Area Forecast Discussion
Issued by NWS Columbia, SC

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
FXUS62 KCAE 181908

Area Forecast Discussion
National Weather Service Columbia SC
308 PM EDT Sun Mar 18 2018

A weak cold front will stall just south of the area tonight.
The front will become a warm front ahead of approaching low
pressure Monday lifting north through the region Monday night.
This low pressure will linger in the area through Wednesday
keeping weather unsettled.


Cold front has shifted south of the forecast area, though the
cooler air is lagging a bit with Augusta at 78 degrees as of
2pm. The front will continue to shift south and stall across
south central GA overnight. Light northeast to easterly winds
expected overnight.

An approaching upper disturbance moving along the Gulf Coast
states will bring increasing upper support combined with
developing isentropic lift over the cooler air mass north of the
stalled front. This will result in pops increasing from
southwest to northeast across the forecast area after 00z-03z
into the likely and categorical range by 09z most of the
forecast area. Overall rainfall amounts are not expected to be
all that much and will have a gradient from higher amounts CSRA
(around a quarter inch) to lower amounts northern Midlands (a
tenth of an inch or less).

Overnight lows will be near to above normal after a warm day and
increasing cloud cover limiting radiational cooling. Lows should
range from the upper 40s northern Midlands where clouds expected
to arrive latest, to the mid 50s in the CSRA.


On Monday, surface high pressure will wedge into the region. An
east or southeasterly low level flow will allow plenty of
moisture to advect into the region, resulting in mostly cloudy
skies. Precipitation timing is a little tough to pin down, but
the highest chances appear to be around daybreak when the
strongest isentropic ascent will be ongoing. As the day
progresses, have maintained chance or likely rain chances, but
with little upper level support expect it to be rather light in
intensity with little in the way of QPF. Some elevated
instability could result in isolated thunderstorms. There will
be a strong north-south gradient in temperatures, with highs
ranging from around 60 in the northern Midlands to around 70 in
the CSRA.

Monday night, a warm front will lift northward into the area.
Models are hinting at instability increasing from the south
during the evening, with the potential for a line of convection
to move through from the northwest during the late evening and
early overnight hours. Most of the CSRA remains in a slight
risk for severe thunderstorms, with a marginal risk extending
well into the central Midlands. The primary severe weather
threats will be damaging wind gusts and perhaps an isolated
tornado due to fairly good helicity values.

Convection lingers across the eastern Midlands east of a wave of
low pressure on Tuesday, where likely PoPs are maintained in the
forecast. Instability looks favorable enough that a few strong
or severe thunderstorms will be possible across that portion of
the forecast area. Later in the day, some increasing upper
level support/short wave energy could result in isolated to
scattered showers farther west across the remainder of the
forecast area. Temperatures could warm significant ahead of a
cold front approaching from the west. Expect low to mid 70s most
areas, but with some clearing ahead of the front even warmer
temperatures are possible.

Cold front will move through Tuesday night, with plenty of
moisture lingering behind it. Mostly cloudy skies and showers
will be likely across most area as winds shift northerly.


Conditions will remain unsettled into Wednesday, with a moist
northerly flow in place. Upper level troughing over the area
and some short wave disturbance moving through will result in
rain chances ranging from likely across the northern Midlands to
slight chance in the CSRA. Temperatures will be significantly
cooler, with highs in the 50s.

Upper level heights will gradually rise across the region late
in the week as the upper trough pushes off the east coast and a
ridge builds from the west. Some differences arise among the
operational GFS/ECMWF models by Saturday as the ECMWF holds the
upper ridge longer and keeps the next shortwave trough and
associated front well west of the area while the GFS brings
another trough across the upper Midwest flattening the ridge and
allowing a cold front and associated moisture to push into the

Temperatures will be below normal with moderation late in the
period. Temperature near freezing may occur Wednesday night and
Thursday night.


VFR conditions this afternoon into evening with mainly diurnal
cumulus dissipating with sunset and higher clouds arriving by
sunset. Light northeasterly winds will persist across the region
in the wake of a frontal boundary that will become stalled just
south of the area. An approaching upper disturbance and
increasing west-southwesterly flow aloft will creating
isentropic lift over the frontal boundary and expect cigs to
lower this evening and fall into MVFR range by 06z-08z then drop
to IFR by 12z. Light rain expected to overspread the area from
southwest to northeast as well and expect vsbys to fall into
MVFR range or possibly lower. Somewhat low confidence in how low
cigs/vis will go as HRRR is not really showing the low clouds or
vsbys while all MOS guidance is in agreement with IFR or lower
conditions developing. Given the pattern leaned toward the more
pessimistic MOS but did not go quite as low. Restrictions
expected to remain through the end of the forecast period though
there may be some improvement very late in the forecast.

EXTENDED AVIATION OUTLOOK...Chance of showers Monday with
deteriorating CIGs. Chance of thunderstorms Monday night,
possibly severe. Flight restrictions possible through Wednesday
with scattered to numerous showers across the area.




$$ is the U.S. government's official web portal to all federal, state and local government web resources and services.