Not much has changed in the models overnight, we're still looking at meager snow amounts in the southern Valley with some more measurable snow possible in the northern Valley. The snowfall accumulation graphic has been uploaded to facebook - check it out there!
This morning we've been seeing a lot of virga on the radar. The northern extent of the precipitation shield on the southern stream low is getting eroded by the dry air in Virginia. Most echoes that we are seeing in Virginia (north of Roanoke) are virga - dewpoints are in the single digits. However, we could see a few flurries today or an isolated snow shower if one breaks through the dry air - that is not likely though.
Okay - so we haven't talked much about timing because the models weren't handling the phasing well.
Now that they are...let's talk timing.
It's not going to be as definitive as previous snows because the snow at the beginning of this event will be extremely light. Therefore it may be on and off throughout the Valley until lunch time.
That being said...light snow may move in as early as 1am in the southern Valley. When I say light snow, I mean very light snow. These are going to be weak bands of snow that won't amount to much in the Valley. If we are going to see any moderate snow, it's going to be during the late morning hours through to the early afternoon - going from south to north. This is when the two systems begin to phase. Some bands may start out weak in Augusta and gain strength through Rockingham and Shenandoah counties - it's the nature of the energy transfer. That's why we'll see higher amounts north of Shenandoah County.
We're going to see a very visible connection between the two areas of low pressure once the energy transfer begins. Once it completes, the coastal low will become dominant and we'll see extremely heavy snows in NYC & Boston.
While this is a rather pitiful snow for the Valley (compared to what it's bringing to the south), it's going to be one of those storm systems that you want to watch unfold - especially tomorrow. This is what we call a "double barrel low" setup - with low pressures side-by-side transferring energy from one to the other.
I will update more later this afternoon. Feel free to comment & ask questions!