Area Forecast Discussion
Issued by NWS Columbia, SC
FXUS62 KCAE 250218
Area Forecast Discussion
National Weather Service Columbia SC
1018 PM EDT SAT SEP 24 2016
An upper-level ridge will continue to build east into the area
through Sunday. A cold front will approach from the north Sunday
and stall across the area Monday providing a focus for scattered
showers and thunderstorms. Another cold front will approach from
the west Tuesday and move east of the area midweek. The air mass
behind this system will be drier and more seasonable.
.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
A high amplitude upper-level ridge over the Mississippi Valley
will gradually build east through tonight as an upper-level cut-
off low over southern Georgia retrogrades westward. At the
surface, weak high pressure will remain over the region with a
backdoor cold front across southern Virginia. Dry air aloft and
near calm wind overnight will aid the development of patchy fog
late tonight. MOS consensus and persistence indicated overnight
lows in the mid to upper 60s.
.SHORT TERM /6 AM SUNDAY MORNING THROUGH MONDAY/...
Amplified upper-level trough over New England with surface ridge
building south. This will result in a backdoor cold front from
the northeast late in the day Sunday or early evening. Moisture
increasing through the day...although mainly low level. Air mass
becoming weakly to moderately unstable ahead of the front. Strong
insolation again so temperatures around 90 in the afternoon.
Greater chance showers in the north late into the evening...more
isolated south with frontal boundary convergence in the north.
With weak dynamics rainfall amounts late Sunday/Sunday night are
expected to be light with less than one tenth of an inch expected.
East low-level flow Monday...resulting deeper moisture. Frontal
boundary stalled across the area should support mainly diurnal
scattered showers and thunderstorms in a weakly to moderately
unstable air mass. Temperatures a little cooler Monday. MOS
overnight minimum temperatures consistent.
.LONG TERM /MONDAY NIGHT THROUGH SATURDAY/...
Deep upper-level trough over the Great Lakes Tuesday...amplifying
along the eastern seaboard Thursday. This system will drive
another stronger cold front through the area Tuesday into early
Wednesday as per latest GFS solution. Chance pops Tuesday into
early Wednesday, drying out from the west by late Wednesday
afternoon. Dry high pressure will build in from the north Thursday
through Saturday with near seasonable temperatures.
.AVIATION /02Z SUNDAY THROUGH THURSDAY/...
Nocturnal cooling and light wind may result in fog late tonight
but expect the fog will be limited because of the dry air mass.
The GFS and NAM MOS were consistent confining IFR fog to the
river valley terminals of AGS and OGB. Heating and mixing should
help dissipate fog by 14z. A diffuse backdoor cold front will move
into the area Sunday afternoon and evening. Moisture will remain
shallow with upper ridging continuing. The chance of showers and
thunderstorms associated with the front is too low to include in
the terminal forecasts at this time. The GFS and NAM MOS support
wind generally northeast less than 10 knots.
EXTENDED AVIATION OUTLOOK...A cold front approaching Monday will
be near the forecast area Tuesday and Wednesday. Widespread
stratus and fog may occur especially during and late night and
early morning hours. There will also be scattered showers and
thunderstorms. Drying may occur behind the front Thursday.