205
FXUS62 KGSP 011740
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
140 PM EDT Wed May 1 2024

.SYNOPSIS...
Dry and warm high pressure will continue through Thursday night,
before an active frontal system moves in Friday and lingers through
the weekend.  Our weather gradually becomes more of a summer time
pattern with afternoon and early evening storms through the middle
of next week.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 138 PM EDT Wednesday: All under control this afternoon across
the region.  Trends look good, so no course corrections.

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 SATURDAY/...
As of 130 PM Wednesday: Upper ridging that will have set up shop
over the CFWA during the near-term will begin to breakdown and shift
eastward as a shortwave trough and diffluent flow moves in from the
southern/central Plains into the lower/mid MS Valley Thursday night
into Friday. Weak vort energy will gradually fill in over the region
and should produce enough forcing for a few showers to develop after
daybreak Friday, especially over the favorable upslope regions with
south-southwesterly winds filtering in better moisture. Eventually
the areas of DPVA will traverse over the rest of the CFWA during the
daytime period Friday, bringing with it elevated PoPs across most
locations with scattered showers and a couple of thunderstorms. As
of now, soundings do not support strong to severe thunderstorms as
the vertical column will be fully saturated with warm air aloft and
only meager instability and deep layer shear. QPF response will
remain on the low end as well, outside of an embedded thunderstorm
with heavier rain rates. Expect temperatures to drop a few degrees
compared to Thursday for afternoon highs as extensive cloud cover
and increased rain chances will be in store for much of the area.

A secondary wave of DPVA will push in soon after the initial round
slips east of the CFWA. A weak attendant boundary will accompany
this area of DPVA and allow for better forcing, while the
environment becomes more saturated as PWAT values will rise up to
1.50" by Saturday. In this case, expect for even better coverage in
rainfall, mainly by mid-morning through the afternoon as the best
overlap between moisture and DPVA will occur around this time.
Profiles continue to support a very saturated vertical column, with
skinny CAPE and weak deep layer shear. This may cause localized
hydro concerns if the QPF response on Friday overproduces and the
same locations get hit multiple times by heavier rainfall rates. The
other factor going into this set up is the presence of a surface
high over New England, which shifts offshore by the end of the
forecast period. This set up will support the development of a weak
wedge-like configuration. Temperatures will drop closer to near-
normal values as a result due to cloud cover and precip locking in
across the CFWA. PoPs will remain elevated through the daytime
period Saturday (end of the forecast period).

&&

.LONG TERM /SATURDAY NIGHT 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 /18Z WEDNESDAY THROUGH MONDAY/...
At KCLT and elsewhere: Not much to get concerned about over the next
24 hours, with prevailing VFR at all terminals expected. Stratocu
was developing over the higher terrain, and also across the
Midlands/Sandhills of the Carolinas. Expect KCLT to have FEW
to SCT clouds around 050, and same at KAVL, until we lose the
thermals. Wind will be light N for the most part. Clouds melt
away with sunset and wind goes calm or light/variable for the
overnight. Would never rule out mtn valley fog, but for now the
air mass looks too dry for fog at KAVL. On Thursday, another
quiet VFR day courtesy of high pressure. Wind returns from the SE
around midday.

Outlook: VFR conditions are expected through Friday. More numerous
showers and thunderstorms and their associated restrictions are
likely on Saturday and possibly into Sunday with the passage of
another cold front.

&&

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

&&

$$

SYNOPSIS...DEO
NEAR TERM...JPT/PM
SHORT TERM...CAC
LONG TERM...SBK
AVIATION...PM