Severe Thunderstorm Warning 87, NWS Columbia, SC

Area Forecast Discussion
National Weather Service Columbia SC
1111 AM EDT Mon Jun 25 2018

.SYNOPSIS...
High pressure will extend from the Atlantic westward into the
Gulf of Mexico through today. A hot westerly flow will continue
north of this ridge locally and high temperatures will be in
the mid 90s to around 100 degrees. A cold front will push into
the forecast area tonight and Tuesday bringing showers and
thunderstorms. Tuesday should be the coolest day in the past
week or so due mainly to increased cloud cover. A more
climatological pattern unfolds for the remainder of the period
with increasing moisture and ridging into the Southeast. This
pattern supports scattered diurnal thunderstorms and above
normal temperatures.

&&

.NEAR TERM /THROUGH TONIGHT/...
The main concern will be the possibility of severe thunderstorms
and localized flooding.

A surface trough will be in the forecast area today ahead of the
approaching cold front. The front is forecast to sink southward
and into the area tonight. Despite strong heating and
convergence into the surface trough, upper ridging will likely
limit thunderstorm coverage this afternoon, except there may be
considerable coverage in the north section late, with moisture
pooling ahead of the cold front plus an approaching mid-level
shortwave trough. The greatest coverage may be this evening
closer to the maximum of diurnal instability and ahead of a mid-
level shortwave trough and in an area of convergence near the
front. There will be a continued threat of thunderstorms
overnight with the front and upper feature in the area. The NAM
and GFS depict strong instability with surface- based LI values
-8 to -10. Forecast soundings indicate considerable CAPE in the
hail growth region. Damaging wind and hail will be possible with
the thunderstorms. Precipitable water is forecast to be around
2 inches. High rainfall rates and possible training near the
front support a possibility of localized flooding. We followed a
guidance for the temperature forecast. Expect peak heat index
values about 105 and just below the heat advisory criteria of
110 today.

&&

.SHORT TERM /TUESDAY THROUGH TUESDAY NIGHT/...
An upper level disturbance will be exiting the CWA to the east
Tuesday morning. Any lingering storms should dissipate through the
morning, if not already out of the area. The frontal boundary will
be near or in the forecast area during the day. Models differ
on the location of the front, ranging from the ECMWF which keeps
it across our north while the NAM pushes it just south of the
CSRA. The GFS is between the two solutions, keeping the southern
FA in the warm sector. We favored the GFS for temperature and
PoP guidance. Showers and thunderstorms will be likely along the
front with PWAT values around 2.00 inches over the Southeast.
Moderate potential instability will support deep convection
although the threat for severe weather may be lower than Monday
with less dry air aloft and wet bulb zero temperatures around 13
kft. Although, high PWAT values and a stalled or slow moving
front supports a threat of localized flash flooding. A
shortwave will move into the forecast area late afternoon/evening
supporting convection past the peak heating time frame.

The increased cloud cover and slightly cooler air behind the front
should make Tuesday one of the coolest days in the past week or so,
with highs only in the upper 80s to the north and low to mid 90s in
the southern FA. Lows will be in the low 70s.

&&

.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
Surface high pressure in the Northeast shifts offshore by mid-
week allowing SW flow to develop across the region. Warm moist
advection will bring back above normal temperatures and
scattered afternoon convection Wednesday. A mid-level trough
moves into the eastern CONUS late Wednesday and Thursday. With a
drier, westerly flow in place Thursday fewer showers and
thunderstorms are expected during the day. Model guidance has
been trending drier for Thursday afternoon. Surface high
pressure builds back into the Northeast behind the exiting
trough near the end of the week. This will push another backdoor
front into the mid-Atlantic, keeping in a chance for showers
and thunderstorms. Upper level ridging and onshore flow develops
for the weekend into early next week. This pattern supports
warming temperatures and a climatological pattern of scattered
afternoon convection. Expect highs in the mid to upper 90s and
lows in the 70s.

&&

.AVIATION /15Z MONDAY THROUGH FRIDAY/...
VFR conditions should persist through the day, until showers
and thunderstorms bring restrictions this evening.

A surface trough will be in the forecast area today ahead of
the approaching cold front. The front is forecast to sink
southward and into the area tonight. Despite strong heating and
convergence into the surface trough, upper ridging will likely
limit thunderstorm coverage during much of the afternoon. The
hi-res models do show scattered convection developing between
20Z and 23Z, but confidence is too low to include in the
terminal forecasts at this time.

The greatest coverage may be this evening closer to the maximum
of diurnal instability and ahead of a mid-level shortwave
trough and in an area of convergence near the front. Kept
thunderstorms in the terminal forecasts during the 00z to 04z
time frame. There will be a continued threat of thunderstorms
overnight with the front and upper feature in the area. Damaging
wind and hail will be possible with the thunderstorms.

EXTENDED AVIATION OUTLOOK...Restrictions possible each day in
early morning fog plus mainly afternoon and evening thunderstorms.

&&

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

&&

Hazardous Weather Outlook
National Weather Service Columbia SC
217 AM EDT Mon Jun 25 2018

GAZ040-063>065-077-SCZ015-016-018-020>022-025>031-035>038-041-260630-
Lincoln-McDuffie-Columbia-Richmond-Burke-Lancaster-Chesterfield-
McCormick-Newberry-Fairfield-Kershaw-Edgefield-Saluda-Lexington-
Richland-Lee-Aiken-Sumter-Barnwell-Orangeburg-Calhoun-Clarendon-
Bamberg-
217 AM EDT Mon Jun 25 2018

This Hazardous Weather Outlook is for the Midlands of South Carolina
and the Central Savannah River area of Georgia.

.DAY ONE...Today and Tonight.

Thunderstorms with damaging wind and hail will be possible this
afternoon and tonight. The threat will be greatest this evening.
There will also be a possibility of very heavy rain leading to
localized flooding this afternoon and especially tonight.

It will be hot today with heat index values peaking near 105.

.DAYS TWO THROUGH SEVEN...Tuesday through Sunday.

The probability for widespread hazardous weather is low.

.SPOTTER INFORMATION STATEMENT...

Spotter activation may be required this afternoon and tonight.

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE COLUMBIA SC
1016 AM EDT MON JUN 25 2018

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0842 PM     TSTM WND DMG     10 E GASTON             33.79N 80.92W
06/24/2018                   CALHOUN            SC   EMERGENCY MNGR

            TREE LIMBS DOWN AND MAJOR DAMAGE TO AN
            ALUMINUM PUMP HOUSE AT 1273 OLD SWAMP ROAD
            IN SANDY RUN. TIME ESTIMATED FROM RADAR.

&&

RC

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE COLUMBIA SC
1036 AM EDT MON JUN 25 2018

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0830 PM     TSTM WND DMG     CAMDEN                  34.25N 80.61W
06/24/2018                   KERSHAW            SC   911 CALL CENTER

            NUMEROUS TREES DOWN AND POWER OUTAGES IN AND
            AROUND CAMDEN. TIME ESTIMATED FROM RADAR.

&&

RC

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE COLUMBIA SC
1245 PM EDT MON JUN 25 2018

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

1100 PM     TSTM WND DMG     1 W NORWAY              33.45N 81.15W
06/24/2018                   ORANGEBURG         SC   PUBLIC

            PECAN TREES DOWN AND METAL SIDING RIPPED
            FROM HOME.

&&

RC