252
FXUS62 KGSP 020132
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
932 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 THURSDAY/...
As of 924 PM EDT Wednesday: Surface and upper ridging will keep
tranquil weather in place through the overnight period. Clear skies,
calm winds and a dry airmass will allow for efficient radiational
cooling with low temperatures falling into the low to upper 50s. The
ongoing forecast remains on track and no changes were needed.

Fair weather will persist across the region for the next 24 hours
as surface high pressure camps out over the mountains, held there
by an amplifying upper ridge. The ridge axis should slide to the
east by the end of the day on Thursday, so the high will weaken,
but the next weather system will remain too far west to affect our
region. It is possible we could see another round of mtn valley
fog late tonight/early Thursday, particularly in the Little TN
River valley, but otherwise the sky will be mostly clear through
the period. Overnight temps will be on the order of five degrees
above normal. The air mass continues to modify on Thursday,
allowing high temps to climb another category above today`s high,
topping out almost ten degrees above normal.

&&

.SHORT TERM /THURSDAY NIGHT 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 WEDNESDAY/...
As of 240 PM Wednesday: The flow aloft will turn more quasi-zonal
with warm thicknesses still in place. At the same, a series of
shortwaves traverse through the flow and allow for at least
mentionable PoPs each day, especially in the mountains where
topography influence will allow for daily showers and thunderstorms
as we remain under a warm and moist airmass through much of the
forecast period as surface high pressure shifts offshore the
Southeast Coast and filters in continuous south-southwesterly low-
level flow. Early next week may present better thermodynamics for
stronger storms compared to the weekend as drier air aloft filters
in and slightly better instability and deep layer shear will be
available. Otherwise, the airmass will remain rather stagnant
through the period with temperatures a couple categories above
normal for highs and lows through much of the extended. The
convective season will be in full swing from hereon through the
Summertime.

&&

.AVIATION /02Z THURSDAY THROUGH MONDAY/...
At KCLT and elsewhere: VFR conditions will prevail at all terminals
through the TAF period. Winds will become light to calm overnight
beneath clear skies. Patchy valley fog will be possible across the
mountains, but not expecting any issues at KAVL at this time. Light
northeast winds Thursday morning will shift to out of the south
during the afternoon. A few high clouds may also make their way into
the area from the northwest.

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...PM/TW
SHORT TERM...CAC
LONG TERM...CAC
AVIATION...TW