Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Columbia SC
230 PM EDT Sat Apr 18 2015
unsettled and wet weather pattern will continue through the
weekend into Monday. A strong cold front will move across the
area Monday night...scattered strong thunderstorms are possible
ahead of the front. High pressure will build over the area
Tuesday and Wednesday bringing fair and drier conditions through
Near term /through tonight/...
weak high pressure and weak low level wedge remains in place over
most of the forecast area. Persistent area of rain showers along
what appears to be a surface boundary lifting NE from the csra and S
midlands. Latest high resolution models shift this area NE across
the forecast area today while appearing to weaken it some. Elsewhere...expect
isolated to possibly scattered light showers developing with diurnal
heating. Instability will be weak but an isolated thunderstorm
could be possible.
Next system will approach from the west/SW late tonight. Axis of high
moisture with surface warm front and associated showers and
possible thunder appears will move into the csra after
midnight...and across the remainder of the forecast area by daybreak Sunday.
Will indicate increasing probability of precipitation from the west late tonight.
Short term /Sunday through Monday night/...
surface and upper level low pressure moving into the
Midwest/Mississippi Valley early Sunday...with surface low
deepening over Indiana late in the day. A warm front moving across
Georgia into South Carolina Sunday morning. Strong low level
convergence noted from the csra north across the Piedmont. Strong
lift expected with area under strong upper level divergence
associated with entrance region 250 mb jet from Gulf Coast north
across Tennessee. Precipitable water near 2 inches...about 3
Standard deviations above normal. Widespread showers/possible
heavy rain expected early ahead of warm front as short wave trough
approaches from south central Georgia. As air mass becomes weak to
moderately unstable...deep layer shear increasing especially
across csra and southeast midlands. Latest high-resolution models
suggest organized convective line may move rapidly across the area
during the afternoon. Although instability fairly weak...there is
some potential for severe thunderstorms mainly csra/southeast
midlands. As short wave energy lifts to the northeast early Sunday
evening...expect a decrease in probability of precipitation and thunderstorm
threat...lowered probability of precipitation from previous forecast...especially by
midnight. Temperature forecast...went a little below MOS
temperatures given clouds/precipitation despite expected warm
A strong cold front will approach the region late Monday...latest
model mean suggests front will move through central midlands/csra
around 03z-05z Tuesday. Models indicate moderate to strong instability...-8
to -10 surface based lifted index/ cape > 3000 j/jg as temperatures rise
into the low 80s. Moisture may be somewhat of a limiting factor
as front approaches but deep layer shear strong. Appears there is
some potential for supercells as 0-3km hodographs become more
favorable. Think main threat damaging winds and large hail due to
very dry air middle levels and low wet-bulb zero heights. Best
chance for rainfall should be during the afternoon hours. Slight
risk of severe thunderstorms Monday afternoon. Probability of precipitation decrease from
west to east as front moves through the area Monday evening. Low
probability of precipitation by midnight. Guidance temperatures mean appears on track.
Long term /Tuesday through Saturday/...
high pressure builds over the region Tuesday and Wednesday
bringing a reprieve from the unsettled pattern. Upper flow becomes
zonal to slightly northwesterly for the second half of the week
which is an more uncertain weather pattern. There are some
indications of low level moisture returning on Thursday and Friday
and more likely by next weekend. Will mention chance rain next
Friday night into Saturday with support from latest GFS/ECMWF.
Temperatures near normal.
given recent wet conditions/pattern and expected moderate to heavy
at times the next two days...especially upstream...there is
potential for river flooding early this week.
Aviation /17z Saturday through Wednesday/...
this afternoon...variable conditions across the region currently. In
the near term...area of showers just NE of ags/dnl moving slowly NE
towards the other terminals...while appearing to decrease in areal
coverage. Will handle with tempo groups at cae/cub/ogb.
Otherwise...will expect some increase in ceiling heights...with high end
MVFR to low end VFR generally expected outside any isolated to
scattered shower activity.
Tonight...a warm front will approach and move into the region late
tonight. Plentiful moisture...and low level winds becoming southeast and
increasing...will promote lower ceilings developing ahead of the warm
front. High confidence of IFR ceilings. Expect rain and associated
restrictions as well late tonight towards early Sunday
morning...continuing through Sunday.
Extended aviation outlook...
expect rain and associated restrictions Sunday...with possibility of
thunder in the afternoon and early evening. Winds will shift to SW
and increase Sunday behind the warm front. Bulk of rain activity
will shift to our east by Sunday night...but lingering ceiling
restrictions possible sun nt. A front will come through Monday...with
scattered thunderstorms expected Monday afternoon and
evening...possibly severe. Breezy conditions will be possible as
well Monday and Monday night. No significant impacts to aviation
expected Tuesday into Wednesday.