enough for a lot of fog this morning east of the mountains -
just generally a murky morning for all.  Improvement will be almost
imperceptibly slow after daybreak, but guidance is hinting at some
breakup of low cloud cover by mid afternoon, and confidence is
somewhat reinforced by the trend toward lower coverage of showers
Tuesday in the latest model runs.  Convection seems somewhat more
likely tonight, toward the end of the TAF period, as the wedge
will be weaker/nonexistent by then, and convection over TN and GA
is progged to push into the area.  It`s unclear how far east any
activity will make it - but went ahead and kept a PROB30 for TSRA
in the KCLT TAF to address the possibility.

Outlook: Restrictions should begin to ease on Wednesday morning,
but another round of TSRA, with potentially better coverage than
on Tuesday, will return and could cause localized restrictions.
Brief drying is expected Thursday, before convection and associated
flight restrictions return ahead of a cold front over the weekend.

&&

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

&&

$$

SYNOPSIS...RWH
NEAR TERM...JDL/MPR
SHORT TERM...RWH
LONG TERM...RWH
AVIATION...MPR