March 9: Overnight Snow/Rain Approaching

Jonathan Carr
By Jonathan Carr March 9, 2019 18:58

March 9: Overnight Snow/Rain Approaching

Discussion: A well-organized low pressure system (a mature mid-latitude cyclone) will track through the Great Lakes between now and tomorrow (Sunday) evening. A warm front, attached to the low, will push a period of precipitation through New Jersey from SW to NE between midnight tonight and late-tomorrow morning. This low is plowing into a SE Canadian high which will provide enough cold for wintry type precipitation for the interior. The best chance for wintry precipitation tonight will be N of I-80 and NW of I-287. We’re talking about N Warren, all of Sussex, N Morris, N Passaic and possibly NW Bergen Counties. While wintry precipitation can still fall slightly S and SE of such geographical boundaries, surface temperatures will likely inhibit accumulations. Here’s the latest short-range HRRR model (courtesy of truewx.com) depicting expected wintry accumulations. This map shows how much snow/sleet can fall. How much sticks will likely be less especially on paved surfaces:

snowfall_total_accum_10to1_PANJDE_hr016

Again this is a warm front passage so most areas should at least go over to a mix of sleet/freezing rain or rain especially once the lower-mid levels warm above freezing. Therefore for safe measure let’s allow the possibility for light snow/sleet accumulations N of I-80 and NW of I-287 with the highest NNJ elevations having the best chance. I doubt anyone up that way would see more than a few inches. The rest of NJ (lower 2/3) should expect rain from start to end. Here’s the same short-range HRRR depicting expected precipitation (in liquid inches). As you can see SENJ is favored for the most amount of overnight rainfall:

precip_total_accum_PANJDE_hr018

Winds should be stiff off the ocean tonight through noon tomorrow. This will be the period that the Great Lakes low pulls air in along the warm front. Tomorrow should feature much milder temperatures as most of NJ (at least the lower 2/3) is warm-sectored. Conditions should improve from late-morning through evening tomorrow. Winds should then switch to the W by Monday AM hours and bring some colder air through the region for Tuesday and Wednesday. Milder temperatures are expected beyond that.

In English: Snow is possible for parts of NNJ tonight mainly N of I-80 and NW of I-287 between midnight and late-tomorrow morning (Sunday). NNJ snow should change over to a mix of sleet, freezing rain or rain by sunrise tomorrow morning as a warm front pushes through from the S/SW. The rest of NJ (S of I-80/SE of I-287) should start and stay all rain from midnight through late-tomorrow morning. Rainfall could be heavy at times and we can’t rule out a few embedded boomers. Winds should pick up later this evening, off the ocean, and persist through most of tomorrow morning. Tomorrow we’re mild as conditions improve through PM hours. AM hours should be mostly cloudy as precipitation tapers off. I’ll have the Monday-Friday outlook posted tomorrow evening to cover the chilly start/mild finish to next week. Everyone have a great Saturday night and please be safe! JC

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Jonathan Carr
By Jonathan Carr March 9, 2019 18:58