Area Forecast Discussion
Issued by NWS Columbia, SC

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FXUS62 KCAE 271838

Area Forecast Discussion
National Weather Service Columbia SC
238 PM EDT Tue Oct 27 2020

Weak high pressure across the area today with warming
temperatures. Tropical moisture is expected to affect our region
Wednesday night through Thursday night with a chance of showers
and thunderstorms. Dry and cooler weather expected over the
weekend as a strong cold front moves through the area.


Upper lever ridge extending into the Carolinas, with a
stationary front to our northeast. With surface high pressure still
in place, clouds lingering in the CSRA and western SC should burn
off later this afternoon as mid level drying takes place. Expecting
temperatures to quickly rise to the lower 80s and upper 70s despite
the extensive cloud coverage earlier this afternoon.

The ridge will weaken overnight, with some of Hurricane Zeta`s
moisture moving across upper and central Georgia. High res models
showed some precip to make it to the CSRA, so bumped up PoPs to
slight chance by daybreak. However, not really expecting much to
fall. Clouds from tropical moisture will be moving in from the west
overnight. As the pressure gradient tightens expecting winds to stay
up near the CSRA, reducing the chances for the same dense fog
formation as this morning. Will see a bit more radiational cooling
in the Midlands, as well as more subsidence, so put patchy fog in
starting around 10z. Dew points will increase slightly overnight so
expecting warmer temperatures. Low to mid 60s.


Wednesday and Wednesday night...moisture will increase Wednesday and
Wednesday night as Hurricane Zeta moves through the central Gulf
coast and Deep South. Weak ridging extending into area from offshore
should result in deeper moisture remaining mainly west of the area.
There should be enough moisture flux and isentropic lift on the
western periphery of the ridge to result in a few showers mainly in
the afternoon and overnight. Prefer blended guidance with high
temperatures from the mid 70s across the Piedmont/Western Midlands
to the lower 80s south and east. Clouds and wind will keep overnight
lows in the mid 60s to around 70 degrees.

Thursday and Thursday night...There remains potential impacts
from the remnants of Hurricane Zeta during this period. The models
remain consistent with a low threat for heavy rain across our area.
However, there remains an elevated risk for severe thunderstorms:

1) There appears to be a threat of tornadoes as the remnants of
the tropical cyclone approach and move through north Georgia
and the Appalachian region early in the day. Hodographs are
quite large across the Piedmont and west Midlands. Instability
may be a limiting factor but kinematic fields looks very strong
especially in the west Midlands and Upstate SC. If the track is
a little further east, this threat will increase.

2) A deep upper low and surface extra-tropical cyclone will be
approaching the region from the west into the evening to provide
strong synoptic lift. More unstable air may spread northeast
ahead of its trailing cold front late in the day. Thunderstorms,
some strong are possible. Breezy or evening windy conditions
possible through the afternoon into the evening. Showers should
diminish quickly during the evening from southwest to northeast with
dry conditions and diminishing winds expected after midnight.


Dry weather is foreseen for the long term. Mid level trough and
associated cold front will be moving off the coast Friday morning.
Surface high pressure along with weak upper ridging will spread dry
air across the region Friday through Saturday night. A dry re-
enforcing front moves through the region Sunday. Moisture appears to
be limited, so will continue a dry forecast. High pressure returns
Monday and Tuesday. Near normal temperatures in the upper 60s and
lower 70s are forecast for Friday. Cooler than normal temperatures
will be felt over the weekend into early next weak as an amplified
upper trough sets up off the eastern seaboard by Monday. Highs
will be mostly in the 60s with lows in the upper 30s and 40s.


VFR conditions this afternoon/tonight, with more visibility and
ceiling restrictions in the morning.

Low stratus at Augusta terminals expected to become VFR shortly,
with clear skies and some cumulus this afternoon. Winds variable at
4kt. Tonight, the threat of vis/cig restrictions comes back as
moisture builds overnight. However, with high pressure weakening,
not expecting the same density of fog as this morning. MVFR/IFR
conditions probable at all locations until shortly after sunrise.
Slight chance of some weak showers in the morning at AGS/DNL as
Zeta`s moisture field moves northward.

EXTENDED AVIATION OUTLOOK...The remnants of a tropical system
Zeta passing northwest of the area is expected to bring
restrictions Wednesday through Thursday night. Gusty winds
possible Friday behind the departing system.




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