Area Forecast Discussion
Issued by NWS Columbia, SC
FXUS62 KCAE 282354
Area Forecast Discussion
National Weather Service Columbia SC
754 PM EDT SUN AUG 28 2016
A upper level ridge of high pressure will gradually give way to an
upper trough. Daytime heating expected to result in scattered
showers and a few thunderstorms through mid week. An approaching
frontal boundary from the north, along with the possibility of low
pressure and increased moisture approaching from the south, may
provide increased precipitation chances late week into next weekend.
.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
Surface high pressure ridging into the area from the north.
Large upper ridge extending from the Mid Atlantic into the Tennessee
Valley and Southeastern states will gradually weaken as a weak upper
level low develops off the southeast coast. Short wave energy
associated with the coastal low will retrograde westward into
South Carolina tonight with PWAT increasing to around 2.0 inches.
Weak instability through the overnight. Widely scattered showers
and a few thunderstorms affecting the CSRA...and moving into the
Midlands from the LowCountry. High resolution models support
highest pops in the east Midlands. Convection may linger into the
late evening due to potential lift associated with upper trough
along the coast. Used guidance consensus for lows in the low to
.SHORT TERM /6 AM MONDAY MORNING THROUGH TUESDAY NIGHT/...
Weak upper ridge axis to our N and NW. Models indicate upper trough
to stall near the coast of the Carolinas, while offshore tropical
depression is forecast to become a tropical storm and drift towards
the NC Outer Banks. For our FA, appearance of good levels of
atmospheric moisture, combined with diurnal heating, provides chance
of showers and thunderstorms, favored towards the E/SE FA near a sea
breeze/best low level convergence.
.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
Tropical cyclone forecast to shift to the E/NE Wed/Thu, as upper
troughiness digs into the Great Lakes/Midwest, with surface boundary
shifting down into the Ohio Valley/Appalachians. Meanwhile, an area
of low pressure, possibly tropical, could develop and move north in
the central to E GOMEX. For our FA, diurnal heating and appearance
of sufficient atmospheric moisture could provide diurnal convective
activity, though lack of upper trigger and discernible surface
focusing boundary could limit activity. For now, guidance blend pops
of slight chance N FA, to chance S FA, look ok.
Significant uncertainties exist between how models are handling
upper troughiness digging into the east coast, surface front pushing
south, and impact on track of possible cyclone. Especially given
uncertainties whether cyclone will even develop, let alone
uncertainties with the track/timing, accepted guidance blend on
weather elements. This provides chance pops, a lowering trend on max
temps, and a ENE wind, which seems reasonable for now
given above factors.
.AVIATION /00Z MONDAY THROUGH FRIDAY/...
VFR conditions expected through the overnight hours but MVFR and
possibly IFR cigs possible 09z-15z time frame.
Afternoon showers associated with some onshore flow and associated
with an upper low off the southeast coast have generally remained
east of the terminals and dissipating early this evening. However
some low and mid clouds blanketing the region with VFR cigs.
Easterly winds around 6 to 9 knots will gradually subside
overnight becoming light and variable to calm. Guidance suggests
some stratus clouds will form during the predawn hours across
eastern SC and push into the Midlands overspreading the terminals.
HRRR also in agreement so with reasonable confidence will carry
MVFR cigs 09z- 15z all terminals. Ceilings may lower to IFR
toward sunrise but confidence low. Winds will pick up from the
east-northeast after 15z at 5 to 10 knots.
EXTENDED AVIATION OUTLOOK...
Chance of late night/early morning stratus/fog, along with a
chance of mainly afternoon/evening showers/thunderstorms through