Area Forecast Discussion
Issued by NWS Columbia, SC

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FXUS62 KCAE 262115

Area Forecast Discussion
National Weather Service Columbia SC
515 PM EDT MON SEP 26 2016

A cold front will slowly cross the area late Tuesday into
Wednesday. The air mass behind this system will bring dry weather
and more seasonable temperatures for the latter half of the week.


a backdoor cold front has become diffuse in the forecast area with
high pressure centered off the Mid-Atlantic coast directing an
easterly flow into the area. Another cold front will approach
from the northwest tonight. The pattern plus heating has helped
support scattered showers and thunderstorms. Expect coverage will
diminish tonight with the loss of heating. The temperature
guidance was close.


Tuesday looks to provide the best chance for precipitation across
the forecast area as precipitable water values maximize just ahead
of the cold front with values approaching 1.9 of an inch with
upper height falls and moderate instability forecast. The cold
front will slowly push into the forecast area Tuesday afternoon
and Tuesday night as the 500 mb flow backs more southerly, nearly
parallel to the front as the upper trough amplifies. The front
eventually pushes through Wednesday as the upper-level closed low
drops southward into the Ohio Valley. Much drier air will then
filter into the area from the northwest with precipitable water
values falling below an inch by Wednesday evening.

Will carry high chance pops across the forecast area Tuesday into
Tuesday evening with diminishing pops late Tuesday night as the
atmosphere stabilizes. Will continue higher pops Wednesday across
the eastern half of the forecast area with lowering pops through
the afternoon from west to east as drier air filters into the

Temperatures will remain above normal with highs Tuesday in the mid
to upper 80s and slightly cooler Wednesday in the lower to mid
80s. Overnight lows Tuesday night will remain mild in the mid to
upper 60s while temperatures will drop a couple of categories for
Wednesday night with minimum temperatures in the upper 50s to
lower 60s.


Medium-range models remain in reasonable agreement. There is
agreement with a closed low near OH/KY THU/FRI slowly lifting
northward into the Great Lakes region over the weekend. At the
surface, weak low pressure will linger to our north across the
Mid-Atlantic and Ohio Valley with cooler and drier continental
high pressure ridging into the area from the west. Models indicate
precipitable water values less than one inch. Despite very cold
500 mb temperatures around -12 C to -16 C over the area Thu/Fri
with steep mid-level lapse rates, the lack of moisture should
limit or preclude precipitation associated with the upper low,
although expect some cloud cover.

Seasonable temperatures are foreseen with Highs in the mid 70s to
lower 80s and overnight lows will be in the mid to upper 50s.


A stalled back door front will slowly become more diffuse tonight as
another cold front approaches from the west during the overnight
hours. Scattered showers and thunderstorms will continue into the
late afternoon, dissipating this evening.

Convective activity associated the cold front approaching from the
west will most likely remain north of the terminals this evening.
Increasing low level moisture and a weak wind field suggests
deteriorating conditions again tonight. Included IFR conditions at
all terminals into early Tuesday morning, becoming VFR by late
morning. Convection near the front will fire back up Tuesday
afternoon. Increasing moisture and convergence along the front
supports more thunderstorm coverage than seen today.

EXTENDED AVIATION OUTLOOK...Chance of showers and possible
thunderstorms, with associated restrictions through Wednesday.




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