December 8-10 Storm Discussion

[Holston_River_Rambler]

Also, around 34 EPS members show the shortwave that rushes in from the north and slows the system down as coming in a little faster than the operational depicts.  Given how changeable and fussy the norther stream has been for this whole system I'd say that is still on the table.  

[Holston_River_Rambler]

FV3 is just a touch NW with its 850 low at hour 84. Just enough so that the 850 low ends up dying in E. TN as it transfers to the coast.

A minor difference in trajectory will have big consequences for many of us on the southern edge. 

(EDIT: tried to make a gif showing this but the TT gif generator kept using the 18z and 0z, instead of the 0z an 6z FV3, so I'm giving up on the image, apologies if you saw that image)

[EastTNWeatherAdmirer]

0z Euro in line with yesterday’s 18z Fv3 GFS, central/upper Tennessee valley looking at potential for historic Winter Storm as Pinapple Express brings in Gulf low and upper high to the north allowing cold air placement along with freezing rain potential. Cold air will attempt to be dammed/ locked in on the upper mountains of TN/NC >3000 ft however below this altitude temps will try to warm up as low pressure favored in the areas of E TN foothills, However the upper valley itself will have a good shot at frozen precipitation as cold, High pressure air will attemp to stay sheltered in the valley as high pressure sinks. Some mixing/rain may initially occur but will change over to a possibility for heavy wet snow.

[Carvers Gap]

This will be a NE TN centric post, so please forgive me on this one...I don't feel any different this morning than the last four or five.  Storm is still headed this way w cold getting reading to battle it out with warm in the northern Valley.  The 0z Euro was strongly in our camp as was the CMC.  The 6z GFS trended back this direction.  The GEFS ensembles still look good as does the EPS for this area.   The 6z FV3 is north which is interesting as the Euro trended a bit south with its snow axis.  Per another poster, I think we do need to keep an eye on getting dry-slotted.  So many things to have to watch for at this latitude and geographical location - warm nose, dry slot, trends/north south, cold available, etc.  Plenty can go wrong, but sometimes things go right.  This is an area that can always leave you with egg on your face.  That is why I think the MRX morning disco final paragraph is a good one....pretty bold but honest.  Not much to add at this point.  I will check in later.

In the end confidence is high that a major winter storm will affect the area starting Saturday night into the start of the new work week.  Like- wise, confidence is highest for heavy snowfall across southwest VA, extreme northeast TN, and the mountains, all where the longest overlap of  favorable thermal profiles and moisture occurs.Moving southward into the valley there will likely be a sharp gradient of moderate/heavy snowfall accumulations from the Tri-Cities area toward Morristown. Further south than that, confidence is rather low in even moderate snowfall,thus only light accumulations are expected at this time.

[tnweathernut]

28 minutes ago, EastTNWeatherAdmirer said:

0z Euro in line with yesterday’s 18z Fv3 GFS, central/upper Tennessee valley looking at potential for historic Winter Storm as Pinapple Express brings in Gulf low and upper high to the north allowing cold air placement along with freezing rain potential. Cold air will attempt to be dammed/ locked in on the upper mountains of TN/NC >3000 ft however below this altitude temps will try to warm up as low pressure favored in the areas of E TN foothills, However the upper valley itself will have a good shot at frozen precipitation as cold, High pressure air will attemp to stay sheltered in the valley as high pressure sinks. Some mixing/rain may initially occur but will change over to a possibility for heavy wet snow.

Welcome to the board and nice first post!  Nice to see Morristown represented.  Fingers crossed modeling consolidates some throughout the day, and gives us a better idea for the eventual evolution of this system and the thermal profile associated with it.

[AMZ8990]

850 temps are looking better this morning via the euro for my area.  we hover around 32 all day Saturday before going below 32 around midnight Sunday morning.  Then we’re under 32 through Monday afternoon.  Looks like the back end of this storm could be interesting too,  Monday is showing promise for a lot of us which would be awesome if that panned out.  Winter storm watches also have filtered into central and northern Arkansas this morning!!

[Knoxtron]

WXsouths paid blog is a little more bullish for the knoxville area north in this mornings update.. last night not so much. 

 

We shall see... in other news. The SREF plumes are getting fun looking at snow totals for TYS (I know I know.. just for fun lol). I'll post an update for a couple cities later in the afternoon if someone else doesnt

[kvskelton]

23 minutes ago, Carvers Gap said:

So many things to have to watch for at this latitude and geographical location - warm nose, dry slot, trends/north south, cold available, etc.  

I've been following NE TN weather for so long I thought what Carvers posted above was a legitimate wintertime forecast!  

Thanks to all for the great discussion in this thread! I hope many of our forum members can score on this one. It's always a crapshoot in my area at this time of year. As often stated by another member (can't remember for sure but I think also Carvers), when you have lots of options, bet the climo. Good luck to all in the Valley and welcome to all the new posters who've arrived during this thread. Nice to see y'all! 

[Holston_River_Rambler]

Michael Ventrice's IBM Deep Thunder model FWIW. I have no clue how accurate it is or where to find it, other than occasional posts on boards and social media. Looks like at the very least more agreement for NE TN.

[1234snow]

After looking at the reduction of QPF on the 6z GFS and FV3 I’m getting a little concerned about the normal dry slotting issues in the valley. I’m always skeptical about how the line of convection around the Gulf can rob moisture transport up in the Valley. Just something to consider looking at future runs.

[TellicoWx]

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.

[Holston_River_Rambler]

In terms of using the NAM for temps as it rolls in throughout the day, it undersold the cold this AM from 30 hours out:

 

 

 

[AMZ8990]

59 minutes ago, *Flash* said:

Being a west TN rep, thanks for continuing to post. I’ll be honest...tracking this one has deflated me the last few days. Only have energy to read what has been a solid, applaudable + educational thread. May chase to Johnson City over the weekend. If anyone has recommendations on a quality waffle/pancake place, let me know. 

I am right there with you man, it has exhausted me as well.  It stinks to always be on the cutoff line.  Maybe the good lord can bless us with a nice surprise!!  I know you’d like to show your 1 year old a good snow so I’m rooting for you.  JC sounds like a good place to go for this one.  Folks who booked trips to the mountains this weekend are gonna be in for a nice surprise it seems, wish I could be up in that location for this one.  Fingers crossed we get some good model trends today,  the euro still has a lot of I-40 specials in its 50 members, maybe we can squeeze one out of there!!  Always enjoy you input too man, hope you and the family are doing well.

[PowellVolz]

Man I’m really close to a good snow


.

[Knoxtron]

SREF 9UTC Plumes

TYS

CHA

TRI

[Carvers Gap]

The 12z NAM is rolling and about into territory where we don't trust it much.  However, of note it has sped up over several runs.  

[BlunderStorm]

2 minutes ago, Carvers Gap said:

The 12z NAM is rolling and about into territory where we don't trust it much.  However, of note it has sped up over several runs.  

I bet if it involves slashing totals north of the Tri-Cities it'll be legit! 

[Carvers Gap]

18 minutes ago, BlunderStorm said:

I bet if it involves slashing totals north of the Tri-Cities it'll be legit! 

No doubt about that.  LOL.  I think we want it to speed up just a bit.  For better or worse, I generally look at the track and shape of the storm and let snowfall totals work themselves out.   

As for the run itself, I caution that the NAM past 48 is sketchy, sketchy territory.  Extrapolating the NAM is at everyone's own risk at that range.  It does do the splits over E TN w moisture.  Definitely a possibility with that.  However, that storm is not even close to being over at that point.  What we need is for the conveyor to kick in...no idea if that happens.  But in terms of overall look, it has a nice comma shape which is what we want.  Northwest TN gets in on the action w this run w a deformation band.  Again, the NAM will play catch-up outside of 48...you can see it by toggling the runs.

Just got back from running so have not had time to post with very much detail, the 6z GEFS still looks very consistent with its previous snow totals BTW.  13/20 members have strong totals(6"+) over the TRI along w a sharp cutoff to the southwest.  Every member has snow accumulation of 2+"(prob higher than that).

So far, this storm is what we think it was...a strong system that will have a sharp cutoff just southwest of TRI to quote MRX.

[Carvers Gap]

31 minutes ago, *Flash* said:

SREF is friendly to BNA. Why...I have no idea. 

It is interesting.  I think the KY/TN an VA/TN border is a transition zone as it often is.  Looks like you all get a front end thump(edit: LOL) and then maybe the ULL or conveyor helps you out(guessing).  

[AMZ8990]

36 minutes ago, *Flash* said:

SREF is friendly to BNA. Why...I have no idea. 

Nice!!

[ShawnEastTN]

Winter Storm Watches are now up from New Mexico to Arkansas.

Sent from my SM-G965U using Tapatalk

[Wurbus]

Looks like the 12z FV3 lays down some big fatties at 72 for the valley.

[PowellVolz]

Looks like the 12z FV3 lays down some big fatties at 72 for the valley.

Holy smokes


.

[Carvers Gap]

***Updated as of 12:45...will update once Euro rolls in a minute.***

Gonna go NE TN / SW VA-centric for the folks up here.  Scoreboard.

12z NAM: Nice run...Looks like it is overdoing the downslope.  I don't want to disregard it completely, because it has happened...not to that extreme though.  But the NAM at range?  Grain of salt whether good or bad after hour 48.

12z ICON:  Been a strike from day one and nothing has changed.

12z GFS:  Strike for NE TN...SW VA hammered.  Again, really looks like it is overdoing the downslope.  Again, likely to happen, but to that extreme?

12z CMC:  Boom. Nice run.

12z FV3:  Nice run for this area and in other parts of the forum area - stuck and still snowing.  Again, the American suite is hammering that downslope.  Maybe they have better resolution?  5-10" over NE TN and portions of SW VA w lollipop amounts much higher there.  Link below.  

12z GEFS:  Backed off a bit on totals all over the map..but still a solid 6-10" mean over both areas.  6" TRI and 10+" for SW VA.  6-10" for southern West Virginia.  

12z UKMET:  Sharp cutoff to the west of TRI...but generally 5-7" over the area.  Overall, the track is a beauty.  Link below.

12z Euro:  Holds serve w the 0z run w more snow over SE KY.  1' for most of NE TN.

And trust me, I am not hanging my hat on the Canadian model!  Glad to see the FV3 w a nice set-up.

Link for 12z UKMET accumulations:

Link for 12z non-inflated FV3 accumulations

 

[Wurbus]

Would the temperature profile over Wisconsin & Minnesota affect the temps a few frames later for us? The NAM has temps in that area in the mid to upper teens, while the FV3 and other models have the air temperature in the single digits. I'm suspecting that is why the NAM is warmer.

NAM at 48

FV3 at 48

[TellicoWx]

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

[Blue Ridge]

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.

[TellicoWx]

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

[Carvers Gap]

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.

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?  

[Carvers Gap]

7 minutes ago, Wurbus said:

Would the temperature profile over Wisconsin & Minnesota affect the temps a few frames later for us? The NAM has temps in that area in the mid to upper teens, while the FV3 and other models have the air temperature in the single digits. I'm suspecting that is why the NAM is warmer.

NAM at 48

FV3 at 48

It might signal a stronger high pressure over top and also give the parent high more cold to feed into the storm.  And always know...everything that I write probably should begin with IMHO.  LOL.