Watching Possible Snowstorm For March 12th-13th

There is growing confidence that a possible snowstorm will affect the Northeast U.S. during the middle of next week, as the ingredients needed for one to occur are beginning to consistently show up on the models. It seems this winter has been relentless with the constant cold and frequent snowfalls. This type of pattern just does not want to let go — not yet, at least.

Most people have already seen this graphic since I posted it on my forum yesterday. The players involved are as follows:
1. East-based blocking to help lock in the cold air over the Northeast with the PV in northeast Canada.
2. A ridge in the West to help the Polar jet s/w energy dive into the heart of the country.
3. A strong piece of s/w energy coming down the backside of the PV (Arctic s/w energy), which may phase with the Polar jet energy.
The biggest question is…IF there is a phase...WHERE does it happen? If there is no phase there will not be a big disruptive storm; it would instead be a weaker storm with lesser impacts. A phase of the various short wave energies in the upper atmosphere would develop a potent storm bringing many impacts of heavy snow, rain, wind, and possible coastal flooding. 
 
As of now, the two most reliable models are saying YES, there will be a phase which would result in a big storm for the middle of next week!
When we take a look at the 12z EURO model run from today at H5, we can see the important pieces of energy coming together. The energy circled in south-central Canada is the Arctic jet energy, the one near the 4 corners is the Polar jet energy, and the one over Louisiana is the southern stream energy. There is triple phase potential with this storm (when all 3 pieces merge together and develop a monster storm), but that does NOT look likely right now. 
 
All pieces of guidance suggest that the southern stream energy will escape ahead of the other two northern stream pieces and shear itself out once it approaches the southeast coast, although there does exist the small chance that they’re handling the energy incorrectly. Right now, I am going to agree with guidance and say that we should only be focusing on the Arctic and Polar energies. 
 
If we take a look at the GFS H5 maps now, we’ll see it has the same general idea as the EURO. The only noticeable difference is that it holds back some of that northern stream energy near the Rockies, which is why the storm system on the GFS is not as strong as the EURO has it. This is unusual because the EURO has a bias of holding back western energy, and the fact that it is not, tells me the GFS is WRONG in this aspect. You can also see how the GFS keeps the southern stream apart from the northern stream, so the phase only occurs between the Arctic and Polar energies (no triple phase).
 
The result is a great-looking trough on the East Coast going negatively titled and producing a potent Nor’easter, bringing heavy snowfall to much of the northeast US — except the Philly and DC Metro areas, which see mainly rain. Although the EURO / GFS are in somewhat of an agreement right now with a storm affecting the area next week, I am not sold yet on the track of the storm.
The three main global models used in the weather industry each show different tracks for the possible storm next week. A EURO / GFS track would bring plowable snow accumulations to much of the interior northeast including NYC Metro area. The Canadian model, CMC, is still not impressed with the setup and believes there will NOT be a phase (which I talked about earlier in the blog). It keeps the heavier snow accumulations in northern New England instead.
My current thoughts are there will be a widespread snowstorm for much of the northeast next week, but how far south and to the coast does the accumulating snow get? Since the storm forms in the Midwest and gains little latitude even after it phases (due to the Polar Vortex located to the north preventing the storm from cutting), it should bring a swatch of heavy snow to much of PA and NY state into New England. Those are the areas I think right now are in a prime spot to expect a snowstorm next week. The area of uncertainty is along I-95 from DC to NYC (Boston will be cold enough to support all snow). If the PV trends further south, the track of the storm will also be further south and more cold air gets into coastal areas to keep precipitation in the form of snow. A likely scenario I see playing out is for the coastal areas to start as rain and gradually change to snow as the storm deepens and track off the coast, changing the direction of the winds. It is VERY possible that the changeover occurs quickly and much of the storm falls as snow and not rain for coastal areas, too, depending on the timing of the phase and location of the PV.
And for those wondering, winter will continue into the third week of March. But we are all warriors by now, aren’t we?
Have a great weekend.
Francesco Paparatto

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