Area Forecast Discussion
Issued by NWS Columbia, SC

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FXUS62 KCAE 111716

Area Forecast Discussion
National Weather Service Columbia SC
116 PM EDT Fri Aug 11 2017

A moist atmosphere will remain over the region through much of
the forecast period. A dissipating frontal boundary remains
over the area as another front approaches this weekend. This
will bring unsettled weather and chances for showers and
thunderstorms through mid next week. Expect near or slightly
below normal max temps.


A broad upper level trough remains over the eastern US. Weak
southerly 850 mb flow over the Southeast will lead to
increasing moisture. At the surface, the sea-breeze and outflows
from convection in the Upstate will serve as triggers for
convection this afternoon. A weak upper disturbance will move
through the Upstate this afternoon/evening and may help support
ongoing showers and thunderstorms moving to the NE. The best
chances for showers and thunderstorms will be across the western
Midlands and along the sea-breeze to the east. Models suggest
the sea-breeze convection should dissipate late this afternoon,
while the showers to the west linger through the evening as the
shortwave moves through.

The potential for severe weather today is limited. Cloud cover
will keep low level lapse rates weak today. A moist
environmental profile will also limit the threat of downburst
winds. PWAT values above 2 inches, expected slow storm motion
and tall, skinny forecast CAPE profiles suggest an increased
threat for isolated flash flooding in the stronger convection
this afternoon.

Tonight, abundant low level moisture over the region will
support stratus development. A stronger nocturnal jet tonight
indicates a better chance for widespread low clouds rather than
fog. Overnight lows will be in the low to mid 70s.


Weak upper troughiness to remain over the E CONUS. A surface
boundary appears will shift south into the region late Sat/Sat
nt, while a weak surface low moves N to NE near the coastal
plain ahead of it Fri nt/Sat. A moist atmosphere will remain in
place. Used a model blend on POPS, which favors POPs eastern
areas due to track of low and better moisture setting up there
with PW up to 2.2 inches.


Upper troughiness to remain over the E CONUS. Though some
uncertainty, some indications that the surface front may slip
towards the southern forecast area Sunday, and move back a little
farther north Monday. GFS indicating significant upper energy coming
through Mon/Tue, with a surface wave moving east across our FA along
the stalled front. Model consensus POPs in the good chance to likely
range. Some indications that the front could slip just to our south
by Wed/Thu.


A stalled frontal boundary has become somewhat diffuse across
the region but abundant low level moisture remains in place. The
pressure gradient will remain weak with winds mainly light and
variable. Expect scattered showers and a few thunderstorms to
develop this afternoon with moderate instability and high
atmospheric moisture content. No thunderstorms in TAFs at this
point because of the uncertainty in coverage. Showers may
continue into the evening with a weak shortwave moving through
the Upstate.

Tonight, abundant low level moisture remains over the SE. A
stronger nocturnal jet with wind speed values around 20 kts
should inhibit dense fog development. However MVFR ceiling
restrictions due to low stratus appear likely with periods of
IFR/LIFR possible early Saturday morning.

EXTENDED AVIATION OUTLOOK...Widespread restrictions are likely
especially due to stratus and fog during the late nights and
mornings. There will be scattered to numerous showers and
thunderstorms especially during the afternoons and evenings
through the weekend.




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