Carvers Gap

That control @Holston_River_Rambler. Delta from high to low...9! The good thing is the mean is negative. I actually favor the control run - wild swings likely. AO looks pretty much the same. This has gotta be that SSW moving things around. This also fits QBO climatology which favors HL blocking. Probably all of that is connected in some way.

I think models are in a huge state of flux right now. They were wrong about the Baja lows. They are wrong about over-doing too many NW Pac lows. They could be overdoing the Aleutian and/or NAO and/or AO HL blocking. We have seen modeling miss on HL blocking at exactly this time of year, but we have seen it score. Just too early to tell.

I am mainly confident, because recent Nina climatology suggests there will be 10-14 days of very cold temps sometime between week 2-4 of January. Plus, this seems to be one of those years where warm-ups get shortened as they draw closer. We are in the "warm-up" which was originally modeled to be anomalous. This morning, I was running in 30+mph winds with wind chills in the 20s. If the more aggressive models are correct, the warm-up may be confined to Dec 24-28th. Might be the most talked about warm-up ever to only amount to about 120 hours of AN temps. LOL. I hope that is what happens!!! I am pulling for the NAO to occur, because I am tired of talking about the MJO (no offense meant to those who like it...it is effective). So far, this has fit Nina climatology like a glove....

The Euro Weeklies are full bore winter in January. They have increasingly BN temps. That LR ext ensemble and the GEPS have broken towards cold today. We were waiting for ensembles to track....some good trends. In the case of the Euro Weeklies...great trends. 95-96(lite) and some 84-85 vibes as you all noted earlier in the thread.

The real fun with that is the NAO and Aleutian's highs bridge across the top. They trap a lobe of the TPV in NA. I think the biggest take away from 12z is that HL blocking is showing up across modeling, and the signal is stronger at 12z than yesterday at this time. Good trends.

Models have "likely" made two big errors this year. One was the Baja low situation for early December. The next one(appears as of now) was the repetitive lows sliding out of British Columbia to off the Coast of California. The Rex block might produce one or two storms on the West Coast...but not the sequence which was causing the endless chinooks. Even though modeling is still working things out....the exiting of feedback helps. Some chinook makes sense...but it was way overdone it appears. Now, is the NAO feedback? IDK. I have definitely witnessed years when models over-did how strong it was and missed the duration (sometimes too little duration...sometimes too much). The same could be said for the Aleutians high - but it has actual precedence for being there and at that intensity. I think we end up w/ a full latitude trough w/ cold dropping into Montana, modifying just a bit, and then heading eastward. I think the difference this year(compared to recent Nina winters), the source is much colder and this cold finds its way all the way to the Atlantic coast. I do suspect models could be too quick with the move back to cold, but again, sometimes they aren't quick enough if the NAO is going to be a player. The storm track could be more favorable as we enter January. As your friend notes, mid-Jan makes a bit more sense or even just the second week of January.

12z is definitely a choose your own adventure. Definitely NOT an easy pattern to model, but LIKELY to produce some interesting solutions on deterministic runs. Normally, I would say check the ensembles, but I think they are at least 24-36 hours behind the curve.

Haha. I am a time traveller.

I mean...really these are some WILD solutions. The 12z Euro is cooking one up as I type - doubtful it verifies. Good trends, but wild.

Even the Euro AIFS at 12z(which has been reluctant of late to budge) completely erases the chinook pattern. I think some version of a full latitude trough w/ some ridges/troughs sliding across the base...sure makes a lot of sense.

Between 180 and 240, the CMC completely erases any remnant of the chinook, and fills NA w/ BN temps again. Impressive if it is real.

12z CMC is on board and about 2-3 days quicker as it has been for a bit. The mechanics for cold an snow are in place around the new year if these trends hold

I suspect the 12z GFS is just a bit quick, but that is a potent winter weather pattern just after 300 that run. By the end of the run, the blues and reds are in the right places w/ split flow. That is a plausible(though certainly not certain) solution. Great trend if it sticks.

If the CFSv2 seasonal is right this morning, LC is could be set to score a pretty coveted seasonal win....and I mean an outright thumping. He dared to go the exact opposite of many seasonal ideas.

Ideally we want the cutter. I think it shakes up the 500 pattern. As for wind, hole mackerel it is howling out there. On my run this morning, I saw a roof blown off shed, and poly from another roof. Constant roar out there right now.

With opposing teleconnections (high in the Aleutians and high over Greenland), modeling "could" have its hand full. The base pattern would be an eastwardly displaced PNA ridge w/ cold attempting to stretch from Alaska into the NE. Cold would roll over the top of that ridge and any storm(Miller B or A) would bring down very intense cold behind it into the SE. I wouldn't say it is a great pattern for snow unless we can score an inland runner. But...it could get crazy cold IF the NAO is as strong as projected on both the Euro and CMC(especially the GDPS). FWIW, ensembles aren't seeing cold fronts at all - just completely washed out until the last minute. That is why I am using them less. It is entirely possible the NAO does not develop, but it is infamously difficult to predict. I am a bit wary of any model where it is absent late in the run. The wind is absolutely howling here....that must be what you all were describing.

The first thing we are gonna have to know(and it is increasing in likelihood) is whether the NAO is a legit player. On modeling where it is missing or weak....it is warm here. When it is present, cold fronts drop through the Plains(instead of sliding through Canada).

The para 0z GDPS is very cold on the 28th-29th before the run ends. I have a feeling (if the NAO strengthens and models aren't hurrying it up too much), that cutter may bring down more cold than models are depicting. If the NAO starts a bit slow, then the GFS will score that timeframe.

Line moved through here this morning. Wind and rain. Both the 0z CMC and Euro move plenty of cold air eastward beginning around the 29th. They could be too fast in breaking down the warm-up, but both have a cutter where the GFS does not. My guess would be the GFS is slightly too progressive, and misses it. If that cutter is legit, cold would roar down the Plains. Not sure how excited about cold on the 30th I am - Music City Bowl would be miserable!

Haha. I was teaching 3rd grad that year. We ran out of snow days in Knox Co...like ran waaaay out of snow days.

The one thing that makes the Weeklies(any brand) fallible is that they tend to perpetuate the week two pattern - true feedback. That is why it is important not to put to much stock in LR ext modeling unless IMHO they change from that two week pattern. In other words, if the model doesn't continue in perpetuity...that is worth paying attention to. I have seen cold patterns modeled for all six weeks...not even make it into week 3. That also works for warm air masses. So, that is why I like looking at the control which is basically just one big deterministic run.

Cherry picking some stuff from the Euro Weeklies, though I didn't think the ensemble was half bad!

@nrgjeff, are the new AI ensembles decent? I notice the 12z GEPS and both AI ensembles (GFS/Euro) had a lot of cold members after 300. The Vols losing three straight was like looking at non-stop chinooks on modeling - same result, same set-up. We needed that Louisville shake-up(red like an NAO! - it's a sign).

I like it a lot better than 16 straight days of chinooks on deterministic runs. LOL. It might still get warm, but I gotta have room for some surprises.