NWS GSP Afternoon AFD Official Guidance
Key message 4: We continue to monitor the evolution of model
guidance for Saturday night and Sunday with some interest, given
the consistent
GFS depiction of snow potential, but a lack of
consistency between models keeps confidence low.
Another short wave diving into the central
CONUS will deepen the
upper
trough to our west Saturday night. The short wave and
trof
axis cross the area on Sunday. This creates
cyclogenesis off the
Carolina coast along the frontal boundary from Saturday. Southerly
flow develops Saturday night with increasing
moisture and isentropic
lift across the area. Deep layer forcing and
frontogenesis takes
place as well. All of the guidance pretty much agrees on this,
although with some differences where the axis of heaviest precip
develops. They also disagree on the amount of cold air available
when the precip develops. The
NAM has come in with enough cold air
and precip for accumulating snow across the area. The
GFS remains
cold enough for snow; however, it has shifted the precip axis to our
east limiting the amount of significant snow to our southern and
eastern
CWFA boundary. The Canadian remains warm enough for rain for
all the mountains but has shifted the precip axis to the east. The
ECMWF continues to be cold enough, but is basically dry with all the
precip to our east. The GEFS
mean continues to shift the precip axis
east but has enough for light snow over our area. The Canadian
ensemble mean also trends with light snow at most. Therefore,
confidence remains low but the chance of accumulating snow
continues. The model blend, and our forecast given the uncertainty,
shows an inch of snow basically along and east of a Greenwood-
Spartanburg-Hickory line with lower amounts to the west. The
eventual result will be highly dependent on the precip axis and cold
air availability, so keep up with the latest forecasts for
likely
changes
