St. Andrews, South Carolina 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

861
FXUS62 KCAE 302353
AFDCAE

Area Forecast Discussion
National Weather Service Columbia SC
753 PM EDT Sun Mar 30 2025

.SYNOPSIS...
Showers and a couple rumbles of thunder continue this evening
before diminishing tonight. Widespread thunderstorms, with
severe storms possible Monday afternoon ahead of a cold front
which will cross the region by Monday evening. Well above normal
temperatures expected for late week with possible record highs
next weekend.

&&

.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
Key Message(s):
- Showers and a couple rumbles of thunder continue through the
  area this evening before diminishing tonight.

- Cloud cover keeps overnight low temperatures mild.

Scattered showers and isolated storms continue across the FA
this evening, characterized by an environment with 200-500 J/kg
of ML CAPE, Bulk 0-6km shear under 25 kts, PWAT`s between
1.5-1.6", and some weak moisture convergence toward the southern
CSRA and southern Midlands, driving most of the activity here.
Overall, the thunderstorm risk has diminished considerably as
weak forcing and shear has not allowed organized thunderstorms
to come together and rather we are seeing clusters of rain
showers with some embedded thunder and locally heavier rain at
times. This activity will continue this evening before
diminishing tonight and we likely stay toward the dry side into
Monday morning as a surface low continues across the Upper Great
Lakes, driving a cold front and associated line of
thunderstorms from the upper Ohio Valley down to northern AL/MS.
This line of strong to severe storms will be west of the FA
Monday morning but will push in during the afternoon.
Temperatures into Monday morning should stick to the low to mid
60s as we keep cloud cover and see increasing southwesterly
850mb flow, aiding in continued moisture advection into the
region.

&&

.SHORT TERM /6 AM MONDAY MORNING THROUGH MONDAY NIGHT/...
- Severe thunderstorms are possible Monday afternoon with highest
chances in the CSRA and southern Midlands.

- Damaging winds will be the primary threat but a few storms may
produce a tornado or large hail.

Overview: An upper level, shortwave trough will advance eastward
into the eastern US on Monday. The associated cold front will move
through the Southeastern US through the near term with a line
of convection ahead of it. This line of showers and
thunderstorms will work into the CSRA of GA and central SC in
the afternoon and potentially bring severe thunderstorms and
periods of heavy rain. The primary threat will be damaging winds
from thunderstorms, but we cannot rule out a few storms
producing a tornado or large hail.

Details: The line of convection should be well west of the FA
early Monday morning. Warm, moist advection ahead of the line
will work to destabilize the air mass in GA/SC despite overcast
or mostly cloudy skies to start the day. This should allow mixed
layer CAPE values to climb into the 750 to 1500 J/kg range
during the afternoon. Greater than 50% of SREF members show
mlCAPE higher than 1000 J/kg with some potential for higher
values if clouds clear quicker than expected. As the line of
convection moves into this high theta-e air mass in the
afternoon we expect thunderstorms to strengthen. Effective shear
values of 30 to 40 kts should allow for some organized cells
embedded within in the linear system. Moderate instability and
moderate shear points to an enhanced risk of severe weather
Monday afternoon. That said, the low level shear and helicity
values are on the lower end of thresholds for a significant
tornado threat and instead favor a cold-pool dominated
convective system. Therefore the greatest threat appears to be
damaging winds. However it`s possible that a few storms produce
a tornado across the Deep South including eastern GA and into
the Midlands. The largest threat of tornadoes is expected to be
south of our area but somewhat extending into the CSRA and
southern Midlands where instability and the lower level wind
fields are stronger. The HREF adds confidence to the location of
the greatest tornado threat showing most of the Updraft
Helicity tracks west and south of the FA. If the higher end of
instability projections are realized then some storms may also
produce large hail. Although PWAT values are greater than 200%
of normal, the storm motion should be quick enough to limit the
flash flooding threat to localized areas.

Timing: Guidance varies greatly on the timing of the line of
convection which lowers confidence in this portion of the
forecast. The most likely timing for thunderstorms to enter the
forecast area from the west is between 1 and 4pm, continuing
eastward into the Midlands through the afternoon pushing east in
the evening.

&&

.LONG TERM /TUESDAY THROUGH SUNDAY/...
- Warming temperatures through period with near record high-
  lows possible toward end of week.

- Slight rain chance Wednesday.

Behind Mondays cold front drier air filters in for Tuesday with
PWAT`s most of the day being around 0.50" before strengthening
southerly 850 mb flow aids in bringing moisture back into the FA
late and into Wednesday. Dry weather is expected to prevail
through the day as upper ridging begins to build in with mostly
clear skies and temperatures into the upper 70s to low 80s.
Heading into Wednesday, increasing moisture to around the NAEFS
90th percentile for PWAT`s with strong/deep isentropic lift,
aid in the development of some scattered showers, mainly across
the northern Midlands where the strongest lift will be. The
main limiting factor is upper ridging and subsidence building
in, which may keep chances at bay. With an increasingly moist
airmass and warm advection taking place, an isolated
thunderstorm cannot be ruled out with this activity as at least
half of the EC and GEFS ensemble members show some MUCAPE
developing into the afternoon. Besides these rain chances
temperatures begin to reach well above normal Wednesday.

The rest of the period is characterized by increasing ridging
and subsidence over the eastern CONUS as a deep upper trough
digs in across the western half of the country. This leads to
continuous southwesterly flow aloft and fairly strong surface
high pressure just off the Atlantic coast. A continued warm
advection regime aids in keeping PWAT`s around 160-180 percent
of normal as shown in both the EC ensemble and GEFS members with
temperatures that reach near records for afternoon highs and
for overnight high-low temperatures Thursday through Saturday.
These anomalous temperatures continue to be shown nicely in the
EC`s EFI signal with values around 1 and and a SOT around 1 as
well Thursday through Saturday and maybe even into Sunday. Upper
ridging and subsidence overall look to keep precipitation
chances on the lower side through the period before breaking
down into Sunday.

&&

.AVIATION /00Z MONDAY THROUGH FRIDAY/...
Stratus leading to IFR ceilings expected to develop overnight.
Showers and thunderstorms Monday afternoon leading to possible
restrictions.

High pressure centered offshore with moist southeast-southerly
flow will continue to transport moisture into the area. Radar
showing showers to the east of the terminals this evening. These
showers will move away from the terminals to the northeast.
Isolated light showers in the area are expected to dissipate
early this evening. Ceilings are currently VFR. Guidance
suggests these ceilings will lower to IFR by around 06z tonight
and remain down through Monday morning. The ceilings will rise
slowly but should mix out by 18z Monday with scattered to broken
cumulus into the mid afternoon. Breezy conditions expected in
the afternoon with southwest winds gusting to around 20 kts or a
little higher as a cold front approaches from the west. A line
of showers and thunderstorms may move through the region in the
afternoon/early evening with impacts at the terminals. At this
time, the timing of the line appears to be 19z-21z. A few severe
storms are possible.


EXTENDED AVIATION OUTLOOK...The cold front is expected to move
through the area after 00z Tuesday with lingering possible
showers/restrictions. Early morning low clouds possible
Wednesday and thursday morning.

&&

.FIRE WEATHER...
The South Carolina Forestry Commission has issued a statewide
burn ban until further notice.

Moisture continues to increase today with scattered showers and
thunderstorms expected into this evening. Rain chances continue
on Monday with more showers and thunderstorms expected ahead of
a cold front.

&&

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

&&

$$