Area Forecast Discussion
Issued by NWS Columbia, SC

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FXUS62 KCAE 231849

Area Forecast Discussion
National Weather Service Columbia SC
249 PM EDT Fri Jun 23 2017

High pressure extending into the forecast area from the Atlantic
today will weaken tonight ahead of an approaching cold front.
The slow moving front will be in the area Saturday through
Monday. Numerous showers and thunderstorms are expected along
and ahead of the front. Unseasonable drier weather expected by
the middle of next week.


High pressure offshore ridging into the area. Satellite
indicating cloud streets and wind gusts now increasing to near
20 knots. With strong mixing...dew points have dropped a few
degrees. Resulting precipitable water around 1.5 inches which is
lower than past couple day. Weak cap evident on model soundings
this afternoon. Despite strong insolation...models suggest
limited convection this afternoon due to drier air mass and weak
ridge. Focus confined to near the coast where the sea breeze
may be active.

The thunderstorm chance may remain low through tonight with the
greater convergence along the approaching cold front remaining
west of the area plus nocturnal cooling. The models indicate
just weak instability with surface-based LI values around -2.
However, considerable shear is indicted with h85 wind near 40
knots. The shear supports possible strong thunderstorms but at
this time the threat appears low because of expected weak
forcing and little instability. Stronger short wave energy moves
by to the north of the area. Mixing should help hold up
temperatures and the temperature guidance was close with lows
mainly in the upper 70s.


A cold front will sag southward through central South Carolina and
east central Georgia on Saturday. PW values in excess of two
inches and 850mb winds speeds 20-30 knots parallel to the
frontal boundary should lead to localized flash flooding,
especially along and south of I-20. WPC has that area in a
Slight Risk for flooding.

The frontal boundary pushes to the coast during Saturday Night into
Sunday. There should be sufficient residual PW behind the front for
scattered diurnal convection, especially south and east of Columbia.

Much drier and cooler air filters into the region Sunday Night into
Monday with highs only in the lower to mid 80s and dewpoints in the
50s to lower 60s. There may be some convection in the far south
related to the sea breeze front.


An unseasonably cool and dry airmass will dominate through much of
next week with highs in the lower to mid 80s and lows in the upper
50s to mid 60s. Some moisture and warmer temperatures will return on
Thursday and Friday as the surface high moves into the Atlantic


High confidence for VFR conditions through at least 06z.

Scattered cumulus across the region through the afternoon.
Limited moisture and weak ridging so expect limited convection.
Gusty south to southwest winds to near 20 knots diminishing
during the evening. Winds will be near 10 knots overnight so
fog not an issue. Latest HRRR guidance and Lamp suggest low
threat for kept VFR through the end of the taf
period although chance of showers and thunderstorms may increase
by 15z-18z Saturday.

EXTENDED AVIATION OUTLOOK...Convection and associated restrictions
will be possible Saturday through Sunday ahead of a cold front.




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