Storm Begins for Jersey

Discussion: The colder trend came to an end on overnight ultra short-range model guidance. Therefore, expectations of how much snow could fall in New Jersey Monday morning are becoming confident. But there’s more to this storm to talk about.

To quickly review, over the last few days, the upper-level data has evolved from a wrapped-up phase to a loose interaction of two pieces of upper-level energy. At the lower levels, this means a Great Lakes cutter (surface low tracks to the lakes) has evolved into a coastal runner (surface low tracks right along the coast/just off coast).  A coastal runner is typically still too warm for most of NJ to see snow accumulations. However, in this case, NNJ elevations could see trace-to-light accumulations of snow when the system ends Monday morning. Also, a lot more of New Jersey could see a non-accumulating snowy burst Monday morning. Let’s break it down by phase:

Phase I: (Begins now and ends at midnight tonight). A few pockets of leading rain have opened up across parts of New Jersey, so the rain has already begun. This first phase is going to be mild, foggy/cloudy, and rainy. Temps should range from upper-40s to 60s from NNJ to SNJ with no snow in the forecast. As we get further into today/tonight (Sunday), winds should pick up, especially for coastal areas. But for the most part, phase I is a gradual build from mild cloudy drizzle (now) to mild gusty heavy rain (midnight tonight).

Phase II: (Midnight tonight to 6AM tomorrow). Once we’re cranking overnight tonight (heavy rain/gusty winds), a series of low pressure will track from S/SW to N/NE either along or just off the coast. This should one, enhance rainfall rates, two, intensify winds, and three, switch the winds around. Once the low is N of NJ latitude, then winds will change from the warmer S/SE direction to a colder N/NW direction. Therefore, temps will begin crashing in this phase but not yet cold enough for a changeover to snow. Instead of ranging from 48-65 (NNJ to SNJ), it will be more of a 32-45 range. Only NNJ elevations have a chance to start seeing some wintry precipitation mix in. The rest of NJ will just see cold rain. So, the main takeaway from Phase I to Phase II is the transition from mild rain to cold rain, all while winds remain elevated.

Phase III: (6AM to noon tomorrow). This last phase is the only phase where accumulating snow is possible and mainly only for NNJ elevations. I do, however, think that areas further S and E of NNJ elevations could see a snowy burst fall from the sky, especially along WNJ. Surface temps will be above freezing though…likely for all areas S of I-80/SE of 287. Regardless, temperatures in the atmosphere will likely crash cold enough to change rain to snow in this phase, possibly for all of NJ. But the surface will only fall to near/just below freezing N of 80/NW of 287. For that reason, we’re only expecting a few inches of snow accumulation in the NNJ elevations in this third phase. PA elevations should do better than this. For all other NJ areas, snow will likely be conversational. That probably goes for SE PA as well. At some point between about 10am and noon, precipitation should shut off for everyone (from SWNJ to NENJ) leaving just stiff/gusty NW winds. Winds should then subside through Monday evening/overnight.

My concern is not the sloppy light snow accumulations that could stack up for NNJ elevations only. I think the primary hazards for this system are wind, flash flooding, and reduced visibility during Monday morning’s rush hour from falling snow (even if not sticking). Winds tonight and tomorrow morning could cause power outages. Heavy rainfall could cause flooding, especially nears creeks and streams with poor drainage. Once into phase III (see above), there could be blowing snow for many along and NW of the 95 corridor. The surface temperatures will inhibit accumulations on the coastal plain. But it could be a blowing snow situation that reduces visibility. Combined with winds, it could be rough driving conditions. Lots of delays possible so at the very least, allow more commute time Monday morning.

In English: First few batches of rain are pushing through NJ. Rainfall and wind intensity will pick up between now and midnight tonight. Temps will then crash after midnight (through the heavy precipitation). By sunrise tomorrow, rain should change to snow for at least NNJ/NWNJ elevations and possibly some lower elevation areas of SWNJ/CNJ/NENJ. SENJ is least expecting any sort of wintry end. NWNJ elevations however could see a few inches of wet snow accumulation when all is said and done late Monday morning. The rest of NJ will be too warm at the surface to accumulate snow. The ending snowy burst could be quite conversational in intensity. But the main safety hazards between this evening and tomorrow morning are gusty winds (40-60mph along coast) capable of producing power outages, heavy rain flooding (a few inches are possible), and reduced visibility during any blowing snow Monday morning (mainly for 95 and NW). It should all wrap up between 10am and noon Monday. Monday morning’s commute continues to look like trash across most of New Jersey. Be safe! JC

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Jonathan Carr

Jonathan Carr (JC) is the founder and sole operator of Weather NJ, New Jersey’s largest independent weather reporting agency. Since 2010, Jonathan has provided weather safety discussion and forecasting services for New Jersey and surrounding areas through the web and social media. Originally branded as Severe NJ Weather (before 2014), Weather NJ is proud to bring you accurate and responsible forecast discussion ahead of high-stakes weather scenarios that impact this great garden state of ours. All Weather. All New Jersey.™ Be safe! JC