Area Forecast Discussion
Issued by NWS Columbia, SC

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FXUS62 KCAE 211844
AFDCAE

Area Forecast Discussion
National Weather Service Columbia SC
144 PM EST Sun Jan 21 2018

.SYNOPSIS...
High pressure extending into the forecast area from the
Atlantic will be shifting farther eastward through tonight.
Moisture will increase ahead of a cold front Monday and the
front will cross the area late Monday night or Tuesday morning.
Showers will be associated with the front mainly late Monday
night. Warm conditions expected through Tuesday. It will be
breezy behind the front Tuesday.

&&

.NEAR TERM /THROUGH TONIGHT/...
Temperatures continue to climb the afternoon with most locations
in the low to mid 60s under sunny skies and light winds. Expect
temperatures to climb another couple degrees with high in the
mid 60s to around 70. With the clear skies and light winds this
evening temperatures will quickly fall with sunset yielding
overnight lows in the upper 30s to around 40 in the northern
Midlands and low 40s elsewhere. In advance of the next cold
front will see some mid and upper level clouds moving into the
area toward daybreak.

&&

.SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
Upper level ridge over the region early Monday will shift
offshore during the day as southerly low level flow increases
ahead of an approaching upper trough and cold front. Moisture
advection will increase through the afternoon with best
moisture transport occurring during the evening and overnight
hours just preceding the front with precipitable water values
rising to around 1.1-1.2 inches, over 200 percent of normal.
Strong shear is forecast with an 850mb jet of 45-50 knots but
instability is quite weak. However, cannot rule out the
possibility of an isolated elevated thunderstorm especially in
the northern Midlands closer to the better upper forcing. The
window of precipitation still appears to be maximized in the
06z-12z time frame. The quick moving nature of this system will
limit rainfall as most of the guidance and ensemble data
suggesting average amounts less than a quarter of an inch.

Strong winds expected behind the front on Tuesday with 850mb
winds still 40-50 knots with deep mixing expected to occur.
Bufkit momentum transfer tool supports wind gusts of 20-30
knots during the day Tuesday and a lake wind advisory may be
needed.

Temperatures will continue to be mild and above normal during
this period with highs Monday in the upper 60s to lower 70s
followed by very warm overnight lows on Monday night in the
50s. Tuesday will be slightly cooler behind the front with
highs in the 60s and the cooler air arriving that evening with
overnight lows Tuesday night back into the 30s.

&&

.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
The extended forecast period will feature fair weather with
near to above normal temperatures into the weekend followed by
the arrival of a strong storm system bringing chances of rain
to the forecast area late Saturday through Sunday.

A weak and somewhat flat shortwave trough will cross the
forecast area on Wednesday as surface high pressure continues
to build into the region from the west. Atmospheric moisture
will be very dry with precipitable water values around 0.25
inches and therefore not expecting any precipitation with the
passing trough. Surface high pressure will become centered
along the east coast into the Carolinas by Thursday with rising
upper heights across the Ohio Valley into the southeastern
states through the end of the week as an upper ridge builds
downstream of an upper trough over the intermountain west.

Medium range models are in reasonable agreement showing the
eastward progression of the upper trough over the intermountain
west into the Plains states on Saturday with additional
northern stream energy diving into the trough and amplifying
the 500mb flow. This amplification of the upper trough will
result in surface low development along an eastward moving cold
front. A moist southerly 850mb jet off the Gulf of Mexico will
strengthen Saturday night into Sunday as the system approaches
allowing for strong moisture transport over the forecast area
to couple with increasing upper dynamics as forcing from the
right entrance region of the upper jet moves into the region.
Precipitable water values increase to over 1.5 inches, which is
2-3 standard deviations above normal, providing some potential
for a significant rain event to occur late next weekend. Will
carry likely pops Saturday night and Sunday with models showing
good run to run consistency on this event.

Temperatures during this period will be near to slightly above
normal with highs Wednesday and Thursday in the upper 50s to
lower 60s becoming slightly warmer by Friday into the weekend.
Overnight lows will generally be in the 30s through the week
and reach the 40s by the weekend with Saturday night being the
warmest night with lows in the upper 40s to lower 50s.

&&

.AVIATION /19Z SUNDAY THROUGH FRIDAY/...
VFR conditions expected to dominate the TAF period.

Clear skies and light winds will remain across the region
through the early morning hours. Ahead of an approaching cold
front mid and upper level clouds will move into the area during
the early morning hours with clouds thickening and lowering
during the late morning hours. Potential for fog during the
early morning hours...mainly at AGS/OGB...remains too low to
include attm.

EXTENDED AVIATION OUTLOOK...Restrictions possible Monday
afternoon through Tuesday morning as a cold front crosses the
region.

&&

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

&&

$$



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