Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Columbia SC
150 am EDT sun Aug 31 2014
a persistent upper ridge will keep very warm temperatures in the
forecast through next week. Moisture will increase this weekend
into early next week bringing back a low chance of afternoon
thunderstorms and higher humidity.
Near term /through Sunday/...
rest of the night...an upper level ridge was off the coast of the
Carolinas. South to southwest flow aloft was spreading high and
middle level moisture across the western and central Carolinas. At
the surface...Bermuda high pressure continued to ridge into the
southeastern states. Moisture continues to increase in the low
levels and similar to last night...expect some stratus/fog to
develop late tonight which will help limit radiational cooling.
Kept overnight lows in the low to middle 70s.
Sunday...upper level ridge remains across the County Warning Area again through the
day. Upper level energy passes west and north of the area. Models
continue the trend of bringing in lower probability of precipitation. Best chance for any
precipitation should remain west and north through the day...with the
possibility of sea- breeze showers pushing into the east later in
the afternoon. Will go no higher than slight chance. Afternoon
temperatures continue rather hot...and due to the cool bias of the models
the past several days...am inclined to continue with going a few
above the met numbers...and will stay closer to the mav. This
brings middle 90s once again.
Short term /tonight through Monday night/...
strong middle/upper level ridge continues to hold along the southeast
coast into Monday night. Short wave energy across the central/northern plains
will continue to move eastward across the Great Lakes and flatten
out the amplitude of the ridge...but still hangs in strong across
the southeast. Flow return to more south by Monday night.
Guidance probability of precipitation/model spectrum only indicating slight chance/very
low chances probability of precipitation through the period. Have stayed close to these
numbers with activity to be more diurnal in nature with only some
weak surface convergence/sea breeze action each day. As for
temperatures...boundary layer temperatures remain quite warm in
the upper 80s/around 90 and expect afternoon temperatures to
continue to be in the Lower/Middle 90s across the County Warning Area through the
Long term /Tuesday through Saturday/...
no changes to the extended forecast. Upper ridge continues over
the area through the extended period. However...the overall upper
pattern is not as amplified...but ridge still holds in across the
southeast as S/ws move west to east in the flow across the northern plains
and Great Lakes and remaining north of the County Warning Area. Low-level moisture
continues to slowly increase through Wednesday as precipitable water values
increase to around 2.0 inches. Precipitable water values decrease slightly through
the end of the period...but remain between 1.5 and 1.75 inches.
With the passing of each short wave...mainly north of the area a weak
boundary tries to move southward into the region Wednesday have
continued with low chance probability of precipitation through much of the long term
period. Best chance appears to be on Wednesday with a weak
surface boundary SW/NE across the Piedmont. Remnants of boundary
linger in the vicinity of the County Warning Area through much of the period.
Otherwise...just a slight chance/chance through the remainder of
the period. Still looks to be diurnal in nature with afternoon
heating with weak surface convergence and little/no upper support.
Temperatures will continue to be above normal through the
remainder of the long term period. Expect afternoon highs in the
low/middle 90s and overnight lows in the low/middle 70s. Normals highs
are in the upper 80s and lows near 70.
Aviation /06z Sunday through Thursday/...
VFR conditions into the early morning hours...then stratus/fog
development expected during the predawn hours.
Eastward moving outflow boundary may approach ags/dnl by
09z...with an isolated shower in advance possible in the western
csra. However will not put in tafs at this time due to low confidence as
boundary moves into ridge. Overnight fog and stratus remain the
focus of the taf period with development expected around 08z
ags/ogb and 10z cae/cub. Combination of increasing moisture and a
weak low level jet overnight will result in early morning IFR/LIFR
fog and stratus between 08z and 14z...with lowest conditions
between 11z and 13z. With sunrise and mixing fog and stratus will
lift into an MVFR stratocumulus deck...then finally mix out by
16z. Remainder of the period will be VFR with potential for
mainly scattered showers and thunderstorms...however confidence
remains too low to include at this time.
Extended aviation outlook...restrictions possible in late night
and early morning stratus and fog each night. Scattered mainly
afternoon showers and thunderstorms Sunday through Thursday.