From Rah AFD and this is why they are on the lower end, smart imho and why they stayed with the advisory (plus roads shouldn't really be an issue)
Recent model trends have produced heavier precipitation tonight and
have come into better agreement with the surface and
thermal pattern
and precipitation amounts. Several of the models now produce
0.10 to 0.15 inches of liquid precipitation per hour for a
couple of hours across the northern half of central
NC. Given
the trend, have opted to increase snow accumulations across the
area with 1 to 3 inches expected across the north and northeast
and a more general 1 to 2 inches in the Triad and Triangle.
Accumulating snow has been expanded south a bit and have
expanded the
winter weather advisory in
Lee, Harnett, Johnston
and Wayne counties. Snow will most readily accumulate on grassy
and elevated surfaces and be slower to accumulate on roadways.
Have opted not to jump on board some of the guidance which is
showing much larger accumulations that range close to or in
excess of 6 inches given the tendency for some of these
algorithms to be overzealous with the snow accumulations, the
warm to start boundary layer and the narrow window of
accumulating snow. Lows tonight will fall into the 30 to 36
range with winds increasing and becoming northerly tonight and
gusting from 15 to 25 mph at times. -blaes