TellicoWx

1 minute ago, Blue Ridge said:

On a somewhat lighthearted note, who would like to place a friendly (hypothetical) bet on what MRX does during the PM update? I see three possible scenarios:

1) Hold serve with watches, no new areas or upgrades. (IE, passing the buck to night shift.)
2) Overcorrect based upon 0z and 6z suites, cutting all but the mountains out of the WSW area and giving the valley a WWA.
3) Push the chips all in, with WSWs extending several counties west of the current watch area. 12-16” in the mountains, 6-12” in TRI, 3-6” toward TYS. John doesn’t receive so much as a WWA, all but guaranteeing warning criteria snowfall in his backyard.
 

1...except upgrade current watch w/o extending it lol

6 minutes ago, tnweathernut said:

It will likely just mean we can get NAM'd at longer leads. lol

The snow maps for the FV3 are pretty.  Would be nice if we all found out they were legit, but i'm not sure any met is buying into them.  Overall though, I will say the FV3 has been MUCH more steady and hasn't jumped around like the current GFS.  Baby steps..............

Think they just renamed the DGEX and hoped nobody would notice lol

Sometimes I ask myself why I even bother trying to figure the GFS out lol. Only model so far this cycle that just obliterates the 850s....just...just go away gfs.

* and how do you upgrade a turd...doesnt that make it a super turd

Comparing the NAM vs the HiRes 3k, you can see how the northern shield is off for you folks in NE TN. Both have close to the same PWAT, with UVVs running -10 to -30 (indicates heavier precip potential) up into SE KY counties along the border. Even tho they are very similar, the NAM has alot less precip and shield. Would think the HiRes shield and rates are closer to reality.

Starting at 54 on the NAM (850s go below 0 for a large part of E TN) and rolling forward in time, the system is backbuilding over the region. This can be seen at the 700 RH level, the UVVs should depict precip falling, but the NAM sim radar has little to nothing. The PWAT isn't great, but at the same time enough that something should be depicted. From 54 thru 66 the 700 RH and UVVs actually get better across the area as time goes.

12z NAM seems off on its northern precip starting around HR54.

1 minute ago, BlunderStorm said:

Well I've went from expecting 6-10 inches to nothing over the course of 6 hours. To tell you the truth I think this is all she wrote.  Not a lot to add atm that you guys haven't already said.

While the trends haven't been great, we are still outside the mesoscale models wimdow. With so many microclimates in East TN, won't completely write off this storm at least the next 24 hr model cycle.

The 850 vort has been shifting south, we lose the lift it provided across the northern area and allows the downsloping to really eat away at everything. The highs being a tad stronger allows even more drying as it reaches further south. Basically it loses its characteristics as a miller B or hybrid from what I can tell.

14 minutes ago, John1122 said:

Looks like the GFS is going to slip by and not even send rain north of 40. Hilarious that it shows a Gulf system that warm noses the 850s into Ohio and rockets temps to near 50 on Sunday now, not producing a bigger precipitation shield.  This thing throws up 3.5 inches of precip into Arkansas and it just dies out after. 

The next 2 runs of models will tell us if the GFS is leading the way or if it's completely insane.

What's shutting the pwats down on it?

00z NAM

12z EPS mean...lowered some, especially middle and west TN

4 minutes ago, John1122 said:

I don't really get one aspect of the forecast being discussed by the WPC for our region. Says all snow very likely in the mountains but freezing rain in the lower elevations. I'm confused by how that happens since freezing rain is a product of warmer air at higher elevations. Most commonly around 3000-5000 feet. I guess there's a very thin later of above freezing air in the atmosphere below 3000 but above the surface? 

All the column profiles I've looked at have a sleet look to them due to a slightly warm nose in the 850 lvl, not sure where they are seeing frz rain. Surface temps are above freezing too.

7 minutes ago, Stovepipe said:

Thanks to everyone that has been posting model run updates as well as great discussion!  I've been too busy lately to get in the trenches, y'all rock.

Can anyone share some of that sweet sweet Euro text data by chance?  Curious about temps at TYS.  It's at least looking like, if we don't get stickage here, I'll only have to drive a short ways towards TRI to play in the good stuff.

Don't have the text data, but on the maps at hr 78/84 when the accumulation happens 850T is +1/-2 and 925T is -1/-2, with a 2m of 34 at TYS.

1 minute ago, ShawnEastTN said:

I know its not a much used/referenced model especially at the end of its run but the RGEM has pretty good feature placement at the end of its run.  I love the RGEM in the short range, and while its not without its faults it has had some uncanny verifications at times in previous winters.

It can be very useful to check for trends in the s/w as it comes ashore

1 minute ago, Carvers Gap said:

GFS did to look overly bad.  Don't forget to add the UKMET and CMC to the Euro/FV3.  Though the storm totals vary...they are very similar runs right now.  

Wish had a lot better access to HiRes maps of the UKie. I plotted the vort for learning purposes, and you can see tell the GFS/NAM are a lot weaker and NW when the absorp into the coastal. Euro/FV3 still have it wrapped up as it's going thru GA.

2 minutes ago, John1122 said:

WPC noted the GFS stays open with the wave, the Euro closes it off at points. That effects the timing and turn of the system.

Someone posted in the MA forum that the s/w is stronger currently vs what was modeled a little bit ago.

Considering the NAM is still in voodoo land at that range, its hard to put it into a camp. 

Basically it looks like it's the NAM/GFS vs Euro/FV3 As far as how the 850 vort unfolds. NAM/GFS (west/less influence on coastal) Euro/FV3 (east/holds coastal and tries to turn it somewhat). CMC is kinda in the middle.

5 minutes ago, Blue Ridge said:

Looking at 850, the FV3 has it on top of HSV at hour 72. At 75, it appears to begin transferring. The kicker is that 850 winds are howling across NE TN from the SE or SSE from hrs 75-84. At 87, they have turned ESE. As Math/Met mentioned yesterday, we need a more easterly component to the winds to stave off as much downsloping as possible. 

Honestly I'm not quite buying what the FV3 spit out. You would think and approach into NW GA like that would shoot the 850s up the valley, plus the natural warming downsloping plays. If it approached from as sw to ne from central AL into NE GA, then yeah it would funnel the cold down the valley.

2 minutes ago, Carvers Gap said:

Probably is a combination of the two working in tandem...but that is about to get above my pay grade!  LOL

Yeah I agree lol...if there is no cold supply, doesn't matter where it pivots.

3 minutes ago, Carvers Gap said:

I think that is the conveyor deal that Jeff/MRX were talking about.  Basically, it catches the fetch off the Atlantic.  Not totally sure.  What do you think?  It comes out in such a weird fashion, I never know what to think?  

I think it revolves around where the 850 absorbs into the coastal, the further west it does like the NAM and GFS , it shuts the moisture feed down quicker and also has influence over pulling or slowing the coastal down. 

Just now, Blue Ridge said:

FV3 is behaving erratically again. Skipped hour 84. Hour 90: light to moderate snow from basically Lebanon eastward. Hour 96: Shield actually expands west. Snowing in Nashville.

College of Dupage site loaded alot better than TT

4 models/4 different outcomes regarding the 850 vort lol, but it paints a picture on each one how the loc greatly effects the snowfall and lift.

12z NAM- Central/ S TN pivot 

12z GFS- TN/Al/MS line

12z CMC- C AL 

12z FV3- NW GA

The closer (As long as it is south of TN line) the greater the lift and ability to pull the cold in at 925/850. FV3 is a paste job if it sticks (surface temps a little warm, but column is below freezing all way thru).

* this is for eastern TN, same would apply tho for west and middle TN. N and NW side of the pivot in regards to your location

Where the trailing 850 low goes, so does the waa and movement in snow ice. 12z NAM and GFS came in further north into TN compared to 06z. CMC pivoted to the coast further south over C AL. 

A couple things I noticed this morning from the 00z Euro, the 850 ul improved greatly as far as the track, but it came with a catch it seems. We lose the lift and downsloping is allowed to play a bigger role, also the lighter rates don't cool the 850s enough over the central and southern valley, As Carver has pointed out, 1-2 degree difference plays a tremendous role. Also the 850 and surface low are too strung out from each other, since the surface low heads straight ots instead of trying to cut. Valley areas need perfect placement of all the players to pan out (as is usual). Even if we end of with all rain, it is still fun to watch and learn from the evolution of this system.