Scientific Forecaster Discussion
area forecast discussion
National Weather Service Columbia SC
1223 am EST Thursday Dec 12 2013
expect dry and seasonably cool conditions through Friday with rain
late Friday night through early Sunday. Fair weather with seasonal
temperatures will occur early next week.
Near term /until 6 am Thursday morning/...
a reinforcement of our cold and dry air mass will occur overnight.
High pressure currently over the area will give way to a slightly
colder and drier area of high pressure. Skies will be mostly
clear or partly cloudy with some high cloudiness.
The temperature forecast appears on track with lows in the upper
20s far north to around the freezing mark elsewhere.
Short term /6 am Thursday morning through Friday night/...
dry high pressure over the area will dominate through Friday.
Highs Thursday will be from the upper 40s north to around 55 south
with a north wind 5 to 10 miles per hour. Very strong net- radiational
cooling conditions will occur Thursday night so expect low
temperatures to fall into the lower 20s. After a cold start the
surface ridge will move offshore and low-level warm advection will
develop Friday. Moisture flux appears weak however through the
day...although with southwest flow aloft...expect increasing middle-
and high-level cloudiness. A weak surface low will develop in the
lower Mississippi Valley and upper trough will move into the
Southern Plains Friday night. Weak cold-air damming/wedge
development appears likely by morning here. There will be a chance
of rain from south to north during the late night...but most areas
will probably stay dry. Precipitable water will remain low with
any quantitative precipitation forecast light. Temperatures expected to rise or remain steady
Friday night due to cloudiness... although cold-air damming may be
developing especially across the north midlands.
Long term /Saturday through Wednesday/...
upper low/surface low will move northeast toward the area early
Saturday. GFS/European model (ecmwf) continue in good agreement with the associated
moisture return/isentropic lift. Weakening surface ridge axis and
evaporational cooling is expected to lead to an in situ
wedge...confidence higher for cooler temperatures especially
across the north midlands. Strong moisture flux/lift across the
region aided by 60-knots low-level jet and favorable upper-level jet
dynamics. Rain confidence is quite high with strong support from
ensemble guidance. Categorical probability of precipitation forecast with highest probability of precipitation
Saturday afternoon/evening. Favor cooler temperature guidance due
to The Wedge pattern. The system could be slow to move out
Sunday...as another upper trough approaches from the west. High
pressure expected to build into the area behind the system for
early next week with temperatures near normal.
Aviation /06z Thursday through Tuesday/...
VFR through the taf period. Dry air mass will remain over the area
with some high level clouds this morning. Winds will be northerly 10
knots or less.
Extended aviation outlook...MVFR or lower conditions are likely late
Friday night into early Sunday as moisture increases ahead of a cold
front which is expected to cross the area Saturday night.