All Zone Forecast Update: Snow Becoming More Likely Friday Morning

We are still very closely monitoring the two snow threats later this week and this weekend, and while there is some evidence that the second storm on Saturday may only be a graze or a miss out to sea altogether, the idea for snow on late Thursday night and Friday is gaining steam.

As far as the rest of this evening goes, we still have strong downsloping winds, which will keep temperatures mild initially. An Arctic frontal boundary is crossing the area and has provided a lot of dynamics as well as a decent pressure gradient, and this is expected to continue for the rest of this evening into the early part of the overnight. We have already had wind gusts up to 40mph at times this afternoon, so these are expected to continue through at least midnight but then gradually lessen after 3:00am. Still, though, even tomorrow we expect winds to stay around 15mph and gust between 25-30mph — so a relief from today but still breezy.

After 6:00pm this evening is when we expect the true temperature drop to take place, and overnight lows will be in the 20s for most of the area. The front will have fully crossed on Thursday, so despite still some downsloping winds, highs will only be in the low to mid 30s. Clouds will also be on the increase out ahead of the storm system for Thursday night into Friday.

A potent Polar shortwave will be diving down into the Plains and gradually amplify as it heads into the Ohio Valley. This will allow it to grab some Atlantic moisture which should allow precipitation to enhance somewhat as it gets closer to the coast. A weak secondary low pressure system will also be forming offshore. Snow should begin shortly before midnight on Thursday night. The question from here becomes if the heavier banding can make it to the area.

This afternoon's NAM model valid for Friday morning shows a potent but elongated disturbance aloft and a moderate band of snow clipping the coast. Cold temperatures aloft also support a fluffy snow that accumulates easily -- assuming we get sufficient lift.

This afternoon’s NAM model valid for Friday morning shows a potent but elongated disturbance aloft and a moderate band of snow clipping the coast. Cold temperatures aloft also support a fluffy snow that accumulates easily — assuming we get sufficient lift.

The mesoscale models — particularly the NAM guidance — show a large area of precipitation blossoming thanks to strong instability aloft and plenty of moisture and lift. They show the potential for moderate or even heavy snow on Friday morning’s commute that lasts for most of the morning, and accumulates a few to several inches. We think this scenario is possible. However, other guidance keeps the main area of lift further offshore with an offshore disturbance, which also has some merit due to the fact that the main area of vorticity — or counterclockwise spin in the atmosphere — is a bit elongated, which may instead consolidate the precipitation offshore instead of allowing it to expand. This scenario would only be a coating to 2″ for the area.

There’s also the compromise where some expansion occurs but then compacts towards the coast as the coastal low develops. This would allow for a 2-5″ event for the NJ shore and Long Island, but only 1-3″ further inland. These potent Polar shortwaves do tend to overperform, so we are currently leaning between the compromise scenario and the snowier scenario — but probably closer to the compromise scenario at this point. Uncertainty is still relatively high, but we will be sure to keep you updated frequently over the next 48 hours.