Carvers Gap

Glad @John1122reminded us of the basketball game. Wow. Insanely good on offense today. You all know that I like the Euro controls. I went back to the last 7-8 runs. They are alternating almost perfectly from warm to cold...every other day. Well, here is today's, and this has support across the 12z suite(even though this was a 0z run). This is a 30 day map for the month of December. Lot of big troughs swinging through w/ the SER flexing as the cold retreats. To me at least, that seams like a reasonable pattern compromise.

I have repeatedly watched the deterministic GFS lead the way over other deterministic and ensembles at this time of the year(during past winters). It maybe doesn't do that as we get later into winter, but it seems to do a little better(than other models) during late shoulder season and early winter. I do admit ensembles carry more weight, but a lot of those ensemble members are cold. At the very least, some very cold weather is not out of the realm of possibility. And if the trend continues during future runs, those ensembles will flip. Fun 12z suite for sure. Pretty big cold signal for Dec 3 and/or Dec 6.

I don't think that is look is a slam dunk, but nice to see 12z deterministic runs(across the board) show a great pattern. Ensembles are understandably slow to respond. I think a lot of the mean temps are skewed on the ensembles. There are 4-5 big ridges out of 20 members. The temps under those 4-5 members are skewing the mean. If those were tossed as outliers, the mean would be much colder. Hopefully, those warmer ensemble members begin to exit as we get closer...that could mean deterministic models may be closer to being right.

Ah, yeah. Thanks for the reminder. I about forgot about the mid-day game!!!

IMHO, there is a decent storm signal showing up IF the cold settles into the Ohio River Valley. There are multiple CAD signatures for W NC. I would also think there is potential for winter storm across the upper tier of the Upper South with the way that storm track sits. We will see if this trend continues going forward. This started late yesterday with both the AIFS and GFS trending colder. The 12z suite is cold across the board. It could just be a batch of data or it could be a continuing trend.

The 12z Euro bring subzero temps into the Ohio River Valley(western sections) 2x. Once is around Dec 2nd and the other is Dec 6h. There is probably some snow field enhancement there, but still...it is very cold here. Single digit real feels by Dec 6th. Maybe a couple of days w/ sub freezing highs for areas north of I40 on two separate occasions.

The 12z Euro looks remarkably similar to the 12z CMC. I am kind of surprised by that. Winter storm potential exists on it as well.

This is the 5-day map from WxBell of the above pattern depicted by the 12z CMC....that is a BIG change. What we are seeing at 12z might explain the model mayhem. Is it the MJO finally exerting influence on modeling? I have sometimes noticed that the MJO doesn't really exert influence on modeling until about d10-12. I have noticed this in reverse when the pattern looked cold d10-15, but the MJO looked like it might stay cold while in the warm phases - nope, almost always flips as reality approaches. Is the SSW starting to have an early impact on the troposphere? Maybe, but it is a bit early for that influence. Either way, the EPO is showing up on modeling big time at 12z. Let's see if the Euro gets on board. I kind of doubt that it does as it IMHO is dealing with feedback issues in the SW. But let's see if it gets moved off of its spot just a little.

And the 12z CMC has similar look to both the AIFS and GFS. EPO anyone?

The 12z CMC has a below zero air mass sitting in the Plains and Ohio River Valley as a couple of impulses originate in the Gulf and head northeastward.

The 12z CMC almost has a winter storm by 198. Big changes on the deterministic models at 12z today - noted that the Euro has yet to run. The Euro AIFS, GFS, and CMC are showing a cold shot around d10-12 which wasn't there on yesterday's runs. It is a bruiser. I doubt the ensembles will switch that quickly, but it is a trend worth watching. This cold front had been on LR ext modeling for weeks, and then disappeared. edit...the CMC is actually close to something good 3x.

The 12z Euro AIF is rolling. You can send me the Christmas card later (for saying the first week of December being warm was a foregone conclusion). LOL. That right there is not a warm look for the eastern 2/3 of North America.

And this would be phase 8. Now, I must warn everyone(newbies especially) that model talk past d10 is not without peril. But it sure seems like the GFS (and about half of the recent AIFS runs) are sniffing out a potential cold shot around December 6th.

And this is a setup that says, "Look out!" This is sitting at d10. As @Holston_River_Ramblershared yesterday, the AIFS caught wind of this possibility first - I failed to note that early...sorry Holston! The GFS is now picking up on the possibility. That is a mechanism for fiercely cold air to be discharged into the Lower 48, especially the Northern Plains, Ohio River Valley, and maybe the Tenn River Valley. There is the possibility that this is being under done. Either way, this is a very cold look at the surface.

And it is very important to be careful w/ 500 maps with cold air on the prowl. I was watching temp maps that were frigid at the surface, but the 500 map looked benign. The surface map(first image) shows a strong cold outbreak into the Tenn Valley after 300 hours. See that string of high pressures. However, the 500 map looks kind of meh. I think there is a 50/50 chance that we see a strong cold outbreak in/around December 6th.