Special Weather Statement, NWS Columbia, SC

Area Forecast Discussion
National Weather Service Columbia SC
603 PM EDT SAT JUL 16 2016

.SYNOPSIS...
A pressure ridge will extend westward from the Atlantic into the
northern Gulf of Mexico. North of the ridge a pressure trough
will be in the forecast area. An upper trough over the area will
weaken on Sunday. Scattered mainly afternoon and evening
thunderstorms are expected for the next few days. Temperatures
will be at or above normal through the period.

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.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
Scattered thunderstorms in progress, and will expect convective
activity to continue to affect portions of the forecast area (FA)
through this evening to early tonight. Isolated severe cells
possible, with threat of locally heavy rain with some of the
training echoes as precipitable water values are over 2 inches.
Otherwise, will expect a decrease in convective coverage later
tonight. Used the guidance consensus for the minimum temperature.

&&

.SHORT TERM /6 AM SUNDAY MORNING THROUGH MONDAY NIGHT/...
The NAM and GFS show surface ridging from the Atlantic more
dominate Sunday although weak surface trough should be near the
area. Upper level forcing should be weaker with short wave troughs
mainly north of the area as upper level trough lifts north. Moisture
remains high across the east midlands and CSRA with precipitable
water around 2 inches. Some drying possible in the west. The
pattern indicates less thunderstorm coverage but with temperatures
in the low to mid 90s...moderate instability expected. The
guidance supports highest pops in the southeast. Will continue
chance pops mainly afternoon.

The surface trough remains across the area Monday and the air
mass moderately unstable. Strongest lift remains north of the
region although models suggest weakness in upper level ridge and a
short wave may track southeast through the area in the afternoon.
Chance afternoon and evening thunderstorms with temperatures in
the mid 90s. Warm overnight temperatures.

&&

.LONG TERM /TUESDAY THROUGH SATURDAY/...
The GFS and ECMWF displayed surface ridging extending from the
Atlantic into the Gulf of Mexico during much of the medium-range
period. The models showed some troughing in the forecast area. The
models indicated upper ridging early but troughing along the east
coast by the middle of the week as ridge shifts west. Some hint of
a backdoor cold frontal passage mid week suggesting increased
chance thunderstorms during that period although GFS ensemble
suggests near climatology or lower pops. Temperatures should be
near or above normal during the period. Scattered afternoon and
evening through much of the period with highest chance mid week.

&&

.AVIATION /22Z SATURDAY THROUGH THURSDAY/...
Main near term concern through this evening is scattered
thunderstorm activity. Will monitor radar trends for appropriate
inclusion of such in the TAFs. Will expect convective coverage to
decrease later this evening/early tonight. Because of high
dewpoint temperatures and expected rainfall, have included some
fog for Sunday morning at OGB/CUB/AGS.

EXTENDED AVIATION OUTLOOK...Increasing potential for restrictions
in convection into early next week.

&&

.CAE WATCHES/WARNINGS/ADVISORIES...
GA...None.
SC...None.

&&