Carvers Gap

I would guess it is maybe there now. With rates increasing over E TN, that is probably the lee side buckling the flow just a hair....Tellico would know more on that.

Yes, I agree.

We have crept to 4.5" of snow so far in my area of Kingsport.

For sure it wasn't the only thing....something pushed the warm air across the valley from east to west. That I don't know for sure what mechanism caused it. I tend to think downslope, but it may just be that TRI takes longer to get colder w/ east to west cold fronts.

Yes, but still a lot to be ironed out. Then a MONSTER warm-up the next week(day 8-14) 5-10 days worth, and then a colder Feb than maybe we have been used to....maybe.

Prob sleet....could be heavy snow though.

TRI has been above freezing all day. I think warming yesterday (clouds moved in later and at perfectly the wrong time) seeded the problems for today. We got too warm yesterday afternoon due to sun. Then clouds moved in and capped that warmth so it couldn't radiate out. Time of day IMO was the single, biggest determining factor of who got what.

It is the evaporation due to heavy precip that cools the air column. Kind of like if you get wet on a cold day, and you feel colder. Once that column cools, snow can travel the entire length of its trip without melting. I suppose it could pull some cold air down, but I would guess it is more due to evaporational cooling. If somebody has a better answer, have at it. I am a bit over my skis so to speak. When we aren't fighting daylight....that is also another factor in cooling.

We have kicked and clawed our way to 4" of snow. Rates right now are decent. Within an hour we should be dealing with cooling due to darkness and higher rates. Hopefully, that will force the rain/snow line to recede.

This reminds me a lot of a storm in 1986 around TRI. Got a good front end thump, and then had mixing issues the rest of the way. I remember having a snowball fight that night in the rain w/ some friends while in HS.

Forgot to mention the lee side slp. Normally that is a huge plus, but when the cold front stalled....it didn't help areas with marginal temps. Never did I imagine that warm air would seep all the way to I-81(further in some cases). Crazy dynamics. Hopefully, as it gets dark and rates increase...maybe some areas will switch back to snow and get thumped.

Moderate to heavy-ish snow in Kingsport.

It is driving me nuts. I LOVE the observations. It is the best part of the storm. The problem is that in NE TN, the storm is 12 hours behind initial reports. BTW, big slug of precip headed TRI's way...I would think rates will flip rain to snow when it arrives. We have hit the leading edge of the precip here.

You are not alone in middle and west TN. Even in Knoxville, the over performed early as the cold air made it that far and stopped. Precip shield expanded northward. Again, the NAM had it - but for the wrong reason (over amped). All modeling missed it until the RAP and HRRR came on board. The model that correctly modeled the cold air intrusion to Knoxville and then stopped it....that is the one that is correct...and the model which correctly backfilled the precip track over middle and west TN without having track issues over E TN. The ICON is the winner in my book. It got both scenarios right with the first and second wave it appears.

I definitely recommend at least trying a dedicated observation thread next time. The problem is that we have model talk and observations buried in the same thread. My two cents, and my opinion is probably worth exactly that. We(NE TN) are about 12-14 hours behind the onset of precip in western areas. While observations are (and we HUGELY appreciate those as it makes it easier to see which model is actually initializing correctly) rolling, the storm is still being modeled in far NE areas.

For several days, the NAM busted badly in the eastern valley as it didn't have any snow east of the Plateau. Globals did much better over here. The final run of the GFS before the event is probably going to verify for the most part with the exception of the foothills which mostmodels basically failed w/ until the last minute.. The Canadian sniffed out the problems in the eastern foothills first. Once the NAM came on board yesterday, it also had it. The HRRR also had it to some extent when it came into range. It is also worth pointing out that the NAM doing well in middle and west TN while not doing well here is easily explainable. It was closer in time to the event and those areas got cold quickly(better ratios). On this end, we were still several hours behind from a modeling standpoint...and it overdid accums on the Plateau and Cumberlands which was feedback. I do think the NC lee side low caused it problems. Once it lost that feedback(and we got closer in time), it did much better. It didn't dial-in here until about 12-16 hours to go. The other problem is that as the system backed and slowed, the NAM tended to feedback. The ICON is probably gonna be the big winner in all of this statewide, and that is probably a shock to most - me for sure. The 3k NAM was particularly good. The 12k NAM was terrible. The RAP and HRRR have been really good as well. I don't like the RAP, but it has done decently this go around. As MRX noted, no model had the warm air pushing to I-81 in NE TN.....personally, I think the front stalled at dawn at the Plateau and then daytime temps caused issues. The front stalling on the Plateau is not unusual. As Tellico noted the other day, Knoxville has a nice pathway for cold air from the Plateau. Chattanooga and TRI do not. The big red flag was when temps in NE TN yesterday beat forecast highs by 8 degrees. That produced a lot of warm air to scour as we got cloudy at dark, and warm air couldn't scour. Then it go banked against the Apps this AM. The NAM itself is I think a false positive. It got some things right, but for the wrong reason IMO. It got incorrectly amped and missed the track, but its snow totals worked out. Why? The cold air moved aggressively into middle and west TN and allowed rates to be crazy good. I have roughy 4" of snow right now. My ratio might be 8:1. If it was colder, I would likely have double that. So, whichever model moved the cold in most aggressively is correct...and I don't which one that is....probably the RGEM? The other thing is that the over-amping of the NAM gave it some semblance of expanding the precip shield. Its precip shield was juiced due to feedback and had a bad track in the East - plenty of snow fell east of the Apps which it didn't have. In reality, that precip shield was going to fill in as the rush of cold air squeezed every drop of moisture out of the air - it was impressive. The entry point of heavy precip was decently modeled and didn't change much. Still looking through some of the reports from middle and west TN which are incredibly helpful. I think the main bust(and let's be honest, nobody cares if a model busts and they get more snow than shown), is the foothills...and that may take some time to figure out.

Yes.

Yeah, man, you all are under that storm prediction center disco from 3:00-5:00 for 1" rates. Have fun.

Humongous slug of moisture about to head through the eastern valley.

Running about 3"+ here as well. Beware, the rain snow line is at John B Dennis. It moved north along I-26 from Eastern Start to John B in about two hours. We still have snow here, but hoping maybe we can hold on until temps start going down as the sun drops lower in the sky.

The wooly warm was right, Holston...and the elk. Go feed that elk, man. Keep it around and keep it happy.

It is right on the line. I just drove KPT to Gray. I-26 is awful from John B to Eastern Star and then it flipped to heavy mix and then rain by Gray. Main snow axis appear to be just to the left of I-81. Colonial Heights should be getting blitzed. Has changed back to moderate to heavy snow now at Gray.

Haha. Yeah, go for it. I think my spell check and lack of proofing got me there...but it isn't all wrong! LOL.

Scientific method. Let's see which one does the best w/ this set-up: Short range models vs NBM:

Probably wise.