Area Forecast Discussion
Issued by NWS Columbia, SC

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FXUS62 KCAE 171043
AFDCAE

Area Forecast Discussion
National Weather Service Columbia SC
643 AM EDT Thu Aug 17 2017

.SYNOPSIS...
A surface pressure trough will linger in the forecast area
through early next week. Upper ridging over the region will
weaken somewhat Friday and Saturday, and then become a little
stronger early next week. The pattern supports partly cloudy
skies with scattered mainly afternoon and evening thunderstorms.
It will be hot with heat index values peaking 100 to 108.

&&

.NEAR TERM /THROUGH TONIGHT/...
The surface pressure troughing in the region plus high moisture
and strong heating should help support thunderstorms. This
morning`s water vapor imagery indicated there may be increased
upper lift by midday and the models have shown more moisture
and low-level convergence. Expect greater thunderstorm coverage
compared to yesterday, but still limited because of upper
ridging with h7 and h5 temperatures 10 C and -5 C,
respectively. The guidance consensus MOS and HRRR indicate
scattered coverage. The relatively warm mid-level air should
limit instability with a diminished threat of severe
thunderstorms. Precipitable water around 2 inches indicates
heavy downpours with any thunderstorms. The temperature guidance
was consistent. Expect afternoon heat index values peaking 105
to 108 and just a little below the heat advisory criteria of
110.

&&

.SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
The models maintain surface troughing. The upper ridging is
shown a little weaker with troughing mainly north of the
forecast area. The pattern supports scattered thunderstorms
especially near the time of maximum heating. Followed the
guidance consensus for the pop forecast. Precipitable water
around 2 inches supports heavy downpours with the thunderstorms.
Instability should remain limited with relatively warm mid-level
air with a diminished threat of severe thunderstorms. The
guidance temperatures were close. It will be hot. Expect maximum
heat index values 105 to 108 and just a little below the heat
advisory criteria of 110.

&&

.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
The GFS and ECMWF show surface troughing lingering through much
of the medium-range period. Upper ridging is depicted building
Sunday and Monday with weakening Tuesday and Wednesday. Low-
level moisture should remain high associated with a southeast to
south flow circulating around high pressure off the Southeast
Coast. The pattern supports partly cloudy skies with a chance of
mainly diurnal thunderstorms through the period. The GFS and
ECMWF MOS plus GFS ensemble mean support pops 20 to 30 percent
with above normal temperatures. Expect highs mainly in the
mid 90s with heat index values 100 to 105.

&&

.AVIATION /12Z THURSDAY THROUGH MONDAY/...
Generally VFR conditions through the period.

Mainly clear skies across the area early this morning. Brief MVFR
fog possible at AGS/OGB until around 13Z this morning.  Widely
scattered convection expected to develop later this afternoon. Have
not included convection in TAFs given low probability of affecting
any one terminal.

EXTENDED AVIATION OUTLOOK...Scattered mainly afternoon and evening
showers and thunderstorms possible each day. Also, low-level
moisture could result in early morning fog and/or stratus.

&&

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

&&

$$
SYNOPSIS...99
NEAR TERM...99
SHORT TERM...99
LONG TERM...99
AVIATION...99


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