Scientific Forecaster Discussion
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Area forecast discussion
National Weather Service Columbia SC
1005 PM EDT Tue Mar 28 2017
a cold front will move through the area tonight and stall near
the csra. The pressure ridge will build southwest across the
Carolinas from the north then move off the East Coast Thursday.
Moisture will return Thursday with a chance of showers...
especially in the csra. A warm front will move through the area
early Friday followed by a cold front late. Numerous showers and
thunderstorms are expected Friday. It will be slightly cooler
Thursday and Friday with unsettled conditions but warmer and
drier over the weekend.
Near term /through Wednesday/...
the cold front will cross our area from north to south tonight.
Much of the moisture has already shifted east of the area ahead
of the front and isolated showers have dissipated. Winds may
remain around 5 mph through the night behind the front. Kept
overnight lows near the consensus...in the middle to upper 50s.
Short term /Wednesday night through Thursday night/...
ridge aloft and at the surface Wednesday and expect strong
subsidence. Although low-level flow from the north...air mass
appears to moderate quickly behind the front and along with
subsidence expect mild afternoon temperatures in the low 80s
with little in the way of clouds. Clouds expected to increase
late Wednesday night across the Piedmont/csra then spread into
the midlands as weak isentropic lift and low-level moisture
flux increases. Moisture appears too shallow for showers until
after 12z Thursday. Upper-level ridge off the coast Thursday
with deep low in the Midwest moving east with southwest flow
aloft developing. Previous models runs suggested cold air
damming Thursday with surface ridge off the New England and mid
Atlantic coast extending southwest into the Carolinas. That's
still the case but appears to be very weak with dry air in the
east midlands...more east-southeast low-level flow and focus
for isentropic lift and deeper moisture in the upstate SC and
portion of the csra. It's possible it may be cooler during the
afternoon in the csra than Pee Dee or east midlands due to
higher probability of showers in that region. Models suggest at
least weak instability near the stalled front in the csra so
mentioned thunder there. Stayed close to current temperature
forecast which is near or slightly below the consensus MOS
guidance given pattern. Warm front may begin to lift north
during the evening and overnight Thursday with increasing deep-
layer shear. Potential for strong thunderstorms late at night
especially toward dawn Friday. Deep lift associated with
approaching upper-level low/strong deep-layer shear at least
moderate instability and approaching cold front/occlusion during
the afternoon supports high probability of showers and
thunderstorms. Storm Prediction Center has region in a risk of severe thunderstorms
Long term /Friday through Tuesday/...
dry conditions over the weekend as ridge builds over the area.
Another deep low in the Central Plains will be moving east-
northeast early next week and bring another chance of showers
and thunderstorms Monday and possibly Tuesday although 12z
models appear a little faster. Temperatures remain above normal.
Aviation /02z Wednesday through Sunday/...
VFR conditions expected through the taf period.
Weak frontal boundary will slide south of the terminals this
evening with high pressure moving north of the area tonight
through Wednesday. Showers which had developed earlier have
dissipated with mostly clear skies expected overnight. Fog
potential overnight will be low as drier air overtakes the
region. Winds will be light and variable overnight...then become
northerly at 7 knots or less from 14z through the end of the
Extended aviation outlook...restrictions likely in showers and
thunderstorms Thursday through Friday night as an cold front
crosses the region.