**Big Dog ULL/Southern Slider Jan 17th -18th 2013**

Reb wrote:I like where I am with this system

I don't know why I laughed but I did.

pippinm wrote:how does this look for the Bristol area?

If the NAM is correct you will be in a winter wonderland come Thursday night.

The 0z models have began running



Man...the NAM is not backing down. MRX wont be able to ignore it much longer

Thanks

Yeah, thats what I'm talking about! May have to run up to, my in-laws in bristol. Although, it looks like I might get a little here if that verifies. It's hard to say at this point. Got an itch yet to do a call map Toot?

Jed33 wrote:Got an itch yet to do a call map Toot?

Ive got the itch..but think I will hold off til tomorrow evening

May God bless me here in South Knoxville with more than flurries this time. Amen!! lol

GFS ftw! It folds to the NAM, lol. Feeling a little better about it now

I'll hold onto my preliminary thoughts until we see the Euro jump onboard. Something to watch with the gfs coming to the nam camp, for sure, but we'll see.

Lol..Im just trying to imagine what it would be like inside the office at MRX right about now after seeing teh 0zGFS




I imagine it would look similar to this but what do I know..lol

Toot, how much for my backyard??? Hahaha... bet you don't miss those posts from me!

Lol, the 12z euro was like the NAM for the most part. It was drier, but had the same track. Not really much more to do but wait and see. If you want to pick a reason for lower accumulation, or for problems look at the amount of rain we are getting. The totally saturated ground could hinder accums. However, according to the data, some serious rates could come down. So, that may help some with the water, lol.

Jed33 wrote:Lol, the 12z euro was like the NAM for the most part. It was drier, but had the same track. Not really much more to do but wait and see. If you want to pick a reason for lower accumulation, or for problems look at the amount of rain we are getting. The totally saturated ground could hinder accums. However, according to the data, some serious rates could come down. So, that may help some with the water, lol.

Yeah! There we go! Too much saturation in the ground for snow to lay... forget that mixed precip tale...

Guys/Gals, we won't get any snow accums because of the over-saturation of the ground. NOTHING to see here...

Impressive run. Hope it verifies

Looking at the 00zNam a little more in depth over on twisterdata I differ a bit with Toot. Toot has valid points and he very well could be correct (nothing tougher to forecast than a ULL swinging through the south) but I'll give some of my reasoning for what I see.

This sounding is from near Athens, TN at hour 42. This is the 1st sounding that comes close to being a snow sounding. All the other soundings were rain (too warm). This sounding is at the time the main precip is moving out. As you can see (circled in red) the snow growth region does not look good and the surface layer is still marginal.



Usually in a ULL type situation the heavy snow band sets up to the west/northwest of the surface low. This is referred to as a trowal. It is clearly seen in the 700mb layer as well as the surface precip layer. Both circled in red. There would probably be heavier precip than what is being shown in this area. I think this is where some light snow accums could be seen. If you scroll through the hours you can see this feature stretch from central MS through northern Ga.

700mb at hour 42


Composite reflectivity at hour 42


I don't think this will be a dynamic enough system to sufficiently cool most locales that do not have a decent bit of elevation (in eastern TN). Areas closer to the Ga. border have a better chance at seeing some snow as they are closer to the ULL and the trowal setup.

:edit: I should add the disclaimer that this isn't my thoughts on this system in general but just my take on the 00z Nam model run and what would occur if it where to play out as modeled.

snowdog wrote: just my take on the 00z Nam model run and what would occur if it where to play out as modeled.

If it plays out as its modeled by the NAM.. east TN will get dumped on as shown by the NAM model..lol

I disagree about precip moving out at hr 42 and I also disagree with you on this relying on dynamic cooling for a changeover. This is not dependant on the cold core of the ULL as seen on guidance. The same airmass that is allowing frozen precip westward right now will be moving eastward as the trough axis slides eastward. Also.. if you move your mouse northward over at twisterdata the snow growth zone looks much better on their skew t.

WBIR up to 40% wintry mix for Thursday. And accuweather says afternoon snow now.

Toot wrote:This is not dependant on the cold core of the ULL as seen on guidance. The same airmass that is allowing frozen precip westward right now will be moving eastward as the trough axis slides eastward.

Here is the skew-t from Knoxville as the main precip starts to get cranking. There is a large column of warmth to overcome and it isn't overcome until just before the precip moves out. This is shown to be true on the Hi-Res NAM precip type on ewall.

I disagree about precip moving out at hr 42

In my last post you can see the composite reflectivity at hour 42. The main precip is leaving Knoxville.

It looks like Knoxville will be on western edge of things to start with. Anyways..here is hr 45 (Precip not moving out at 42) showing HEAVY precip over much of east TN.




Here is the sounding for around the Morristown/Greenville area


Snow all day long!

Toot wrote:Here is the sounding for around the Morristown Greenville area

Yeah, I alluded to those areas that have some elevation would do better.

In east TN Morristown and Greeneville are not really considered elevated. Im sure there will be spots that miss out but the NAM and now the GFS show a pretty good thumping over a good chunk of east TN. Its hard to deny that now.

Toot wrote:It looks like Knoxville will be on western edge of things to start with.

If Knoxville is on the western edge then this isn't an eastern TN snowfall but more of a mountain event because you can't go too much further east from Knoxville before you start getting into a good bit of elevation.

Toot wrote:In east TN Morristown and Greeneville are not really considered elevated. Im sure there will be spots that miss out but the NAM and now the GFS show a pretty good thumping over a good chunk of east TN. Its hard to deny that now.

Looking at the location of the skew-t you provided, they are elevated.

snowdog wrote:
If Knoxville is on the western edge then this isn't an eastern TN snowfall but more of a mountain event because you can't go too much further east from Knoxville before you start getting into a good bit of elevation.

Lol..there is alot of land in between Knoxville and the mountains..believe me ive lived here all my life!



Meanwhile guess who joined the party?

The 0z CMC

Canadian and Ukie look similar to the Nam/GFS track. Looks like the track is roughly nailed down.