Carvers Gap

Area of slp might be 10 miles to the NNW of where it was at 0z on the 6z Euro. Cold air moves in slightly(and I mean slightly) quicker. Going to be a tight fit for our areas and eastward, but that track (along with earlier cold air) would make huge changes. Looks to me like the front itself is the changeover line on model, meaning once the heavy rates arrive so does the cold air.

6z GEFS

Steady run by the 6z Euro. Chattanooga folks are in the mix on the 6z Euro run.

For NE TN peeps, we have the 3k/12k NAM and the 0z Euro in our camp. GFS was trending that way. Morristown westward looked good overnight. Need one more jog like the 3K NAM for our area. I don't like sharing a foxhole with the Euro or NAM as they have been jumpy this winter. Though, one would think at this range that they are starting to narrow the cone. For now, heaviest snows looks to fall somewhere between the west side of the Plateau and Bean Station(little shout out to a well named city) or maybe even Bluff City.

MRX... National Weather Service Morristown TN 628 AM EST Thu Mar 10 2022 ...Discussion: During the day Friday, a potent shortwave trough will quickly dig across the plains while baroclinicity takes place across the Tennessee Valley. Southerly low level flow will ramp up on Friday advecting moisture and warmer air poleward. High temperatures on Friday will easily rise into the mid 60`s and possibly upper 60`s assuming skies can clear out as expected. Heading into Friday evening, the trough continues to dig into the Mississippi River Valley inducing low level cyclogenesis across the western Gulf of Mexico. A resulting surface low is progged to deepen and lift northeast. Increasing jet dynamics develop after 00Z and quickly lead to a saturated profile with precipitation developing Friday evening and into Friday night. The atmosphere will be warm enough for much of this precipitation to be rain. As the cold front sweeps through the area early Saturday morning, much colder air will quickly filter in as 850mb temperatures crash. With plenty of upper level support in place, we will likely still see plenty of precipitation across the area that will be heavy at times. Recent data suggests that some drier air within the -12 to -18C layer could limit dendritic growth initially but eventually enough moisture moves back in for efficient dendritic growth leading to heavy snowfall rates. There are a number of factors that make this snow forecast a bit uncertain and difficult. As mentioned in previous discussions, recent warmth and warmer soils will tend to mitigate initial snow accumulations, and it will take very high snowfall rates to overcome these factors. With that said, there could be a window of 3 hours or so with heavy snowfall rates that would allow for some snow to accumulate on mainly grassy surfaces. At this point, believe impacts to roads will be limited but cannot rule out some patchy snow on roads especially across the northern Cumberland Plateau, southwest Virginia, and across the mountains of East Tennessee. The actual snow forecast remains largely unchanged from the previous forecast with amounts up to 2 inches across the northern Plateau, southwest Virginia, and East Tennessee mountains. There are some signals for higher amounts up to 4 inches in the highest mountains of southwest Virginia, and the Smokies. Elsewhere, expect mainly 1 to 2 inches of snow north of I-40 and a dusting elsewhere. Obviously lower confidence remains across the valley where more negative factors are at play that would limit snow accumulations. Moisture pushes east through the day Saturday with lowering PoPs expected from west to east. The forecast does hold onto PoPs a bit longer than NBM guidance as sufficient low level moisture and even an increase in low level lapse rates could support snow shower activity through the day Saturday. Temperatures will be much colder Saturday with highest barely expected to get above freezing. A northwest winds will bring those wind chills into the lower 20`s during the day. Finally, high pressure situated across the Southern Appalachians will bring clearing skies, and calm winds which will allow temperatures to bottom out. Lows in the teens seem likely across much of the area with single digits not out of the question in the higher terrain.

Those(sleet and zr) are great signs. Many good storms have mixing issues. I am sure someone understands the physics, but have seen that many times here.

@Holston_River_Rambler, are you able to make a gif of the track or precip shield(like you did for 12z) for the 18z run?

18z Euro was a textbook track...couldn't draw it up better.

The heavier looks for the eastern valley...some are just some monsters.

March storms are just notoriously difficult to nail down. The book on this won't be closed until Friday at 0z - if then. Just because most of us are in this thread...the 18z GFS is just one bowling ball after another.

I was laughing, because if I speak in an absolute...I will certainly be wrong. Yes, I think that sounds about right. Not sure about ratios, but I think it possible that the cold charges in more quickly. Best case is modeling holds/consolidates the track from 12z and then ups totals as they begin to see the system. A GOM system to inside Hatteras could be pretty strong. Strung out could cause thermal profile issues.

I look at track. Once that gets relatively nailed down, then time to wait and see if modeling begins to up totals like some March storms can do from time to time. March storms can sometimes verify stronger than modeled. Time will tell.

This is a battle between a very strong cold front and a storm that will want to pull north along that front. To me, it looks like the front is pushing and forcing the storm just a hair eastward at 12z. That allows for a hair less organization. I will have to look at the norms, but this might be the strongest front relative to norms IMBY. Remember, in NE TN many of these fronts got hung up before getting here.

Correct - maybe. LOL

Could be power issues if the totals are legit.

Hard to get much better of a look than this.

Looks like the slp is indeed SE which follows the trend of other 12z modeling. It is also 1mb weaker. Storm is slightly more strung out.

Looks like it has a SE trend as well. I am only out to hour 50 or so. Looks like it may make a clean pass.

AT 57, the gradient is flatter.

12z Euro is rolling. It is following a similar 12z GFS trend of a very slight sharpening of the gradient ahead of the storm at 30.

One further note and just to beat a dead horse... Notice the cold(orange) is moving a bit quicker. Also notice the location of the genesis of the slp. That is pretty much textbook for winter storms in E TN. I make no promises as far as snow, but that is a great location. Also, notice less of a warm-nose into TN. Good trends on both the GFS and its GEFS ensemble below. As @Holston_River_Rambler, that is a jog SE. It may be just a wobble, but we really couldn't have withstood another jog NW in E TN. Trends matter at this stage.

12z GEFS for comparison 12z -> left.....6z -> right Note the cluster of lows is back to being over Upstate-ish SC and not over the eastern slopes of the Smokies. Good trend if you live in E TN, ie would imply less warm nose. The 12z GEFS is trying its best to get a clean pass. It is strung out a bit more as the snow totals are lower due to that. At first glance, I was like, this is trending closer to MBY. Really, I think what this implies is there is less energy transfer to the coastal plain. The SLP simply stays as one and slide up through central NC. Of note, a tertiary slp forms at the base of the departing storm. That cluster has crept a bit closer to the coast. It is probably too late in the process for that to have meaningful impacts here, but keep an eye on that.

The 12z CMC is still on board as well. For now, I think we are looking at 2-4" in the eastern valley with higher amounts(maybe much higher) on the northern Plateau and points in middle TN as well. This is a potent looking system.

Big storms often have bands of sleet. This is certainly showing up on this run.