Carvers Gap

The 0z EPS control run wins the award for coldest run of the year. TRI barely makes it above zero on this particular run for this particular day. Temps the next night(after this hour) over the TRI region drop to -10 to -15F. Those temps would push for record lows. Now, this is just one map, but it does exemplify what can happen with so much cold waiting in the wings and a 500 pattern which supports it. Models are showing some hints of the colder pattern breaking down right at the end of the month, but could be a cold couple of weeks getting to that point. The ensemble snow runs are pretty massive.

Problem is that we don't have a ton of fresh, cold air in place. Really depending more on the track. This system has been on modeling since almost day 16(?). This is the beginning of a cold cycle within this pattern which is why. Normally(and this depends on where one live...but will use the eastern valley as an example), a track from New Orleans/Mobile into South Georgia to inside Hatteras...that is the money track. That is called an inland runner. The closer that gets to the coast, the more difficult it is to get precip to come over the mountains. The close that track gets to us(unless cold air is in place already), the more mixing becomes a problem - see the last two storms for that reference. Also depends on the strength of the system. Stronger - need it on the outside of the best track envelop. Weaker - need it closer like running along inside edge of the coastal plain. Middle TN actually benefits from a track through E TN or along the spine of the Apps or W NC. The exciting thing about the pattern after this, plenty of cold in reserve.

Downsloping could/will be an issue. Thing is, if the slp placement is wrong on the GFS....it should be less. My concern is that this starts as rain north of I-40, and the surface cools due to evaporation cooling (overnight onset). That could creat an ice situation on the west side of the eastern valley as cold air gets banked against the Cumberlands.

I am still not bought-in on this storm yet. Too many good forecasters say to be wary, but the 0z NAM was used by MRX to mention a non wintry solution. 6z changed. I am glad I am not in their shoes. This comparison is in no way a criticism of them as it came out AFTER their morning disco. Normally, I wouldn't use the NAM at range, but since it was mentioned in a disco, thought it was worth a look. The single frame is the end of the 12k 6z NAM. The double frame is a comparison of the last two runs. The 6z NAM is pretty much the same as the 6z Euro.

6z NAM went with the Euro.

Through 75 on the 6z Euro, definitely a jog south.

The 6z Euro through 72 is south with its precip shield through 72 which fits trends from overnight. We will see where it goes.

I normally wouldn't use the NAM at range, but that is a major winter storm on 6z - ice, sleet, snow. I got up this AM, and was expecting the "poof" deal. Just looking at modeling, this is a significant winter storm north of I-40. I The NAM actually keeps the primary slp along the GOM. I do think the warm nose is going to be a problem, especially in the eastern valley. So, my expectations are low...but this looks like a mess IMBY. Let's take a minute and look at timing. In the eastern valley, the GFS warm nose moves through in the very early morning ours while it is dark. I can tell you from experience, that brings all kinds of headaches. The low passes to our southeast during the morning hours Sunday. The Euro is slightly slower. One would think the Euro would have more mixing issues....but it has less. The 6z Euro is rolling. Colder through 63.

I still have my doubts with this system in regards to the warm nose. MRX went out of its way to downplay any threat. They specifically used the NAM as a reference for a non-winter event. I totally understand their trepidation with models all over the place. But the 6z NAM.....

I thought the faster solutions tended to not cut....or is this for the 50/50 which would suppress the second wave?

Significant change by the gfs.

Southeast trend by the gfs. Man, it almost caved. Not there yet, but close.

Yeah, it is digging less and almost 150-200 miles further along.

This run of the GFS is faster with slightly less digging. Might result in a less robust system. That would be good for the Valley.

18z GFS looks slightly more progressive at 42. Let’s see where this ends up.

Let us not discount how cold the 12z GEFS is. Crazy cold.

Yep forgot about that. I do think it does a better job with the warm-nose(maybe Jeff said that in the other thread). But tough right now to discount the steady Euro run which actually has support from the GEFS and its own EPS. Guessing one of the two blinks by 0z. There is an argument to be made that it will cut, but that almost requires an amped solution over Louisiana. And the model with amping problems is the one cutting it. Tough call. Never thought I would see the day where the Euro has the consistently most progressive model run.

Yep, delayed their release.

Normally, I would never even give a GFS/CMC combo any weight in comparison a Euro/UK/GEFS/EPS combo. I mean that last combo is stout. I would throw out the GFS/CMC solutions or minimize their influence in my thinking. However, they have done ok with the past couple of storms. Seems like the Euro woefully missed the warm-nose for E TN. Not sure the GFS did much better though! That said, this will be a test of those models as they were recently updated. FTR, I am not sure the GEFS received the update or not. Seems like it was supposed to, but I never checked.

This is like overtime in college football. We got our 2pt conversion with the Euro. Now to 18z, to see if the GFS converts or folds. The 12z GEFS rejoined the Euro camp. The models with the newer updates are the GFS and CMC. They are either too amped, or their updates have better physics in the region.

EPS slp placement barely moved compared to 0z.

It is not often that I get to share 1' totals form a model deemed "Dr. No" while the rest of the models say, "No." I have low confidence in this map. It needs some support outside of the UK.

LOL. There is more....

There is way more snow in E TN. Snow falls almost through 120.

Still plenty of snow falling at 111 over NE TN.