Carvers Gap

The 12z GEFS and GEPS snow mean is going back up. That is usually a signal those models are on the hunt. The 12z EPS(an ensemble!) has the lows next week at or below zero over portions of TRI. I would suspect something is going to occur with that front - anafront, slider, miller. That is a big time front, and "should" have something react to it.

The 12z GFS agains looks far too suppressed. The 12z CMC looks about right. Both give systems a chance to come back north which they likely will. It has snowed in Charleston, SC, back during the early 90s. However, none of those setups have verified this winter. Remember the Key West snow showers? Didn't happen. Remember the central Florida snows on modeling? Didn't happen. Cold has been continually over modeled this winter. Could it happen? Sure, once in a blue moon. However, climatology supports those systems being further north. Up to this point there is zero ensemble support for those ultra suppressed runs(at leas in regards to snow in the orange groves). For now, we will have to rely on ensembles as the GFS has just been off its rocker of late.

Good little window early to late next week. Things that have not verified this winter: 1. Snowstorms in Florida and extreme levels of suppressed flow 2. High numbers of clippers. For now(stress now), the pattern is a warm up and rain pattern. Next week is cold and dry looking. Like Jeff, let’s keep those waves south and let them work back. The CMC is pretty adamant with overturning. Other modeling kinda got there last night with a late developing wave which skimmed E TN.

The good thing is that came back well north. We probably want our storms that far south with the northern trend being legit this winter on modeling.

Yeah, that has been overdone all winter. I am not sure why modeling has been so extreme with the extent of the souther edge of cold at range. But across the board it has done that, and been badly wrong. But agree, that would be an extreme event.

MJO. CPC has a great site about it. Draw a line down the middle. Generally it rotates counterclockwise. For cold weather, we don't want to be on the right. 4-6 are huge warm signals, but sometimes can get an oddball snowstorm in one of those. 3 we can tolerate. 8-1-2 are best. 7 is transition. Which numbers are good changes with each month. In general, we don't want stalled convection over Indonesia(Maritime continent - MC) or the eastern Indian Ocean(IO) - that is the shorty story. That teleconnects to a southeast ridge(SER) here. The black line is the predicted plot. Red dots are where we are now. Think of it as looking at what is upstream from us in the atmosphere. At some point in Feb, we are likely headed to 4-6. It takes a while to learn about. That said, if you simply look at a satellite map of the aforementioned areas, you can see it or you can see that convection is about to move into those areas. If you learn to read the plot and satellite maps, you can often predict weather up to 20-30 days in advance for our back yard. Very reliable, but not foolproof.

A very cold air mass and a very active STJ on both the CMC and Euro - I feel like I have said that before? The details aren't worked out right now, but that is about as good a look as one can get for a winter storm in the south. That has been a very consistent look. Details TBD, but might make for some fun model watching for the next few days.

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)