Area Forecast Discussion
Issued by NWS Columbia, SC
FXUS62 KCAE 191436
Area Forecast Discussion
National Weather Service Columbia SC
936 AM EST Thu Jan 19 2017
A high pressure ridge in the forecast area will weaken today
ahead of an approaching warm front. The front will move into the
region tonight and lift north of the area Friday. Another warm
front will develop and move into the region Saturday ahead of
strong low pressure. The low will be near the forecast area
Sunday and Monday.
.NEAR TERM /THROUGH TONIGHT/...
Clouds are slow to move in to the CWA this morning, so I
nudged the temps up a degree or two and and adjusted the sky
cover accordingly. I still expect thicker clouds to move in
later this afternoon as a jet streak approaches from the west,
but the delay will allow us to get a little warmer than
Moisture will be on the increase tonight ahead of a warm front
and mid-level shortwave trough. The models depict the greatest
forcing during the 09z to 12z time frame especially in the
northwest section. The shortwave trough should dampen as it
moves into the ridge supporting the light rain amounts indicated
by the models. The temperature guidance was consistent.
.SHORT TERM /FRIDAY THROUGH SATURDAY/...
The shower chance should diminish Friday. Moisture will become
shallow in the wake of the mid-level shortwave trough. The
models display the warm front and associated isentropic lift
shifting northeast of the forecast area. The models display an
increase in moisture Friday night and Saturday associated with
another warm front. Deep moisture is depicted Saturday ahead of
a mid-level shortwave trough. We followed the guidance consensus
and forecasted chance pops Friday night and likely Saturday.
Thunderstorms may occur Saturday. The GFS displays surface-based
LI values lowering to near -5 during the afternoon in the CSRA.
Less instability is shown farther northeast. Increased shear
associated with a low-level jet and this instability supports
possible severe thunderstorms.
.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
The GFS and ECMWF show a warm front ahead of strong low pressure
in the forecast area Saturday night. The warm front may lift
north of the area Sunday ahead of a cold front. The associated
low should be near the area Sunday night and Monday. The models
indicate high shear Saturday night into Sunday night. The GFS
depicts the greatest instability Sunday afternoon and evening.
Severe thunderstorms may occur. The main limiting factor may be
convection south of the area limiting the transport of moisture
and instability farther north. The main axis of instability and
strongest shear should have moved northeast of the area by
Monday morning, but significant cyclonic curvature will still
support showers across the area. The system should be lifting
north of the area Tuesday with a diminished shower chance.
.AVIATION /15Z THURSDAY THROUGH MONDAY/...
Upper level ridge and surface high pressure will build across the
region today. VFR conditions should prevail for the TAF period
with high level clouds remaining across the region. Could see
mid level clouds increasing late this afternoon as moisture
increases ahead of an approaching warm front.
Light and variable winds overnight will become northeast
this morning then veer southeast during the afternoon.
Latest models indicating an upper trough moving in from the west
late tonight. As a result, expect rain to develop across the
area during the pre-dawn hours Friday. MVFR conditions may be
EXTENDED AVIATION OUTLOOK...The chance for showers will continue
into the day Friday. More showers...and associated
restrictions...are likely Saturday through Monday as a low
pressure system crosses the region.