Light snow likely tonight for coastal sections

As a major winter storm is hitting the Southeast, model guidance has made subtle shifts to the northwest, showing the storm grazing our area. However, climatologically speaking, a storm that dumps heavy snow to the coastal regions of the Southeast tend to track too far east for major snowfall to our region, which is what will occur this time around.

However, the precipitation shield is pretty expansive — expansive enough to allow some light snow to enter coastal sections late tonight through early tomorrow morning. The further south and east you go, the more likely you are to find a couple of inches of snow.

Today's 18z NAM valid for 4:00am Wednesday morning shows a progressive 500mb pattern, which explains why most of the precipitation will miss out to sea.

Today’s 18z NAM valid for 4:00am Wednesday morning shows a progressive 500mb pattern, which explains why most of the precipitation will miss out to sea.

One reason the precipitation shield becomes so expansive is because of vorticity that streams through the northeast, and vorticity maximum that is streaking through Eastern PA. This helps to tug precipitation back to the west, despite an offshore track. The reason why this storm will not be major snow producer is that the Polar Vortex is pressing down on the pattern a bit too much, giving very little room for our system to amplify — the wave spacing is poor. Thus, we are left with an elongated area of vorticity, which only supports light snow, as opposed to an area that is more consolidated and amplified.

Precipitation looks to start between 8:00 and 9:00pm in South Jersey, and between 10:00pm and 11:00pm for the rest of the region. The snow will primarily be quite light, with perhaps a few brief bursts of moderate snow, before ending between 5:00am and 7:00am tomorrow morning.

Today's 18z NAM valid for 1:00am Wednesday morning shows light snow moving into the region, with heavy snow remaining just offshore. Image credit goes to instantweathermaps.com

Today’s 18z NAM valid for 1:00am Wednesday morning shows light snow moving into the region, with heavy snow remaining just offshore. Image credit goes to instantweathermaps.com

Today’s 18z NAM run gets light snow into the entire region during the overnight tonight. Temperatures will be quite cold throughout the entire atmosphere, so ratios could certainly be around 15:1 or so, but we do not foresee enough lifting in the atmosphere for ratios to exceed 20:1. Dry air will be quite prevalent on the northwest side of the system, so snowfall cutoffs will be quite sharp, and moderate to heavy precipitation will have a tough time advancing too far northward.

Our snowfall forecast map can be seen below:

Our snowfall forecast map for tonight's light snow event.

Our snowfall forecast map for tonight’s light snow event.

There is a chance that we may have to bump up parts of SE NJ and E LI into the 2-4″ range, however, since based on the subtle modeling trends, more precipitation may be able to sneak into eastern sections of the region. Although the large-scale weather pattern is not favorable for a major snow event, there is still enough uncertainty to warrant the chances of a 25-mile shift to the northwest, which could put places like Cape May County in a zone of even a 3-5″ potential. This would also shift the 1-3″ line back towards Southern Middlesex County and through Queens and parts of NYC. NYC itself should not get more than 2″, even in the “snowiest case scenario.”

Regardless, this event will still have to be watched closely, and we will keep you updated.

 

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