Area Forecast Discussion
Issued by NWS Columbia, SC

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348
FXUS62 KCAE 171128
AFDCAE

Area Forecast Discussion
National Weather Service Columbia SC
628 AM EST Sun Dec 17 2017

.SYNOPSIS...
High pressure will shift off the Southeast Coast today. There
will be increased moisture in the southerly flow on the backside
of the offshore high Monday. Additional rain chances throughout
the week with a weak front across the area.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
A subtropical ridge will continue to extend into the
Southeastern states today promoting zonal flow aloft. At the
surface, high pressure will be centered offshore which will
promote southerly flow. Moisture and clouds will be on the
increase through the day with PWATs climbing to over an inch.
Models show weak isentropic lift in the southern portion of the
area toward the end of the period and shortwave energy moving
into the area. Have continued to indicate increasing pops during
the late afternoon mainly in the western half of the forecast
area. Given the moderating airmass, high temperatures are
forecast a few degrees above normal today, in the upper 50s to
lower 60s.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH MONDAY NIGHT/...
Models indicate some uncertainty with the pops for the
overnight period tonight. May see some light rainfall across the
west and north early, with the NAM indicating precip becoming
quite limited overnight. GFS limits rainfall also, but tries to
bring precip back across the southern portions of the cwa
towards morning. Generally went along with scattered rain north
early in the night, with that area falling apart, then some
light rain developing south towards Monday morning. Through the
day Monday, slight chance of rainfall still appears on track.
Drier forecast for Monday night as lift weakens across the
region. Temperatures should be above normal.

&&

.LONG TERM /TUESDAY THROUGH SATURDAY/...
Uncertainty in the longer term. An upper low currently spinning
across the southwestern United States will be ejecting eastward
Tuesday into Wednesday. This will bring another increase in
moisture and rain chances in advance of this low. For now, have
continued with low chance showers on for Tuesday across western
portions of the cwa. Then all models indicate a higher
probability of rainfall from Tuesday night through Wednesday
night as the upper low and associated surface low moves through
the region. This system should be moving east of the cwa by
Thursday/Thursday night, but models indicating yet another
northern Gulf system possible by Friday although focus may
remain west of the area near frontal boundary through most of
the day. Temperatures generally appear to remain above normal
through the long-term period except potential for weak cold air
damming in-situ wedge on Thursday.

&&

.AVIATION /12Z SUNDAY THROUGH THURSDAY/...
Generally VFR conditions expected through the TAF period
outside of early morning fog/stratus.

Surface high pressure will shift off the coast this morning and
remain offshore through the day with upper ridging aloft over
the region. Moisture and clouds will increase through the day,
although ceilings are still expected to be VFR. There is a
slight chance for rain this afternoon and tonight, but the
chance is too low to include mention in current TAF issuance.
Winds through the period will be southwesterly at 5 knots or
less. MVFR/IFR fog/stratus has intermittently developed at fog
prone AGS/OGB this morning, but increasing clouds and limited
moisture should preclude widespread development. Have included
tempo group with mention through 13Z. Models show potential for
stratus development early Monday morning given increased
moisture near the surface, although confidence is too low to
include at this time.

EXTENDED AVIATION OUTLOOK...Boundary will remain stalled across
the region with rain and associated restrictions at times
through Wednesday.

&&

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

&&

$$



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