Carvers Gap

Dear 12z Euro, That was a proper model run. Yours truly, Carvers Gap

Re TRI: The avergage high is roughly 46F. It has been 35F so for the month.

TRI is -8.0F for the month. We have had five straight days below freezing(all day). Modeling ended up being pretty decent. If we can sneak through the last 4-5 days of the month without a huge warmup, we could end up with some impressive numbers for January.

We are going to need a little bit of a SER in conjunction with a strong EPO. Basically, we need the eastern trough to begin retrograding a bit and pump the SER as it retreats west. It is a little bit of thread the needle, but that has been the scenario for this particular window for some time.

The storm next weekend I "think" has been modeled as rain on pretty much every run, ie the first storm is rain. Each successive storm pushes the cold southeast. Just to clarify when I am talking about a system, it will be the storm after the one which rains. The 0z GFS and Euro are very suppressed. The CMC is very similar to its 12z run. I would guess that the GFS and Euro are overdoing suppression yet again. The 12z GEFS has the second storm on roughly January 20th. The overrunning event is pressed into E TN, W NC, and the Research Triangle. I think that is probably where we want it as it has room room to work back. The 0z Euro has a decent snowstorm which mimics the 12z GEFS track almost exactly. So, there is a little bit of agreement there even at this range. That is a pretty classic track for E TN and Carolina snows. We tracked a bunch of those between 2000 and 2015 or so.

Man. @tnweathernutbout to hit the "No!" button. I might be with him on this. Ack. Apparent temps. This didn't verify the first time models were almost universally showing this. However, with more snowpack....this is often what comes after overrunning events. Time will tell.

12z Euro looks good. I will give the GFS some credit on this. All of those will runs(where it had one storm right after the other) might not be too far off. Location is TBD, but the storms are showing up now.

This is a good example of what we see with overrunning. We see a big high sliding into the Plains with a southeast ridge (SER) flexing a bit. You can see the SER pretty clearly hear with the ridge east of the Apps. Cold would theoretically bank against the western slopes of the Apps or against the western slopes of the Plateau. The GOM would be open for business as precip would be pulled northeast by the SER. At this range it is very tough to know the location of the stalled boundary, because modeling likely won't have strength of the cold air mass modeled well. This is the 12z GEFS...most recent run.

The Euro would be my go-to until American modeling evens out. Its ensemble(EPS) was a statewide winter storm of varying precip types. Definitely too soon for details. During recent winters, the cold has not been able to get over the Plateau(cold for overrunning is generally low to the ground compared to other events). But way too early to know. Snowpack will almost surely have an impact on how far the cold can make it southeast. During recent winters, it didn't have the skids greased with snow. Cold getting to the Apps is plausible.

The 0z Euo had this. I think this is the more likely scenario based on recent winters. That said, I think blending the CMC, Euro, and GFS has yielded pretty good results. The Euro nailed this last system. edit: The 0z EPS looks much more like the AIFS at 6z. Pretty good look on the EPS, and again, a very strong signal.

The 12z GFS has the same pattern as the CMC....just has it in Charleston, SC. It has been in error every, single time this winter when it does this at range. IMHO that pattern is coming back northwest....maybe by a lot.

Glad you are posting. Stay with it. It is a great(sometimes frustrating) hobby!

The 12z CMC has the overrunning event. The 12z GFS was too fast with the cold. CMC is potent.

I would also add this. There are some clippers this week which may have light impacts on the northern Plateau, SE KY(especially), SW VA(especiallly), and NE TN(especially higher elevations).

The 0z GEPS had this after multiple waves of energy along a stalled front. This is the last in the series...just a little later than the GEFS. (please refer to my last two posts as this started a new page) Overrunning has a very strong signal(so far) on modeling. Still 7-9 days out...this will 100% change with smaller details yet to be worked out.

The 6z GEFS had an almost identical setup but was faster. It was centered from the 18th-20th. Timing is key and differences exist at this range. But seeing similarities is a good thing at range. This look has been on modeling almost since d16 of that time frame was on modeling. So, to see consistency from that far out is a good thing. I like that it is on ensembles. I will add that often modeling is too far southeast with overruning - so beware. It will often correct westward. The last storm on this 6z GEFS run looked like this(preceded by other impulses):

This is the overruning event captured in about four frames. Notice that each passing wave brings the ice and snow line eastward. Sometimes, the first wave is the stronges(w Tenn folks know this from a few years back). Sometimes, as seen with this setup(NOT the gospel), the last wave is the strongest and can resemble(or even be) a Miller A track. These are just waves that slide along a slow moving frontal boundary. This boundary is slow on many deterministic models and slow on ensembles. If you put those maps in motion(just look at temp anomolies), you will see a hiccup or two as they slide across the TN Valley. Those hiccups are the front stalling. A stalled front is a hallmark of overruning events. I think the chance of this occuring is growing with each models suite. I don't know if the overruning will be the Ohio Valley, TN Valley, or even mid-South. I would think our forum area is prime for this type of setup. Just watch the blue lines press southeast......The third frame would be M TN snow. The last would be E TN snow, and is the strongest of the four distinct impulses. Note, this only occurs during a roughly 72 hour window. Wave 1 Wave 2 (below) Wave 3 (below) Wave 4 (below)

I also note this often. There is a reason the first settlers settled in the valleys of the State of Franklin area of NE TN. The weather was less severe, the valleys could be farmed, and it probably looked like home to a lot of folks from Scotland/Ireland/combo of both. They were smart. They weren't looking for snow totals. Most were farmers. They wanted the longest growing season they could manage.

Kingsport has been pretty fortunate. I can’t complain. Now, we can get downsloped from 3 different directions. We aren’t unlike Chattanooga in that regard. We just benefit from latitude. Yesterday, the precip just didn’t get far enough north. It happens. We also have two massive industrial plants in KPT which create a unique heat island. La Niña is the bigger culprit. We just get less precip during those years. We have had a base La Niña pattern since about 2017. That said, weak LA Ninas can work from a nickel and dime approach. I have probably had snow in the air almost all of January. Just an ebb and flow. Let’s see how the rest of winter plays out. We have about 2.5-3 weeks left of cold and March (I am surrendering February).

Officially I would say 2” here. 2.5 in the grass. 2 on the back table. Pretty unscientific measures for MBY - a tape measure check. We got dry slotted up here big time and from the word “go” the northern shield never developed in a robust manner. Precip also split over northern Alabama and just never recovered. I think someone noted that the precip got ahead of modeling. I think the southern end of this moved so quickly it never really allowed the northern edge to develop. It underperformed north of I-40 almost regardless of location - just looking at reports. Greeneville did better than me and that should have been a prime downslope area. Mathmet had a post about it. I just think the precip didn’t get as far north as modeled. Again, SW VA likely did better due to the orographic lift and they caught some precip which rotated west of me(moving NE). I do agree and think downslope in Washington Co could have been an issue, because the fetch just ran out of steam. When the fetch is weak, a weak fetch will be impacted by the least bit of downslope. Just watching the radar, it looked like it just ran out of steam as the Knoxville precip ran NE. Easily the toughest 2” of snow I have had in a long time.

Some model runs are loaded up with potential, and others are pretty barren. Time will tell. Hopefully we can reel in another event or two.

The overrunning look has been honking on models for the last 7-10 days at least. The SER is about to fire once again, and that promotes overrunning (stalled cold fronts). To me, an overruning event would probably affect only the western 1/3 of the state. The last few events like that couldn't get over the western edges of the Plateau. But let's see. The cold appears to be stronger than the last few overrunning events of the past several years. When it is strong, the overrunning can push to the spine of the Apps. When cold dumps into Texas, that is a sure sign overrunning is possible for western areas. Overrunning is not the only option as John noted overnight(reference his post about a redux). I also think it is growing likely that we see an anafront IF the cold is as strong as modeled. And let's be clear about this so the gnashing of teeth is limited when the time comes. Long range ext modeling is crystal clear that a pattern change is incoming when the MJO rotates into warm phases. The good thing is that so far the warmer temps have been pushed back to around the end of the month after originally being depicted for the 20th. Personally, I just want to see January's average temps in the tank. I think February will be much above normal. It wouldn't surprise me to see a record high or two broken. Then, I think we do this one more time during March(late Feb if we are lucky). If we can get the MJO to haul you-know-what across the warm phases, we could be in business quicker. However, the end of January puts us at about 4.5 weeks with a colder pattern, and that is about the max duration that we can swing. That doesn't mean it can snow when the MJO is in warm phases - it does and has before, but just tougher to get the job done. Short story....we have about 2.5 more weeks of good cold to deal with. The AI hints we might be done with the cold around the 26th. Global ensembles keep us in the freezer to the end of their 16 day runs. I wouldn't be surprised to wake up one morning and see those flip shortly after the 25th...but I think we have until the last few days of the month. The 18-22(maybe 23rd) looks like a good window to watch.

Ended up with 2-2.5" of snow. It was a battle all the way. The amped models missed badly IMBY. The NAM was never right....even its last run was amped. The RGEM was the closest yet again. Lower totals around TRI had very little to do with downsloping and more to do with the storm just didn't make it far enough north and/or we got dry slotted. The actual storm for this area never looked even remotely close to anything modeling had outputted. SW VA did better as elevation helps with incoming southerly flow coupled with lift from higher elevation. They also benefited from those last streamers which went west and north of the western edges of TRI. It is possible the Eastman/Domtar bubble was likely legit at fault on this one - you could see KPT fill in last on radar. That constant heat island is always a bear when we are dealing with virga and/or marginal temps. Great to see Chattanooga folks with a great storm. Almost half a foot ain't bad! TRI should have a few more chances before this pattern runs out of steam later this month.

The next big window (excluding a couple of clippers this week for northern areas) is the 18-22nd. Winter options on the table are a cutter, overrunning, ana front or coastal. An ana front looks plausible. Overruning also plausible. I think we see at least one cutter. Rain chasing snow looks likely in cutter scenarios. Still a good 13-15 days left before a significant warmup. The cold analog package for January (wild card month) are likely going to win.