Good morning everybody, I just wanted to pop on here as there has been chatter about a late-week system. I certainly cannot rule that out just yet, but as with any coastal storm, a lot of atmospheric elements have to come together, and very important in that checklist the axis orientation of the upper level pattern over the northeast U.S. and eastern part of the country in general.

The graphic I’ve attached to this post shows the current model guidance for an upper level pattern which visualizes a look that you do NOT want to see if you want a coastal storm to be drawn close enough to A) Slow down and develop a winter storm for the greater WMass region and B) position it close enough to bring accumulating snow to the region.

Big coastal storms are almost always comprised of northern stream wind and low pressure energy with southern stream moisture, amplified by both a clash in colder temps northwest and warmer temps southeast, and steered by what’s called an upper trough or upper low pressure system.

As of now, our upper low looks to be “positively-tilted”, but what does that mean?

1. If positive, the low’s axis is oriented southwest to northeast.

2. If neutral, the low’s axis is oriented south to north.

3. If negative (what you want for big snowstorms, usually), the low’s axis is oriented southeast to northwest.

The graphic attached shows option #1, which means the moister southern pieces don’t “phase” with the colder northern pieces, and so the upper low just sweeps the undeveloped storm out to sea, and we get some light snow, or mixed rain and snow showers.

For now, that’s what I see happening Thursday night into Friday, but I will of course keep you updated as we get closer, especially if there are any big changes to the forecast!