Carvers Gap

The BIG question in my mind was this, "What happens after the Dec29-30th cold front?" I think a probable, and even likely answer, is now this. Dec 29-Jan10 is a transition timeframe as the eastern ridge retrogrades into the West. We get a TBD window where the EPO ridge just brings it. It would be hard to find a deterministic or ensemble run which doesn't end up here. The 12z EPS has that EPO ridge in place around 216, and then begins pushing a trough towards the east at that time. By 324 we get this -> The original window was Jan 8-10, and they may yet still verify. I would say the window is now Jan 12th, give or take a few days. Sometimes a big pattern like this is preceded by a big storm. Modeling across various products at 12z has a progression which makes sense given the analogs for this winter, recent Nina climatology, the QBO state, and...it is January - climatology fits. Good trends. Now, it is time to reel this look in. Get the pattern right, and then we can track. edit: Notice how well that tele connects? Cold in Europe. Cold in the East. HL blocking. Trough near Hawaii. Four quadrants of cold air. IF that builds, that could be tough to break down.

The 12z EPS gets there at the same time....all of the frames aren't posted yet. Pretty good continuity. And if we are too assume that ensembles are struggling to see cold this winter....they are cold now. What if the warm bias is still in play? The 12z EPS is gonna look about as good as it has all winter at Jan 10+.

The 12z AIGEFS at 360. It has the EPO ridge in place by 240, and then takes a couple of days to kick everything eastward - common theme for the 12z suite. Honestly, this look might be too cold. But see the NAO isn't really gone?

The Euro AIFS 12z deterministic run. I just go w/ a 5 day window to see the trend...Pretty good signal, right? That is a crazy cold run by the way.

And the 12z GEFS...did it finally find its way? That looks a lot like the GEPS. And that makes a lot of sense. IF that can verify w/ that little bit of SER, that is an Apps snowstorm map as well as sliders for the rest of the forum.

This is where I think we are headed - starts about 300 on most models. Somehow, the Canadian model seems to get this figured out a bit more quickly of late. It overdoes the cold, but generally gets the idea right. BTW, the 12z Euro has a cold front Jan4-5 w/ a low running just out to sea - keep an eye on that. I mean there is always a chance we don't score with this, but I would have a really hard time naming a time when this didn't work. Maybe December 17-18? Lost of great winter analog maps looks like this.

You all know that I like the Euro Weeklies control run...the CFSv2 at 6z is also crazy cold like that. The key right now is for the EPO ridge to build and the NAO to retrograde over the top into that EPO ridge. If that happens, there is really nothing to stop the cold from heading south. With deep snowpack over Canada, the skids are greased.

One thing I am noticing on several deterministic runs and on some ensembles(wonky GEFS at 12z)...there is a strong signal for an Arctic discharge just after the 10th. The AIFS Euro definitely shows this. IF that EPO ridge goes up, and I think it does, we could see very cold air sent into the Lower 48. Some modeling sets the EPO ridge too far to the the West, but I bet we do ok w/ that look.

I definitely know your avatar and Cottonwood as a location. Good to have you back and posting again this winter. You do a great job.

Did you have to make a new account? You have been on the forum for a while, right?

Sending an active STJ into an NAO block could get wild during January. It is probably feed back as the GFS is just chocked full of it, but that look has precedent.

Definitely a warm trend between say Jan 4-8. The pattern change to an eastern trough still looks good by Jan8-10th. Modeling could easily be missing a cold front in that range. Still, things look reasonably on track. Dec29-Jan10 looks like a transition time frame where the ridge retrogrades into the West. Jan 10 looks like a new pattern w/ an EPO ridge in the West. It has taken a while for the dust to settle, but that is where I "think" we are heading.

I had not noticed that, but whoa! See, I think middle and west Tenn have to really guard against this. This has been a really common feature in past winters. These cold fronts head to Texas(there you go @Daniel Boone) and the front gets hung-up over our forum area.

I was 50/50 on going to the MCB. I ended up staying in Kingsport. I have a kiddo who plays in the band for the good guys which is why I wanted it to be warm. They are gonna freeze their tails off! I about froze at the Vandy game. Thankfully, they are young and good at what they do!!! I get to make the midnight run to Knoxville tonight for pickup! I do love it, though. I should be here for the 0z runs. Haha. I slept-in a bit this morning - by my standards. Then I went running, and pretty much froze. Stopped at four miles and had enough of the wind chill. As for modeling. I think they jumped the gun just a hair and are correcting. It is more than common for models to be about a week ahead of the actual pattern change. Overall, the BIG event is Jan 8-9 when the EPO ridge goes up. I still see that, and it looks like it is moving forward with time. Also, models lose things in the 5-7 day range...so there is that. I still very much like where we are headed. VERY MUCH. Honestly, I like reading what you all post. So, sometimes I just back down my volume a bit which can be a bit much. Our daily 12z GFS "this ain't gonna happen" post -> but if it did -> The Day After Tomorrow.

Fun story, before I read Holston's posts on this...my family just called it the Twilight Zone. That area always has the worst weather - thunderstorms (especially out of the northwest), snow showers, wind, etc. I have traveled that section of road for forty years. Same deal for that long. Again, Alpine, Wy, has a very similar deal as does an area just north of Jackson(snow hole area). I think that place is Moran.

For an industrial plant to cause this, it would take something like a massive settlement pond from a paper plant to cause the life and the moisture - like lake effect. There is nothing to the northwest of Gray that fits that bill - not even a lake. That little snow line is really similar to the gap in the mountains west of Knoxville which allows Knoxville to get more snow...not quite the same setup, but similar. FWIW...BAE and Eastman are due north....and they would actually deter dendrite formation - you can trust me on that one! Hahah. Those plants affect weather, but I have never seen those plants add snow to anyone's back yard. Lots There is a notch in Bays Mountain near Laurel Run park. There is another notch near Baileyton. Wind cuts through those places and also to the east where the mountain range terminates at the radio towers. Those wind flows converge back near Gray when NW winds run perpendicular to Bays. I think the orographic lift between the three area then combines to create convergence in the lee of Bays. Think of a sports car cutting through air in a wind tunnel. Air goes around each side and then over the top. It converges again behind the car. I think that is what happens. That band has been there a long time. @Holston_River_Rambler, I agree. a small glass manufacturer won't cause that. That industrial park over there is pretty much defunct. I don't even really count that as an industrial plant - very small w/ maybe one stack. If that line of thinking was used for Eastman, there should be a HUGE snow belt downwind from it. Hahah. It is 100% orographic life along w/ those gaps in the mountain. Your last graphic there is right on the money w/ ONP. There is another one of these in Alpine, Wy. Where there is a break in the mountain, these little bands set up. I used to live on Boone Lake and would drive to Kingsport when younger(every morning). I drove through that band so many times. Again, you all have done a great job with this. That area is just one of strong convergence. Even during summer thunderstorms...same. Always a lot of convergence there.

Out of Bristol.

I am on a roll this morning. I absolutely hate agendas. This came from a local met, and I am embarrassed for this person. "Possibly aided by an industrial plant in Hawkins Co." That just burns my biscuits. I have news for folks not from this area...we certainly have lots of industrial plants in Kingsport, and they do affect the weather. But there ain't jack crap upstream from that snow band. It is orographic lift from Bays Mountain which sets up in the lee of the mountain. We have studied and documented it here. I don't understand how a local met hasn't seen this about 1000x time already - and this person should know!!! 2" in Gray reported on the ground

Seeing MRX(almost gleefully) this morning say that their forecast area had a 40-60% of being AN...after looking at that statement it got me to thinking. It may well go warm, but what I am seeing is not a slam dunk. Why not mention the potential for at least a cold period that month? Big and honest question: When is the last time that weather office had forecast a BN month for winter? We certainly have had BN temp months, but when is the last time they have actually posted a BN forecast for a winter month, and how often has that occurred? We went like 20 straight days with BN temps from Thanksgiving to mid-Dec, and barely a peep. Christmas goes warm...and their site is flooded with warm graphics. So, I want to know this...when is the last time they have forecasted a BN month for temps during winter? I am rarely critical of that office, but let's see how they caption December which "should" be within a few tenths of normal either way. Are we going to see lots of red and oranges for a few tenths of within normal? Those folks are pros there, but I would sure like to see them at some point not carry the company water.

Man, the GEFS ensemble and deterministic after d8 are waaaaay out there on an island. The 18z GEFS going the deterministic run. The 18z GEFS ensemble has no support from any other ensemble run. The 18z AIGFS(which JB hates) is truly an awesome pattern by the end of its run. edit: Some halfway support from the 18z AIFS Euro. But the AIFS Euro looks pretty good. I think the cold will be centered back a bit further west than early December which is probably not a bad thing.

I also think the 8th is starting to be a trackable window. No guarantees, but it is showing up across modeling and at 500 on ensembles. With the NAO block likely in place, it is certainly a realistic option.

Kind of a minor event possible on NYD from the Plateau into SE KY, SW VA, and border areas of NE TN. Maybe we can cook something up per the 18z RGEM. I don't think anything more than a dusting or snow showers, but we have seen these trend south at the very last minute - as in the radar is the only thing that verified this far south.

The 18z GFS definitely trying to get in on the action. It has a storm which cuts into the forum area, but still manages to stay south. The good thing? It is the GFS at 10 days. The great thing? Good storm track.

I think the dry conditions(outright drought) in some areas of the forum is worth a continuing discussion. The southern edge of our forum is really dry as is west Tenn/eastern Arkansas. The southern Apps, as is typical w/ La Nina, are BN for rainfall. MBY is normal which has not been a usual occurrence of late. Thankfully, I think as we trend towards El Nino this summer....we will see a normal summer for temps, rain, and a reduced risk for endless summer next fall. If El Nino takes hold early enough, we could see cooler than normal temps later in spring.

That is a really good run of the Euro Weeklies(which are now dailies!). Ridge out west w/ it bridging across to Greenland. This is generally supported by some of the colder analogs. This pretty much holds throughout the run. Now, I have been doing this for a while....it likely won't hold for 6 weeks. The weeklies kind of just roll with week one and don't really move from that pattern sometimes. As @John1122notes, that storm track is a good one if it verifies. A word of caution: There has been no more fickle beast in wx modeling than LR modeling this winter. I wouldn't develop a long term attachment!!! I have 2x30day chunks at 500 posted. I mainly have done that, because each kind of tells a different story - both good for winter in the Tennessee Valley. I add two control images - you know I like the control. The temps map I think is a little bit less washed out, and it gets cold on that control run! The snow map is very similar to the ensemble, and that is likely a good sign. It is basically snow climatology, but I will take average vs none. But it gives us a good idea of the storm tracks possible - sliders, cutters, and inland runners. And if you need something to be concerned about if you like snow...I have that for you as well. Now, the good thing is that BN precip prob means it has been cold. I definitely am in the school of thought that we do a lot better when cold is in place. So, there is good and bad with this map. I don't have to explain the bad.