Scientific Forecaster Discussion
Area forecast discussion...updated
National Weather Service Columbia SC
1043 PM EST Sat Dec 27 2014
high pressure over the Carolinas will move offshore as low
pressure develops over the western Gulf Coast. This will push a
cold front toward the area with showers beginning early Sunday
morning and persisting into Monday when the cold front will
finally cross the region. Dry weather returns behind the front for
the remainder of the week. Rain chances will increase again into
Near term /until 6 am Sunday morning/...
upper level pattern features highly amplified 500mb flow with an
upper ridge centered over the Bahamas/Cuba area with a positively
tilted upper trough extending from the Dakotas southwestward to
The Four Corners region. Surface pressure map indicates high
pressure centered over the western Atlantic ridging into the
southeast coast and this will weaken overnight giving way to an
approaching cold front from the west.
Area of rain moving northeastward from central Georgia is pushing
into the forecast area late this evening...associated with strong
southwesterly moisture transport and precipitable water values rising above 1.25
inches. Laps/RUC analysis soundings indicate the significant dry
air that was over the forecast area earlier has moistened with precipitable water
values now just under an inch. Have adjusted probability of precipitation upward into the
categorical range for parts of the csra and western midlands for
overnight to account for the band of rain lifting northeastward.
Dry air will continue to limit measurable rain and cut down on
rainfall amounts...still thinking a tenth of an inch or less
Temperatures this evening have dropped off quickly and expect to
see overnight lows early as clouds increase and thicken through
the evening hours which will curb radiational cooling and
temperatures may actually hold steady or slightly rise later
Short term /6 am Sunday morning through Tuesday night/...
models generally keep much of the rainfall just west of the County Warning Area
for much of the day on Sunday...and have gone with highest probability of precipitation
across the west...and drier across the east. Another shortwave
will push across the region late Sunday night...with the best rain
chances occurring after midnight Sunday night and into Monday
morning as the surface cold front moves towards the region. Will
continue with a chance for rainfall on Monday as the front moves
through...with drying beginning to occur late Monday night. Dry high
pressure will begin building into the forecast area during the day
Above normal temperatures are expected with highs in the 60s to
lower 70s both Sunday and Monday ahead of the front...then highs
drop back into the 50s for Tuesday. Overnight lows will be in the 50s
Sunday night...then cool to the 40s Monday night...then finally
into the 30s by Tuesday night.
Long term /Wednesday through Saturday/...
strong Canadian high pressure will remain centered off to the west
of the forecast area on Wednesday...then it will gradually
push eastward into the southeast on Thursday...then push off the
coast into Friday. Dry weather is forecast into Friday...then moisture
is expected to return through the day Friday as a warm front lifts
northward from the Gulf Coast states. Models begin to increase
rain chances Friday night into Saturday...and have generally gone
with chance probability of precipitation for that time frame. Although temperatures will be
on the cold side Wednesday into Friday...temperatures will increase
Friday into Saturday...which will keep readings warm enough that
the precipitation will be all liquid.
Aviation /04z Sunday through Thursday/...
high clouds continue to slowly increase across the area as a low
pressure system develops in the western Gulf of Mexico. Expect some
showers to affect ags/dnl overnight...and cae/cub toward daybreak.
MVFR conditions will develop across the area overnight. Winds
generally light and variable becoming southwest around 5 knots after
sunrise Sunday. Expect periods of light rain to continue with MVFR
conditions towards the end of the taf period. Southwesterly around 6
Extended aviation outlook...restrictions possible Sunday night
through Monday as the next frontal system moves into the area and
SC...Flash Flood Watch through Tuesday evening for scz030.