Jan 7: Snowfall Approaching

Jan 7: Snowfall Approaching

Written on 01/07/2020
Jonathan Carr

Discussion: Our system has trended towards an expanded field of snowfall. It hasn’t trended towards more snow than yesterday’s expectation just further N into New Jersey. There is going to be a sharp cutoff of precipitation on the N/NW side of this light system. If you are in NNJ, especially NWNJ, you are least favored for any kind of snowfall. If you are in SENJ you are most favored for a warmer rain-to-snow scenario. Areas between stand to see the best chance of accumulations hence the jackpot zone of the snow map.

This is a weak and fast-moving system. It is currently over W NC/SC and should track across the S Delmarva Peninsula this afternoon through evening. It’s already into the 40s in many places today. Temperatures are expected to gradually fall through sunset and into evening hours. The surface temperature profile is still modeled to be marginal (close to but above freezing) during most snowfall. For this reason we believe that a decent amount of snowfall could actually fall but struggle to accumulate especially on paved surfaces. That’s why C-2 is our biggest zone despite 2-4 possibly/actually falling and melting down.

I would like to speak to a small wildcard scenario where parts of SENJ (Ocean and Atlantic Counties) could behave more like zone C instead of A/B. This would be if precipitation rates are high enough to bring colder air down to the surface. If such happens it would be slightly convective in-nature with linear segments of lifting and sinking air (meso bands). Again it would only mean C-2 of accumulation for SENJ instead of C-1 or just a dusting. Either way I still recommend setting the alarms for Wednesday morning.

After this clears out we are pretty cold and windy (wind chills!) Wednesday overnight into Thursday. Then the mild stuff moves in Friday to set up a very mild weekend.

Click here for full resolution snow map!

In English: Rain should approach SWNJ by late-afternoon and spready into CNJ/SNJ by early-evening. Temperatures should gradually fall and change rain to snow from NW to SE during evening hours as the precipitation shield expands to include some of NNJ. NWNJ is least favored for snow via cut-off. SENJ is most favored for a warmer rain/snow mix via marine mass/flow. The I-95 corridor (NJTP) and points immediately SE of such are most favored for the coldest/wintry impacts. The above snow map represents our expectations mostly for natural surfaces. The surface is above freezing. In order for snow to stick to roads we’ll need wildcard meso-banding to bring colder air down…something that is a lower probability but cannot be called until it’s happening. Have a great night and please be safe! JC

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