Snow look to start in the area around 5am and it should be light at first. This should last a few hours before sleet starts to ix in around 7. Precipitation should still be relatively light. By 9am Philadelphia should be fully transitioned to sleet and it will stay that way for the next few hours. I could see 1-3" of pure sleet if mesocale models are correct. By 1pm the area should be fully transitioned to rain however if low level cold hangs on longer like some models suggest we could see a glaze of ice before this happens.
I am forecasting 1-3" of snow and sleet combined for most of the Philadelphia metro area. Further to the northwest I like 3-5" for eastern Pennsylvania while further south and east the quicker transition to rain will likely cause totals to be a bit lower.
New York City:
In New York City snow will start to fall around 9am. It should being relatively light as the low dew points and dry air will start to eat away at snow growth. Snow will get heavier in the coming hours and it will be moderate come 11am. Snow will stay like that and possibly get heavy at time up until around 3pm when I expect the changeover to take place. I believe there will be a quick transition to sleet as the id levels become flooded with warm Pacific air. I am expecting about 3 hours of sleet before a change to freezing rain around 5pm and plain rain soon thereafter.
My snowfall accumulations map shows New York City and the 5 boroughs as well as Long Island getting 1-3" of snow with the possibility of a bit more if the warm air holds off for long enough. Just northwest of 1-95 I have 3-5" of snow where I expect the cold air to be a bit more prominent with 5-8" in northwestern New Jersey in the higher elevations. I am also most concerned about the icing potential in this area. If the mid levels of our atmosphere warm a bit sooner while the cold air stays locked in at the surface ice may form and cause problems in the area.
Boston's snow should start to move in around 1-2pm and pick up in intensity by about 3. By 5pm multiple models are showing the potential for heavy snow setting up over the metro area. The heaviest snow moves past the area but moderate snow will likely still be occurring by 7pm with mixing not too far off. By 9pm I expect snow to transition to sleet for a few hours. Not long after that sleet will flip to a mix of sleet snow and rain by 11pm before going to plain rain shortly after midnight.
My snowfall my for Boston is showing 3-5" in the immediate metro area. I expect the cold air to keep precipitation snow longer in the hills of Massachusetts northwest of the city and I like a general 5-8" for that area. Further south in southeast Massachusetts and Rhode Island I am predicting a quick 1-3" before snow changes to sleet and rain.