Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Columbia SC
823 PM EDT Thursday Jul 30 2015
a weak cold front will slowly cross the area late tonight then shift
toward the coast Friday into the weekend. Highest chance of
showers and thunderstorms Friday into the weekend will be across
the southeast midlands. Temperatures will be above normal.
Near term /until 6 am Friday morning/...
latest analysis shows the weak cold front extending from eastern
PA southward into central NC...through the upstate and back
through central GA/al. Regional radar showing most of the
convection has shifted south and east of the forecast area...with
some additional convection over the eastern Pee Dee region. Very
little convection occurring along the frontal boundary right now.
However...precipitable water values remain very high around 2.2 inches with some
weak instability still available and until the front moves through
feel that slight probability of precipitation are warranted. Winds will gradually shift to
the northwest and northerly by Friday morning behind the front.
Cooler temperatures are lagging behind the front so still expect
overnight lows in the middle 70s.
Short term /6 am Friday morning through Saturday/...
a broad upper trough over the southeastern states will amplify
through Saturday. 12z GFS and NAM models show a frontal boundary
just east of the forecast area by Friday morning with surface high
pressure building in from the west. The 12z European model (ecmwf) is further east
with the location of the front than previous runs which is more in
line with the NAM and GFS. The local model is the furthest west with
the location of the front. The weak frontal boundary will remain in
the area through Saturday. Convergence along the front combined with
ample moisture will promote a chance of showers and storms into
Saturday. The best moisture will be along the coast on Friday with a
west-east gradient of precipitable water across the forecast area ranging from
less than 1.5 inches west to over 2.0 inches east. The NAM is much
drier than the GFS for Saturday but both show drier air moving in
from the northwest with the best moisture along the coast. High
temperatures both days are forecast near to slightly above
climatology...in the lower to middle 90s.
Long term /Saturday night through Thursday/...
models remain in fairly good agreement through the long term. The
broad trough will remain over the southeastern states through early
next week with the weak frontal boundary eventually dissipating.
The best moisture will remain along the coast. By the middle of
the week...the upper ridge over the Southern Plains expands
eastward and a weak Lee-side trough develops across the area.
Near to slightly above normal high temperatures are expected...in
the lower to middle 90s.
Aviation /00z Friday through Tuesday/...
VFR conditions expected for most of the taf period. 88d regional
composite shows only some widely scattered rain showers/thunderstorms and rain across the csra
this evening. Much of the activity from earlier today has either
diminished or moved southward into the lowcountry or central Georgia.
An approaching cold front will move into the region late tonight and
slowly move southeast across the area on Friday. Time sections
indicate that winds overnight will be light/calm and the possibility
exist for some local mfr conditions for fog. Have continued the
mention of fog at ags/ogb during the early morning hours. After
12z/13z...expect VFR all taf sites.
Extended aviation outlook...scattered afternoon and evening
convection with restrictions expected Friday through Monday.