It’s Complicated

Light showers turned to moderate showers for a time this afternoon as a pulse of energy moved through the jetstream. How cute, huh? 

You won’t think that after you read the next paragraph.

Once this little “wave” passes through, drier air will work down from Northern New England. This is a good thing if you’re looking forward to waking up to sunshine tomorrow – mainly across Northern Mass/Southern NH, but also possible down to Boston and over to Worcester. That’s the good news. The bad news is that the clearing comes at a price. This new airmass will lower the dewpoint below freezing across the board. And, pray tell, why does this matter? Well, when the precipitation returns Wednesday night, the air temperatures will cool near the dewpoints, and voila! We have snow.

Is it really that simple? Sort of. Two things going for the snow: the lower dewpoints I described above and the fact that the precipitation arrives at night…when the temperatures naturally cool. What works against accumulating snow is the fact that it’s April and the ground is warmer. Plus, the upper atmosphere is marginally cold. In many cases, this is small potatoes. Nonetheless, I have a snowfall/sleet map – that you may or may not be interested in – to the right. Focus on the “coating” more than the 2″. Higher elevations above 800ft. have the best chance for seeing that 2″. In all cases, the roads will be wet, not white. Accumulations limited to the grassy surfaces (if you’re lucky enough to have any), sidewalks, car tops and decks.

I think I’ve spent enough time on the snow. Now how about some warmth? It’s elusive now, but come late week, it will be staring us in the face. Might take some prying, but the warm front should pass early on Friday and bring in the partly sunny skies. These too are tricky forecasts. If the front doesn’t budge, our goose is cooked. Either way, from the Merrimack Valley north, Saturday is warmer than Friday, no doubt in my mind.

We’ll go over it all again tomorrow. I might even have some definitives in there.