Trends in the guidance, particularly the
ECMWF, towards a warmer
event have received quite a bit attention in the last 24 hours.
While these trends are are potentially positive as they would
support a rapid
erosion of the wedge and less widespread ice
accumulation in Georgia, they represent only a portion of the
guidance. About half the EPS members keep temperatures in Atlanta 20
degree colder than the
ECMWF on Sunday, while half the GEFS members
keep the Atlanta near or below freezing through Sunday. These
inconsistencies reflect the the models struggle to resolve the wedge
and its potential strength. Historically models overestimate the
ability of strong mid-level
WAA to erode the wedge. This has been
particularly true when the wedge is being reinforced by dry
CAA and
evaporative cooling. Given these considerations, we seem to be
trending towards an event where we start off with a fairly
widespread mix of light freezing rain and sleet on Saturday. As the
southerly
flow intensifies Saturday night and Sunday it may erode
the southern edge of the wedge while the core of the wedges strength
holds true in northeast Georgia. This would lead to contracting
temperature gradients and a potential switch over to rain in parts
of northwest and central Georgia. It wouldn`t be surprising if
temperatures gradients between Athens and Macon exceeded 30 degrees
on Sunday! Where the wedge traditionally holds strong in northeast
Georgia
icing may continue through the entire day on Sunday.
Significant and very impactful ice accumulations of 0.25 to 1.25
inches may occur.