First, let’s tackle the up coming storm for for Wednesday night into Thursday morning because this is a pressing matter.
New model data coming out is certainly colder with higher moisture content, but more importantly the water vapor satellite image is far more impressive than I thought would evolve for this storm.
What stands out to me is not so much the moisture transport and “coma head” development, but note the dry air over southern Oklahoma and northern Texas. That dry air, red colors, means there is very strong sinking motion in the atmosphere, which means there must be strong lifting to counter act that sinking air. This tells us we are dealing with a dynamic, mature Sub Tropical disturbance here which also means there is more moisture to work with.
The wild card in this forecast is the ability for cold air to get into the New York City and Philadelphia metropolitan areas ahead of this storm. That aspect of this forecast is still very much an unproven uncertainty despite all the models pointing to a colder boundary layer setting in by tomorrow evening. Given the date in front of me, here is the latest forecast.
The forecast at this point is as follows. For the northern interior, I only expect scattered snow showers with a trace to an inch of snow at most. Slightly further to the south over much of eastern Pennsylvania, northwestern and northern New Jersey, and much of Connecticut I’m expecting 1 to 3 inches of light snowfall. Most locations will be around an inch as the cut off is going to be pretty tight.
For western and northern suburbs of Philadelphia through north-central New Jersey, the immediate New York City metropolitan area and Long Island, I expect 2 to 4 inches of snow by Thursday morning. The snow will be light to moderate with some slight mixing in at times along the immediate coast. There area where I expect the most snowfall will be over the Philadelphia metropolitan area to the central New Jersey coast. These locations will have the ability to fall under the influence of enhanced mesoscale banding which may push snowfall totals up to 8″, however that will be VERY rare. Most locations will range from 3 to 6 inches between Wednesday night and Thursday morning. Finally, extreme southeastern New Jersey will still have mixing issues and will be the last to go over to all snow, thus the snowfall totals of 2 to 4 inches. Could southern New Jersey get pushed into the 3 to 6 inch potential? If the boundary layer temperatures, the surface, is actually colder than I currently expect then the snowfall totals will be significantly higher.
I expect the snowfall to start from southwest to northeast between 7 PM and 10 PM tomorrow and then end between 7 AM and 9 AM on Thursday. I don’t expect virga to be an inhibiting factor here.
Want a different solution for this weekend’s storm? You have about 10 different solutions to pick from. As I said this morning, I don’t think we really have a handle on the potential of this storm until Thursday evening when we have sampling of the Arctic disturbance in this whole set up. With out that arctic disturbance, we basically have a very progressive pattern that leads to the storm exiting out and developing too far east over the western Atlantic. If the Arctic disturbance interacts with the Polar and Sub Tropical disturbances a bit faster, than we have a major winter storm on our hands on Saturday night into Sunday. I don’t think the wise approach is to let our guard down until we can rule out the ability of that Arctic disturbance to interact with the whole set up on the East coast. Models, all models, are notorious for under estimating the influence of Arctic disturbances, thus my suggestion to wait this out a bit and keep an eye on the observations and soundings for this disturbance.
Right now, obviously this storm is a miss but a very windy and cold miss at that.
I was going over some Sea-Level-Pressure models, and the Canadian model NAILS the northeast this weekend with deep deep pressure and a large-scale storm. It shows it it going out to sea, gathering strength, and then turning back in. However, this is only one model, so... Basically wait and see.