Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Columbia SC
145 am EST Thursday Dec 5 2013
a warm front has lifted north of the forecast area. An increasingly
warm flow in the wake of the warm front will result in well above
normal temperatures through the end of the week. Chances of rain
increase again by Saturday as a cold front pushes into the area.
Near term /until 6 am this morning/...
warm front appears to still be situated near the csra with
widespread dense fog across much of the forecast area. Regional
radar showing an area of light to moderate rain moving
northeastward across the western midlands...associated with a weak
shortwave...and have increased probability of precipitation significantly in this area
through 09z. Temperatures expected to hold nearly steady in the
middle 50s north to lower 60s in the csra.
Short term /6 am this morning through Friday night/...
dense fog Thursday morning will gradually diminish as surface wind
increase ahead of the frontal boundary. A dense fog advisory is in
effect until 10 am. The forecast area will reside in the warm
sector Thursday and Friday with a deep moist southwesterly flow
aloft resulting from a deep trough in the western Continental U.S. And a
downstream ridge centered over Florida and extending up the East
Coast. Surface high pressure centered over the western Atlantic
will persist into Friday with southerly flow aiding in the
continual moistening of the atmospheric column. Precipitable water
values will remain high with values between 1.20 and 1.70 inches.
Weak warm advection/isentropic lift Thursday into Thursday night
may result in a few showers...though there will be little in the
way of upper level support. The main upper forcing will be to
the west of our area in the vicinity of a cold front that will
cross our area Saturday. Kept low chance probability of precipitation across the western
midlands Thursday and Thursday night...then dry weather Friday.
Probability of precipitation increase again Friday night as the cold front approaches.
Temperatures this period will be very warm with maximum temperatures well
above normal...some 12 to 20 degrees above normal...with highs in
the low to middle 70s Thursday and between 75 and 80 Friday. Record
highs do not appear to be in jeopardy. Overnight lows will be
significantly above normal...around 20 to 25 degrees above normal
in the upper 50s to lower 60s. A few highest minimum temperature
records may be within reach Thursday night.
Long term /Saturday through Wednesday/...
the medium range models are in good agreement as to a cold front
moving through the midlands and csra on Saturday. As the front moves
south and east of the area...a cold polar air mass is forecast to
build east of the mountains...setting up a possible cold air damming
scenario for Sunday. Low level forcing along the frontal boundary
and isentropic lift from southwesterly flow overrunning the near
surface cold layer warrant high chance to likely probability of precipitation across the
forecast area. Highest probability of precipitation are indicated behind the frontal passage
Saturday afternoon into Sunday.
Difficult temperatures forecast on Saturday given a daytime frontal
passage which could mean warm temperatures southeast and falling
temperatures in the northwestern counties...depending on exact
timing of the front. Models are indicating cold air damming
potential on Sunday with saturated soundings and strong temperature
inversion just above the surface early Sunday with precipitation
falling into the near surface layer further enhancing a wedge.
Kept maximum temperatures for Sunday on the cool side of guidance which favor
the ec MOS guidance. A warm up seems likely on Monday as upper flow
backs again in response to energy reloading in the upper trough
across the plains. With relatively high precipitable water values
early next week and persistent southwesterly flow aloft...will hold
on to the inherited low chance and slight chance probability of precipitation through
Tuesday. Dry and cool weather returns Wednesday as high pressure
builds in form the northwest.
Aviation /07z Thursday through Monday/...
dense fog advisory out for visibilities 1/2 Michigan or less entire area until
15z. Restricted ceilings until 12z will begin to lift after 15z
improving to MVFR/VFR ceilings/visibilities after 15z. Heating and mixing
should bring improving conditions by midday Thursday with VFR ceilings
after 17z with areas of MVFR visibilities.
Area of showers associated with upper level short wave to move
across the western portions of forecast area and should exit the area into NC
Extended aviation outlook...stratus and fog are possible again
late Thursday night and Friday morning because of continued high
low-level moisture in the south flow well ahead of an approaching
cold front. Showers and associated restrictions will occur
Saturday and Sunday associated with this slow moving front.
SC...dense fog advisory until 10 am EST this morning for scz015-016-
Georgia...dense fog advisory until 10 am EST this morning for gaz040-