Dynamic Winter Storm set to Pack a Punch... Impacting Millions.

The National Weather Service estimates that more than 150 million Americans are being impacted by a major winter storm that is rapidly developing and impacting a HUGE chunk of the Eastern US right now.

Winter Storm Warnings continue from the Lower Mississippi River Valley Clear through the parts of the Northeast while Ice Storm Warnings have been posted for parts of the Appalachians and even into Dixie.

Wave of Warm Air Aloft

What makes this system so difficult is that although surface temperatures are very cold thanks to the presense of an arctic airmass, the strength of the deeping low pressure system is sending a wave of warm air aloft known as a "warm nose".

As mentioned during a tweet earlier this afternoon, watching the placement of the "zero line" at 850 mb level for 0C/32F (where purple meets white). This will be critical as to who sees a big snow and who sees a a bunch of sleet or freezing rain for all parties involved.

This 850 mb zero line has been steadily moving north with model guidance over the last 24 to 36 hours. That has changed the landscape on where the heaviest snow will fall, and also where the potential exists for damaging ice.

Threat for Damaging ICE

Thanks to this warm nose, it is becoming clear that parts of Eastern Kentucky, Central Tennessee and into parts of the Appalachians including through Southeast Ohio and Pennsylvania as well as the Catskills in Southern New York could be in line for significant freezing rain accumulations. Today's data, hires NAM below, shows where the potential will be for a half inch to even close to an inch of ice in some locations.

This will of course create a lot of problems with downed trees and power lines. If this materializes, some people could literally be without power for weeks.

With that being said, this si a very large and dynamic system that will spread all modes of precipitation as it charges through the Ohio River Valley this evening and into the Northeast overnight and into your Tuesday.

The latest run of the GEM (Canadian model) shown below gives an approximate placement/intensity of snow (blue), sleet (orange), and freezing rain (pink) as we go through the next 24 hours.

So how much snow?

As talked about frequently on my social media pages, models have been steadily and in some cases dramatically trending north with placement of this storm and its expected precipitation shield including snowfall. Take a look at the two images below from the Euro showing projected snowfall (using 10:1 ratio). The image on thee left was from yesterday and the one on the right was from today. The axis of heaviest snow has literally moved 100 miles north over the last 24 hours. This will obviously have major impacts on who will see primarily a bunch of sleet, and those that could see significant totals inexcess of a half foot or more.

Leaning on the newest guidance, it is likely that the heaviest snow will occur in a band setting up across portions of Southern Indiana through Western and Northern Ohio where 4 to locally 8" will be possible. Further south for Louisville and Central Kentucky, those amounts look to be significantly less thanks to the presence of some of that warmer air aloft helping to "sleet down" totals on the order of 2 to 4" for most. For Eastern Kentucky, where freezing rain will be primary precip type, snow/sleet totals only looks to reach an inch or two.

How about New York?

I'm including snowfall projections from this afternoon's run of the GEM here since it seems to be handling this storm better than both the GFS and Euro currently. With that said, like we've seen across the Ohio Valley, there has been a signficant (although not quite as dramatic) push to the north with the warm nose aloft. This will keep snow totals down for Central and Southern Parts of the state where sleet and freezing rain will be more of a factor.

However, it appears the cold air will be more than sufficient to keep it nearly all snow from Rochester through Buffalo as well as the climatologically favored regions of the North Country where 10"+ could be easily achieved. Adding in lake enhancement on the backside of the system, favored areas downwind of the lakes could be looking at 10 to 15 inches by Wednesday morning. (notice the difference in the two images below with low resolution GEM on the left and the hires version on the right.)

With this being said, while it will be business as usual for many in New York, it will be the first significant winter storm for many across the Ohio Valley. So enjoy, but be careful if you have to drive and take it easy moving the snow.

Also, we are still monitoring a second storm that is slated to arrive Thursday/Friday which will come with the potential for a similar set up to this one. We will begin discussing this in detail starting tomorrow.

Be safe and stay tuned.

-Jeremy Kappell

Meteorologist, Speaker, Talk Show Host, Blogger and American Patriot