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000
FXUS62 KCAE 191309
AFDCAE

Area Forecast Discussion
National Weather Service Columbia SC
909 AM EDT Fri Apr 19 2024

.SYNOPSIS...
Moisture increases Friday and Saturday as a cold front moves
into the area. With strong heating, diurnally driven isolated
showers and thunderstorms are expected to develop. The front
becomes stationary near or slightly south of the area Sunday.
Deep moisture and lift across the area will result in numerous
showers Sunday and Sunday night. Temperatures Sunday and Monday
are expected to be well below normal in the 60s.

&&

.NEAR TERM /THROUGH TONIGHT/...
9 AM Update: A ling of showers with embedded thunderstorms has
developed over the upper CSRA. This line is heading east as the
shortwave mentioned in the early-morning discussion continues
moving through the larger scale pattern. SPC analysis shows some
MUCAPE in the 200-300 J/kg range with some enough shear that
will likely keep this activity going for at least the next
couple of hours or so. Not expecting anything severe as it is
elevated convection, but brief downpours and some breezy winds
are possible under these showers and storms.


Early-morning discussion: A weak shortwave is moving through
Georgia early this morning with thickening mid-level clouds
pushing into the CSRA. While radar shows some light returns
moving into eastern Georgia, forecast soundings indicate a
fairly significant dry layer in the low levels with much of the
rain likely evaporating before reaching the ground. May get some
light rain or sprinkles in the CSRA early this morning,
however.


In the wake of this shortwave, upper heights are expected to rise
this afternoon into evening which will lead to highs similar to
yesterday, in the mid to upper 80s. This will also work to preclude
convective development with broad subsidence over the forecast area.
Warming temperatures aloft will also limit instability with forecast
soundings trending less impressive than yesterday. Moderate
destabilization still remains possible this evening with HREF probs
of sbCAPE > 1000 J/kg around 70 percent in the western portion of
the forecast area. The most likely location for any storm
development will be along the higher terrain in the Upstate which
will move towards the forecast area by evening and along an area of
enhanced surface convergence associated with a front near the NC/SC
border. As a result, have scattered storms possible across the north
with more isolated activity along and south of I-20. SPC continues
to maintain a marginal risk for severe weather associated with any
storms that do develop. With dry air aloft and strong low level
lapse rates, there remains a risk for isolated damaging wind gusts
and a bit more limited severe hail risk as deep layer shear will be
sufficient for storms to become more organized. With a loss of
daytime heating, storms will likely dissipate before midnight. The
front begins to shift south over the area Friday night into
Saturday morning, although lows remain mild in the low to
mid-60s.

&&

.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
Surface high pressure centered over the Plains states will
build eastward through the day and a frontal boundary will sink
south of the forecast area by 00z Sun. 500mb flow will be zonal
across the region with some confluence due to shortwave energy
moving through the Ohio Valley into the northeast and Mid-
Atlantic states by Saturday evening. Despite above normal PWATs,
expect any showers and convection to hold off until after 18z
with increasing pops late afternoon and overnight as shortwave
energy within the westerly flow moves into the forecast area.
Chances for convection will be related to the location of the
front during the afternoon as surface instability will be
maximized along and south of the boundary while more stable
conditions expected on the cooler side of the boundary. Severe
storms appear unlikely at this time. Max temperatures expected
to range from the upper 70s deeper in the cooler air over the
northern Midlands to upper 80s in the southeastern Midlands and
CSRA closer to the boundary.

Phasing of a digging upper trough over the middle of the
country and a weaker southern stream upper trough will result in
weak surface low development on Sunday which will track
eastward along the Gulf Coast on the stalled surface front.
Widespread rain is expected to develop over the forecast area
with increasing isentropic lift Sunday afternoon. Overall
rainfall amounts are expected to be around a half to three
quarters of an inch. Strengthening low pressure off the coast
should support CAD setup with well below normal max temperatures
expected in the 60s.

&&

.LONG TERM /MONDAY THROUGH THURSDAY/...
An upper trough axis will cross the forecast area on Monday and
quickly shift offshore Monday night. Ensemble mean PWATs are
below normal and drying further through the day which is a
limiting factor for precipitation but enhanced mid level lapse
rates due to 500mb temps around -22C during peak heating may
lead to isolated showers mainly across the eastern Midlands and
lower CSRA. Surface instability is nonexistent with the forecast
area well into the cooler air north of the surface front near
the FL/GA line. Cool wedge conditions may linger into Monday
leading to uncertainty in max temperatures as there is large
spread in the ensemble max T guidance but will lean toward the
cool NBM guidance with highs in the mid 60s.

Tuesday through Thursday should feature a relatively dry air
mass with PWATs below normal (50-90% of normal) and a general
warming trend through the week. A weak frontal boundary is
expected to move through the forecast area on Wednesday but with
limited moisture and northwesterly flow chances of rain are
very low.

&&

.AVIATION /13Z FRIDAY THROUGH TUESDAY/...
VFR conditions anticipated through the TAF period.

A few showers are moving through eastern Georgia and western
South Carolina this morning, a few of which could affect the
terminals through around 15z. However, guidance indicates these
could dissipate, so will continue using amendments to address
this activity. Otherwise, Expect cumulus clouds to develop
after sunrise today with winds increasing out of west between 5
to 10 knots. Isolated thunderstorms could develop late this
afternoon into the evening, although confidence in impacts
specifically at the terminals is low so have not included
mention in the TAFs at this time. Any convection that does occur
is likely to be over by 00z tonight.

EXTENDED AVIATION OUTLOOK...Increasing confidence in
restrictions Sunday into Monday with possible developing wedge
conditions.

&&

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

&&

$$