Here Comes Winter (Dec 4-8)

Discussion: Monday and the first part of Tuesday should feature milder conditions with SW flow ahead of the cold front. The cold front itself should bring a period of moderate to possibly heavy (at times) rainfall Tuesday PM into Wednesday AM. Wildcards surrounding this frontal passage include convective potential (embedded thunderstorms) and tail-end flurries as precipitation tapers off. Either way temperatures are going to shift from mild to cold after the front moves through. From Wednesday through at least December 18^th looks to feature colder temperatures and an overall favorable pattern for winter storm development. Expected blocking is impressive (-NAO) near Greenland with a spiking ridge in the W US (+PNA) which is playing off a –EPA upstream in the E. Pacific. This will allow the jet stream to dip and hold over our region with pure Arctic air spilling within the trough (thanks to a -AO). This will create favorable divergence on the front lower side of the trough for a surface low to form. Exact dynamics and sfc low location will depend on vorticity signature. Whether or not the surface low tracks favorably for a precipitation shield to get thrown over NJ (off the ocean) is yet TBD. With that said I am watching this Friday PM into Saturday morning for possible wintry precipitation from a weak coastal low. I’m pretty “meh” on this right now as it could easily slip east. The GFS says game on while the Euro keeps the system weak and out to sea. It could be a close call for SENJ so for now I’ll continue to track it. I’m also watching next week for something possibly bigger. We’re going to have to take each mid-range forecasting period at a time but I’m starting to get that “something is going to happen” feeling.

Monday (Dec 4) high temperatures should range from upper-40s to mid-50s NWNJ to SENJ. Skies should be partly cloudy. Winds should be light out of the E/NE. Overnight lows should fall into the 40s for most with NNJ elevations likely dipping into the 30s.

Tuesday (Dec 5) high temperatures should range from mid-50s to lower-60s NWNJ to SENJ. Skies should gradually increase in cloud coverage through AM hours. Rain could start as early as afternoon but will likely start by early evening hours. Rainfall should continue overnight with a very small chance of a few embedded boomers. Breezy rainfall is the most rational expectation. Winds should be breezy-to-gusty out of the S. Overnight lows should fall into the 40s for most.

Wednesday (Dec 6) high temperatures should reach the upper-40s/lower-50s. This high temperature will likely come during early AM hours. Once the cold front is through by mid-to-late morning, temperatures should fall steadily throughout the day. Let’s give it until noon for rain to taper off although it will likely do so a few hours earlier for most. Let’s also allow a small chance for precipitation to end as non-accumulating snow, especially for points NW. Not really excited about this SE of the turnpike so likely just a cold rain for such. Winds should be breezy-to-gusty out of the W/NW. Overnight lows should range from upper-teens to upper-20s NWNJ to SENJ. Only extreme SENJ has a chance to hang near-30.

Thursday (Dec 7) high temperatures should range from upper-30s to lower-40s NWNJ to SENJ. Skies should be partly cloudy. Winds should be light-to-breezy out of the W. Overnight lows should range from upper-teens to upper-20s NWNJ to SENJ.

Friday (Dec 8) high temperatures should struggle to escape the 30s statewide. Skies should start partly sunny and increase in cloud coverage as a coastal low passes by. A wintry mix or possibly even a mostly-snow event is possible Friday evening into Saturday morning. It’s far from guaranteed from this point. It doesn’t look major but could possibly be disruptive if everything aligns perfectly. SENJ would be favored over NWNJ for this. You’ll likely see special articles from me this week if the potential stays on the table through Tuesday. Otherwise Friday would probably stay dry and cold with precipitation just-missing offshore. Winds would likely rock counter-clockwise from SE to N/NE around the passing weak cyclonic system to our SE. Overnight lows would likely hang in the 20s statewide.

An early look at the weekend indicates continued colder temperatures with another frontal passage Saturday into Sunday. This should knock daily highs and lows down even a few degrees colder than this week. Once Saturday AM clears from any possible coastal low influence, the rest of the weekend should be mostly dry…aside from any lake-effect streamers or squalls that might form. NWNJ would be favored for such over SENJ. Next week has the potential to keep me busy if the favorable pattern for winter storm development holds true. Let’s take another look in a few days. Everyone have a great week and please 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 and forecasting services for New Jersey and immediate 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 discussions ahead of high-stakes weather scenarios that impact the garden state. All Weather. All New Jersey.™