I'll get right to it.
Nor'easter. Snow begins Monday night between 10pm and midnight. Snow is heaviest between 4am and 2pm on Tuesday, beginning to taper by 3-4pm. We'll see snow showers Tuesday evening and overnight (and a nominal bit of additional accumulation) and maybe even some flurries on Wednesday morning.
Berks, Lancaster, Lebanon, Lehigh, Montgomery Counties (as well as north Jersey and NYC), 14-18"
Philadelphia, Chester County, south Jersey, northern Delaware, 8-12"
Delaware, extreme south Jersey, 4-8" with mixed precipitation
Is this a blizzard?
Strictly speaking, a blizzard is a severe winter storm that has sustained winds of 35mph or more and visibility of under 1/4 mile for three hours or more. We'll have winds of 15-25 mph on Tuesday morning and afternoon with gusts as high as 35-40mph, but expect visibility to be 1/4 mile or less for much of Tuesday morning and afternoon. So it's really just semantics--whatever you call it, we'll have a sucky, cold, snowy, wind-driven hellscape that will have the following impacts:
Power outages - Since it's a heavy, wet, wind-driven snow, we'll see widespread downed trees and power lines.
Travel snafus - Don't even think about trying to drive on Tuesday morning and afternoon. When people try anyway, there will be bad results. And cancelled flights up and down the eastern seaboard.
School closings - A snow day is all but guaranteed for Tuesday across the region, but the good news (at least the silver lining to this bad news, which I've become an expert at finding lately) is that because of the sun angle (it's mid-March) and the end time, we might just see delays on Wednesday. (This would change if there are widespread outages in an area or we hit - or exceed - the upper limit of those snow totals.)
Speaking of which:
Chance of delay Tuesday, 0.77%
Chance of early dismissal Tuesday, 4.22%
Chance of cancellation Tuesday, 95.01%
[Note: yes, the percentages for Tuesday add up to 100%. You're welcome, math teachers!]
Chance of delay Wednesday, 46.13%
Chance of cancellation Wednesday, 19.12%
Windy on Wednesday; Wed and Thu are still below normal (highs in the mid 30s). Highs slowly climb through the 40s over the weekend (when we may have some snow showers but no big) and into early next week.