Another snow threat is evolving for the weekend, but is this a major storm?
Right now I say no. The reason why is simply because this pattern is far too progressive to allow for a low pressure system to slow down off the New Jersey coast and develop. Yes, there is plenty of moisture, as you can see with the water vapor satellite picture off the Southeast coast. Yes, there are plenty of mid and upper level disturbances in the Polar and even Arctic jet stream. However, we have no blocking in the Atlantic!
This aspect of the weather pattern is why a major winter storm is not likely because as one disturbance moves over the Philadelphia and New York City metropolitan areas on Friday night and Saturday morning, another disturbance is on the way to kick that disturbance out into the Atlantic. As a result you end up with a fast moving low pressure system that will have to pick up moisture and develop a precipitation shield at a rapid rate and have perfect timing. As we learned last night, looking for perfect set ups are hard to come by.
As such, I think what we have here is a light to MAYBE a moderate snowfall on Friday night into Saturday morning. The low pressure system will develop along the Arctic cold front on Friday night over eastern Virginia. Temperatures will be crashing through the 40′s, 30′s, and 20′s on Friday evening as cold air works in.
By late Friday night through Saturday morning, the low pressure system will track through the New Jersey coastal waters with a swath of light to moderate snowfall over the region. Unlike the previous little event, this time snow accumulation won’t be a problem. The question is whether there will be enough lifting and moisture to produce a measurable snowfall. So right now I’m going with the idea that this fast moving disturbance is going to have a limited amount of moisture to work with and only about 6 to 8 hours over any given location which leads to around one to four inches in snow accumulation. Most locations likely will only have one or two inches.
What could enhance snowfall? These are the following potential influences:
1. The snow ratio ends up MUCh higher around 20:1 or 25:1 thus leading to a snowfall of 6 or 8 inches.
2. The low ends up moving slightly slower, thus allow for longer period of precipitation and more moisture transport from the Atlantic
This option is unlikely given the progressive nature of the pattern, but you have to at least list the threat.
3. A mid level disturbance enhances the precipitation shield, leading to convective banding and heavy snowfall in a short period of time.
At this time though, these option are not likely. Overall look for a light to moderate snow threat from 5 AM through 5 PM Saturday with snowfall accumulations of 1 to 4 inches. The best accumulating snowfall will be from the Delaware River on east through Connecticut and eastern Long Island. The best potential for snowfall amounts over 3 inches will be over much of New Jersey.