Carvers Gap

I think we wait to see the rest of the 12z suite before passing a verdict. To me, it looks too wound up. It looks like feedback. That is a bias of that model. The bigger problem is that the 12z NAM is by far the most significant winter scenario we have seen in modeling this week. The suck factor would be off the charts. If it isn't feedback, I do think it is because the storm has been sampled better. It started jumping around as soon as that northern vortex came on board.

12z 3K NAM and 12z 12k NAM:

The 3k NAM managed 6" of sleet somehwere in the Upstate or SW NC. That just seems way too wound up. Seems like feedback.

The NAM is stubborn, and it that is what is concerning. RIght now it seems our choices are either snow or ice or both. That run is a far more significant winter storm (in regards to impacts) than anything that has been modeled this week. If that is the trend, that is an icy trend and a concern. IMHO, that is a winter storm no matter how one slices it.

Looks like whatever is going to fall will be frozen. Most of that falls at night in E TN. That 12z NAM run would be crippling. Let's hope folks get enough warning - if that is the case. That is 100x worse than 3-7" of snow.

That is an ice storm.

If school systems are in session(assuming the 12k NAM is correct) when that hits...everybody is walking home or stuck.

In may ways, the 12z NAM is the worst case scenario in terms of long term impacts.

Either way, the 12z NAM is a significant winter storm for pretty much the entire forum. Those amounts will turn out the lights if they verify.

3.5" of sleet in northern Alabama. I just don't see that being realistic. Maybe it will be, but it just seems a bit "off" compared to even its previous runs which seemed a bit off.

Here you go, @matt9697. I took a screenshot of the ensembles when they "hang up" or pause. Looks like the 20th or 21st are a window for overruning. If this look continues for several days, I would be surprised for their not to be some type of event like that. Lots of cold and a little bit of SER.

Yes, we have some commentary in the January thread. As of last night, that signal was there. I haven't checked this morning. I would suspect that is still there unless there has been some sort of overnight flip(which could happen at this range).

The trade right now might be snowstorm for ice storm for some areas. Oof.

The HOT donuts sign has returned for this thread. Now, back to model watching for me. I really don't see a ton of changes from overnight modeling. There is an ebb and flow with each model run. We have seen that overnight. MRX correctly noted (as did all of us as we watched it roll in!) that the 3k NAM is a notable outlier. But it scores a coup enough of the time that it probably should be factored, especially if you make money doing this for a living. The 6z 12k NAM is noticeably less amped, and thus, its snowfall totals sharply increased. It is now the 3k NAM vs all comers. Get your popcorn ready. Who knows what this day will bring or what model trends will be presented? But at least the answer to that question is that today has promise in that it won't be boring.

Man, I could easily be wrong, but with the 6z 12k NAM coming back onboard....the 3k might come back around as well.

I just want to know if we can incorporate that sensor data into our weather models.

Anyone can make a correct forecast if they wait until the event is under way. At that point it really isn't a even a forecast product, but a statement of the obvious.

I don't want my comments to come across as prideful. I know they have a model which has gone rogue(3k NAM). If I got paid to do this, it would give me pause as well. (The 12k NAM at 6z is now back in the winter storm camp). I understand the call, and respect them as professionals. A watch is appropriate(for now) for the eastern 1/3 of the state - for now. However, they need to understand that they have already busted twice this week with little acknowledgement (that I know of) of those errors. And yes, errors do happen in weather. It just goes with the territory. But the morning disco today seemed a bit preachy in spots, bordering on talking down to folks. I could do without that. They also need to understand there are many, many decisions made with their products(timing, impacts, amounts, significance) in mind. If they are right on this one, they will be 1 for 3 this week. I say this often. Luck cannot be part of effective safety protocol.

I knew all I needed to know when I saw the forecast package of WSWs on a straight line along the SW VA border last weekend and nothing below. That has never verified, and it didn’t last weekend. All of that despite clear modeling trends which depicted the possibility for wintry precip south of that line. Due to lack of proper advisories this week around TRI, I actually have a family friend who got caught in jt and likely totaled their car. I just about didn’t make it home Sunday due to their forecast (I should not have listened to it). Unimpressed this week, and that is very rare criticism from me. With the ground so cold, impacts from any frozen precip will be immediate and impactful around TRI. Are they going to make the same mistake a third time this week? I am all for conservative forecasts 48-72 hours out. This areas is tough to nail down, but we have already seen two misses this week alone due to waiting until the event is underway to issue winter wx products. We have school systems in this area(we all know who they are) which will open if the forecast isn’t clear.

0z GFS holds serve....

I was living with the Philistines that winter(Orlando). I missed my only two Tennessee winters and two football seasons while living in that furnace. I missed the World's Fair win over Bama and the 82 winter. I gotta a lot of great memories from Disney and Epcot....but no Tenn football, no mountains, and no winter just didn't jive with me! That said, the 18z EURO AIFS stalls that frontal boundary at the Apps just after 240(edit). It has an overrunning even modeled - lasts 48-72 hours.

Modeling this phase out west is no joke. It is amazing modeling can do this. We are relying on effective programming, reliable/ timely data of the storm, reliable/timely data in front and behind the storm, and trying to model chaos. The weather along the West Coast (just watch the news) shows how volatile things are in that corner of the world. The phase for this storm occurs just east of that area.

The 0z RGEM is running right now. Out to 45, pretty steady and nothing like the 0z 12k NAM. Might have jogged one county north vs two states.

This is where it goes at 42...

ARW. Pretty reliable little model that Jeff recommended years ago. I tend to look at it to keep steady. Hour 38 with two views - Ohio and GOM. You can see the moisture transport a little bit stuggling along the Ohio River. Now, go look at the convection along the GOM. It is cutting off the fetch. That is the main concern. That said, that is a really healthy, southern winter storm depicted there.