100
FXUS62 KCAE 261831
AFDCAE

Area Forecast Discussion
National Weather Service Columbia SC
231 PM 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 will return for Wednesday
through Friday with the next chance of showers and thunderstorms
returning Saturday and Sunday.

&&

.NEAR TERM /THROUGH TONIGHT/...
A series of shortwave troughs and associated MCS`s will push through
the area over next 18 hours or so ahead of the deepening low over
the central US. Ridging aloft remains in place over much of the
eastern US, with the primary axis sitting just to our northwest, so
northwest mid-level flow is present over SC and GA. The first of
these MCS`s that will come at least close to our area is developing
over TN as 18z and will steadily slide east before turning
southeasterly this evening as it rounds the ridge axis. Ahead of
this, a generally unstable airmass will develop with somewhere
between 1500-2500 j/kg MU CAPE will develop, but only around 1000
j/kg ML CAPE thanks to pervasive dry air at low-mid levels. The
tightening height gradient aloft as the primary trough axis pushes
southeast will increase mid-level flow (40-50 knots at 500mb) enough
to provide modest deep layer shear this afternoon and into the
evening. But given the lack of forcing, mid-level entrainment, and
noticeable dry air below 700mb, airmass thunderstorms this afternoon
will remain very isolated with only a few expected to initiate prior
to 22-23z; however, any deep convection that does develop and become
established will have a fairly high probability of producing severe
weather given the dry mid-levels and modest shear. Convective
coverage will likely increase somewhat, especially across northern
SC, this evening as the first of the MCS`s moves it way southeast
out of the Appalachians. The environment will still remain favorable
for severe thunderstorms given the diurnal timing and any organized
cold pool should be plenty to trigger convection until diurnal
instability wanes. Hi-res guidance is mixed on exactly how far south
the convection will make it (mostly staying over NC) but most of the
HREF members have any at least some thunderstorm activity moving
across northern SC between 23-02z. So PoP`s increase, mainly from
Columbia north into the northern Midlands, during this timeframe.

The next MCS in the series is progged to push towards the region
late tonight into Monday morning. Again most of the HREF members
develop this MCS within the prefrontal trough of the primary trough
and then send it southeast over the Appalachians between 06-10z. The
severe threat with this MCS would be very limited given the diurnal
timing, but some gusty winds and heavy rain would remain possible.
This MCS however will play a role in complicating the severe threat
for the rest of the day Monday.

&&

.SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
The active weather pattern will continue Monday into Monday
night as low pressure tracks through the central Great Lakes and
pushes a cold front through the SE US. Although there is high
confidence the front will be moving through the region
confidence is currently low as to storm development and
coverage with much surrounding the convection and movement of
the MCS tonight. The MCS is expected to be moving toward Upstate
SC tonight however models continue to weaken the remains as it
crosses the mountains. Model soundings indicate some CIN in the
area Monday morning along with low level lapse rates under 5.5
C/Km and 850 mb winds turning more westerly. Even though
thunderstorms may not form in the morning and early afternoon
hours the front will still be west of the area and act as a
focusing mechanism for convection during the late afternoon and
evening hours as it crosses the region. CAPE during the
afternoon and early evening ahead of the front will be around
2000 J/Kg or higher with pwat values aoa 1.75 inches and DCAPE
around 1000 J/Kg. Divergence aloft during the late afternoon and
evening will be weak with winds at 35 kft expected to be a
maximum of 60 knots. With the potential for damaging winds and
hail SPC has expanded the slight risk to include the entire
forecast area tomorrow. High temperatures tomorrow will be in
the upper 80s to low 90s with lows Monday night in the mid 60s
to around 70.

Tuesday and Tuesday night are expected to be convection free as
the front will be offshore and high pressure along with drier
air will be building into the region. The upper level trough
will remain over the eastern US however with pwat values
dropping to under 1 inch by midday and 850-500 mb lapse rates
under 6.0 C/Km do not expect much in the way cloudiness and any
cumulus which develop will be vertically limited. Highs Tuesday
afternoon will be in the upper 80s to low 90s with lows in the
low to mid 60s.

&&

.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
The upper level pattern will remain highly amplified and
progressive through the long term with changing conditions
across the region. Upper level trough will remain over the
eastern US through Friday while the surface will be controlled
by high pressure and drier air. This will keep partly clear
skies over the area with increasing clouds Thursday as a mid
level disturbance moves through the region. This feature will be
quickly ushered offshore as the upper level trough axis swings
through the region Friday afternoon. High pressure will be
moving across the region Saturday with increasing moisture
Saturday afternoon as return flow from the Gulf begins. By
Sunday the high will be east of the region with a trough of low
pressure moving into the area and possibly becoming a focusing
mechanism for convection. Temperatures through the long term
will be near to slightly below normal.

&&

.AVIATION /18Z SUNDAY THROUGH FRIDAY/...
VFR conditions expected outside of any shower-storm activity
this evening and overnight.

Relatively dry air over the region will help limit how dense the cu
field will develop this afternoon and evening. Winds will continue
to remain weak this afternoon, from southwest up to 10 knots. Shower
and storm potential will slowly increase after roughly 21z with a
few pop up thunderstorms possible, but not enough confidence for a
TAF mention at this time. More organized convection is possible
closer to 00z at CAE and CUB as a system slides to our north, but
again confidence is still too low for a direct mention so only went
with VCSH at those sites for now. There will be a lull in shower-
storm activity after roughly 03z across the area before another wave
of showers-storms possibly moves through between 06-12z Monday.


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

&&

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

&&

$$