-- Discussion containing changed information from previous version are highlighted. --
769
FXUS62 KCAE 240927 CCA
AFDCAE

Area Forecast Discussion...CORRECTED
National Weather Service Columbia SC
527 AM EDT Mon Jun 24 2024

.SYNOPSIS...
Above normal temperatures are expected to continue for the next
several days. Isolated to scattered showers and thunderstorms should
occur each afternoon and evening, with better rain chances likely
toward the end of the work week.

&&

.NEAR TERM /THROUGH TONIGHT/...
KEY MESSAGES:

-Max heat indices around 105F today.
-Scattered afternoon storms in eastern area. Marginal risk for
 severe weather with damaging wind gusts primary threat.

Early this morning, showers continue to move into the Upstate
associated with a prefrontal surface trough. While HiRes models
indicate these showers will weaken as they approach the forecast
area, some light showers will be possible this morning.

The surface trough will push through the area this morning with
winds shifting from SW ahead of it to NW behind it. These NW winds,
along with models indicating some slightly warmer temperatures at
850mb indicate favorable conditions for downslope flow across the
area. This will lead to warmer temperatures, with highs approaching
100F across much of the area. Dew points will likely mix out,
however, especially in the NW portion of the forecast area which
will lead to similar heat indices to yesterday, around 100F in the
NW to around 105F in southeast, where dew points will likely be
higher. This remains just below heat advisory criteria which is heat
index greater than 108F. Afternoon storm development is expected
near the trough with surface convergence providing forcing in a
moderate to potentially strongly unstable airmass. Deep layer shear
still remains fairly weak, generally 20 knots or less. With strong
low level lapse rates and forecast soundings showing some dry air
aloft and an inverted-V, stronger storms could produce a damaging
wind gust. A marginal risk remains in place in the far southeastern
portion of the forecast area. With a loss of daytime heating
tonight, chances for rain will continue to decrease overnight. Lows
will be in the low to mid 70s.

&&

.SHORT TERM /TUESDAY THROUGH TUESDAY NIGHT/...
KEY MESSAGES:

-Hot conditions continue. Max heat indices 100-105, slightly
 drier conditions in the north Midlands.
-Widely scattered to scattered afternoon thunderstorms mainly in
 the southeast Midlands.

Upper level ridge building again as long wave trough axis off
the coast. Deep moisture will shift east of the area. A weak
frontal boundary will be across near the southeast Midlands in
the afternoon. Drier air is expected to advect into the SC
Piedmont and north Midlands where precipitable water is expected
around 1.00 inch. In the east, precipitable water above 1.5-1.8
inch or a little higher. Temperatures will rise into the upper
90s during the afternoon with relatively strong subsidence over
much of the area. Weaker capping in the east at least early in
the afternoon. The air mass remains dry above 3km which should
limit convective coverage overall. The CAM models are
suggesting scattered thunderstorms will focus near the frontal
boundary/trough in the southeast Midlands and coastal Plain. Low
level convergence will be the main forcing for convection,
possibly enhanced by the sea breeze. Showers will be more
limited into the central Midlands. Overall, expect the heat
index range from 100-105 across the region. Overnight lows
continue to range in the low to mid 70s.

&&

.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
-- Changed Discussion --
KEY MESSAGES:

-Hot conditions continue. Max heat indices up to 107.
-Widely scattered to scattered afternoon thunderstorms each day.

An upper level trough will move from the Mississippi Valley into
the Carolinas and Georgia by Thursday. The diffuse
boundary/front remains near the region Wednesday so continued
threat of scattered afternoon thunderstorms mainly in the
southeast Midlands/CSRA. Lower pops west. There may be stronger
dynamics for thunderstorms Thursday afternoon as the GFS/ECMWF
show short wave trough moving through the area. Weak
front/boundary near the area. Overall shear not that strong.
But soundings show weaker capping, moderate instability and more
pronounced inverted V, suggesting wind threat. NBM pops
suggesting scattered thunderstorms. With higher chance rain,
temps a tad cooler.

The ensembles continue to show the strong upper ridge building
into the area over the weekend and remaining through early next
week. Relatively high confidence for continued hot temperatures,
above normal, upper 90s to near 100 degrees. Lower confidence on
convective coverage. The NBM suggests scattered coverage at most
and mainly diurnally driven.
-- End Changed Discussion --

&&

.AVIATION /10Z MONDAY THROUGH FRIDAY/...
VFR conditions expected through the TAF period.

Showers moving through the southern Appalachians associated with
a surface trough approaching the area are expected to weaken as
they approach the terminals with leading to scattered clouds
below 10kft and maybe an isolated shower. Isolated showers and
storms will be possible this afternoon, mainly at OGB but
confidence is too low to include in TAF. Winds will shift from
the SW to W most of today with some gusts between 15-20kts this
afternoon. Winds shift out of the N tonight.

EXTENDED AVIATION OUTLOOK...Increasing chances for afternoon
scattered showers and thunderstorms and associated
restrictions Tuesday through Friday.

&&

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

&&

$$

SYNOPSIS...
NEAR TERM...
SHORT TERM...
LONG TERM...
AVIATION...