Snow moves in between 10pm and 12am tonight an it'll be on the light side, but with temps in the upper 20's, everything will easily stick before temps begin to rise before dawn.
Any snow falling changes to rain by tomorrow mid-morning as slightly warmer air moves in, then the precip cuts off rather quickly after that. Highs will be in the upper 30's to low 40's, so any snow on the ground will be gone by late afternoon. Expect a coating to 2" in most areas, and I'm leaving the 2" mark in there just in case someone gets a "lollipop" amount.
As the intensity picks up and temps drop, snow will begin to easily stick on all surfaces, especially after sundown. I believe at this point, we pick up 2-4" of snow in the NYC area until we begin to question what kind of mixing and/or changeover we may get, if any.
Models continue to differ beyond that first round of snow. The GFS has our low pressure doing a full westerly approach, with warm air working in rather quickly and changing things to heavy rain for the NYC area; before back to a mix or snow as everything departs. Our short range NAM has a colder solution, with low pressure scooting to the south of us, keeping colder air in longer, before we dance on the rain/snow/mix line.
All of this bears close watching and to the chagrin of some, this may be one of those storms where we have to watch the radar and temps of the low and mid-levels of the atmosphere as everything unfolds. If there is no changeover, we get romped with a 10-14/12-18" type snowfall. If we dance the rain/snow/mix line, we could see a 2-4/3-6" type snowfall before we change to rain or ice/sleet, then another 1-3" on the backside. It's also possible precip cuts off on the back-end and there's nothing for a cold air to work with for a second round of wintry precip.
Either way, Monday is going to be a major major problem in the morning commute-wise, especially if theres any rain or mix involved in this. Expect flash freezing to occur overnight Sunday as we dip into the single digits, then only recover to near 10 on Monday. Anything slushy or wet will near-instantly become solid ice and treacherous.
We'll modify somewhat on Tuesday and into the upper 20's to low 30's and that may be pushing it depending on what the localized effect of snow cover (if any) does; then our next system on Wednesday may help us invoke some melting of icy surfaces with low to mid 40's possible.
Very cold air moves back in for Thursday and Friday, then we modify a bit on Saturday before another cold push comes in. With cold air rushing in from the Great Lakes region, look for a continuation of these quick shots of bitter cold air and quick shots of seasonable air.
