Here we go again! The first significant winter storm of 2019 will start to bear down on our region this evening into Sunday afternoon. Models have trended a little warmer with this storm meaning the impacts should not be as severe as previously thought, but uncertainties still remain. Heavy snow should enter our region between 5 – 8pm tonight as the low pressure system advances northeast. This is where things like the duration of precipitation types/changeover gets a little tricky. Warm air will start to flood the atmosphere at 5,000 feet above our heads as the storm gains latitude eventually changing the snow over to sleet/freezing rain. The faster the warm air evicts the cold air above us will determine how much snow we accumulate. Regarding the dynamics of the system, there will likely be a heavy band of snow that develops at the beginning of the storm and pushes through our area that will be another factor in determining how much snow we accumulate before our precipitation changeover. Here is how I see accumulations playing out currently:
Even more uncertainty remains at the surface where the low level cold air will attempt to fight with the warm air to retain itself due to the cold air damming from high pressure over Canada. The longer the low level cold air holds itself at the surface will determine the difference between a severe ice accretion event or minor ice accretion event to cold rain for northwestern, NJ.
Eventually I think the low level cold air will giveaway to the warm air changing it over to a cold rain, but again the question is when. This is a very tough storm to forecast so stay tuned for updates throughout tonight. After the low passes starts to pull away from our region Sunday afternoon, an artic invasion of frigid air will flash freeze anything left on the ground as there will be a dramatic temperature drop Sunday night into Monday. Wind chills could potentially get as low as -22°F with actual temperatures either below or just around 0°F.