Carvers Gap

LOL. That is a great line. I always forget about mountain torque events in Asia. I am assuming this is good or us?

Just looking at the 18z EuroAIFS....that is a pretty good look. It is wild to see the Jan 2 cold front trend today. I think we see several cold fronts forced south and east. That seems like it has slider or clipper potential. But with modeling bouncing around right now.....I hope today is the beginning of the ship being steadied, ie we get a fairly predictable pattern.

I have been wanting to post that GEM map all day. We were doing Christmas with some of my family...I definitely was sneaking a peak at models. But my 12z model deep dive...just now happening. There is an interesting demarcation point after the 5th...does it warm up and we get a heavy rain event as Holston posted? Or does end up frozen(not at those levels)??? I tend to think the cold hangs around, but that is an educated guess and by no means fact.

The very definition as an outlier, but it deserves its moment since it is inside o 240. Departures from normal....That would include -11F IMBY. I have to look at chinook maps for a couple of weeks on modeling. So, humor me...haha.

I have found that the Euro coupled with the GEPS(Canadian ensemble) has been decent this winter. When the two are singing the same song...good thing. When the GFS starts to trend towards them...better thing. The GEM only goes out to 240, so I kind of use the GEPS to see where it might have gone if it went past 300 hours at the deterministic level. Both get to a pretty similar place. BTW, the ensembles have moved quite a lot over the past 48 hours. Right now(rightly or wrongly), I don't trust any model which breaks the NAO down too quickly. Unrelated, it just kind of seems like about the time the NAO makes its exit...the EPO/PNA is gonna pop. That has been a pattern for several winters. NE TN folks have generally not benefitted from this, but with the cold pool so strong...I have to think the cold doesn't get held up at the Plateau or even the Apps.

Some great trends on modeling for the past week or so....still a tough pattern to model. I like @John1122's analog discussion above about 1982. It was one of only two Tenn winters which I missed while living in winter purgatory - Orlando, Florida. I read the newspaper articles about the ice storm, and about Tennessee beating Alabama during the World's Fair. I will say that it got crazy cold during those winters in Orland and wiped out many orange groves that were never replanted.

The 18z GFS find the cold air mass. All...winter...long -> so far. It has almost 50 degree changes(colder) over the GLs. Trending quickly towards what the GEM has had for days. The 18z AIGFS is on board. Honestly, there are so many cold fronts modeled...I have no idea how many there are. Dec 29, Jan 2, Jan 5, Jan 8?.

Now, merge that with the 12z GEM...and we are in business!!!

Sorry, we have been traveling for most of the day.... It has been very right for the 29-30th event...scored the coup. The 18z AIGFS has the Jan 1-2 cold front. The run-to-run for the 18z GFS is MUCH colder. Do I think it gets below zero without snow? Unlikely as the GEM is often too cold. But it ofter correctly sees cold fronts during winter when other models do not - just add back a few degrees for the cold bias. The 18z AIGFS is basically the 12z GEM but just not on steroids...one cold front after another.

Record lows. Seems to be an outlier at 12z, but…it caught the Dec 29th front first. Teens below zero.

The 12z GEM would shatter some records. Crazy run. A few places would have all time records at risk.

The 12z CMC and GFS in a bit of a model battle for Jan 1. The 12z has snow and below zero temps. My money is on the Canadian.

After a super quick skimming of models. The 0z Euro and 0z GEM are cold beginning sometime around Dec 28-29. The GFS really does not like the idea of the Jan 2 cold front...but sends one a few days later. Some of the AIFS models agree w/ the GFS...but for now, I am riding with the coldest models. Why? We have seen a tendency for models to miss or under-do cold fronts. I may try to update 500 here in a sec. That update was pretty much surface focused. As for snow? I have to think one or more of these really cold fronts is going to produce winter precip. It is worth remembering that models often lose systems in the the day 5-7 range...only to find them again, and they restrengthen. We may have short lead times on fronts which bring snow with cold fronts.

Fun with maps...the 18z GFS. We should see these types of runs given the potential for HL blocking. There are gonna be WILD swings as exemplified by the r-2-r map below.

Shiver me timbers. Trough drops into the East and holds. Slider present. NW flow present.