St. Andrews, South Carolina 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

807
FXUS62 KCAE 040545
AFDCAE

Area Forecast Discussion
National Weather Service Columbia SC
1245 AM EST Wed Dec 4 2024

.SYNOPSIS...
An arctic air mass will settle over the area today with below
normal temperatures likely into Wednesday. Thursday will be
breezy with near normal temperatures before a dry cold front
moves through and temperatures fall again. Forecast confidence
decreases late this weekend and into early next week when a
pattern change may bring a period of unsettled weather to the
region.

&&

.NEAR TERM /UNTIL 6 AM THIS MORNING/...
Key Message(s):

- Unusually cold temperatures though tonight.

Another cold night is in store across the area as a modified
arctic airmass settles into the southeast. While we won`t get
cold enough to reach record levels (which is 16 in both AGS and
CAE), it`ll still be cold enough where your typical cold
protection actions will be appropriate. Early this evening,
temps and dew points are running just a hair above forecast, so
I made a slight adjustment upward to the hourly temp forecast
overnight, but nothing overly noticeable.

&&

.SHORT TERM /6 AM THIS MORNING THROUGH THURSDAY NIGHT/...
Key Message(s):

- Warmer and breezy on Wednesday ahead of next cold front
- Windy and turning colder again by Thursday.

After a very cold start on Wednesday, surface high pressure will
shift offshore as a potent upper low dives southeastward into the
Great Lakes region. This will create a southerly flow to develop
under mostly sunny skies which should support warmer temperatures
with highs in the upper 40s to mid 50s, although still below normal.

The upper trough will dig further southeast across the Ohio Valley
into New England Wednesday night into Thursday which will push a
cold front through the forecast area Thursday afternoon into
evening. Ahead of the approaching frontal boundary, warm advection
and a mixed boundary layer should support milder overnight lows,
likely occurring early around midnight Wednesday night in the mid to
upper 30s with temperatures likely rising into the 40s during the
predawn hours Thursday. Guidance suggests a strong 850mb jet around
50-60 knots and ensemble situational awareness table (ESAT) shows
anomalously strong, 99th percentile 700/850mb winds, so expect
breezy conditions Wednesday night continuing into the day Thursday
as the cold front approaches. A Lake Wind Advisory is probably going
to be needed but a wind advisory cannot be ruled out although
confidence is not high enough at this time that criteria winds will
be mixing to the surface.

Moisture will be increasing ahead of the frontal boundary with PWATs
rising to around 0.6-0.7 inches but forcing along the front is
limited and west/northwesterly flow quickly develops with
downsloping flow which will limit rainfall chances. Hi-res guidance
suggests measurable rainfall will remain to our west and will
continue with a dry forecast at this time. Temperatures ahead of the
front should be mild with highs ranging from the upper 50s west to
the lower 60s east. Strong cold advection expected Thursday night as
another strong high pressure system builds into the forecast area.
Expect lows to be in the lower to mid 20s.

&&

.LONG TERM /FRIDAY THROUGH TUESDAY/...
Key Message(s):

- Dry weather and warming trend Friday into Sunday.
- Increasing chances of rain early next week though details remain
uncertain.

Despite some uncertainty in guidance during this period, a
transition to a more unsettled pattern appears likely late weekend
into early next week.

At the beginning of the extended forecast period ensemble consensus
depicts a split flow upper level pattern with an upper trough over
New England and the Great Lakes region and a cutoff low over AZ/NM
with upper level ridging along the west coast. Surface high pressure
will build over the Carolinas on Friday with cold advection
returning temperatures to below normal again with highs expected in
the 40s. A gradual warming trend is expected over the weekend as
500mb heights remain northwesterly on Saturday but back more
westerly by Sunday combined with air mass modification and the
surface high shifting offshore by Sunday allowing for southerly low
level flow. Highs are expected to be about a category warmer each
day over the weekend with highs in the low to mid 50s on Saturday
and mid 50s to around 60 on Sunday. A dry forecast is expected to
continue through Sunday.

More uncertainty with the forecast early next week as GEFS/ENS
ensembles differ on the timing of how the cutoff low over the
southwest is picked up and evolves in the overall upper flow pattern
with the GEFS being more progressive and less amplified compared to
the ENS. The resulting sensible weather for our area is increased
chances of rain early next week but timing remains uncertain as does
the amount of potential rainfall. Will continue to show increasing
chances of rain early next week but keep pops in the chance range
this far out until details are better resolved. Higher confidence in
warmer above normal temperatures Monday and Tuesday with a continued
warming trend as southerly/southwesterly flow is expected.

&&

.AVIATION /06Z WEDNESDAY THROUGH SUNDAY/...
VFR conditions continue through the TAF period.

Dry high pressure ridge over the area this morning will move to
the southeast by this afternoon. The pressure gradient will
tighten a bit by the afternoon and southwest winds will
increase to 10 to 15 knots with perhaps a few higher gusts. Mid
level moisture is expected to increase by 00z Thursday ahead of
a frontal boundary moving east of the Mississippi river.
Southwest winds will continue into the evening.


EXTENDED AVIATION OUTLOOK...Low-level wind shear possible
Wednesday night ahead of a cold front. Otherwise, no significant
impacts to aviation expected.

&&

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

&&

$$