Carvers Gap

Yep. Very true. Also, a northwest jog has been discussed for several days. It is one reason I try not to be too emotional about modeling. The wx is gonna do what it is gonna do...and not a thing I can do about it but observe, predict, and revise...and enjoy the process. This is a fun hobby for the most part.

Good deal. After so many years of Memphis having to sit and watch others get snow, you all are on the books with yet another one! It has been a good 4 years for you all generally.

18z RGEM...surface temps are an issue for Chattanooga as is decreased overall precip. Sleet and ZR mixed w/ rain and snow. Not sure I buy that, but the WxBell algorithm has it.

Kuchera for 18z RGEM (left) and for side-by-side comparison w/ 12z. Slight jog northwest, but pretty massive expansion of precip field which we are seeing across modeling.

The RGEM really beefed up amounts. The 18z RGEM brings the entry point in the forum area slightly north of 12z. It still flattens the system as it heads eastward. That slight changes increases amounts over middle TN. Last minute northwest trends are not uncommon. We actually "stole" a system many years ago from North Carolina on a 48 hour trend at the last minute. If the cold in middle TN is stronger than expected, there will be a likely limit as to how far it can trend northward. More than anything we are seeing an expansion of the northern precip shield vs a major movement of the snow demarcation line to the south. About a one county jog northwestward for the southern extent of snow. Also to account, there is a certain amount of ebb and flow noise in modeling.

Awesome, man! How much are the predicting for your area, AMZ?

The 20z RAP at 21h looks nearly identical to the 18z RGEM at the equivalent time.

So, my pessimism aside, if modeling bumps up totals at 18z, it likely means they are playing catch-up. If you like lots of snow, that is a good thing...wherever this sets up. The best winter storms rarely stop increasing totals, even during the last run prior to the event. The 18z ICON is a good trend it appears. Also, of note, El Nino systems tend to overperform at times.

We were 7 degrees over projected highs at TRI today.

At first glance, that looks too high for most of TRI. They must be banking on good rates and the bigger model runs. There is certainly some model support for that. The NBM is around 3-5" of snow here. I admire their courage. Without the NAM on board, I am still holding my cards on amounts. I honestly don't know for TRI.

Actually, I hadn't looked at the RAP. Its recent run looks like the RGEM from 12z w/ slightly more precip on the northern edge. Are you saying that models may be underestimating totals since cold air is already in place? Just trying to make sure I understand. Thanks, man.

The RAP over the eastern valley is usually pretty poor, but we'll see. A system trending northwest is not out of the question at the last minute. OTH, the RAP and NAM being over amped is also not out of the question at this range.

The 18z NAM again looks like it is experiencing feedback issues. And that is a known bias of that model. It turns the line of precip well north and much earlier over the eastern valley. It could score a coup and certainly has before, but big totals(which aren't on other models) are usually indicative of feedback. We'll see. I also have seen the NAM overestimate my totals by 3-4x the actual amount in reality.

3k NAM trended SE and expanded northern precip shield.

The wind in combinations with temps in the 30s has been very cold. I know some out and back runners who had it good on the way out, and then had an 18 degree WC headwind on the way back.

Advanced teleconnections.

That is awesome. Didn’t u also have the fully black wooly worm?

12z GFS is a glacier.

Again, for the eastern valley(MBY) these are the three or four models that I use in order from here on out: RGEM, HRRR, 3kNAM, RAP. I haven't looked at the ARW, but it can be good as well. Enjoy ya'll, I have to head out for a bit. Bring it on home.

This post is not for Holston or the veterans. Here are some tricks old timers use. It has been a while since we have tracked a decent storm for the eastern side of the state - maybe three or four years in the valleys? The biggest thing to watch right now are trends. If totals continue to go up with each run today, that means models are still likely playing catch-up. If modeling begins to reduce totals, same general idea...models are playing catch-up re: reducing totals. Trends, even small ones, in regards to precip axis placements matter a lot as a small move can have huge implications 300miles away. Think of it like this. If a hurricane is coming into the coast at a 30 degree angle, any change to its trajectory changes the landfall quite a bit. If it is coming in at a right angle to the coast, it doesn't change as much. Because this is flat, but turns over the eastern valley, entry points(into the eastern valley) for the system and the jet make a big difference in the eastern valley. Models are still moving some and that is expected as they get new data. This would appear to be moving around less which makes it easier. Miller A's are known to change even at the very last model run - and this is not a Miller A. So, hopefully this is a bit more predictable. Good trends overnight as totals went up. Let's see what 12z brings to the table.

In all seriousness, the 12z NAM(3k and 12k) does look like it is still on the juice to some extent as it is still trending SE in small steps. One thing to watch, at least one of them had a NW jog at one point - the 12k did later in the run but was south earlier in the same run. The Hi-Res 3k NAM took another jog SE. So, tough to know what NAM trends are when one goes one way and one goes the other during the same run. It could score a coup. But which one(hi-res or 12k) and which run? In the eastern valley, we do want the NAM on board at some point, because it is in coming into range where it can score a coup and has certainly done so in the past. It appears that MRX either tossed the NAM or didn't weight it heavily overnight. We will see what other mesoscale models show at 12z in relation to it. And this isn't about betting or winning or losing. Sure, have at it in re: to one's own backyard. However, our ultimate goal is to watch trends and to find out where it goes. We really have two model cycles left to get a decent idea: 12z and 18z for most and 0z overnight for eastern areas. One thing to watch, a lee side low is developing on models which hammer E TN the most. That is a good feature for E TN peeps. Keep an eye out for that one.

Nah, I meant it is a good run.

The 3k NAM is currently working its issues out.....

12z HRRR inbound..........might want to take a look.

I haven't looked closely to overnight trends. Is the 12z HRRR more or less than overnight runs?