Update, 2 PM: The rain/snow line continues to hang through the city at this point. It may change back to snow at the tail end of the event but it's going to be tough to coax much more accumulation than what's already dropped in the city. "Officially", the airport picked up a trace through 1 PM although by looking at various road cameras in the city it looks like the city's northwest half picked up closer to an inch of snow.
We have a couple of hours of precipitation yet to go around Philly and points northwest, with the coastal starting to wrap up and take over in the Atlantic, moisture should begin to push eastward and the storm should continue to work its way up the coast. Again, some of this may fall as snow in Philly or immediate South Jersey later this afternoon as colder air begins to draw into the storm but there's enough mild air in the lower atmosphere to screw things up a bit with the snow-starved's wishes for much.
North and west, things look much better for you all -- generally two to three inches so far, maybe one more to go in the next couple of hours. Roads are pretty tough to navigate around so drive carefully if you must be out.
Update, 12:30 PM: I drew in a rain/snow line on the radar screen shot above (explanation on the above graphic here) and below for a reference point to show you where it's snowing and raining around the region. Generally it's snowing from Long Branch or Asbury Park north and west of a line to Philadelphia. South and east of there it's rain or a mix with sleet in spots. Generally, the northern suburbs are doing pretty well from this event and have picked up an inch or inch and a half of snow in the 11 AM with snow thumping at a solid moderate to heavy rate around the northern suburbs.
Back edge of the precip shield is approaching Baltimore now, having just exited DC and is continuing to push northeast. We should see a continued light to moderate snow in the northern and western burbs over the next two to three hours, with probably another one to two inches, perhaps three in a few spots farther up to the north. The city will probably waffle a bit between rain and snow depending precipitation intensity, mixing with sleet at times. Farther southeast will likely see rain continue as the coastal storm intensifies.
As we work into the midday hours, you're seeing precipitation push north into the region as that energy transfer is finally starting to take place. It's snowing at a pretty good clip to the west of us over Western and Central Pennsylvania but the energy transfer to the developing coastal took a bit longer than expected as that primary low was a bit stronger and held its energy longer. That said, we're seeing that transition taking place finally and precipitation broke out a couple of hours ago near Washington and is pushing into our region.
Radar shows what appears to be heavy precipitation over New Jersey...that likely is not as heavy as reality -- probably the presence of sleet that's being detected by the radar along the New Jersey Turnpike and Route 206 corridor through South Jersey -- west of that is snow in general. As precipitation pushes northward, the thing we will watch is if the "milder" air aloft nudges west to change things over in Philly from what is snow as of 10:45 AM to a mixed bag. You're on the fence in the city...east of that, the snow/sleet/rain line may waffle along the Route 206 corridor or nudge west. North and west of the city is still good for a couple of inches, perhaps three in higher elevations, of snow through the afternoon.
The bulk of this event should fall between now and 4-5 PM before things wind down. Back edge of precipitation is about 90 minutes west of DC and moving relatively quickly. We have about a five to maybe six hour window to coax a couple of inches of accumulation out of this system.
Check radar for current (what's falling) updates. Feel free to share information with us via twitter, Facebook, or comments as well! I'll have another update in a couple of hours on here...more frequent stuff on Facebook and twitter.