496
FXUS62 KGSP 051849
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
249 PM EDT Tue May 5 2026

.WHAT HAS CHANGED...
Increased concern for severe weather and localized heavy rainfall
threats Wednesday night.

Low confidence in rain potential this weekend into early next week.

&&

.KEY MESSAGES...
1. Dry conditions expected again today. A Fire Danger Statement
is now in effect for this afternoon for part of the North Carolina
Piedmont.
2. A cold front arrives Wednesday and produces scattered
showers and thunderstorms from Wednesday afternoon through
Thursday night. Isolated large hail and damaging wind are
possible. Localized, brief heavy rainfall is also possible,
but flash flood risk appears low, and extremely isolated.
3. Rain chances continue for portions of the weekend into Monday
then drying for Tuesday.

&&

.DISCUSSION...
Key message 1: Dry conditions expected again today.  A Fire Danger
Statement is now in effect for this afternoon for part of the
North Carolina Piedmont.

High pressure over the western Atlantic continues to drive mostly
clear and dry conditions across the western Carolinas today.
A zone of upper confluence and associated focused forcing was
visible on water vapor imagery well to our northwest, over the
Upper Ohio Valley and aligned with an apparent surface front
extending from southern Illinois into western Ohio.

Forecast profiles depict a deep dry layer beginning at around
800mb, with only a weak capping inversion in the subsidence layer.
Expect dewpoints to mix out significantly again today, resulting in
widespread RHs bottoming out in the 25-30% range during peak heating
this afternoon.  Also expect WAA winds to be as strong or stronger
than yesterday, as the influence of the approaching frontal system
results in a 3-5mb pressure gradient across the forecast area.
Low-end fire weather concerns are therefore in order - and NCFS has
indicated the need for a Fire Danger Statement in certain parts of
the NC Piedmont, where fine fuel moisture may dip below 8% again,
and the meteorological conditions so described will enhance the
risk of fires catching and spreading.  So, a Fire Danger Statement
is in effect through 8 PM this evening for a chunk of the Piedmont
this afternoon.

The front will slow on approach tonight, but low-level moisture will
nonetheless increase, rapidly eroding the dry slot and bringing
an end to fire wx issues for the next few days.  Hi-res guidance
continues to even depict a subtle shortwave lifting out of the
Lower Mississippi Valley this evening into tonight, resulting in
some isolated showers over the Smokies and Balsams this evening.


Key message 2: A cold front arrives Wednesday and produces
scattered showers and thunderstorms from Wednesday afternoon
through Thursday night.  Isolated large hail and damaging wind
are possible.  Localized, brief heavy rainfall is also possible,
but flash flood risk appears low, and extremely isolated.

A cold front looks to approach the area Wednesday, but the forecast
remains somewhat murky with respect to how convection will evolve
on Wednesday.  As a 500mb speed max amplifies over Tennessee early
Wednesday morning, well-organized convection will eject off the
surface front and barrel east toward the Carolinas.  The 12z CAMs
(including most REFS members) depict the arrival of a decaying
MCS around daybreak.  Shear during this time will be limited (as
the MCS will likely have outrun the speed max) and any lingering
instability should be elevated, and feature anemic lapse rates
even then.  Consequently, think the severe risk with whatever
deteriorating convection makes it here early Wednesday will be low.

Model consensus, however, is for redevelopment of convection later
Wednesday.  300-600 J/kg sbCAPE is supported - especially across
the western half of the CWA - for the afternoon and early evening
hours, where the 12z HREF depicts a 40-70% chance of sbCAPE >
500 J/kg...a notable increase since last night`s 00z cycle.
Shear should steadily increase as the upper speed max migrates
eastward on Wednesday afternoon, eventually pushing into the NC
mountains and northeast Georgia.  However, synoptic forcing will
be in a bit of a lull during peak heating, unfortunately making
initiation more difficult to pinpoint during the period when the
convective parameter space looks best.  Several of the 12z CAMs
support upstream initiation over northern Alabama and Georgia
within an axis of low-level frontogenesis, and then translate
this feature into the Upstate Wednesday evening, and through the
first half of Wednesday night before the advancing front drives
convection to our south and east.  Though surface-based instability
would become increasingly paltry going later into Wednesday night,
the increased synoptic forcing and elongated hodographs are enough
to make the 12z HREF`s signal for severe potential believable.

Should severe storms develop Wednesday evening/night, there`s
support for mainly a hail/wind threat, and especially over
northeast Georgia and the western Upstate.  In these zones, the
latest HREF and REFS guidance depict updraft helicity bullseyes
arriving after 21z, supportive of the rotating updrafts needed to
support large hail.  Meanwhile, a wind threat would normally be
a slam dunk with organized convection, but in this case may be
somewhat muted as increasingly, deep layer shear looks to have
a large along-boundary component.  Still, would expect to see at
least a few surging segments along the line.  Tornado risk still
looks like it should be kept in check by a lack of good low-level
SRH and high LCLs.

Consequently, the bigger issue could turn out to be heavy rain;
with some hi-res guidance depicting two or even three rounds of
ample rainfall for the Smokies, Balsams, and northeast Georgia.
12z HREF PMMs generally depict up to 1-1.5" of rain in 6 hours,
and 2-2.25" in the 12 hours leading up to daybreak Thursday.
Whether this is enough to cause more than isolated, low-end hydro
issues is debatable: almost the entire forecast area remains in
D3 drought, with rainfall deficits of 6 inches or more...so think
that antecedent conditions alone should keep the flood threat in
check, though nonzero.  Nonetheless, given the orientation of the
boundary and the simulated reflectivity forecast from the 12z CAMs,
it would appear there`s some potential for training storms...and
therefore will at least need to monitor hydro closely.


Key message 3: Rain chances continue for portions of the weekend into
Monday then drying for Tuesday.

The cold front from Thursday stalls to our south on Friday, then a
series of Gulf Coast low pressure systems move east along the front
through Sunday before a scouring cold front moves through from the
northwest on Monday. Confidence on the evolution of these systems is
low as guidance differs on which wave will be stronger with more in
the way of precip for our area. In fact, one model has little with
the weekend waves saving it for the front on Monday. The model blend
has the better chances Sunday night into Monday, but of course, this
could and will likely change. Temps drop below normal for Friday,
rise to near normal Saturday, above normal Sunday and Monday, then
back to near normal Tuesday.

&&

.AVIATION /18Z TUESDAY THROUGH SUNDAY/...
At KCLT and elsewhere: VFR on tap for Wednesday.  Gusty SW winds
will continue through this afternoon and evening, with frequent
gusts of 20-25kts expected at all terminals, and occasional higher
gusts possible.  Cirrus will steadily increase through the evening,
and a FEW/SCT cu field already visible on satellite will expand
for another few hours before dissipating after sunset.  Some of
the statistical guidance depicts MVFR cloud bases developing
tonight at KAVL and other mountain/foothill sites, but confidence
remains limited so just hinted at this in the KHKY and KAVL TAFs.
VCSH was added on Wednesday morning for the predicted arrival of
a decaying MCS around and after 12z.  Scattered TSRA looks likely
again Wednesday afternoon into Wednesday night, but for the 18z
TAFs, this only affects KCLT, where a PROB30 was added.

Outlook: Restrictions are likely with a cold front crossing the
area from late Wednesday through early Thursday.  TSRA may develop
with this front.  Confidence is low past this point.

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...None.
NC...INCREASED FIRE DANGER until 8 PM EDT this evening for NCZ056-
     057-068>072-082-504.
SC...None.

&&

$$

MPR/RWH