-- Discussion containing changed information from previous version are highlighted. --
864
FXUS62 KCAE 240603
AFDCAE

Area Forecast Discussion
National Weather Service Columbia SC
203 AM EDT Fri May 24 2024

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

&&

.NEAR TERM /UNTIL 7 AM THIS MORNING/...
Hi-res guidance continues to highlight the potential for
convection moving into our area from the west during the evening
hours. Sufficient instability remains in place to maintain
isolated convection favoring the Northern Midlands. Chances of
severe weather appear to be low but non-zero with relatively
high DCAPE values in excess of 800 J/kg supporting an isolated
damaging wind threat. Expect any lingering convection to
diminish after midnight. Overnight lows will likely be mild in
the upper 60s to around 70 degrees with limited radiational
cooling due to convective debris cloud cover and a 20-25 knot
low level jet.

&&

.SHORT TERM /7 AM THIS MORNING THROUGH 6 PM SATURDAY/...
The first shortwave trough in a series of disturbances will push
across the area Friday with some distinct height falls and broad
upper level diffluence developing. Deep moisture with PWAT`s over
1.5" and sufficient surface heating during the day will produce
moderate-high instability throughout the afternoon; HREF and GEFS
members prog somewhere between 1000-1500 j/kg ML CAPE developing in
the afternoon and evening with a deep mixed boundary layer. The
shortwave aloft will produce some impetus for some weak shear but
generally less than 30 knots in 0-6km layer. HREF and MPAS ensemble
members are consistent in producing widespread convection by roughly
21z, but the storm features depicted are representative of the
environment with somewhat weak updraft velocities and UH. So the
severe potential Friday looks to be more of quantity over quality
event with numerous weak convective cells and a few isolated severe
cells; damaging winds will be the primary threat given the modest
dry air aloft driving up DCAPE and hail a secondary threat given the
lack of storm organization.

As we move into Saturday, the shortwave and larger scale trough to
our north will move east and on the backside, force some northwest
flow below 500mb over our area. This will help drop PWAT`s slightly
and increase dry air aloft as weak ridging also builds in. Moderate-
high instability however is expected to develop despite this, with
between 1500-2000 j/kg ML CAPE developing in afternoon; GEFS and ECE
probs of greater than 1000 j/kg are 80-90%. Convection will
generally struggle to initiate in this environment based the forecast
soundings and model depictions, but any storms that are able to get
established would have a high probability of producing damaging winds
given the aggressive entrainment aloft and deep boundary layer
mixing. So relative to Friday, convective coverage will be less
widespread but each individual storm will have a higher likelihood of
producing severe weather and the upper ceiling on wind speeds-
damage is higher.

&&

.LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...
A deep mid-level trough will slide eastward and strengthen over
the Great Lakes as we move into Sunday, helping weaken our
ridging aloft as heights begin to steadily fall. Moisture is
progged to return in the GEFS and ECE members with nearly
unanimous agreement in PWAT`s bumping back above 1.5".
Consequently the GEFS and ECE members then show sufficient
instability developing into the afternoon and evening thanks to
strong heating and the weak height falls aloft. There will be
not a strong synoptic mechanism for initiating convection on
Sunday however, so much like the previous few days, some
isolated-scattered thunderstorms will pop by the evening. By
Monday however, a secondary shortwave will force the primary
upper level trough axis eastward and help push an associated
cold front towards our area. Heights falls aloft and moderate-
high instability will likely develop ahead of any surface front
in the afternoon and the potential exists for a scattered-
widespread severe threat; the combination of synoptic forcing,
strong mid-deep layer shear, and robust instability all could
line up Monday afternoon but there are some potential issues
related to the diurnal timing of the front. Beyond Monday, drier
air should steadily fill in behind Monday`s trough and reduce
diurnal convective activity chances for the middle of next week.

&&

.AVIATION /06Z FRIDAY THROUGH TUESDAY/...
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VFR conditions generally expected during this forecast period.

Shower and storm activity ended up being few and far between
yesterday and as a result, low level moisture will be lacking to
support any stratus developing across northern portions of the
forecast area. Blended guidance has trended towards VFR
conditions at all terminals through the early morning hours. Do
expect scattered showers and thunderstorms to develop across the
area this afternoon into this evening but confidence is not high
enough to include TS in the TAF at this point. Winds increase
out of the west late morning into afternoon between 5 to 10
knots.

EXTENDED AVIATION OUTLOOK...Restrictions possible at times
through early next week in afternoon and evening showers and
thunderstorms.
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&&

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

&&

$$