Welcome to the “pre show” for our winter storm. Light snow is falling across much of the area and everyone should see flakes within the next hour or two. Light snow will gradually become moderate by mid day today before heavy bands begin to move in after lunchtime. Extremely heavy snow bands on the order of 2-6″/hour are forecast to move through during the afternoon and evening hours. Exactly where they linger the longest will determine who gets the most snow. During this time, winds will begin to gust into the 30-40mph range and whiteout conditions are certainly possible. Stay off the roads if you can at all help it. These snowfall rates are where plows struggle (or like our last storm are recalled off the roads for extremely dangerous conditions). Thundersnow is a distinct possibility in these bands as well.
As the storm progresses this evening into the early overnight hours, the dry slot will punch in bringing an end to widespread precip. However, instability within the dry slot will keep convective snow showers going (think hit or miss summer thunderstorms). These convective snow showers won’t last long in any one place but will be extremely heavy and carry with them the risk for thundersnow (again, think summer thunderstorms).
Here’s one model depiction of how the storm will play out. I like that it shows the transition between light/moderate snow this morning to very heavy snow this afternoon with snow hanging on until the lighter precip arrives in the evening. I’d be skeptical of the model bringing the mix all the way back into the mountains but an adjustment W from last night’s map is likely in order.
Here’s a visual of that adjustment west with the mixing line. It’s possible some locations in the pink will see a few sleet pellets but it won’t meaningfully cut down on accumulations. I also expanded the up to 36″ zone because of the crazy intense dynamics and associated snowfall rates being reported to our SW across parts of NY, NJ, and PA.
This is likely my last update here for the day as I watch things play out. I’ll be geeking out over observations and satellite stuff over on my twitter feed @JackSillin as well as on the forums at 33andrain.com so check those out if you’re interested.
BTW, there’s more snow in the pipeline for the weekend. It could be another fairly sizeable storm for some but nowhere near the magnitude of this beast. More info on that after we take care of this one!