Area Forecast Discussion
Issued by NWS Columbia, SC

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579
FXUS62 KCAE 231826
AFDCAE

Area Forecast Discussion
National Weather Service Columbia SC
226 PM EDT Wed Aug 23 2017

.SYNOPSIS...
An approaching cold front will cross the area tonight into
Thursday. High pressure will build into the region for the end
of the week...bringing a cooler and drier airmass. Tropical
activity could affect the region next week.

&&

.NEAR TERM /THROUGH TONIGHT/...
Regional radar as of 18Z shows a few newly developed isolated
showers across the forecast area while a majority of the shower
and thunderstorm activity remains to our northwest. Satellite
imagery shows a substantial cumulus field has developed. Surface
analysis reveals the frontal boundary in the Upstate of South
Carolina and northern Georgia currently. The front will continue
to approach the area this afternoon and move into the area
tonight bringing increased chances of showers and thunderstorms.
The northeastern portion of the area remains outlooked by the
SPC in a marginal risk. Strong winds appear to be the primary
threat given DCAPE values up to 1300 J/kg in the northeastern
portion of the area. 0-6km shear is relatively weak so expect
disorganized pulse convection. Instability appears moderate.
Precipitable water values currently range from around 1.6 to 1.9
inches. High resolution models keep a majority of the activity
near the Pee Dee region, so have kept the highest POPS there.
Activity will continue into tonight given the frontal boundary
in the region. Temperatures are on track this afternoon and are
expected to max out around the middle 90s. Overnight low
temperatures in the lower to middle 70s.

&&

.SHORT TERM /THURSDAY THROUGH THURSDAY NIGHT/...
Thursday morning, the cold front will be over the eastern Midlands
with dry air pushing from the west. Recent model runs have pushed
the dry air in more quickly, therefore lowered PoPs in the western
Forecast Area (FA). There is some uncertainty in the location of the
front for the rest of the day. Most models push the front, and
develop afternoon convection, east of the FA. The GFS develops a
weak low on the boundary which brings moisture back into the
Pee Dee. The amount of moisture advection seems overdone,
therefore favored a drier forecast. The best chance for
thunderstorms will be in the eastern FA in the early afternoon
as a shortwave moves over. Dry mid-level air would indicate a
downburst wind threat if convection develops.

Expect near normal temperatures in the mid 80s to lower 90s for
Thursday with lows in the upper 60s and lower 70s Thursday
night.

&&

.LONG TERM /FRIDAY THROUGH TUESDAY/...
Dry high pressure ridging into the mid-Atlantic will dominate Friday
and Saturday. NE flow will bring near normal temperatures to
the FA. A low pressure system may develop along the old frontal
boundary off the coast. Moisture advection over the surface
ridge and a broad upper level trough will bring back chances for
showers and thunderstorms Sunday into early next week. Moisture
advection out of the Gulf of Mexico associated with tropical
depression Harvey will bring increasing rain chances near the
end of the extended period.

&&

.AVIATION /18Z WEDNESDAY THROUGH MONDAY/...
A cold front currently draped along the Appalachian region will
move into the forecast area tonight. Ahead of the front, shower
and thunderstorm activity is expected to develop later this
afternoon and continue into tonight. Most of the activity is
expected to be north of the terminals, closer to the Pee Dee
region. Will continue to handle with VCTS until better certainty
in the timing of terminal impacts. Strong winds will be biggest
threat with gusts around 30 kts possible. Some of the model
guidance is indicating potential for fog/stratus developing
during the early morning hours on Thursday. A 15-20 knot low
level jet and drier air filtering into the area in the wake of
the front should help reduce fog potential. Confidence is too
low to include in the current TAF issuance. The front will be in
the eastern Midlands Thursday morning promoting a chance of
showers and thunderstorms mainly east toward the end of the TAF
period.

EXTENDED AVIATION OUTLOOK...No significant restrictions to
aviation expected through Sunday.

&&

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

&&

$$



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