Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Columbia SC
1019 am EDT Wednesday Jun 3 2015
a pressure trough will be near the coast through Friday. A strong
upper-level low will remain over the forecast area through
Thursday and then shift just northeast of the area Friday.
Near term /through tonight/...
convergence along the stalled front in the forecast area and
instability associated with the 500 mb low will help support showers
and thunderstorms. The Storm Prediction Center WRF has greater coverage this evening.
This appears reasonable because of recovery time from last night/S
widespread convection and lingering cloudiness. An exception may
be the csra where a differential heating boundary will be
established because of Morning Sun and widespread thicker
cloudiness in central South Carolina. The NAM has surface-based
Li/S lowering to near -6 in the csra this afternoon. The moderate
instability and heavy precipitation loading could help support
severe wind gusts in a few of the thunderstorms. The heavy rain
threat will continue because of the stalled front and possible
training...although higher precipitable water values have shifted
closer to the coast. Generally used the cooler temperature
guidance today because of cloudiness and the cold upper low.
Followed the guidance consensus for the temperature forecast
Short term /Thursday through Friday/...
the models display an inverted trough near the coast through
Friday. The 500 mb low should be over the area Thursday. The models
shift the upper feature just northeast of the area for Friday.
Expect 500 mb temperatures near -12 Thursday and -10 c Friday.
Lingering moisture and instability associated with the cold
temperatures aloft will continue to support a chance of showers
and thunderstorms. We leaned toward the higher guidance probability of precipitation
because of the pattern. Followed the cooler high temperature
guidance because of cloudiness. Used the guidance consensus for
the low temperature forecast.
Long term /Friday night through Tuesday/...
the models indicate weak upper troughing lingering early in the
medium-range period but the pattern becomes flatter with time. 500 mb
temperatures near -10 warm to around -8 for Monday through
Wednesday. Expect general surface ridging early...but a diffuse
boundary and associated moisture may linger. The models display
more surface troughing toward the end of the period. The GFS...
European model (ecmwf)...and ekd MOS plus GFS ensemble mean have probability of precipitation of 10 to 40
percent during the period. The MOS has temperatures close to
Aviation /14z Wednesday through Sunday/...
restrictions are possible throughout the period. MVFR ceilings are
expected to lift late this morning. Thunderstorms may move into
the forecast area this afternoon brining ceiling and visibility restrictions.
Showers have moved east of the taf sites. There is a slight
possibility of a few showers in the forecast area this morning...however the
majority of todays precipitation is expected after noon.
Yesterdays showers have worked to stabilize the airmass which
decreases confidence in thunderstorm development and intensity
this afternoon. Restrictions to both ceiling and visibility may occur in
With high surface moisture and light winds overnight low ceilings are
favored across the forecast area Thursday morning.
Extended aviation outlook...restrictions possible in mainly
afternoon and evening showers and thunderstorms each day. Low
confidence in restrictions in late night/early morning stratus