-- Discussion containing changed information from previous version are highlighted. --
179
FXUS62 KCAE 260811
AFDCAE

Area Forecast Discussion
National Weather Service Columbia SC
411 AM EDT Wed Jun 26 2024

.SYNOPSIS...
Hot temperatures with heat indices over 100 F are expected to
continue through the period. Isolated to scattered showers and
thunderstorms should occur each afternoon and evening,
particularly in the eastern Midlands and coastal plain. As a
front approaches, better coverage is likely Thursday.
Increasing heat impacts Friday through the weekend. Another weak
front will move into near the area Monday with possible better
convective coverage.

&&

.NEAR TERM /THROUGH TONIGHT/...
-- Changed Discussion --
KEY MESSAGES:
-Heat Advisory in effect today for the eastern forecast area as
 heat indices expected to reach 108F.
-Isolated storms develop along the sea breeze late afternoon.

A low level moisture boundary remains draped over the area today
from north to south with significantly drier air in central Georgia
and deep moisture along the coast of South Carolina where PWATs are
above 1.7 inches. Upper level heights remain similar today with high
pressure ridging over the area and low level winds shifting out of
the southwest as a front to the northwest begins to approach the
forecast area. This will lead to at least some weak warm advection.
Model consensus shows well above average temperatures at 850mb
remaining over the area which as a result will push highs to
near 100 everywhere. Strong boundary layer mixing today will
allow dew points to mix out significantly with lower dew points
in the west where the driest air is and a bit higher in the
east. As a result, heat indices will be higher in the east and
will max out around 108F. A heat advisory is in effect for
the Columbia metro as well as counties south and east. A
marginal increase in deep layer moisture expected today but high
pressure continues to dominate. As a result, isolated showers
and storms may form along the sea breeze in the far eastern
portion of the forecast area but most of the area will remain
dry. The approaching front tonight will keep winds out of the
southwest as lows remain mild, in the mid 70s.
-- End Changed Discussion --

&&

.SHORT TERM /THURSDAY THROUGH THURSDAY NIGHT/...
-- Changed Discussion --
KEY MESSAGES:
-Scattered showers and thunderstorms in the afternoon and evening,
some possibly severe. Wind damage is the main threat.
-Hot conditions with the max heat indices of 100-105.

Upper ridge centered out in the Desert southwest with trough
developing in the eastern CONUS. A positively tilted short wave
trough is expected to move across the area Thursday afternoon.
The air mass is expected to be more moist with precipitable water
1.5 to 2 inches especially in the eastern Midlands. Some mixing of
drier air aloft expected in the western Midlands and Piedmont. HREF
guidance suggest weak to moderate instability with highest CAPE in
the east, generally 1000-1500 J/kg. Surface front/trough in the
Piedmont in the morning appears to set up in the east Midlands in
the afternoon. So expect convergence to be enhanced in the east.
Deep layer shear still appears relatively weak, however it does
appears stronger near the NC/SC border, above 20 kts. CAM models
suggest scattered thunderstorms. With short wave trough moving
through to enhanced lift in a potentially moderately unstable
environment, this appears reasonable. Isolated severe mainly in the
east Midlands and Pee Dee where confidence is also higher for
convective coverage. Temperatures should be a little cooler than
previous days with deeper moisture. NBM guidance is trending cooler
in line with Mos. Cut temps a bit from previous forecast, mid to
upper 90s. If showers develop earlier, temps may be a little cooler.
But confidence is relatively high for heat index values to be a
little lower.
-- End Changed Discussion --

&&

.LONG TERM /FRIDAY THROUGH TUESDAY/...
-- Changed Discussion --
KEY MESSAGES:
-Increasing heat impacts expected again Friday through the  weekend
with heat index values 105 to 110.
-Scattered afternoon thunderstorms each day.

Behind the boundary and trough passage on Thursday, broad flat
ridging will develop across much of the Southeast US. GEFS and EC
members are consistent in pulling the primary jet well north across
the Great Lakes, positioning us under the zonal, slightly
northwesterly flow regime of the ridge. Hot temperatures expected
through the weekend.  The ensembles are indicating relatively high
precipitable water across the region so may be deeper moisture will
keep temps down a bit. Kept chance pops mainly diurnally driven
convection. Slight increase in pops early next week as the ridge
weakens as upper trough moves through the northeast CONUS.
-- End Changed Discussion --

&&

.AVIATION /08Z WEDNESDAY THROUGH SUNDAY/...
Brief restrictions due to low clouds possible this morning but
otherwise VFR.

Low clouds have developed in the Pee Dee early this morning
which guidance has continued to trend towards overspreading over
the Columbia terminals along with OGB. Confidence remains
highest in restrictions at OGB where low level moisture is
highest, although still uncertainty as to whether ceilings will
be IFR or low MVFR. Have included a tempo group for IFR ceilings
just before sunrise. Shortly after sunrise, any low clouds will
dissipate with high based cumulus possible and winds increasing
out of the south around 10 knots. Winds remain elevated
overnight which should limit potential for restrictions.

EXTENDED AVIATION OUTLOOK...Increased chance of rain and
restrictions each afternoon Thursday through Sunday as
additional moisture moves over the region.

&&

.CAE WATCHES/WARNINGS/ADVISORIES...
-- Changed Discussion --
SC...Heat Advisory from 11 AM this morning to 7 PM EDT this evening
     for SCZ016-022-027>029-031-037-038-041-135>137.
GA...None.
-- End Changed Discussion --

&&

$$