Friday continues to look interesting

Tuesday morning, I gazed out the classroom window at fat white flakes tumbling through the air. There was no accumulation, but the feeling of winter was overwhelming. I am mentioning this mainly because the sensation of tracking a potential significant snow-producing storm for this Friday ... is equally as overwhelming.

There continues to be a lot of uncertainty with this forecast however. At this point, I wouldn't say things are looking promising for snowfall in southern New Hampshire, however we've seen a lot of shifting going on, and that will continue to occur... one way or another.

The operational models, GFS and NAM, continue to display a classic case of disorganized energy, with multiple packets of vorticity cancelling each other, and resulting in a weaker system.

The forecast is for low pressure originating in the southeastern US to move off the Carolina coast Thursday evening and to track southeast of the 40/70 benchmark on Friday. Precipitation spreads across southern New England however strong high pressure to the north will create a sharp cutoff, leaving areas of northern New England dry. The high pressure will also serve to drain cold air down into the region, supporting wintry precipitation.

The main thing that we want to see for snow in southern New Hampshire is energy to become more consolidated with a stronger low at the surface. This would spread precipitation further north and at the same time support cold air drainage. We see this in the GFS ensemble runs, as well as the 06z operational run, although it has not been supported by the following 12z run. The 9z SREF is also promising. Verbatim some of these solutions bring a 3" to 6" inch tree-snapping snowfall to southern NH, VT and western MA. In addition, if model guidance starts leaning this way, we might need to actually talk snowday potential Friday.... we'll see. It's October, so climatology is saying "not in your wildest dreams". Everything needs to be right to get an October snow. We've seen a gradual north trend which I think will continue, but to what extent is the question.

First forecast maps later today if models warrant it.