113
FXUS62 KGSP 031852
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
252 PM EDT Fri May 3 2024

.SYNOPSIS...
Dry and warm high pressure moves off the Carolina coast as a
front approaches from the west then stalls over our region for
the weekend. This front will result in periodic thunderstorms
and showers starting today and lingering through the weekend. A
general summertime pattern sets up early next week, which will
likely support scattered thunderstorm development each afternoon.

&&

.NEAR TERM /THROUGH SATURDAY/...
As of 220 PM EDT Friday: Upper ridge axis slowly moves east as an
upper trough and a series of short waves move into the area. Surface
high pressure dissipates as a weak surface low and trough move in.
Copious moisture and weak forcing will lead to steadily increasing
convective chances. Scattered showers and thunderstorms are
developing and will move northeast across the area this afternoon
and evening. Atmos is weakly unstable with poor mid level lapse
rates. Bulk shear is also weak. That said, there are steep low level
lapse rates with DCAPE over 800 J/kg over the the I-77 corridor
where heating has taken place. The overall chance of severe is low,
but can`t rule out a strong or severe storm. While brief, heavy
rainfall is possible with any storm, the flood threat is also low.
Lows tonight will be around 10 degrees above normal.

Coverage and intensity should drop during the evening. However, CAM
guidance shows an uptick in shower activity overnight in the
continued moist and weakly forced atmos. Coverage then continues to
pick up through the day Saturday as forcing becomes better.
Instability and shear will remain on the weak side, while forecast
profiles show an even more saturated atmosphere. This suggests and
even less chance of strong to severe storms, with a slight uptick in
heavy rain potential. That said, the overall flood risk remains low
given the relatively dry antecedent conditions. Highs will be near
normal due to clouds and precipitation.

&&

.SHORT TERM /SATURDAY NIGHT THROUGH MONDAY/...
As of 240 PM EDT Friday: The rest of the weekend looks active right
into the first part of next week. A baggy upper trof overhead
on Saturday night slowly lifts northeast with a short wave
passage, and this bit of lingering forcing will be able to keep
shower/thunderstorm activity on a slow wane into the early morning
hours. Guidance suggests that it will never die off entirely,
so the fcst retains some fairly high precip probs. That sets the
stage for Sunday. Models show less forcing, but an uptick in the
available buoyancy in the afternoon. That should make for a more
thermodynamically-driven day, with better than climo coverage
of showers and storms. Forecast soundings off the NAM show some
pulse-severe wind damage potential with mid-level dry air and
a shallow inverted-V, so it would not come as a surprise if it
was a busier day than Saturday. A stronger short wave lifting
northeast over the TN/OH Valley regions on Monday will continue to
support diurnally-enhanced convection, so we continue with above
climo precip probs. Temps look to be on the order of five degrees
above normal.

&&

.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
As of 143 PM EDT Friday: The bulk of the medium range looks like a
summer preview. After a baggy upper trof moves past Monday night,
we should spend the remaining week underneath a low amplitude,
relatively fast, WSW flow aloft. Within this flow, the model
guidance shows a steady train of short waves moving through, mostly
around peak heating each day, that will enhance our convective
coverage each afternoon/evening. Overall, the air mass shows
little change from one day to the next, as a wavy surface front
will be strung out to our north in the WSW flow. Buoyancy will be
modest and shear will be light, which suggests that chances for
severe storms will be relatively low, but in such a pattern we
eventually seem to manage to crank out a few pulse severe storms
each day. Precip will be spotty and showery, which keeps the heavy
rain threat at bay, but eventually there could be a few spots that
start to see an increased risk of flash flooding, especially if a
more coherent, stronger short wave comes along, such as what the
GFS shows next Friday. Lots of uncertainty, though. Temps will
remain in that 5-10 degree above normal range for most days,
perhaps on the high side of that either Wednesday or Thursday,
which one of those days might get a break in the wave train and
thus reduced shower coverage and higher temps.

&&

.AVIATION /19Z FRIDAY THROUGH WEDNESDAY/...
At KCLT and elsewhere: Showers and isolated storms are developing
across the area and moving NE this afternoon. Have added TEMPOs at
the locations most likely to see activity. KCLT with just SHRA for
now, while KAVL/KHKY has TSRA. A cell may affect the SC sites but
will amend as needed. S to SW wind expected through the afternoon.
Activity diminishes somewhat this evening but returns overnight.
Have PROB30s in place for that. Cig and vsby restrictions develop
overnight as well, so have MVFR to MVFR before 12Z and IFR after
12Z. Light and variable wind expected overnight with S to SE wind
for all but KAND, where it will be ENE, Saturday.

Outlook: Enhanced moisture will combine with a weak/stalled front
through early next week, resulting in a period of active/mainly
diurnal convective weather each day. There will also be the
potential for restrictions associated with widespread fog and/or low
clouds each morning.

&&

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

&&

$$

SYNOPSIS...DEO
NEAR TERM...RWH
SHORT TERM...PM
LONG TERM...PM
AVIATION...RWH