-- Discussion containing changed information from previous version are highlighted. --
435
FXUS62 KCAE 261439
AFDCAE

Area Forecast Discussion
National Weather Service Columbia SC
1039 AM EDT Sun May 26 2024

.SYNOPSIS...
Isolated to scattered thunderstorms possible today in a moist
and unstable air mass. A more organized system is expected to
cross the eastern US Monday and Tuesday with additional chances
for thunderstorms. Drier weather is expected to return
Wednesday into next weekend. Temperatures will generally be
above normal through Wednesday then near normal Thursday through
Saturday.

&&

.NEAR TERM /THROUGH TONIGHT/...
Morning analysis features a frontal boundary situated across the
Ohio Valley westward to a low over central Kansas with a
secondary warm front developing over central OK/AR. WV imagery
shows a broad upper trough across the middle of the country with
a lead shortwave pushing eastward over Missouri while some
downstream shortwave ridging was moving into the southern
Appalachians and Gulf Coast regions. Mesoanalysis reveals some
drier air has moved over our area with PWATs ranging from 1.1
inches over the Upstate to around 1.4 inches over the eastern
Midlands.

Low pressure over the Plains is expected to lift northeastward
to near the western Great Lakes region by this afternoon as the
upper trough shifts eastward. Weak shortwave energy is forecast
to move through the TN Valley this morning and possibly into the
Carolinas around peak heating which could support scattered
thunderstorm development in a moderately unstable atmosphere
with HREF forecast SBCAPE values 1500-2000 J/kg and HRRR DCAPE
values over 1000 J/kg. This should provide a possible severe
threat late this afternoon and evening with damaging wind gusts
and large hail as the primary threats. HREF members favor the
northern Midlands as convection develops to our west and moves
east with the mean flow diving across the northern Midlands this
evening so have highest pops there with a gradient to lower pops
toward the CSRA and southeast Midlands. Storms could linger into
the late evening hours through midnight before diminishing with
the loss of daytime heating and atmospheric stabilization. More
organized convection is expected along an approaching cold front
over the TN Valley late tonight but that activity should remain
to our west through 12z. Temperatures expected to be above
normal again today with highs pushing into the lower 90s.
Overnight lows tonight should be mild with convective debris
cloud cover with lows in the upper 60s to around 70 degrees.

&&

.SHORT TERM /MONDAY THROUGH TUESDAY/...
Monday looks to be another potentially active day, though it
will depend somewhat on what evolves on Sunday. A deep upper
trough will move through the Ohio Valley and take on a neutral
or slightly negative tilt. Deep southwest flow will usher in an
increasingly moist airmass, with PW values above 1.75". Surface
dewpoints in the upper 60s to low 70s should combine with
temperatures in the upper 80s to low 90s leading to SBCAPE
values around 2000 J/kg or more. Shortwave energy ahead of the
upper trough combined with the attendant approaching front will
likely serve as a focus for convection. However, the best
dynamics may be either north of south of our region, and there
is some question on whether these features will sync with the
timing of best instability. That said, SPC has kept the SC
Midlands and CSRA in a Marginal Risk (1/5) of severe weather,
with damaging wind gusts being the primary concern. It should be
noted that the tail end of the HREF member solutions indicate a
broken line of decaying convection moving through the area
Monday morning, the remnants of a well-developed line of
convection progged to move through eastern TN and the upstate
Sunday night. That is then potentially followed by another round
of convection Monday afternoon and evening in conjunction with
the frontal boundary moving through the region.

The front will pull slightly drier air into the region with PW
dropping to around 1". This boundary may be slow to completely clear
the area though, and some overnight showers and storms may linger
across the eastern Midlands through 12z Tuesday morning. Lows should
still be mild Monday night with values in the mid to upper 60s.

Dewpoints fall into the 50s Tuesday afternoon, and there will remain
a slight chance of showers and storms for the extreme eastern
Midlands. Other areas are expected to be dry after the morning
convection ends from west to east, and highs will make the upper 80s
and low 90s as skies clear. Lows Tuesday night a bit cooler with the
drier airmass in place, generally in the low to mid 60s.

&&

.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
Broad upper trough generally remains to our north mid to late
week as multiple disturbances rotate through. This will
generally keep our area under zonal flow aloft, while PW values
remain between 0.7" and 1". Dewpoints remain in the 50s while
temperatures cool a bit more by Thursday, with highs in the low
80s, then generally return to more seasonal levels for Friday
and Saturday. There remain some model discrepancies regarding a
few weak disturbances moving through the region especially late
week, so NBM guidance seems reasonable at this time. The result
is no rain in the official forecast Wednesday through Friday
with only low end slight chances by Saturday. Overnight
temperatures also get a reprieve with lows in the upper 50s and
low 60s during this time.

&&

.AVIATION /15Z SUNDAY THROUGH THURSDAY/...
-- Changed Discussion --
VFR conditions expected outside of any shower-storm activity
this evening, overnight.

Some scattered late afternoon convection is possible but is
favored in areas north of the terminals so nothing included in
this forecast. Otherwise, expect cumulus cloud development by
mid morning through the afternoon with light winds picking up
after 15z to around 5 to 8 knots from the southwest.

Showers and storms become a bit more likely after 22z,
especially at CAE and DNL as a system moves down from the
northwest. Confidence remains too low in both timing and
coverage for a TAF mention for now. Another round of showers-
storms is possible late overnight into Monday morning, but
timing and coverage is again uncertain.

EXTENDED AVIATION OUTLOOK...Restrictions possible Monday
afternoon in scattered thunderstorms as a cold front approaches.
Otherwise, significant restrictions not expected.
-- End Changed Discussion --

&&

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

&&

$$

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