Carvers Gap

If the 12z Euro comes on board, likely time for a thread. This event literally lasts for a week on the GFS. So, looks like modeling has the cold again. As BNA notes, really tough to know where that boundary goes. Might even wait until 0z (to make a thread) to see if modeling continues to hone-in on this. But this is thread worthy if ever there was one - if it holds.

Just a nasty, nasty set-up.

The CMC reloads the ice pattern again for middle and west TN late in the run. My guess(and it is only that) is that modeling is underestimating the extend of the cold front. My gut says that cold slides along the surface for 100-150 miles further than what is shown there - if that model is even right. I can't decide right now if I want any part of that!!!!!

The Tropical Tidbits 12z GFS 258 snow accumulation map is full Euro from the other day...obviously it includes ice. But it is pretty hilarious. Nearly the entire state is green! Never seen anything like it.

Seems like TYS has been on or near that line all winter for several events.

Give me no part of the GFS at 246 - none at all. Want no part of that.

The 12z CMC now has a significant winter storm in middle and west TN at 126

12z CMC is continuing the trend of bumping up totals slightly, but especially on the Plateau.

Just glancing at the boundary, looks like the GFS has pressed it steadily southeastward since 0z. If trends hold from previous systems...it will keep pressing SE for a few more runs, then lift it back northwest, and then back SE a hair....been going on all winter.

The axis for ice has pressed about 50-100mi southeast(depending on location) on this run which surprises me as I though the initial onset was a bit warmer on the souther fringe of this. Massive hit for some areas. There are areas along the KY/TN border with 1.5+" of ice accumulation.

The axis for ice has pressed about 50-100mi southeast(depending on location) on this run which surprises me as I though the initial onset was a bit warmer on the souther fringe of this. Massive hit for some areas. There are areas along the KY/TN border with 1.5+" of ice accumulation.

Not sure. Would have to check. I just assumed it was a slight increase in the qpf.

Looks like west and middle TN are going to get hammered again on this run. As of 132, places in middle TN have 1" of ice accumulation on the 12z run of the GFS. Wow.

Yep. 12z GFS looks like it may double down on its 6z run...out to 108.

12z GFS on right and 6z on left for comparison.

12z GFS has a definite uptick in snow accumulation - both Kuchera and non-Kuchera. The 12z suite across the board has seen a slight uptick in general - so far.

For comparison, here is the 0z EPS for the 10-20th. Not a great signal but a weak signal. That does not take into account ice I don't think. So, one might wonder if the southern extent of that is indeed icy. Biggest takeaway I have is how far south the extent of frozen precipitation is....

Yeah, agree. Need it moving towards 8 or COD and then we get enough help from the Pac to push the cold eastward.

For reference, here is the 6z GEFS 10 day snow map beginning on Wednesday so as to eliminate tonight's shenanigans.

Very realistic and has occurred many times in the past....my guess it that is does bank against the Plateau(if the cold indeed pushes that far). Then a couple of fronts will likely press it onward. But the setup on modeling is a classic old school set-up for ice in western sub-forum areas. Used to happen like that when I was a kid and lived in Knoxville(70s). I share this often, but I used to think our cold came from due West, because Memphis was always coldest first w/ ice.

Worth saying about 1000x.

The 16 day run of the 6z GFS. It is going to be the zero or the hero. LOL. Of course the Euro had something similar as well just a few days ago. Of course, a lot of this is ice - so be sure to make that distinction. That would be a really big pattern for this entire subform. This is the potential for the pattern if the cold presses like the 6z GFS had.

Kind of an interesting test today....the NCEP/MJO plots show the MJO heading for 8 or COD just under the 8 plot(meaning background phases of MJO are cold). Let's see if modeling follows suit today.

That is no knock on the Euro BTW. It is a fantastic model, but it is shoulder season time, and that model is very mortal when seasons begin to change. All modeling is bouncing all over the place right now with this boundary and even with this current storm. I don't really have a "go to" model at this point. I think we are just going to have to rely on pattern recognition for a while. So, the real answer I am going to be looking for is the how strong the cold front will be later this week, its speed, and location. In other words, we needs its vector...victor.

I don't think the Euro is modeling this front well. I see some posts on other forums where Arctic air is often modeled too quickly and overdone. Indeed, that is often the case, and I don't disagree. However, there are times(because cold air is relatively low to the ground) that modeling misses the southerly extent of the cold air. Ditto to BNA above in saying that modeling is struggling with the Arctic front. When models can't reach consensus 12 hours from now, they don't have the late week pattern nailed down either IMO. The pattern has the potential to support a big overrunning event. I am just going with prior knowledge and not modeling...there should be an event. It is going to depend on whether the cold gets hung up on the Plateau(very plausible) OR seeps into the eastern valley and banks against the west slopes of the Apps. So, my guess is that western forum areas get hit with 1-2 ice/snow/mix systems(one significant) and then the from presses east towards the eastern valley. I think the 6z GFS may be on to something. Now the really question for me is whether a system remains to run the cold when it moves into the eastern valley. So for now, I am not swaying with model runs...just think this has a reasonable chance of occurring. We spotted this evening's system a couple of weeks ago by recognizing the pattern and knowing that a storm was possible. That doesn't mean we get snow tonight BTW, but it has been something to track and the NWS has issued winter weather products for various locations.