486
FXUS62 KCAE 181844
AFDCAE

Area Forecast Discussion
National Weather Service Columbia SC
244 PM EDT Thu Jul 18 2024

.SYNOPSIS...
A frontal boundary will be stalled across the region for the
next several days with increased shower and thunderstorm
chances. Some locally heavy rainfall is possible which could
result in increasing level in area rivers. Temperatures will be
near to slightly below through the middle of next week.

&&

.NEAR TERM /THROUGH TONIGHT/...
Key Message(s):

- Scattered to numerous showers and thunderstorms this afternoon
  and evening, with the potential for strong winds and locally
  heavy rain especially in the northern portion of the area.

Convective initiation has begun in the higher terrain of the
western Carolinas a bit earlier than some of the CAMs indicated.
RAP analysis early this afternoon indicates that strong
destabilization is already occurring with sbCAPE exceeding 2500
J/kg across the entire forecast area. The ridge has begun to
breakdown on water vapor imagery but there remains no trigger
over the forecast area for convection to fire up, yet. This
will change over the next several hours as a cold front in
North Carolina continues to advance towards the forecast area.
As convection develops ahead of this front, will likely continue
to get development to the south and east as storms continue to
build off an outflow boundary into a strongly unstable airmass.
A bit more organization remains possible as well with the HREF
mean deep layer shear around 20 knots approaching the NC/SC
state line. As a result, will likely see multicellular
convection develop along a boundary in the northern portion of
the forecast area with more scattered activity in the southern
portion of the forecast area. Have favored slightly faster
timing in storm activity owing to differences in observations
versus CAMs and with higher instability, likely will see
somewhat linear multicells speed up.

A severe threat remains in place for with the highest potential
in the northern forecast area with damaging wind gusts the
primary concern as highlighted by SPC as well as CSU ML
probabilities, which have been consistent in the threat for
days. While coverage will decrease overnight, the boundary being
in the area will at least keep slight chance for convection to
linger past midnight. Seasonably warm overnight in the low to
mid 70s.

&&

.SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
- Likely to numerous afternoon and evening showers and
  thunderstorms with the potential for gusty winds and flash
  flooding
- Daytime temperatures expected to be near normal

Upper level trough will continue digging into the Lower MS
Valley with the remains of the frontal boundary stalled across
the SE US. Although the frontal remains will continue weakening
there will be enough to initial convection along the boundary.
Instability on Friday will be moderate and with pwat values
around 2 inches the potential for locally heavy rainfall and
gusty winds will again be present. With the mid and upper level
winds being 30 knots or less cell movement will be relatively
slow and combined with any training cells the potential for
localized flooding could quickly increase. As such nearly all of
the CAEs SC counties are in a WPC ERO slight risk for Friday.
The synoptic situation will be slow to chance on Saturday with
the main difference being the upper level trough axis slightly
east of Fridays position. Overall this will keep the forecast
very similar with showers and thunderstorms likely in the
afternoon and evening along with the potential for locally heavy
rainfall and gusty thunderstorms winds.

With the convection and associated clouds temperatures are
expected to be near to slightly below normal with afternoon
highs in the upper 80s to low 90s.

&&

.LONG TERM /SUNDAY THROUGH THURSDAY/...
Key Message(s):

-The pattern remains favorable for daily chances of afternoon
 and evening showers and thunderstorms

The upper level pattern will be very slow to change as a highly
amplified pattern will remain from the eastern Pacific through
the western Atlantic. The remains of the frontal boundary will
continue becoming more diffuse each day however remain a
focusing and trigger mechanism across the SE US. With the upper
trough and corresponding shortwaves rotating through the base
and across the region expect the daily showers and thunderstorms
to continue. Have remained cautious in raising pops yet likely
pops each afternoon and evening. With pwat values also remaining
around 2 inches the potential for locally heavy rainfall and
gusty winds due to precip loading will continue. With several
days of locally heavy rainfall possible the potential for flash
flooding and hydro related issues will need to be monitored.

WPC continues to depict a Marginal Risk ERO through Sunday.
Daytime temperatures through the period will be near to slightly
below normal with upper 80s to low 90s each day.

&&

.AVIATION /18Z THURSDAY THROUGH TUESDAY/...
Generally VFR conditions expected through the TAF period with
restrictions possible in thunderstorms.

A cold front dropping into the area today will generate
widespread thunderstorms with coverage highest over the Columbia
terminals and OGB between 21z and 1z. Confidence is a bit lower
in thunderstorm chances for the Augusta terminals so have left
VCTS in the TAF but hesitated to put in a TEMPO group. Storms
over Columbia and Orangeburg do have the potential to produce
wind gusts exceeding 35 knots but confidence in the placement of
strongest storms is a bit higher to the north. With lingering
moisture, models are indicating the potential for restrictions
to develop around sunrise in the form of low clouds but have not
explicitly forecast restrictions yet as confidence is limited.

EXTENDED AVIATION OUTLOOK...Periods of showers and
thunderstorms may cause restrictions each day. In addition,
brief early morning restrictions may become more likely around
sunrise into the weekend.

&&

.CAE WATCHES/WARNINGS/ADVISORIES...
SC...None.
GA...None.

&&

$$