Probably because the models seemed to tone things down a good bit with their last runs. That said, we are in storm mode now... there is no real reason to focus so much on numerical guidance that is almost never correct with final feature placement anyway. BUT, there is a major problem with most of the runs tonight... they initialized the low way too weak at hour 0. Obviously, if they are way off at hour 0, they will be terrible at hour 24... in fact, the American models show the low stronger in 24 hours than it is now--and that's after deepening it all day tomorrow.
I don't know Philly all that well, and I hear that Rob G. is a good meteorologist. I would certainly hesitate to disagree with him. Based on the local forecasts here in CT, I can see that they don't really know what to do... the models tonight say varying things, all the other data says otherwise.
If the low continues doing what it has for the past 6 hours another 6 hours, I think there will be a lot of places raising their amounts.
Despite what the usual naysayers have said in this thread and elsewhere, this is not a run of the mill storm. The strength alone almost assures that places on the East Coast (i95 included) will see conditions very near blizzard -- if not true blizzard -- criteria for a time Mon or Tue.
should read: the American models show the low weaker in 24 hours than it is now.
Rob G is a great weatherman. Have you checked out his site? If not here's the link.
http://www.fox29.com/_ezpost/data/9715.shtml