Scientific Forecaster Discussion
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Area forecast discussion
National Weather Service Columbia SC
640 am EDT sun Aug 25 2019
a front will be stalled just south of the forecast area through
Monday. The front will become a warm front and may lift northward
and into the area Tuesday and linger Wednesday. Low pressure
tracking northeastward will stay well off the southeast coast.
An approaching cold front will move into the area Wednesday night or
Near term /through tonight/...
a cold front was stalled south of the csra. Cold air damming was
occurring with cool high pressure ridging into the area from the
north. Surface low pressure located off the East Coast of
Florida is forecast to track northeast to a position well off
the SC coast tonight. This low is being monitored by the
hurricane center for possible development. Some Atlantic
moisture from the offshore low may produce a few showers across
the eastern midlands this afternoon. However, shallow moisture
will limit precipitation.
We expect below normal temperatures given clouds and a cool
northeast flow. Have favored the cooler guidance temperatures
today with highs ranging from the mid 70s north to the lower 80s
south. Went near guidance consensus tonight for lows in the mid
to upper 60s.
Short term /Monday through Tuesday night/...
the models show surface high pressure wedging into the forecast
area from the north with the front stalled south of the area
Monday and Monday night. Low pressure is depicted staying well
off the coast. There may be weak h85 warm advection mainly
Monday night. 500 mb ridging may linger through Monday with moisture
becoming deeper ahead of troughing Monday night. The pattern
supports considerable cloudiness with a chance of showers mainly
Monday night. The Wedge pattern and weak lift support little
instability so we do not expect thunderstorms. The guidance was
consistent with chance pops. The high temperature guidance is
likely too high because of The Wedge pattern Monday.
The models show the front becoming a warm front and lifting into the
forecast area Tuesday and Tuesday night. A dampening mid-level
shortwave trough is also depicted moving into the region. There
should be increased moisture and instability with a greater
shower and thunderstorm chance. We followed a guidance consensus
for the pop forecast. The NAM, GFS, and European model (ecmwf) indicate h5
temperatures relatively high at -5 to -6 c Tuesday. Cloudiness
should also help limit instability. Believe instability will
remain weak plus the models indicate weak shear with h85 wind
less than 25 knots. There is a diminished chance of severe
Long term /Wednesday through Saturday/...
the GFS and European model (ecmwf) show surface troughing in the region
Wednesday with an approaching cold front. The European model (ecmwf) has been
faster moving the front into the region. Both models depict the
front stalling near the coast late in the week. The closeness of
the front supports keeping a chance of showers and thunderstorms
in the forecast. The GFS and European model (ecmwf) MOS have pops 20 to 30 percent
during the period. The MOS indicates near-normal temperatures.
Aviation /12z Sunday through Thursday/...
the cold front has stalled south of the taf sites.
High pressure building in from the north with cold air damming
across the area. MVFR/IFR cigs across the area this morning.
Models have been consistent with MVFR cigs for most of the
daylight hours. Could see VFR cigs develop late in the day into
this this evening as slightly drier air filters in from the
north. Rain chance appears low with no significant lift. Winds
will continue northeast around 10 knots.
Extended aviation outlook...widespread IFR or MVFR conditions
may linger during much of the outlook period because of a front
remaining in the region.