Area Forecast Discussion
Issued by NWS Columbia, SC
FXUS62 KCAE 050325
Area Forecast Discussion
National Weather Service Columbia SC
1025 PM EST Sun Dec 4 2016
A low pressure system in the western Gulf of Mexico will move
northeastward and reach the Ohio River Valley Tuesday. The
associated warm front will likely remain south of the forecast
area through Monday then lift north to a position near or into
the area Tuesday ahead of a cold front. The cold front will cross
the forecast area Tuesday afternoon with dry high pressure briefly
building across the area for midweek. Another cold front will
cross the area Thursday. Much colder conditions will follow this
front for the end of the week.
.NEAR TERM /UNTIL 7 AM MONDAY MORNING/...
Surface high pressure will ridge into the forecast area from the
north through tonight. Isentropic lift will occur over the wedge
ridge. Periods of rain will continue with little temperature
change. The models indicate the strongest lift associated with the
h85 jet through the evening with diminishing lift late tonight.
Forecasted less rainfall late tonight. An average of the NAM,
GFS, ECMWF plus the SREF mean supports total rainfall through
tonight of 0.5 to 1 inch.
.SHORT TERM /7 AM MONDAY MORNING THROUGH TUESDAY NIGHT/...
By Monday morning, upper impulse, surface wave, and bulk of
associated precipitation, expected to be pulling away from our FA to
the NE. Frontal boundary will shift into the region with a new area
of dry high pressure building in behind it into the Mid Atlantic.
This may allow some scouring out of the in situ wedge and associated
lower cloudiness, mainly northern FA, though plentiful mid-level
cloudiness expected to remain. Closed upper low, currently over
northern Mexico, will open and shift NE through the SE CONUS/Mid
Atlantic states through Tuesday. Satellite water vapor imagery
confirm a good tap of tropical moisture from the E PAC into the
system. As upper and surface system moves NE from the Gulf coast,
upper lift and isentropic lift combined with abundant atmospheric
moisture expected to provide another batch of widespread rain
overspreading our region from the WSW late Monday, Monday night
into early tuesday. In situ wedge will develop at the surface in
response to the rainfall, with a typical secondary low developing
near the coast Monday night into Tuesday. Wedge boundary will lift
north some as a warm front, due to a strong SW 50 kt low-level
jet. Some question as to how far north the wedge boundary/warm
front can get. Some possibilities that the warm front could move
into our southern FA. Associated instability and shear could
provide a severe threat across that area.
.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
Behind the departing system, drier air will move in aloft late
Tuesday into Wednesday, but low-level wedge and associated low
cloudiness could be slow to scour out Tuesday night/Wednesday. Upper
trough will swing from the central CONUS to the E CONUS Wednesday
through Friday, ahead and south of which an upper impulse will ride
across the southern tier of states and across our region Thursday. A
cold front will move through our region Thursday. Models indicating
just enough moisture associated with front and upper impulse to
warrant slight chance POPs. Behind the front, cold dry polar high
pressure will shift into the SE CONUS. Breezy conditions possible
Thursday and Thursday night. A lake wind advisory may be needed.
The center of the high is expected to be overhead by Saturday
morning with appearance of strong radiational cooling conditions.
Long range MOS projected lows in the mid 20s. Will undercut
guidance a little as those numbers may be a little high as they
are skewed towards climatology that far out. For now, think lower
20s reasonable with possibility that these numbers could be
lowered a tad as we get closer to the event. Daily record low for
Columbia for Dec 10th is 20, and for Augusta is 16. Some timing
differences between GFS and EC on the next system. GFS sweeps a
front through our FA Sunday, while EC indicates a slower system
Sun nt and Mon.
.AVIATION /03Z MONDAY THROUGH FRIDAY/...
Widespread IFR conditions will continue overnight. A wedge-ridge
pattern will continue through the period. Continued isentropic
lift north of the warm front will bring a trend of lowering
ceilings and visibilities. There will be significant shear
associated with a low-level jet. Latest CAE VWP indicating winds
at 2kft from the SE around 30kt so will mention LLWS at all TAF
sites for much of the overnight period. Not much improvement
after sunrise Monday with conditions possibly improving to MVFR by
18z before IFR conditions return by around 00z Tuesday.
EXTENDED AVIATION OUTLOOK...Expect widespread IFR conditions
associated with a warm front through Tuesday. Drier conditions are
expected Wednesday, but then a cold front may bring more showers
and associated restrictions Thursday. Breezy conditions may be
associated with the front.