December 2018 Pattern And Forecast Discussion

[Chattownsnow]

looking at the GEFS I see the HP trend is stronger than 12z. I can't post images as it is a no-no. LP in the gulf is basically the same as the 12z GEFS. However snow output decreased likely due to other influences and minor differences. As always, tiny changes make a world of difference. 

[Holston_River_Rambler]

1 minute ago, Chattownsnow said:

I can't post images as it is a no-no.

Why's it a no-no? 150 hour or so ensembles seems pretty reasonable to me. 

[Chattownsnow]

1 minute ago, Holston_River_Rambler said:

Why's it a no-no? 150 hour or so ensembles seems pretty reasonable to me. 

What I have is from weatherbell and I didn't think I could post from there. It's paid site, though I know that info can be gathered elsewhere from the GFS

[Holston_River_Rambler]

Ahh, understood. 

[Chattownsnow]

Just now, Holston_River_Rambler said:

Ahh, understood. 

Yeah the maps are a lot clearer and easy to see trends for me anyways. 

[jaxjagman]

We have to many winter threads going,can we lock one up ? or not post on it no more,confusing where to post things at

[TellicoWx]

The 850 vort came north into the TN valley vs N AL/N GA on the 18z vs 12z, leading to stronger waa and more ice vs snow before the changeover to rain. The surface low can take the same path, but with a weaker high allowing the 850 north most here would end up with a cold rain. GEFS mean lowered some due to a couple more members with that evolution.

[BlunderStorm]

49 minutes ago, jaxjagman said:

We have to many winter threads going,can we lock one up ? or not post on it no more,confusing where to post things at

Yeah, either we keep the old one up and run it til winter ends or we use the monthly one and create a new one each month. Personally I like sticking to one thread all winter but we have been focused on the December Thread so I don't know.

[jaxjagman]

1 hour ago, BlunderStorm said:

Yeah, either we keep the old one up and run it til winter ends or we use the monthly one and create a new one each month. Personally I like sticking to one thread all winter but we have been focused on the December Thread so I don't know.

And this is what i'm talking about.I got bashed for starting a slight severe risk thread,but yet when there is a dusting of snow risk we start a thread here sort of speaking no one has a problem with this.I admit i like severe as much as snow but lets not do double standards here,it's what it seems to me.Any snow or severe risk should deserve a thread,if it happens or not

[John1122]

This thread is for December discussion, the other is for the general winter pattern as a whole or so it appears to me. I could have sworn I put the November to January temp comparison in the other thread but I believe it was moved to this one, if not, I meant it for that thread. Personally I'd have named this December Pattern Thread or something, but I don't have an issue with it named as it. Clearly it denotes December.

Also, I don't recall anyone starting a thread for a dusting of snow being predicted nor anyone being bashed for starting any other thread, but I could have missed it.

That said, back on topic for the December pattern. I'll take the storm track the GFS is showing and roll with it. Pretty strong high in the midwest and a stormtrack along the Gulf is almost as good as we can hope for this far out.  There's going to be daily wobbles and as always, 50 miles will make the difference for a lot of people on heavy rain vs heavy snow.  If you blend the 0z GFS and the  12z Euro the track is probably for an I-40 special across the state.

[jaxjagman]

11 minutes ago, John1122 said:

This thread is for December discussion, the other is for the general winter pattern as a whole or so it appears to me. I could have sworn I put the November to January temp comparison in the other thread but I believe it was moved to this one, if not, I meant it for that thread. Personally I'd have named this December Pattern Thread or something, but I don't have an issue with it named as it. Clearly it denotes December.

Also, I don't recall anyone starting a thread for a dusting of snow being predicted nor anyone being bashed for starting any other thread, but I could have missed it.

That said, back on topic for the December pattern. I'll take the storm track the GFS is showing and roll with it. Pretty strong high in the midwest and a stormtrack along the Gulf is almost as good as we can hope for this far out.  There's going to be daily wobbles and as always, 50 miles will make the difference for a lot of people on heavy rain vs heavy snow.  If you blend the 0z GFS and the  12z Euro the track is probably for an I-40 special across the state.

Yes there has been on this board with your second paragraph

[mississaugasnow]

How does Nashville handle snow? Coming down this Thursday-Sunday for the Thursday night football game followed by spending the weekend seeing the city. Sorry to go off topic. It would be pretty funny if I came down from the Toronto area and while here see my biggest snowstorm of the year. Biggest storm for Toronto this year has been 4"  

[jaxjagman]

17 minutes ago, mississaugasnow said:

How does Nashville handle snow? Coming down this Thursday-Sunday for the Thursday night football game followed by spending the weekend seeing the city. Sorry to go off topic. It would be pretty funny if I came down from the Toronto area and while here see my biggest snowstorm of the year. Biggest storm for Toronto this year has been 4"  

Maybe a weak system Thursday it looks dry right now but temps look cool to me maybe lower 40's,game time.No clue

 about the weekend right now

[BlunderStorm]

Tonight's Euro isn't much in west Tennessee but increasingly gets better the further east you go especially north of I-40 until eventually you get up into my neck of the woods. In total it showed 21-24 inches after 33 hours of consistent moderate snowfall with no hat tricks at any point before during or after. I can dream.

[TellicoWx]

10 minutes ago, BlunderStorm said:

Tonight's Euro isn't much in west Tennessee but increasingly gets better the further east you go especially north of I-40 until eventually you get up into my neck of the woods. In total it showed 21-24 inches after 33 hours of consistent moderate snowfall with no hat tricks at any point before during or after. I can dream.

Yeah, you guys get clowned on that run. Euro and Ukie, FV3 to an extent trying to phase the Northern stream in now...should be an interesting week of runs.

[tnweathernut]

The 6z GFS FV3 says “good morning”.  Classic track for a heavy TN Valley snowstorm.

 

[Carvers Gap]

The 12z Euro and 6z FV3 looked pretty good for I-40 north....probably better than good.  Still, this thing is going to wobble around all over the place at this range.  Somewhat amazed that it has held similar a solution for some time.  The EPS is north and a bit lighter.  The CMC is north of the FV3 and Euro.  Plenty of options still on the table.  The 6z GEFS mean looks decent for most of the state, Arkansa, western portions of NC, southwest VA, and KY.  Don't have much time for analysis this AM.

[AMZ8990]

38 minutes ago, tnweathernut said:

The 6z GFS FV3 says “good morning”.  Classic track for a heavy TN Valley snowstorm.

 

Saw that too, I’m drooling on my way into work this morning!! Haha

[Coach B]

6 hours ago, mississaugasnow said:

How does Nashville handle snow? Coming down this Thursday-Sunday for the Thursday night football game followed by spending the weekend seeing the city. Sorry to go off topic. It would be pretty funny if I came down from the Toronto area and while here see my biggest snowstorm of the year. Biggest storm for Toronto this year has been 4"  

Nashville handles snow pretty well if you are patient. Tennessee actually uses plows and pretreats roadways with brine and salt. In my experience it's much better than the states to our south which apparently budget next to nothing for snow removal. That said, it won't be anything like removal in Toronto. We really only work the major roads and interstates.

Nashville is far enough north to get some snow every year, but they'll get pretty wound up for the first one. If we are lucky enough to have a winter with multiple significant winter events they'll be complaining about it just like the Yanks.

[AMZ8990]

7 hours ago, jaxjagman said:

And this is what i'm talking about.I got bashed for starting a slight severe risk thread,but yet when there is a dusting of snow risk we start a thread here sort of speaking no one has a problem with this.I admit i like severe as much as snow but lets not do double standards here,it's what it seems to me.Any snow or severe risk should deserve a thread,if it happens or not

Yeah we only made the December thread so we could have individual conversations about what’s going on in December only.  The regular winter spec is more for he entire winter outlook, climo outlook for Jan and February versus just December.  We had so much to talk about long term temps changing cold vs early December cold snap that we decided to divide the two to help not getting anyone confused.  I can change the name of this thread if that would help some.  And Jax, I don’t know who gave you a hard time about the severe thread but I don’t feel that way at all.  The severe thread is vital to our discussions and it is also of great help in alerting people to possible severe outbreaks.  You do a great job with that and I don’t want to see those severe threads go anywhere.  

[Coach B]

That FV3 is about the only thing that really likes south of 40 in TN. I won't totally give up hope as long as that low tracks down towards the Gulf coast.

[tnweathernut]

Yep, it’s probably going to be a long week of tracking.  I feel like we have been following this period forever already and we still have 144+ hours to go.  lol

The Euro and FV3 have been performing admirably at the 120 hour range, so I take comfort in the setup shown at 120 (i.e. low pressure in SE TX and sprawling HP over the top).  Really, almost all modeling has this same basic setup with minor variations of the HP over the top.

The biggest unknown I can see ....deals with the HP to the north and how it builds in over the top of the southern slider.  Key will be the confluence to our northeast.  If that lifts out quicker and/or the timing of the southern wave slows down even more, we likely see a further north low and more northerly track.  I have seen many cases where strong HP over the top is pushed aside when there is nothing to hold it in place!  Unfortunately at our latitude it wouldn’t take much to dash the hopes and dreams of those wanting snow. If the confluence holds, the HP likely holds and then we would be in business SOMEWHERE (maybe widespread) in our forum.

i think yesterday’s solutions were about as suppressed as you will see and not very likely.  Another big unknown seems to be dealing with possible northern energy diving in to the southern branch.  That can be notoriously hard for models to pinpoint so if that is real, expect more changes in the next 2-3 days.

Lastly I’d say let’s get this Pacific feature on land to see how modeling changes (as modeling will be able to run with a fully sampled feature).  I don’t think this feature is in a data sparse area, but having it on land and being fully sampled won’t be a bad thing.  

Happy tracking.  We should probably fire up a storm specific thread if modeling holds today at 12z in showing a potential early season winter storm.  

However we handle the other two non-specific winter threads is fine with me.

[Carvers Gap]

Outstanding discussion this morning.  I noticed some discussion about the thread name overnight, so I placed a comment in banter about how things transpired in terms of thread naming.  I did tag a mod so they can get things sorted out.  Other than that, I really have nothing more to add on the subject.  We have a potential storm to discuss, so let's enjoy the moment.

[Holston_River_Rambler]

500mb analogues for GFS at hour 120 from CIPS:

 

[John1122]

The FV3 track and positioning of upper features is textbook for us and you can look back at some big past storms and see virtually that exact set up. HP in the area of SE Minnesota to Chicago and another near Pennsylvania will often show up in our major snow events.  

The last few years we've seen this level of model consistency for days on end, only to have it go awry in the last 2 days.  Oddly we see these set ups verify from way out for storms for almost every other area of the country.  Even last year's very odd deep south snows held steady and worked out. 

For me, I may get truly excited if this looks good on Friday. 

[Bango]

19 minutes ago, John1122 said:

The FV3 track and positioning of upper features is textbook for us and you can look back at some big past storms and see virtually that exact set up. HP in the area of SE Minnesota to Chicago and another near Pennsylvania will often show up in our major snow events.  

The last few years we've seen this level of model consistency for days on end, only to have it go awry in the last 2 days.  Oddly we see these set ups verify from way out for storms for almost every other area of the country.  Even last year's very odd deep south snows held steady and worked out. 

For me, I may get truly excited if this looks good on Friday. 

I feel you, in addition it seems like more often its the qpf totals that start getting dramatically slashed in halves 24-48 hours prior to well modeled events....that is usually the Charlie Brown I look for as we gett closer

[nrgjeff]

Looking for a couple things this morning, still 6 days out. Need vort max to track south of here. Need high press (HP) north anchored and still spilling in somewhat. I am less worried about the surface low which looks good. 

First the 500 mb vort max should track to our south for snow. Right overhead is not good enough, especially this case. If HP is very strong, anchoring cold, and the vort max goes overhead, WAA may cause ice. That's like in Ferris Bueller where faking a fever lands you in the doctor's office. Wrong outcome, lol!

Next HP has to be firmly anchored in the right place, and even still building in. Agree 100% with John's snapshot above. Also I'm looking for HP/cold to keep spilling in from the Plains and Midwest. Down the East Coast won't work here, though the Carolinas love it. You can almost feel the right pattern on the good model runs; isobars and thickness lines are packed tight - all wound up and energetic. Reverse is true on bad model runs with HP already starting to retreat with loose isobars/thickness lines. HP must anchor very firmly, especially this case. Midwest / OV air is not particularly cold or dry, so evaporative cooling will only be a slight help. Again HP/cold still spilling in (not retreating) would make it all work out.

I mention the surface low pressure (LP) looks good. LP has been shown well south consistently across model runs (NWP). I would call it safely south, from a pro-snow perspective.

In conclusion, the concern is the temperature profile. Gee, what's new down South? 500 mb vort max should be south to take care of the mid-levels. HP should firmly hold, and continue to supply low level cold. Both will depend on confluence (of the jet branches) location and timing, per previous page. Quick check: 500 mb vort max and surface HP look & feel.

Finally, I think somebody in the sub-forum Region will get it. Odds are best I-40 north IMO. Perhaps even Kentucky, but NWP verbatim is I-40. Most of my pessimism / nit-picking is to get it into MSL-HSV-CHA, always a huge chore.

[TellicoWx]

Just got home from work and looking at the 00z Euro Ens members. Definitely not good south of 40. Here's the numbers compared to 12z: Loc/ % +/- of 3"/ % +/- 1"+

CHAT: 22% (-30%), 32% (-38%)

TYS: 22% (-22%), 48% (-8%)

TRI: 44% (-14%), 82% (+4%)

PLAT: 46% (-16%), 74% (0)

MTN: 72% (0), 94% (+4%)

[John1122]

The flow snow isn't looking too bad on the RGEM over the next 42 hours for the Mountains/Plateau and parts of Kentucky. There's a pretty favorable angle showing up and a decent connection to Lake Michigan.  

[John1122]

The 3k NAM also shows some potential if you happen to get under a snow streak with some 1 inch+ bands showing up in Middle Tennessee.