Area Forecast Discussion
Issued by NWS Greer, SC

Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000
FXUS62 KGSP 082329
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
729 PM EDT Mon Aug 8 2022

.SYNOPSIS...
A typical summertime pattern continues with a subtropical ridge in
the western Atlantic extending over the southeastern U.S. through at
least the middle of the week. Moisture will pool ahead of a cold
front approaching from the north on Wednesday and cross the area
Thursday. A reinforcing cold front will cross the region from the
north on Friday and usher in much drier air and cooler temperatures
through the upcoming weekend.

&&

.NEAR TERM /THROUGH TUESDAY/...
As of 545 PM EDT Monday: Widely scattered convection continues
across most of the forecast area, with a pocket of enhanced
convection along the periphery of a weak boundary extending out of
northern GA into the southern SC Upstate.  SBCAPE hasn`t changed
much since the last update, lingering around 2500-3000 J/kg for
most of the area.  DCAPE has ticked upward in a pocket along the
I-77 corridor, with values of 900-1000 J/kg there...a slightly
worrisome feature if convection ever starts to trigger in that area.
Elsewhere, values remain much lower, limiting any severe risk.
CAMs still depict activity dying off with the loss of daytime
heating this evening, but some precip could linger over northeast
GA/western Upstate where there could be some light upslope flow.

Not much change through the near term with the overall pattern. If
anything, the Atlantic subtropical ridge might drift a bit farther
west through Tuesday. After the convection dies off late tonight,
we look for more low stratus and locally dense fog in the mtn
valleys. Low temps will be mild. Tuesday looks like another
quintessentially summer day across the western Carolinas. The
better coverage will be seen over the mtns where the differential
heating will be a trigger, but the area east of the mtns should
see at least scattered storms. Fcst soundings are not particularly
compelling in terms of the severe weather potential, with weak
lapse rates and a lack of dry air at mid-levels, so severe storms
look isolated at best. High temps will be right around normal.

&&

.SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY/...
As of 130 PM EDT Monday: Western Atlantic anticyclone is expected
to gradually breakdown during the short term as broad eastern
CONUS troughiness begins to sink further south towards the
region. An attendant cold front will approach the CFWA from the
northwest on Wednesday as the upper trough axis slides across the
Appalachians. Better moisture advection building along and ahead
of the frontal boundary will allow for PWAT values to climb near
~2". With waves of vorticity riding in the vicinity of the cold
front and base of the trough aloft, expect an enhancement of shower
and thunderstorm coverage during peak heating on Wednesday. Profiles
place a deep warm cloud layer (~10,000+ ft) and limited instability
(500-1500+ J/kg SBCAPE) due to warmer air aloft across the CFWA,
so the severe threat will be somewhat limited, but the hydro threat
will likely see an uptick from normal. One thing that will be to
our advantage is that the westerly steering flow (10-15 kts) will
be strong to enough to keep any showers and thunderstorms that
develop moving just enough to avoid any significant training of
storms. With the initial frontal zone lingering across the CFWA,
expect for some of the activity to continue into Wednesday night
and early Thursday. Temperatures will be near-normal for Wednesday
as more extensive cloud cover and better coverage for precip will
be in store.

Longwave upper trough will dig further south into the eastern-third
of the CONUS by Thursday as the initial frontal boundary sinks south
of the area and a reinforcing cold front rushes in behind the weaker
initial front by Thursday night into Friday. Expect another round
of numerous to widespread showers and thunderstorms during peak
heating Thursday. Profiles are generally the same as Wednesday,
but a gradual dip in thicknesses (colder air aloft) will help
provide better instability on Thursday compared to Wednesday as
long as cloud cover doesn`t remain extensive during the morning
hours Thursday. This would likely provide a slight uptick in the
severe threat, but the main concern will still be the relatively
elevated hydro threat, especially if antecedent conditions are
in place in locations that receive appreciable rainfall from
the previous few days prior to Thursday. Gusty winds and small
hail will be accompanied with any thunderstorms that develop both
days outside of any severe storms. Expect Thursday to be the last
convectively driven day for the rest of the week with more on this
in the medium range. Temperatures will remain at or even slightly
below normal on Thursday.

&&

.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
As of 230 PM EDT Monday: The reinforced cold front should do a
complete fropa by late Friday morning. Deep dry air advection will
filter into the region as broad high pressure sets up shop across
the OH Valley and Mid-Atlantic going into the weekend. The upper
trough axis should shift offshore by Saturday as drier and cooler
air spills over the CFWA during the weekend. One monkey wrench being
thrown into the forecast is the potential for the CFWA being exposed
to a synoptically favored pattern for an MCS run or two by late
weekend into early next week as deep ridging builds over the High
Plains. Otherwise, a post-frontal regime will be in store through
at least the first half of the weekend. The overall airmass will
begin to modify by D6/D7 as we return to a more normal summertime
pattern. A brief taste of fall this weekend temperature-wise,
while more normal temperatures will be in store by early next week.

&&

.AVIATION /00Z TUESDAY THROUGH SATURDAY/...
At KCLT and elsewhere: Convection has become increasingly sparse,
and as the sun sets and daytime heating diminishes, it will
become increasingly unlikely for us to see any further storms.
Maintained at KCLT through 02z.  Otherwise, VFR conditions outside
the mountains, with guidance generally in agreement on no low
cigs at KCLT or the Upstate sites, with drier low-level profiles
than the past few nights.  The mountain sites are still expected
to see intermittent IFR/LIFR cigs with at least MVFR/IFR visby.
Winds go light and variable overnight, and flow returns to SSW
after dawn.  Tuesday should feature similar conditions to today -
scattered thunder, with the best potential for early triggering over
the mountains, and gradual expansion across the Piedmont/Upstate
zones through afternoon and evening.

Outlook: A typical summertime pattern of scattered diurnal showers
and thunderstorms will persist through the middle of the week. Fog
and low stratus may develop each morning in the mountain valleys
and wherever appreciable rain fell the previous day. Shower and
thunderstorm coverage, and associated restrictions, may increase
along a passing cold front by late week.

&&

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

&&

$$
SYNOPSIS...DEO
NEAR TERM...MPR/PM
SHORT TERM...CAC
LONG TERM...CAC
AVIATION...MPR


USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.