Scientific Forecaster Discussion
fxus62 kcae 280117 aaa
Area forecast discussion...updated
National Weather Service Columbia SC
917 PM EDT Mon Mar 27 2017
a series of troughs will move through the area through early
Tuesday and possibly trigger some showers and a few thunderstorms.
A cold front will move through the area Tuesday night. High
pressure will build into the region Thursday from the north
while moisture increases across the area. This may set up
unsettled conditions for the later half of the week with below
normal temperatures possible Thursday but warmer than normal
over the weekend.
Near term /until 6 am Tuesday morning/...
afternoon scattered convection has since waned with the loss of
heating and atmosphere stabilizing. Current regional radar
showing a couple of large areas of convection across Tennessee
and northwest Georgia this evening but only a couple of isolated
showers along the I-85 corridor in the upstate. That convection
to the west will continue to lift east-northeastward as a strong
upper trough also moves east into the central Appalachians by
early morning Tuesday.
Lowered pops across the forecast area through midnight to slight
chance or less but then pops increase late tonight through the
predawn hours as the upper energy approaches along with 500mb
height falls and deeper atmospheric moisture. Hi-res models
indicate most of the activity will remain to our north and west
through morning so lowered the high chance pops in the northern
and western midlands. Plenty of debris clouds will remain over
the forecast area tonight along with another southerly 30-35
knot low level jet which will help keep the boundary layer
mixed. This will result in poor radiational cooling and another
night with mild well above normal overnight lows in the upper
50s to around 60 degrees.
Short term /6 am Tuesday morning through Wednesday night/...
upper level low will be moving east across North
Carolina/Virginia with trough axis through SC through midday.
The stronger dynamics remain northeast of the area but scattered
showers and a few thunderstorms expected. A weak surface front
will be approaching from the northwest late in the day but
moisture ahead of the front will be limited and upper level
ridge developing. So little in the way of showers expected by by
20z. Expect clearing late Tuesday evening as both the upper
trough and surface front push through and slightly drier air
moves into the area. Pre-frontal conditions Tuesday and warm
advection. Air mass modifies quickly under ridge Wednesday with
subsidence. Expect temperatures to be near or slightly above MOS
guidance for Max temperatures. Guidance looks good for overnight
min temperatures. Temperatures remaining above normal with
highs in the lower to mid 80s and lows in the middle to upper
Long term /Thursday through Monday/...
the Thursday and Friday periods remain the most unsettled
through the expected. Upper ridge into the southeastern states
through Thursday then shifts east Thursday night as deep upper
level low moves from the Mississippi Valley to the east. Still
the possibility of a weak cold air damming wedge Thursday as
ridge builds south from the north but the ridge appears to be
off the New England coast resulting in more east low level flow
in the region. So confidence remains low and in fact the latest
models suggest weaker wedge scenario...especially in the Pee Dee
and east midlands where drier air may be present. Models
indicate moisture may be shallow and the strongest isentropic
lift and low level convergence remains along stalled front in
the csra and upstate regions. Still think temperature guidance
may be too high given the pattern but may little change to
current forecast. Highest pops in the csra Thursday. Warm front
may move north Thursday night and occluded front approaches from
the west early Friday. Strong deep layer shear possible but
instability appears weak. Still potential for strong
thunderstorms through Friday afternoon. Dry conditions over the
weekend although moisture may return early next week.
Temperatures remain above normal.
Aviation /01z Tuesday through Saturday/...
VFR conditions expected for the period.
Showers have mostly dissipated across the area with a few
persisting over northeastern Georgia. Potential for convection
overnight as a weak frontal boundary moves through the region.
Confidence in timing and coverage are currently low so have kept
mention out of tafs and will adjust as confidence increases.
With the front crossing the area threat for fog/stratus is
low...however a low level jet will be over the area producing
wind shear between the sfc and 1 kft. Potential for additional
convection after 16z...with highest potential further north and
have included vcsh for cae/cub/ogb.
Extended aviation outlook...restrictions possible Thursday as
wedge conditions develop over the area. Increasing confidence in
showers and thunderstorms Thursday night and Friday morning as a
cold front crosses the region.