Area Forecast Discussion
Issued by NWS Columbia, SC

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FXUS62 KCAE 211037

Area Forecast Discussion
National Weather Service Columbia SC
637 AM EDT Sat Oct 21 2017

Fair weather will continue through early Sunday. A cold front
will bring a chance of showers and thunderstorms Monday and
Tuesday, followed by much cooler temperatures for mid to late
next week.


Satellite showing some patchy fog forming near some area lakes
and rivers, and across portions the southern cwa. Fog expected
to burn off quickly after sunrise. Models continue to show
strong upper ridge centered across the southeast again today.
Center of the surface high will slowly move off the east coast
through the afternoon. Surface winds remain out of the northeast
through the day, then begin to turn more out of the east late
in the afternoon. Airmass still remains dry. Temperatures will
be above normal again this afternoon, with readings in the lower


Tonight: The region will remain along the western periphery of
a strong upper level ridge. At the surface high pressure will
build into the region from off the coast of New England, while a
weak coastal trough forms to the east. There will be an onshore
component to the low-level flow which should aid in advecting
Atlantic moisture into the area. Some stratus could also develop
toward daybreak, especially across the CSRA and southern
Midlands. This should all result in a warmer night, with lows in
the 50s which is above normal.

Sunday and Sunday Night: The upper level pattern will become
more highly amplified as the ridge remains just off the southeast
coast while a deepening trough/closed Low shifts out of the
central/southern Plains and into the lower Mississippi Valley.
At the surface, there is some indication that a weak inverted
trough will lift northwest across the CSRA and southern
Midlands, supporting a chance of rain in those areas by Sunday
afternoon. Rain chances will then begin to increase across most
of the area Sunday night as moisture deepens ahead of the
approaching upper trough. Temperatures on Sunday should reach
highs in the upper 70s to lower 80s, with nighttime temperatures
Sunday night only dropping to lows in the lower to mid 60s most

Monday and Monday Night: The deep upper level trough will
continue to shift eastward toward the area, along with its
associated cold front at the surface. Deep moisture will
overspread the area ahead of these features, with precipitable
water values rising as high as 2 to 2.25 inches. Strong upper
divergence associated with the left exit region of a 90 kt upper
level jet, combined with the deep moisture and strong forcing
for ascent ahead of the cold front will support likely rain
chances in many areas by late Monday, with categorical rain
chances everywhere Monday night. There is the potential for some
severe weather to develop with the passage of a 40-45 kt low
level jet proving sufficient wind shear. However, the limiting
factor may be the lack of strong instability. While this could
set up a high shear/low CAPE (HSLC) scenario, just not enough
confidence at this time to advertise the potential for severe
weather in the hazardous weather outlook or other products.


The upper level trough axis and a potent cold front will shift
across the area Tuesday morning, with rain chances quickly
tapering off from the southwest. Strong cold air advection will
develop during the day, which could result in breezy conditions
at times. A deep upper level trough will then shift over the
region during the middle of the week, providing a blast of
unseasonably cool weather. Despite the cold pool aloft, moisture
will be insufficient to support any precipitation across the
area. Dry weather will persist into late week, with some
moderation of temperatures expected.


High confidence in VFR conditions through much of the period
with the exception of possible brief fog/stratus at favored
AGS/OGB through sunrise.

Dry high pressure both aloft and at the surface continues to
dominate. Patchy mvfr fog towards sunrise at ags/ogb due to
river valley fog at both locations. All other sites remain vfr.
Light winds pick up by 15z around 5 knots from the east.

may occur in stratus and fog during the early morning hours
Sunday. A frontal system may bring widespread restrictions in
showers late Sunday into Tuesday, with thunderstorms possible
Monday and Tuesday.




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