December 2017 Temps, Chaos, Winter Mix, Snow, Christmas

[nrgjeff]

Advertised cold weather pattern should commence around December 6 and work in here well by Dec 7-8. I would like to limit precipitation charts to within 5 days. The exception is NWFS for the Mountains and Plateau, which is more skillful because it does not require an exact storm track. Discussion of favorable pattern (odds) is OK and even encouraged past Day 5, just no charts please.

The good news is SER intrusions have departed recent model runs. Oh there is always a trade-off in the South. Northwest flow in the Plains gets as close as the Mississippi Valley at times, which opens the door for mild interludes within the cold pattern. Even with some variability the cold 6-15 day period carries high confidence. I put it near 85% in the 6-10 day; better than 50% in the 11-15 day. Still a slight risk that Day 10 mild interlude is the end, but I think cold reloads for the 11-15 day.

Near textbook upper level pattern really lacks surface source region support though. Alaska and most of Canada cold is not strong. Manitoba and Ontario will get cold but it barely gets colder points north. Quebec looks strong but it's not our trajectory. Sustained cross polar flow from Siberia is required for impressive cold this time. A few days would not be enough since temps are AN in Alaska. Northern US snowpack deficit is a gaping hole in the equation for record or even just strong cold.

So I think the 6-15 day will be cold enough to put one in the Holiday mood, but not particularly impressive. First front (6-10 day) may under-achieve as usual coming into a warm regime. Second front (11-15 day) should verify so long as it actually gets in here (>50% chance). If the upper level pattern holds through weeks 3-4, we might be able to talk about stronger cold anomalies. Right now looks like some lows in the 20s first half of Dec. If looking for teens or colder, more time in the cold pattern is required. 

A minority of ensemble members show a decent pattern for winter precipitation in the 11-15 day. Others are cold but dry. A smaller minority is too warm. I am looking for an active southern branch through the Deep South, not NW flow and zero SER attempts.

[jaxjagman]

SOI took a big spike between the 26-28 then a nice drop off the 29th.I think looking at Asia in the long range we COULD see a strong cold front/system mid month,the 11-15 period  give or take you mentioned above.

 

 

[nrgjeff]

Mid-December reload indeed looks good as we walk in Monday morning. Right now the new 11-15 day period looks pretty cold.

Everything else is progressing forward nicely into the 1-5 day and 6-10 day. So, we have the first wave later this week. Then, it should relax for 1-2 days early next week. Late next week appears another bout of cold comes through.

Over the weekend models toyed with anything from mild air creeping in from the Mid-South on northwest flow, to a weak SER which is evil Sith garbage. Northwest flow variability is easier to handle, esp if willing to take it to the ski areas. Any hint of even a short-wave SER ahead of a low is total disaster everywhere.

In the 5-6 day I'm even getting interested in some Plateau and Mountains snow Friday night or Saturday. Diurnal timing will be in play. Jury is out at lower elevations with lots of PVA north. Need it all or mostly south.

[John1122]

There was a model shift again today but sadly to a much weaker and more sheared out clipper at the end of the week. I'm just hoping to get flakes in the air at this point. I think that will happen in the next 5 days. Right now Tuesday night into Early Wednesday might see some flakes. I think we at least get snow showers in the area Friday-Saturday.

[John1122]

The clipper bounced back on the 00z GFS, not quite what it was a few days ago, but widespread 1-2 inch totals for the eastern 2/3rds of the valley. Unfortunately it went from arriving Friday night to arriving Saturday afternoon when we will be at peak warming. Which will definitely effect totals and even though the GFS is all snow and way south with the snow, I wouldn't be surprised to see p-type be an issue for some areas.

 

[tnweathernut]

Good post, John.  I share the same concerns.  I was a bit interested when timing showed an arrival overnight Friday into early Saturday morning, but an afternoon arrival and a weak vort pass north of our area are likely big obstacles.  Still will be nice if we can score some snow falling from the sky before December 10th, even if mixed with rain!  That, and the biting cold should be enough to put people in the Christmas mood........

[ShawnEastTN]

I think even with the potential afternoon arrival of the first vigorous clipper, that even if the surface is high 30s maybe even up to 40, will still see flakes as the dominant p-type if not the only p-type.  Just so amazingly cold for this time of the year for pretty much the entire column, minus the surface if during the afternoon. 

[nrgjeff]

Plateau should get flakes. Mountains definitely will. Boundary layer may get above freezing just ahead of precip. However evaprative cooling should get the air below freezing before anything even hits the ground. At lower elevations I would shave the chart 1/2 to 2/3. Also make sure CHA = zero. (Edit to line up with Jax below: Also go zero I-65 west.) Seriously, that PVA north...

First cold wave temps are behaving well on the models. Despite lots of bitter cold chatter, we all knew the source region was meh. Now round two is due in here next week. By then some snow should be spread across the fruited plain to our north, at least sections of it. Source region temps are still a joke, but air would modify less over partial snow cover So, as usual, I look for colder temps with the second shot. Hopefully it will include PVA to our south. Gnashing of teeth over the milder 11-15 day is not necessary. The two cold shots are progressing into the 1-10 day.

Attm the 16-20 day looks milder; that is the week leading up to Christmas. With variable northwest flow remaining in place, one could imagine the next cold front Christmas week. The 16-30 day period ebbs and flows have sped up this morning, not a surprise in northwest flow. Both Euro and CFS weeklies also hint at the milder followed by colder again around Christmas. All-in-all this December is a vast improvement over the last two.

[jaxjagman]

Never get excited  for weak clippers around here.Just like every year they look great 7 days out then when it gets closer it equates to nothing,just like this one seems to be doing.Least it's not 70 degrees though..lol

[ShawnEastTN]

18Z GFS seems to be pretty progressive to lift trough out at the end of the weekend...  Maybe rebuilding, still waiting on GFS, also further minimizing the weekend clipper for the forum, keeping it more north.

[John1122]

00z says hold the flakes south of the Ohio river as well. Clipper very east and north. Figures. Looks like the GFS is as bad as ever at medium range.

[Chattownsnow]

Well shoot this looks pretty good to me!

[Chattownsnow]

[tnweathernut]

Wonder if the UK is over amped, or if it's sniffing something out?  Seems most modeling wanted to creep west at 12z vs their prior runs. 

I do know the UK can be over amped at times, but I also know within 48-72 hours I have seen the precip field more expansive on the northwest side of a Miller A many many times.  I think that leaves the NC mountains and north GA in a good spot, maybe even areas further east.  Whether some in east TN can also score remains to be seen, but I think the chances went up with today's 12z runs.  That alone leaves us at least in the ball game.

Good luck to our brothers and sisters down south of us.  I hope you guys get some white stuff from this early season Miller A.  As an aside, I think seeing something like this bodes well for the rest of the year and perhaps we see several more gulf systems later this winter.

[John1122]

Looking eerily like a repeat of last winter with systems east of me, south of me and north of me after having looked pretty good a few days out. I could see this system laying down 1-3 in counties that border North Carolina with increasing totals as you go up in elevation and east. Sort of a slightly further south/east version of the one miller A from last year that gave 4-5 inches along the border areas and 1-3 elsewhere in the region. With the way it's evolving, I could see flakes being in the air from maybe Knoxville and East.

[weathertree4u]

51 minutes ago, John1122 said:

Looking eerily like a repeat of last winter with systems east of me, south of me and north of me after having looked pretty good a few days out. I could see this system laying down 1-3 in counties that border North Carolina with increasing totals as you go up in elevation and east. Sort of a slightly further south/east version of the one miller A from last year that gave 4-5 inches along the border areas and 1-3 elsewhere in the region. With the way it's evolving, I could see flakes being in the air from maybe Knoxville and East.

I think it is time to be thankful for the cold that we have honestly! While I would rather see snow in my neck of the woods as well, I realize it is only December and we have allot of Winter yet to go!

[weathertree4u]

51 minutes ago, John1122 said:

Looking eerily like a repeat of last winter with systems east of me, south of me and north of me after having looked pretty good a few days out. I could see this system laying down 1-3 in counties that border North Carolina with increasing totals as you go up in elevation and east. Sort of a slightly further south/east version of the one miller A from last year that gave 4-5 inches along the border areas and 1-3 elsewhere in the region. With the way it's evolving, I could see flakes being in the air from maybe Knoxville and East.

I think it is time to be thankful for the cold that we have honestly! While I would rather see snow in my neck of the woods as well, I realize it is only December and we have allot of Winter yet to go!

[ShawnEastTN]

15 minutes ago, weathertree4u said:

I think it is time to be thankful for the cold that we have honestly! While I would rather see snow in my neck of the woods as well, I realize it is only December and we have allot of Winter yet to go!

True!  I generally never expect to see much of anything in December above a flurry.  Maybe we will see a bit more shift NW over the next 24 to 36 hours, we've seen it before in those last hours many times.  Granted would not expect enough NW trending to make a huge difference to most of the forum.

[ShawnEastTN]

1 hour ago, John1122 said:

Looking eerily like a repeat of last winter with systems east of me, south of me and north of me after having looked pretty good a few days out. I could see this system laying down 1-3 in counties that border North Carolina with increasing totals as you go up in elevation and east. Sort of a slightly further south/east version of the one miller A from last year that gave 4-5 inches along the border areas and 1-3 elsewhere in the region. With the way it's evolving, I could see flakes being in the air from maybe Knoxville and East.

You might do good up in Campbell County with that clipper after all according to the 18Z NAM, I would take what is shows for you at my house if I could.  Nice trajectory to tie you into a little Lake Michigan moisture for a bit with some lift from the S/W, could get nice little upslope snow going.

[BlunderStorm]

Well, it seems our clipper is almost a no show on the NAM as of the next run it is still a little far out though. It looks as though will be entering a prolonged period of dry cold which has been indicated for quite a while. For those in the mountains and plateau it seems as though we will receive some glancing blows from clippers with NW flow snow over the next two weeks with flurries elsewhere. Little activity is showing up below our forum region after the weekend system passes through. I have noticed the GFS indicating some activity near the end of next week but nothing seems consistent. For the time being I will enjoy our chilly weather with or without snow as Christmas nears.

[nrgjeff]

Warmer 11-15 day period should not cause panic. It should verify but it will not last. Even if we miss snow in the 1-10 day, snow from Texas (Hillcountry/Pecos) to the Deep South is a win for the weather pattern. It's encouraging at the very least.

I am leaning colder again for the end of December, perhaps as early as Christmas. Ensembles keep some blocking and try to introduce new cold into the Midwest day 14-15. CFS is still mild here 16-20 day, but punts the Western Canada Chinook blowtorch on lower 500 mb heights. Barring a SER disaster, it's good to see actual North American cold building.

[Chattownsnow]

30 minutes ago, nrgjeff said:

Warmer 11-15 day period should not cause panic. It should verify but it will not last. Even if we miss snow in the 1-10 day, snow from Texas (Hillcountry/Pecos) to the Deep South is a win for the weather pattern. It's encouraging at the very least.

I am leaning colder again for the end of December, perhaps as early as Christmas. Ensembles keep some blocking and try to introduce new cold into the Midwest day 14-15. CFS is still mild here 16-20 day, but punts the Western Canada Chinook blowtorch on lower 500 mb heights. Barring a SER disaster, it's good to see actual North American cold building.

Thanks Jeff. Your knowledge and unbiased approach are what make you my favorite MET on this, or any other board. When you speak, I listen. Some in the Southeast forum wish you would post more over there lol. The weenies I don't think would like what you have to say all the time however. 

[EastKnox]

Just now, Chattownsnow said:

Thanks Jeff. Your knowledge and unbiased approach are what make you my favorite MET on this, or any other board. When you speak, I listen. Some in the Southeast forum wish you would post more over there lol. The weenies I don't think would like what you have to say all the time however. 

Let me echo this.  As soon as I see a post from you or Carver's Gap, I get a little giddy inside.  I can't wait to see what kind of knowledge I'll take in.  I only hope that I can return it with intelligent posting this winter.

[EastKnox]

18z NAM pushing precip closer to us for this weekend - every run seems to have a NW tick.

[Chattownsnow]

5 minutes ago, EastKnox said:

18z NAM pushing precip closer to us for this weekend - every run seems to have a NW tick.

if that run was truth, I could see it snowing through some binoculars from my porch. Very close to me north of Chattanooga. 

[ShawnEastTN]

14 minutes ago, EastKnox said:

18z NAM pushing precip closer to us for this weekend - every run seems to have a NW tick.

Sure does!  Though, the fear would be is it being NAM-tastic in over doing it with moisture, and how much would be virga (concerning forum area).

[John1122]

The NAM is an unprecedented snow event for most of the deep South. I've never seen the entire Texas gulf coast, Louisiana coast and into the panhandle getting accumulating snow. It'd even be an amazing event for Atlanta and Birmingham.

[Coach B]

8 minutes ago, EastKnox said:

18z NAM pushing precip closer to us for this weekend - every run seems to have a NW tick.

That run is impressive from the TX gulf coast all the way thru the Delmarva! Some Deep South peeps are either going to get a real treat or are going to get NAMMED. 

[Bango]

1 minute ago, Coach B said:

Thinking KTRI should do well with about 50-75 more miles nw, and i assume because the axis of precip we wouldnt get robbed from the southern mnts as most the moisture could run up the valley direct (?).

[nrgjeff]

Thank you all. I post in the Southeast, Mountains and Foothills more than in their general threads. 

2 hours ago, Chattownsnow said:

Thanks Jeff. Your knowledge and unbiased approach are what make you my favorite MET on this, or any other board. When you speak, I listen. Some in the Southeast forum wish you would post more over there lol. The weenies I don't think would like what you have to say all the time however. 

 

2 hours ago, EastKnox said:

Let me echo this.  As soon as I see a post from you or Carver's Gap, I get a little giddy inside.  I can't wait to see what kind of knowledge I'll take in.  I only hope that I can return it with intelligent posting this winter.

We all learn from each other. I have been here several years, but still learning some micro-climates from long time residents on the board.

Hello 18Z NAM! 12Z Euro shifted NW too. I'm not too excited about either, but that energetic system dropped moderate to heavy snow in the mountains of northern Mexico. Light snow is sticking in the Pecos region of West Texas. Other Texas advisories/warnings are not for sticking snow, but it's still snow in Deep South Texas. Energy coming from Mexico occasionally surprises, but it is close to the US and I believe well sampled. Around here I think above 2,000 FT for snow from North Georgia to the Carolina Mountains.