That's why it's a watch. You put them out 48 hours in advance when 6+ looks likely. Which it did. There's no reason it can't be adjusted to an advisory.
As expected the dividing line has edged from Philly to Trenton to now near somerville. That sleet line will almost always make it to 78. It will come down to front end thump and if we can manage 4 to 5 before the pinging. Even 3 gets me to double digits for the winter so I'd be happy
Reminds me of a dec 2013 storm when it was like 60 and raining in AC and in the teens up in nw nj. We had like 4 to 5" with temps in the low 20s but it still went over to sleet