Jan 10: Rain and Cold Expected

Discussion: A surface low will generally track along the Appalachian Mountains from SW to NE this Friday-Saturday. There’s nothing overly remarkable about the upper-level physics. We have above-average 500mb height anomalies departing the east coast as below-average 500mb height anomalies approach from the W. Cyclonic vorticity is pretty run-of-mill and all this under a typical S/SW 250mb jet.

I’m fairly confident in most precipitation falling as rain between early Friday morning and late-Saturday morning. Expected precipitation is between a half-inch and two inches from SNJ to NNJ. NWNJ might exceed 2 inches but should fall short of 3. SENJ is favored to see the least amount of precipitation. We might see a break in the precipitation Friday night as the southern and northern energy parallel each other progressively through our region.

Rainfall could be moderate-to-heavy at times but the biggest concern IMO is the freezing potential once rain has tapered off. An Arctic front is expected to push through between late-Saturday morning and Saturday afternoon. Friday looks very mild with high temperatures likely in the 50s. Saturday should start off warm in the middle of the rain during early AM hours. Therefore Saturday’s high should be reached before sunrise. Once the rain tapers off and the Arctic front rolls through, temperatures are expected to steadily drop through all of Saturday leading to a cold Saturday night. I’ll have the weekend outlook posted tomorrow but this article is focused on the Friday-Saturday precipitation.

They say back-end snow is an old wives tale but it’s possible in this case. The best favored area for precipitation to end as either sleet or snow is NWNJ. SENJ and points SE of I-95 should likely stay plain rain the entire time. I do not expect accumulations of wintry precipitation, even in NWNJ. Again, my biggest concern are areas still wet when the Arctic front moves through on Saturday just after the rain tapers off.

In English: Moderate to heavy rainfall is likely between Friday morning and Saturday morning. About a half-inch to 2-3 inches (SNJ to NNJ) are possible. Temperatures will be mild for the rainfall but will crash just after the rainfall ends. Just a small chance of some back-end flurries or sleet in NWNJ. With that said, Saturday should start on the mild side just after midnight (50-60F) but temperatures should steadily fall through Saturday leading to a colder Saturday night. Please watch out for any standing puddles or wet surfaces that haven’t yet evaporated on Saturday afternoon. They will likely freeze. I’ll have the weekend outlook posted tomorrow which will update this forecast if needed. Otherwise have a great night 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 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