128
FXUS62 KCAE 231441
AFDCAE

Area Forecast Discussion
National Weather Service Columbia SC
1041 AM EDT Thu May 23 2024

.SYNOPSIS...
A frontal boundary will approach the region Thursday night and
Friday and is expected to stall near the area resulting in
chances of showers and thunderstorms Friday through Sunday.
Another more organized system is expected to be crossing the
eastern US Monday and Tuesday with additional thunderstorms.
Drier weather is expected to return Wednesday.

&&

.NEAR TERM /THROUGH TONIGHT/...

Satellite imagery showing mostly clear skies across the forecast
area with mainly just some patchy higher clouds moving overhead
in the west southwesterly flow. This is allowing temperatures to
rise quickly this morning with many locations already at or
above 80 degrees at 14z. GOES derived PWATs a bit higher than
HRRR initialized at around 1.5 inches and dewpoints are in the
upper 60s. Shortwave energy moving through the MS/OH Valleys has
flattened the upper ridge that was overhead on Wednesday while a
frontal boundary remains northwest of the region across southern
Ohio into southern Missouri.

Overall thoughts on the forecast today remain generally
unchanged, with the expectation of convection initiating to our
west over the TN Valley in vicinity of frontal boundary with
some upper level forcing and then moving towards the forecast
area late this afternoon and into the northern Midlands this
evening. Latest HRRR has trended a bit slower and more scattered
in nature with the convection and little expected over our
forecast area through mid afternoon due to a lack of forcing
and low level convergence features despite moderate instability
forecast with MLCAPE values around 1000 J/kg. Some drier air
aloft and DCAPE values approaching 1000 J/kg should support
isolated strong to severe thunderstorm threat of damaging wind
gusts and large hail. SPC has the northern Midlands outlooked in
a marginal risk for severe weather. Temperatures today should be
similar or slightly warmer than yesterday with highs in the
upper 80s to lower 90s.

Convection may linger past midnight across the northern Midlands
but any severe threat should diminish by late evening as the
atmosphere restabilizes. Cloud cover should limit radiational
cooling overnight and expect mild lows in the upper 60s to
around 70 degrees.

&&

.SHORT TERM /FRIDAY THROUGH FRIDAY NIGHT/...
Pattern will be becoming more conducive to convective activity as
the weak frontal boundary stalled just north of the area becomes a
focusing mechanism and several short waves begin a progression
through the region. With southerly flow at the surface continuing to
slowly advect Gulf moisture into the region pwat values will be
increasing with the AGS area reaching 1.5 inches midday Friday and
the central Midlands by mid evening. With plenty of instability the
main question will be a trigger mechanism and divergence aloft. With
the upper level ridge being flattened by the expected short waves
expect the best potential for a trigger to be over the northern
Midlands with lowering chances in the central Midlands through the
CSRA. Once convection initiates expect outflow boundaries to be
sufficient to trigger additional thunderstorms to the south as there
will be plenty of instability however winds aloft and any divergence
will be limited. SPC outlook has almost the entire forecast area in
a marginal risk and agree with this as some dry air will persist in
the mid levels with DCAPE values ranging from 800-1200 J/Kg across
the area Friday into Friday night. With this in mind have adjusted
pops up slightly into the high chance range north and tapered to
slight chance in the southern CSRA. Much of the convection appears
to initiate during the mid afternoon and linger into the late
evening to early overnight hours especially across the northern
Midlands which will be closer to the surface boundary. High
temperatures Friday will be in the upper 80s to low 90s with
overnight lows in the mid to upper 60s.

Saturday and Saturday night appear to be another day of potential
for convection however in the upper levels weak ridging will be
pushing into the region. Much of this time frame will depend on if
there are any remains of the surface boundary across the area
however this currently looks unlikely due to convection Friday. This
will leave the area without a trigger mechanism and winds in the mid
to upper levels will be weakening with height. There will be plenty
of instability on Saturday so breaks in the clouds allowing for
strong heating should be enough to initiate convection with outflow
boundaries or weak short waves crossing the area aiding in spreading
the convection across the area. DCAPE values will again with most
models agreeing on values between 1100 and 1500 J/Kg. This again
will be a period which needs to be monitored as storms which develop
could become strong to severe. Highest pops will again be across the
northern and eastern portions of the forecast area where the best
upper level support will be. High temperatures Saturday will be in
the low 90s with lows Saturday night in the upper 60s to around
70.

&&

.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
The active pattern will continue with upper level ridging trying
to return to the SE US however another weak surface boundary
will be stretched across the region. Much of the convective
potential for Sunday will depend on where the surface boundary
will be and any remaining short waves crossing the region
however with plenty of instability expect strong heating to
again initiate cells and with DCAPE values once again AOA 1000
J/Kg outflows from thunderstorms should be plenty to generate
new cells. The main focus of the long term remains the Monday
and Tuesday period as low pressure moves into the central Great
Lakes with an upper level trough digging into the mid MS Valley
Monday and through the eastern US Tuesday. Models have
differences in timing and strength of this feature with the GFS
being more aggressive while the ECMWF takes a broader and more
progressive approach. With the anticipated instability and
potential upper level support will continue to monitor the
potential for Monday and Tuesday as thunderstorms which develop
could be strong. As the upper trough axis moves offshore Tuesday
night drier air along with weak high pressure will begin
building into the region. Temperatures will be above normal
Sunday the gradually cool to slightly below normal on Wednesday.

&&

.AVIATION /15Z THURSDAY THROUGH MONDAY/...
VFR conditions generally expected during this forecast period.

High clouds passing over the terminals early this morning with
generally light and variable winds. A bit higher moisture today
will lead to widespread cumulus around 5kft. As surface high
pressure shifts offshore, winds will be out of the SW generally
between 5 to 10 knots. This evening, a shortwave will move north
of the terminals with low chances for convection to impact the
terminals so have left out any mention of showers or storms in
the TAF but will be worth monitoring with future updates.

EXTENDED AVIATION OUTLOOK...Low probability of restrictions
during the late week period into the weekend from afternoon and
evening convection.

&&

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

&&

$$