-- Discussion containing changed information from previous version are highlighted. --
504
FXUS62 KGSP 010818
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
418 AM EDT Wed May 1 2024

.SYNOPSIS...
Dry and warm high pressure will build across the through Thursday,
before an active frontal system moves in Friday and lingers through
the weekend. The atmosphere remains unsettled with afternoon storms
possible early next week.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 3:25 AM EDT Wednesday: Over the past hour or so, we`ve seen
a handful of isolated showers develop over Mecklenburg, York, and
Chester Counties. A lack of sfc-based instability should prevent
this activity from producing any thunder/lightning and it should
fizzle out over the next hour or 2. Of greater importance is the
patchy fog that has been developing across our area over the past
few hrs. At present, the more dense fog of 1/2 sm or less is pretty
much relegated to the fog-prone NC mtn valleys, but we are seeing
a handful of sites in the eastern Upstate and southern NC piedmont
reporting visby of 1 to 2 sm. As such, I issued an SPS for patchy
dense fog that is in effect until 9 am this morning. If the dense
fog becomes more widespread, a Dense Fog Advisory may be needed.

Otherwise, a well-defined upper shortwave will move off the Atlantic
Coast today. In its wake, heights rebound as upper ridging amplifies
over our area again. At the sfc, what`s left of the weak frontal bndy
will also move offshore as weak high pressure spreads back over our
area and keeps us dry thru the near-term period. Despite weak low-lvl
winds from the north, temperatures this afternoon should rebound a
decent amount under mostly clear skies and increasing thicknesses.
Most of the guidance has highs topping-out 1 to 2 categories above
climatology. Although dewpts are expected to mix out some this aftn,
it`s unlikely that min RH values will reach critical thresholds.

&&

.SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
-- Changed Discussion --
As of 155 AM Wednesday...Upper level heights remain in a definite
ridge config Thu and expect deep layered drying to continue for
another day. This will lead to abv normal temps while sfc td/s
remain in the l50s making for a rather pleasant day with afternoon
fair-wx Cu. On Fri, the pattern begins to break down as a srn stream
s/w approaches from the west and crosses during max heating while
llvl moisture increases destabilization. However, this system will
only generate a weak sfc reflection as it fights neg forcing and
rather warm temps aloft. Also, the dynamic fields remain meager as
the upper s/w attenuates interacting with the departing ridge. So,
with low-end shear and only modest sbCAPE, the llvl convg zone wont
have much to work with and an organized or severe tstm threat is not
expected. Will anticipate mainly outflow driven cells or multicells,
a few of which may become quite strong, through the
afternoon/evening with reduced convec activity after sunset as the
mlvl energy traverses east.
-- End Changed Discussion --

&&

.LONG TERM /SATURDAY THROUGH TUESDAY/...
As of 230 AM Wednesday...The ext range continues to look active and
will likely be transitioning into more of a summertime pattern.
Upper heights become loosely divergent yet moreso zonal each day as
rounds of mlvl srn stream vort energy traverse the flow. Large scale
high pressure centers remain well north and east of the fcst area,
which leaves general low pressure at the sfc maintaining ill-defined
areas of sfc convg over the FA. Hard to pinpoint the best chance and
locations of afternoon convec in this setup as the models continue
to indicate modest sbCAPE developing over most areas while shear
levels remain quite weak. This will set the stage for afternoon heat
driven activity or modified pulse tstms into the evening hours each
day. Some of these cells will have the potential to become rather
strong and precip rates could become high enuf for minor hydro
issues with any given area of anchoring or training. Saturday looks
to have the best chance for any possible localized hydro concerns as
the column becomes deeply saturated, while mid-level dry air mixes
in Sun-Tue. Max temps will lower a bit to near normal Sat due to
widespread cloud cover, but the other days shud see temps pushing 5-
7 degrees abv normal. With the enhanced warm afternoon temps and no
airmass change, mins will only be able to drop off into the 60s each
morning or abt 8-10 degrees abv normal over all areas.

&&

.AVIATION /08Z WEDNESDAY THROUGH SUNDAY/...
At KCLT and elsewhere: Winds have already become calm at numerous
sites with reduced visby/fog beginning to develop at a handful of
sites across our area including KAVL, where they have been reporting
1sm or less visby for the past couple of hours. Guidance continues
to suggest that most sites across our area will see reduced visby
overnight an into the morning. Thus, I have MVFR visby with TEMPOs
for IFR at the Upstate terminals and KCLT beginning around 09z. I
have TEMPOs for 1/2sm or less at KAVL and KHKY, although the other
terminals could certainly see visby drop below 1sm as well. Visby
restrictions should dissipate by 13z at most sites, leaving mostly
clear skies with just a few passing cirrus for the rest of the period.
Winds will pick up from the N to NE by the early afternoon, and then
go light and vrb again later tonight.

Outlook: VFR conditions are expected Thursday and much of Friday.
More numerous showers and thunderstorms and their associated res-
trictions are expected on Saturday and possibly into Sunday with
the passage of another cold front.

&&

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

&&

$$

SYNOPSIS...SBK
NEAR TERM...JPT
SHORT TERM...SBK
LONG TERM...SBK
AVIATION...JPT