Area Forecast Discussion
Issued by NWS Columbia, SC

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FXUS62 KCAE 240213

Area Forecast Discussion
National Weather Service Columbia SC
1013 PM EDT Sun Apr 23 2017

An approaching low pressure system will slowly cross the region
tonight through Monday night bringing showers and thunderstorms.
Dry weather and above normal temperatures will return by Wednesday
as high pressure takes control.


Latest analysis continues to show a nearly stationary front
extending from Burke County, GA to Orangeburg to Myrtle Beach.
Closed upper low has developed over northern Alabama with
surface lows over northern and southeast Georgia. Showers and
thunderstorms will persist, and a line of stronger storms with
frequent lightning and heavy rain has developed from near the
Newberry/Fairfield county line south through Columbia and into
Barnwell County. There is still the possibility of isolated
severe weather. A small tornado threat still exists given the
increased helicity values in vicinity of the frontal boundary,
and SPC has kept area outlooked in a slight risk for severe

Precipitable water values peak tonight with anomalously high
values close to 1.75 inches, and with the slow movement of the
convection and orientation which may favor some training there
is the threat of heavy rainfall and possible isolated flooding,
certainly in the urban areas and other typical low lying
locations. A flash flood watch remains in effect through the
day Monday. WPC has part of the area outlooked in a slight risk
of excessive rainfall with 2 to 4 inches expected.

Overnight lows tonight will remain above normal but will
feature a gradient from the mid 50s western Midlands and upper
CSRA to mid 60s eastern Midlands.


The closed upper low to the west will shift eastward across
Georgia to off the southeast coast Monday into Monday night
bringing the coldest 500mb temperatures (as low as -18C) over
the forecast area creating steep lapse rates. Moderate
instability is forecast on Monday and the axis of highest
moisture will pivot over the Midlands and keep chances of rain
high. Heavy rain will remain a threat across the northern and
eastern Midlands with training convection likely. Could see
strong storms once again. SPC has the central and eastern
Midlands outlooked in a marginal risk. Extensive clouds and rain
will hold temperatures in the mid 60s northwest to mid 70s
southeast. The surface low and upper low will lift northeast of
the area Monday night and allow for cool advection resulting in
overnight lows in the mid 50s.


Generally fair weather and a return to well above normal
temperatures expected by the middle of the week.

An upper level ridge will traverse the forecast area on
Wednesday with southerly low level flow which will support warm
advection. A weakening upper trough lifting northeast from the
Mississippi Valley into the Ohio Valley Wednesday night into
Thursday will push a weak cold front into the area by Thursday
night into Friday morning bringing a low chance for rain. The
front will become diffuse Friday into the weekend as the upper
ridge builds back over the southeastern states. Increasing
moisture and instability will bring another chance for diurnal
convection Sunday.

Temperatures during this period will be well above normal with
highs in the mid 80s to around 90 degrees with lows in the 60s.


A nearly stationary front is currently draped across the
southern CSRA and southern Midlands. Showers and thunderstorms
will continue through the night. A line of stronger storms has
developed east of Augusta, and will progress slowly eastward
with frequent lightning and heavy rain. Some severe weather is
still possible. Widespread IFR restrictions likely through
Monday morning, with possible improvement to MVFR by Monday

EXTENDED AVIATION OUTLOOK...CIG restrictions continuing Monday
night/Tuesday morning.


GA...Flash Flood Watch through Monday evening for GAZ040-063>065-
SC...Flash Flood Watch through Monday evening for SCZ015-016-018-


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