There are is definitely a lot to discuss with the upcoming Friday/Saturday winter storm that could end up being significant and potentially historic. While it has become certain that there will be a big winter storm, the uncertainty lies in determining the overall storm track and placement of heaviest snowfall accumulations. Given that it’s only Tuesday night, a lot can change on specifics, so it’s important to keep that in mind, especially when reading any forecasts that are based entirely on forecast models. I know I bring this up a lot, but I always want my audience to be aware of the limitations of such an approach. I’ll be discussing the various solutions that are being shown on the latest model guidance, but in addition, I’ll be pointing out specifics that the models may not be handling well with this system. Due to the complex nature of this upcoming system, I may be required to do a follow-up article that includes some changes, if needed.
Discussion (Friday through Weekend System):
A vigorous shortwave (disturbance) will be moving into the Pacific Northwest, and as it moves southeastward, it will dig into the Southern Plains. A surface low will move/develop over the Plains in response to this disturbance and move eastward across the Southeast, as this disturbance treks eastward. This will eventually trigger the development of a long-wave trough in the eastern U.S., and colder air should begin getting wrapped around the low pressure system. This energy will eventually transfer to the coast, and a coastal low should move up the coast.
There is higher than average confidence on how this system will evolve, but the specifics on the exact track are going to be difficult to nail down. The GFS model and most of its ensembles, along with the Canadian model, have the original surface low moving up through Tennessee before its energy gets transferred to the coast. The European model is now showing a more southerly track across the Gulf Coast states, which would allow for some accumulating snow to fall farther to the south and would shift the core of heaviest snowfall farther south, also. On almost all guidance that I have seen, a pretty stout warm nose is initially present well north into eastern Tennessee and even southern regions of Kentucky. This is likely due to the placement of the original surface low and the orientation of the long-wave trough.
To complicate this forecast even further, a cold air damming scenario could set up east of the Appalachians, allowing temperatures to stay below freezing at the surface in places, despite the warm air advection that will likely try to pump northward, overrunning this cold. This sets up a tricky forecast from Northeast Georgia, parts of Upstate South Carolina/extending east and central-east North Carolina (excluding the coast) Even with the system taking a more northerly track, the colder air at the surface may not get out quickly enough before a nasty ice situation unfolds across the mentioned areas.
The latest Canadian represents this possible ice situation well on Friday:
Snowfall will likely start falling across northern and central Arkansas Thursday night going into Friday and expand into parts of southern Missouri and into the western third of Tennessee. Snow will eventually spread eastward into Kentucky and parts of the lower Ohio Valley through Friday and eventually expand into the Mid-Atlantic states including West Virginia, Virginia, North Carolina, Washington, D.C., and into the Mid-Atlantic states later on Friday going into Saturday. Southern Pennsylvania, including Philadelphia could be hit hard, along with parts of New England, especially along the coast. This is going to be a slow-moving system, and backend snow could fall as far south as the northern third of Mississippi, Alabama, Georgia, much of Tennessee, and into northern parts of South Carolina. Depending on track, there will likely be a region of very heavy snowfall amounts falling, including many of the regions that I just mentioned. This system has the potential to rival or beat some of the historical winter storms of the past and is looking similar to the January 1996 blizzard.
Just To Reiterate A Few Points:
• The European model has been depicting a more southern track. I’m skeptical of this solution currently, although I’m not ruling it out entirely. If there is a southern trend in the track, snowfall accumulations would likely fall farther south and the heaviest snowfall accumulations would shift south. This would also exclude the most northern regions mentioned in this article from getting heavier accumulations.
• A warm nose extending as far north as eastern Tennessee could cause many of these regions to get rain before possibly seeing a transition to some snow (possibly heavy) on the backend of this system. Accumulations would be possible but not as heavy as in surrounding regions.
• Due to cold air damming, an icy situation could setup initially across northeastern parts of Georgia, Upstate SC and possibly extending eastward across the state and into central-eastern portions of North Carolina (excluding the coast). A transition to snow could eventually occur in these regions, with higher accumulations occurring the farther north one goes.
• The core of heaviest snow accumulations could fall somewhere from northern Arkansas/southern Missouri into northwest and north-central Tennessee, across Kentucky, and particularly into the Mid-Atlantic states extending into parts of North Carolina. Many regions in this zone could be measuring snow in feet before all is said and done.
I will continue to monitor this situation closely. I posted a map that shows a 72-hour snowfall output map based on 15 previous winter storms that look similar to this one, courtesy of CIPS Analog Guidance:
Just keep in mind that I’m expecting snow to fall west of this region as mentioned in my article, but I did want to show you this map.
Anyway, I will definitely have to make edits to this forecast, since it’s a difficult and tricky forecast. Someone is going to get hit very hard with this winter storm, and at this point, it’s a matter of determining where. More updates to come. . .