Area Forecast Discussion
Issued by NWS Columbia, SC
FXUS62 KCAE 291707
Area Forecast Discussion
National Weather Service Columbia SC
107 PM EDT MON AUG 29 2016
Daytime heating and an onshore low level flow expected to result
in scattered showers and a few thunderstorms through Wednesday,
favoring areas closer to the coast. A tropical cyclone is forecast
to develop in the Gulf of Mexico and move NE across North Florida
and offshore the Carolina coast mid to late week. Behind the
cyclone, drier cooler high pressure will build in for most areas
.NEAR TERM /THROUGH TONIGHT/...
Large upper ridge extending from the Mid Atlantic into the
Tennessee Valley and Southeastern states will gradually weaken as
a weak upper level low just off the southeast coast continues to
slowly push westward. Surface high pressure will continue to ridge
into the area from the north. Weak surface moisture flux
convergence extending from the Pee Dee southwest across the
central Midlands. Air mass weakly to moderately unstable across
the area...moisture a little higher than the previous day...with
precipitable water up to 2 inches across the southeast Midlands.
Radar at 17z indicating scattered showers across the area...mainly
central SC. Focus may shift to the south and east during the late
afternoon as convection near the coast moves inland. This is
supported by HRRR. Raised pops across the central and east
Midlands/CSRA. Convection mainly diurnal but a few showers may
continue overnight with upper level low near the coast and weak
short wave troughs rotating to the west. Despite considerable
cloudiness...temperatures above normal with highs in the lower 90s
and lows tonight above guidance due to expected late night
.SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
Weak upper ridge axis to our N will weaken and shift west. Upper
trough will dig into the Great Lakes/Midwest, with surface front
shifting down into the Ohio Valley/Appalachians. Upper energy will
remain stalled near the SC coast. TD 8 is forecast to shift NW
towards the NC Outer Banks then curve NE out to sea, with minimal if
any impact on our FA. Weak surface ridge axis will extend down the
eastern seaboard and W Carolinas. Low level ENE flow will promote
best low level moisture flux convergence near the coast and our
S/E FA. So, chance pops, diurnally favored, mainly E/SE FA.
.LONG TERM /THURSDAY THROUGH MONDAY/...
Main concern will be status of TD 9, which is forecast to
strengthen into a tropical storm, and move N into the E GOMEX.
Upper trough to dig into the E CONUS, with surface front pushing
south into our region Thu/Fri, acting to pick up the tropical
cyclone and shift it to the NE. Official forecast has the cyclone
moving across N FL Wed nt/Thu morning, and moving NE offshore the
Carolinas Thu/Fri. These factors would bring a chance of showers
and thunderstorms along with possibly breezy conditions.
Generally accepted model blend, though did bump up wind speeds
some late Thu into Fri. Behind the cyclone, it appears drier and
cooler air will work into the region, with surface high center
shifting into New England and ridging down the eastern seaboard.
However, both GFS and EC cut off an upper low near the coast late
in the period, which along with the possibilities of a low level
ENE flow, could continue to provide some shower chance for
portions of the S/E FA.
.AVIATION /18Z MONDAY THROUGH SATURDAY/...
VFR conditions expected outside of morning stratus.
MVFR strato-cu continues across central SC. Expect ceilings to
rise to VFR by around 16z-17z.
Extensive cumulus fields across the region through the afternoon
although ceilings now VFR. Scattered showers across the area will
add vicinity to CAE/CUB terminals based on latest radar
trends...but not expected to result in reduced visibility or lower
ceilings. Winds northeast 5 to 10 knots. Scattered showers should
diminish during the evening. Stratus possible again late tonight
into early morning. Appears to be less support from the lamp
guidance...but will continue persistence forecast since low level
moisture likely high and east low level flow continues.
EXTENDED AVIATION OUTLOOK... Chance of late night/early morning
stratus/fog, along with a chance of mainly afternoon/evening
showers/thunderstorms through mid week.