Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Columbia SC
211 am EDT Thursday Aug 21 2014
drier air and a building upper ridge just to our west will reduce
thunderstorm chances through Friday...and lead to hotter high
temperatures. An approaching cold front and increasing moisture
will increase the thunderstorm chance over the weekend.
Near term /until 6 am this morning/...
scattered convection has ended across the area this evening.
Still some activity well upstream over eastern Tennessee and northern Georgia but at
this time expect those storms to stay either well west of the
forecast area or dissipate before reaching our area given the
latest hrrr cycle. Nocturnal cooling with dry air aloft and light
wind should help support areas of fog toward sunrise. Overnight
lows in the in the lower and middle 70s still look reasonable.
Short term /6 am this morning through 6 PM Friday/...
upper ridge will build just to our west. This and a low level
downslope flow will lead to warming temperatures. Models continue to
indicate maximum temperatures near 100 degrees most areas...and continue to
indicates dew points mixing down into the middle to upper 60s across
the northern and western counties to near 70 or lower 70s across
the southeast midlands. This keeps heat indices just below our
heat advisory criteria of 110f. Only slight chance of
showers/thunderstorms expected due to building ridge aloft...and fairly
dry low level air leading to and high levels of free
convection/high convective temperatures.
Long term /Friday night through Wednesday/...
upper ridge to our west with upper trough and closed low to our
NE...providing a northwest flow aloft for our forecast area. Some timing
uncertainties with a back door front. Models trending a little
slower with it of late...with possibility that it may not make it
to our forecast area until Saturday afternoon or evening...slowly pushing
south through Sunday. Increasing probability of precipitation/thunder chance along and
south of the boundary...with cooler temperatures north of it. Front to
push to our south early next week...with surface and upper ridge
over the eastern Seaboard.
Aviation /06z Thursday through Monday/...
expect VFR conditions to dominate the period...with early morning
MVFR conditions at ags/ogb.
Cirrus from upstream convection continues to blanket the area and
will work to limit fog development. With the clouds expected
through much of the night have decreased the fog threat at
cae/cub/dnl to a tempo group while maintaining MVFR fog at
ags/ogb. Fog which develops will quickly erode with sunrise with
the remainder of the period VFR. Chances of diurnal convection
remain too low to include in tafs. Winds through the period will
be westerly at 5 knots or less.
Extended aviation outlook...MVFR or IFR conditions possible in late
night and early morning fog through the period. Isolated afternoon
and evening thunderstorms may also bring restrictions.