Severe Thunderstorm Warning 185, NWS Columbia, SC

Area Forecast Discussion
National Weather Service Columbia SC
632 PM EDT MON SEP 19 2016

.SYNOPSIS...
A weak cold front will merge with a trough off the southeast coast
tonight. This trough will linger near the coast through much of the
week and a chance of showers and thunderstorms will continue.

&&

.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
As of early this evening, water vapor imagery depicts the axis of
an upper level trough approaching from the west. Meanwhile, the
low level circulation associated with the remnants of former
tropical cyclone Julia lingers off the Cape Fear coast and a
surface front/trough extending out along the back side of the low
is making southward progress through the northern and eastern
Midlands.

As the night progresses, the upper trough will develop into a
cut-off low and linger over the region. At the same time, the
surface trough will shift south of the area, causing the low level
flow to shift north-northeasterly.

The latest high resolution mesoscale models have scaled back on
the coverage of precipitation through this evening, so have
adjusted the forecast accordingly to indicate scattered showers
and a few thunderstorms across the northern, central and eastern
Midlands, with only isolated showers and thunderstorms elsewhere.
Given moderate instability and the possibility of mid level dry
air entrainment, an isolated strong thunderstorm with gusty winds
is possible but overall the severe weather threat is low. Will
expect most of the activity to dissipate by late tonight. Behind
the surface trough, the N-NE low-level flow could provide stratus
development late tonight.

&&

.SHORT TERM /6 AM TUESDAY MORNING THROUGH WEDNESDAY/...
An inverted surface trough will continue near the coast through
Wednesday. The models show an h5 cut-off low in the region
positioned with a spread from the Central Savannah River Area to
central Coastal Plain. The main forecast concern is a possibility
of heavy rain because of slow movement in the stagnant pattern
with difluent heights northeast of the h5 low, and tropical
moisture wrapping around the offshore low which was once Tropical
Storm Julia. The h85 jet is forecast to mainly wrap into North
Carolina with weak advection into the forecast area. However, the
ECMWF has indicated a stronger jet and convergence in the
forecast area compared to the NAM and GFS, but all these models
have QPF less than 2 inches through Wednesday. Most SREF members
have rainfall less than 1 inch at Columbia through Wednesday. The
threat is too low for a flood watch at this time. Despite the cold
mid-level temperatures associated with the upper low, instability
will likely remain weak because of cloudiness. However, the NAM
does depict surface-based LI values -5 to -6 Tuesday which may
occur if significant breaks in the cloudiness occurs. Therefore,
strong wind and hail are not out of the question. The pattern
supports the lower maximum temperature guidance. The MOS was
consistent with the minimum temperature.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/...
The GFS and ECMWF show the h5 low remaining over the area with a
surface inverted trough near the coast through Thursday or Friday.
The models display these features much weaker or dissipated by
Saturday. However, a cold front is shown moving into the area
Sunday or Sunday night. The GFS and ECMWF MOS have pops 30 to 40
percent through Friday, and 20 to 30 percent Saturday and Sunday.
The MOS indicates near-normal high temperatures through Thursday
with above normal values ahead of the cold front during the
weekend.

&&

.AVIATION /22Z MONDAY THROUGH SATURDAY/...
Scattered ongoing convection mainly over the eastern and southern
portions of the forecast area late this afternoon. Upper level
trough will continue to slowly approach from the west and cut off
over the region tonight. Weak frontal boundary/surface trough
will swing through our FA from the north tonight. Given latest
radar trends, will back off on mention of convection in the TAFs
over the next several hours, except for a mention of VCSH at OGB.
Will amend for convection into tonight if confidence increases.
Models indicating a light NE wind tonight behind the trough, and
potential for stratus to move into the region from the NE late
tonight. A later arrival of stratus plus dry air aloft could
promote fog at fog prone AGS. Will expect a slow return to VFR by
midday Tuesday, with diurnal showers/possible thunderstorms mainly
after 18Z.

EXTENDED AVIATION OUTLOOK...Chance of showers and possible
thunderstorms, and associated restrictions. Late night/early
morning stratus/possible fog.

&&

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

&&

HAZARDOUS WEATHER OUTLOOK...UPDATED
NATIONAL WEATHER SERVICE COLUMBIA SC
158 PM EDT MON SEP 19 2016

GAZ040-063>065-077-SCZ015-016-018-020>022-025>031-035>038-041-200900-
LINCOLN-MCDUFFIE-COLUMBIA-RICHMOND-BURKE-LANCASTER-CHESTERFIELD-
MCCORMICK-NEWBERRY-FAIRFIELD-KERSHAW-EDGEFIELD-SALUDA-LEXINGTON-
RICHLAND-LEE-AIKEN-SUMTER-BARNWELL-ORANGEBURG-CALHOUN-CLARENDON-
BAMBERG-
158 PM EDT MON SEP 19 2016

THIS HAZARDOUS WEATHER OUTLOOK IS FOR THE MIDLANDS OF SOUTH CAROLINA
AND THE CENTRAL SAVANNAH RIVER AREA OF GEORGIA.

.DAY ONE...THIS AFTERNOON AND TONIGHT.

AN ISOLATED THUNDERSTORM OR TWO MAY REACH SEVERE LIMITS AND
PRODUCE STRONG GUSTY WINDS LATE TODAY AND EARLY TONIGHT.

.DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY.

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION IS NOT EXPECTED AT THIS TIME.

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