Area Forecast Discussion
Issued by NWS Columbia, SC

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FXUS62 KCAE 251751
AFDCAE

Area Forecast Discussion
National Weather Service Columbia SC
151 PM EDT Sat Mar 25 2017

.SYNOPSIS...
A weak front will move into our region late tonight and Sunday.
A series of systems will affect our region next week, providing
a chance of showers, and possibly thunderstorms, at times.
Above normal temperatures expected through the period.

&&

.NEAR TERM /THROUGH TONIGHT/...
Moisture will be on the increase through tonight associated
with an onshore flow circulating around offshore high pressure
and a weak cold front approaching from the west. A lingering mid-
level cap combined with moisture remaining too shallow should
limit the shower chance through the evening. Increased moisture
and an eroding cap may lead to showers in the west section late
tonight ahead of the upper trough. However, the GFS and NAM MOS
plus most SREF members indicate showers will remain west of the
region through tonight. Also, the ARW displays just isolated
coverage in the west section toward morning. The higher
temperature guidance may be better tonight because of mixing and
cloudiness ahead of the weak front.

&&

.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
Upper trough will move through the region Sunday. Surface front will
approach the forecast area (FA) late tonight. Most of the associated
convective activity is expected to weaken or remain to our N and W
as main upper dynamics stay to our north and diurnal cooling takes
place.  Front to set up mainly near the Piedmont and CSRA Sunday and
provide a focus for scattered mainly diurnal showers, and a few
thunderstorms given weak instability. Chance POPs still appear in
order, mainly N and W FA. Front to linger in the vicinity Monday. No
upper trigger Monday but diurnal heating, along with convergence
along old front or sea breeze, could provide a slight chance of
showers, maybe an isolated thunderstorm.

&&

.LONG TERM /TUESDAY THROUGH SATURDAY/...
Active pattern suggested by models with a series of systems that
could affect our region through the period.

Upper disturbance progged to roll through Tuesday time frame, with
an accompanying surface bounday. Progged instability values
generally weak to moderate. Both GFS and EC indicate some upper
ridging over the SE CONUS Wednesday as a closed upper low moves into
the southern Plains. The surface front appears to stall in our
vicinity, with a possible weak wedge-like regime to the north of it.
Some question as to where the front/weak wedge may set up, which
provides some uncertainty for Wed/Thu. The front would presumably
eventually lift back north as a warm front ahead of the next system,
that GFS and EC generally bring into our region Thu nt/Fri time
frame. However, confidence of model timing and position of closed
upper systems can be limited late in the forecast period. So, some
limited confidence on specifics mid to late week. Generally used a
model blend, which provides mainly slight chance to chance POPs at
times through much of the period, and above normal temps
generally, though any weak wedginess could limit max temps on a
day or two mid week for parts of the FA, mainly north, if it
sets up.

&&

.AVIATION /18Z SATURDAY THROUGH THURSDAY/...
Expect VFR conditions through the evening with MVFR conditions
developing overnight.

Moisture will be on the increase through tonight associated
with an onshore flow circulating around offshore high pressure
and a weak cold front approaching from the west. However, the
initial low-level dryness and just weak isentropic lift support
the MAV and NAM MOS plus SREF guidance mainly indicating
continued VFR conditions through the evening. Increased moisture
ahead of the weak front and greater isentropic lift plus
nocturnal cooling supports restrictions developing toward 12z.
The GFS and NAM MOS plus many SREF members indicate MVFR
ceilings and visibilities developing.

A lingering mid-level cap combined with moisture remaining too
shallow should limit the shower chance through the evening.
Increased moisture and an eroding cap may lead to showers
beginning around 12z but expect scattered coverage with the
chance too low to include in the terminal forecasts at this
time.

Followed the NAM and GFS MOS for the wind forecast with
mainly south wind near 10 knots during the day and southeast
less than 10 knots during the night.

EXTENDED AVIATION OUTLOOK...Moisture in a southerly flow and
weak front just northwest of the region may help cause periods
of MVFR or IFR conditions during the outlook period especially
in the early morning hours associated with nocturnal cooling.

&&

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

&&

$$



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