Southern stream moisture will get drawn into this system, and
with Canadian high pressure to the north, that provides a good
setup for wintry precipitation. There is an anomalous upper-
level ridge over the southeastern CONUS, so that does favor a
setup for a wintry mix for most areas vs. all snow.
Precipitation is most likely to overspread the area from
southwest to northeast late Wednesday night into early Thursday
morning. A potent jetmax along with southern stream moisture
suggests that moderate to heavy precipitation is possible
shortly after the onset. This can be seen in most guidance in
the form of a strong jetmax at the mid-levels that has origin
from the Gulf of Mexico. There is still some uncertainty as to
exactly where this band of heavier precipitation sets up.
Temperature profiles do appear cold enough for snow at the
onset for most areas, therefore, significant snowfall is
possible before changing over the a wintry mix. The best chance
for the heavier snow appears to be across the northwestern half
of the CWA (where colder temps aloft will hold on longer, and
where most of the guidance has the original band of heavier snow
setting up). A dry slot may cause precipitation rates to
decrease some Thursday afternoon, but more overrunning Thursday
night will cause more wintry precipitation to develop. With
warmer air aloft, sleet and freezing rain will become more
likely during this time (although snow will hold for a while in
the Allegheny Mountains and Potomac Highlands). Significant ice
accumulation from freezing rain is possible, especially near and
east of Interstate 95 into central Virginia. A Winter Storm
Watch is in effect for the entire CWA for these reasons.