The last ten runs of the Operational GFS model (below) shows the trend of snow suppression to the south due to dry, arctic air moving in from the north and an upper-level pattern of confluence (you need divergence to get rising air for a prolonged, heavy snow event).
Either the North American Model (below) is having major convective-feedback issues, or if accurate, there are going to be a lot of angry people on Sunday morning that are currently sitting underneath Winter Storm Watches (WSW). Remember a WSW means there is the “potential” for 5″ or more in our region… a Winter Storm Warning means 5″ or more is expected. This forecast could totally be a complete bust. Notice too that the NAM favors the over-running steady snow along/north of interstate 66 in Northern Virginia on Saturday afternoon/evening. But look at that major Snow Hole over central Virginia (ouch!) Again the NAM may be trying to “strengthen” the surface low that develops on Saturday night/Sunday morning too quickly, robbing “energy/lift” needed to keep snow falling across a large portion of northern and north-central Virginia on Sunday.
European Ensembles Looking a bit better this morning, but still show that a boom/bust scenario is certainly still in the cards:
The “Mean” of the 50 Ensembles:
Looking at this image (below) you can see why the National Weather Service placed their Winter Storm Watches (WSW) where they did (south and west of DC) for the “potential” of 5 or more inches.
Last but not least, the latest European Operational Run – the image (below) that I would base my snow map off of because it agrees with the mean of the ensembles (above):
This is why you see the 1 to 3″ forecast north and east of the Potomac River and the 3 to 5″ forecast south and west of the DC Metro.
I hope and pray that we don’t end up with a massive snow hole as there is nothing better than kids and adults (some of whom are kids at heart) having the opportunity to get out and play in the snow late Saturday afternoon and on Sunday.