FXUS62 KCAE 192108
Area Forecast Discussion
National Weather Service Columbia SC
508 PM EDT Thu Jul 19 2018
A weak front remains stalled near the CSRA and S Midlands and
will continue to provide a chance showers and thunderstorms
through the evening mainly for that region. A weak wave of low
pressure will move NE along the front across the coastal plain
tonight and Friday. This will push the front northward, along
with the deeper moisture. An upper trough and surface boundary
will lead to chances of showers and thunderstorms throughout the
region Saturday afternoon, Saturday night, into Sunday, some
possibly severe. A deep upper trough will then remain over the
eastern U.S. into the middle of next week, providing a
continued chance of showers and thunderstorms.
.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
A surface front remains nearly stationary across south-central
GA this afternoon, while water vapor imagery shows that weak
troughing persists aloft. High precipitable water values and
enhanced low-level convergence in proximity to the front have
lead to numerous showers and a few thunderstorms across portions
of the CSRA and the southern/eastern Midlands so far this
afternoon. These showers and thunderstorms are expected to
persist through the remainder of the afternoon, possibly
spreading a bit northward along developing outflow boundaries.
The severe weather threat appears rather limited, but heavy
rainfall and localized flooding is a possibility. Temperatures
should reach highs in the upper 80s to lower 90s.
Tonight, a weak wave of low pressure will develop along the
front, then lift to the northeast across the coastal plain. This
will cause precipitable water values to increase from the south
across much of the forecast area. While all areas with the
exception of the northern Midlands look to have scattered showers
and thunderstorms, numerous showers and thunderstorms could
develop overnight across the eastern Midlands in the vicinity of
the passing wave of low pressure. Northeast low-level flow
along the back-side of the low will likely result in the
development of low stratus across much of the area, however a
coupled flow at the surface should prevent fog from forming. Low
temperatures should be in the lower 70s most areas.
.SHORT TERM /6 AM FRIDAY MORNING THROUGH SATURDAY NIGHT/...
Models continue to indicate a deep upper trough approaching the
region Friday and Saturday. On Friday, upper energy will move
northeast from the Gulf towards the South Carolina coast along a
stalled front. The best thunderstorm chances will therefore be
in association with this feature, mainly impacting southern and
eastern portions of the forecast area, although models have been
trending a little farther north. The biggest threat for Friday
is still locally heavy rain. But as the trough digs deeper on
Saturday, shear and instability will increase, and SPC has
placed the area in a marginal risk for severe storms with
damaging winds. Storms will develop during the afternoon in
conjunction with a shortwave, and could persist through the
.LONG TERM /SUNDAY THROUGH THURSDAY/...
The upper trough will develop into a cutoff low on Sunday and
Monday, and then linger over the Gulf coast Tuesday through
Thursday. Another large scale trough will also move in on
Thursday. This setup will allow moist southerly flow to persist
through the long range period. Several shortwaves are also
expected to rotate through the area, therefore scattered showers
and thunderstorms will remain possible each day.
.AVIATION /21Z THURSDAY THROUGH TUESDAY/...
A majority of the convection has moved out of the forecast area
with only a few isolated showers remaining for this afternoon.
Additional convective development is not expected at this time.
Tonight, a wave of low pressure will pass northeast along the
coastal plain. Ceilings should lower to MVFR levels across the
area within the northeast flow on the back-side of the low late
tonight into Friday morning, with the potential for IFR ceilings
at OGB/AGS/DNL, especially in the 09-13Z time frame. Fog should
not be much of a factor given sufficient low level mixing.
Scattered showers and thunderstorms are possible tonight,
especially across the eastern Midlands and CSRA, but chances
appear highest at KOGB due to the proximity of the low and have
added SHRA to the forecast there beginning around 07Z.
EXTENDED AVIATION OUTLOOK...The chance for mainly afternoon and
evening showers and thunderstorms will continue each day.
Periods of late night/early morning fog/stratus are possible
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