2016-2017 Great Tennessee Valley Winter Discussion

[John1122]

1 hour ago, cleTNwx said:

Quick question...those Snowfall Totals (in inches) what time period do they represent?  Central KY for instance...is the model saying 9 inch possible in previous 24 hours?  How does the model work?

Still new and learning.

Thanks in advance!

In the Central Kentucky event there, it happens from 108-126 basically. So it's a 18 hour window of heavy snow.  The GFS event is actually 3 days later and its totals start around 174-192. 

[jaxjagman]

#volatility

[John1122]

GFS is loaded with cold/warm up just enough to rain/cold with a parade of cutters with cold chasing. I never trust models showing cold chasing moisture as it does with several snow chances on there. So I'd discount those backside chances almost entirely tbh. 

The GFS is super frigid. Next Wednesday midday temps are in the upper 10s to mid 20s across the entire Valley. That's nothing compared to the air mass behind the next storm that rolls in about 48 hours after the frigid Wednesday, which verbatim is another potential wintry overrunning scenario. Models scour out cold too fast almost every time in those situations in the Eastern half of the valley. The GFS churns out 0 degree cold with no snow cover. Just to the north where there is snow cover it's -10s in the Ohio Valley.  Then it warms just enough to rain again before another massive Arctic outbreak is roaring into the upper midwest with more -20s and -30s. 

If any of that proves true, the amount of cold air on our side of the globe and snow build up to the north should mean good things. The parade of cutters shows an active storm track continuing and that matters more to me than the exact track of them at this point. Especially with the sheer volume and weight of the Arctic being unleashed that run.

[ShawnEastTN]

9 hours ago, John1122 said:

GFS is loaded with cold/warm up just enough to rain/cold with a parade of cutters with cold chasing. I never trust models showing cold chasing moisture as it does with several snow chances on there. So I'd discount those backside chances almost entirely tbh. 

The GFS is super frigid. Next Wednesday midday temps are in the upper 10s to mid 20s across the entire Valley. That's nothing compared to the air mass behind the next storm that rolls in about 48 hours after the frigid Wednesday, which verbatim is another potential wintry overrunning scenario. Models scour out cold too fast almost every time in those situations in the Eastern half of the valley. The GFS churns out 0 degree cold with no snow cover. Just to the north where there is snow cover it's -10s in the Ohio Valley.  Then it warms just enough to rain again before another massive Arctic outbreak is roaring into the upper midwest with more -20s and -30s. 

If any of that proves true, the amount of cold air on our side of the globe and snow build up to the north should mean good things. The parade of cutters shows an active storm track continuing and that matters more to me than the exact track of them at this point. Especially with the sheer volume and weight of the Arctic being unleashed that run.

I never get excited for backside snow following rain usually the cold doesn't arrive fast enough in those situations chasing the moistures exit, but for December I'm happy just seeing flakes fall even briefly with no accumulation.   Better yet 6Z, 276H and 288H are beautiful beautiful fantasy.

[nrgjeff]

I am starting to believe this colder weather pattern will last the full 6-8 weeks, not a 2-3 week secondary pattern. First the short-term..

GFS cannot decide between a Virginia snow bomb or a Deep South nocturnal tornado outbreak, lol! Euro is remarkably consistent run-to-run, at least as well as it can be with a sharp boundary across the Ohio Valley. Speaking of the OV, yes I think a cold zonal flow that benefits them early would benefit us late. Anyway look for continued model choke jobs in the 6-15 day, but let your heart not be troubled.

Evidence is increasing that the cold pattern holds for 6-8 weeks, of course with the usual mild interludes. Bering sea pattern is strikingly stubborn. One has to like our chances with a full 6-8 weeks to try. Sure most systems will disappoint, be timed wrong, or whatever else goes awry in the South. Just remember a happy ending is all that matters. Ask Ben Zobrist for the Cubs. He started slowly and then got the MVP! No my account is not hacked. I am truly optimistic. Could be like 2010-11 with a cold and stormy start for December and January, and mild end of winter starting around February. 

[John1122]

That big ridge that cranks up over SW Alaska at the end of the GFS is a dream for winter lovers in the East. As with everything beyond day 5 of the GFS, it too is subject to major changes from run to run. It's being very insistent with cold though. That has too be good. If we lock in 6-8 weeks of relative cold from mid Dec to mid Feb, you can't ask for much more from winter, just have to imagine you eventually catch a break with the snow pack dropping south and the tendency for cold to stay over it and suppress the storm track. The Midwest and Ohio Valley go glacial during that run, building up a 10-20 inch snow pack over most of it. That would be a way above normal snow pack for this time of year.

[tnweathernut]

Modeling is looking good, IMO.  I am not sure where we go after a few cold blasts or if we end up with a legit chance at snow/ice, but this is only early December.  Just finding cold on the map is a good thing and finding cold THIS cold in December will certainly make people feel "Christmasy".  I do think with the amount of cold showing, our chances of scoring are much higher than average for the time of year.

There will be a winter where we all look back and say.................. "remember when winter started and we were unsure about how it was going to play out, who saw that coming?"  The DC area had that winter a few years ago.  I can guarantee people in the mid-south and Carolinas were thinking "another relatively snowless winter" was on the way in early February of 1960.  After all, it had been almost 10 years for some at that point and it was almost Valentines Day when the first snow hit.  Big years happen and they will happen again. Just hope we are all around to recall the "BIG" one when it does happen.

[Carvers Gap]

The 12z Euro dumps the cold into Washington, Oregon, and California.  I was very surprised by that.    It does build a -EPO and is in the process of kicking the trough east on d10.  The second cold shot for the valley is muted at best if not eliminated during that run.  But...I might trade a missed cold shot for what might happen if that rolls forward a few more days.

[Coach B]

7 minutes ago, Carvers Gap said:

The 12z Euro dumps the cold into Washington, Oregon, and California.  I was very surprised by that.   

The GEM ensemble appears to do the same thing. 

[Carvers Gap]

45 minutes ago, Coach B said:

The GEM ensemble appears to do the same thing. 

Thanks.  I will give them a look.  The 12z Euro is not terrible.  It may actually move to something better if indeed a -epo builds in.  We might get robbed of the second cold shot only to have the trough roll east with all of that Arctic air.  Still, that was a pretty big move from what it has been showing for the past week.

Edit:  I would add that it is not a big move on the global grid, but that SE ridge means big changes to next week "if" it is correcf and if it holds.  Instead of a cold week next week, would be very warm if that run verifies.  But who knows right now....

 

[nrgjeff]

Everything will be fine. Euro may indeed be right but that's OK. These things take a few weeks to really settle in over the South. Remember Ben Zobrist started slowly before being so clutch (MVP) in the WS for the Cubs. #baseball_metaphors #clutch_bering_sea #it'll_happen

[Carvers Gap]

8 minutes ago, nrgjeff said:

Everything will be fine. Euro may indeed be right but that's OK. These things take a few weeks to really settle in over the South. Remember Ben Zobrist started slowly before being so clutch (MVP) in the WS for the Cubs. #baseball_metaphors #clutch_bering_sea #it'll_happen

True.  That +EPO from the last several runs would eventually cause us to lose our cold anyway IMO.  Seeing a -EPO is not a bad thing post d10....if indeed that run is even correct.

[John1122]

The GFS and Euro actually look fairly similar temp wise on Day 8-10 with the GFS being a little slower to shoot above normal. The Euro shows the Southern tier warming but the cold air begins to suppress it by day 10, GFS does the same and it overcomes the warmth by day 12.

 

Day 9 GFS.

 

Day 9 Euro

 

These spikes continue as storms cut on the GFS beyond this, followed by -10-15 degrees below normal temps for a couple of days. It's funny that a 1024 HP centered over Haiti on the Euro is holding off cold from a 1040 over Minnesota.

 

[Daniel Boone]

I don't like what I'm seeing on todays runs. John you made a good point, imo. Those cutters are disturbing. As long as that troughiness continues in the west we'll prob. have that problem as the se ridge will try to pull up especially without strong upstream blocking. Let's hope that trough doesn't deepen out west, and everything goes the way previous model runs were showing.

[John1122]

I'm well pleased with them tbh. Because of this. We had potent winters in 2013-14/2014-15 because of this. Even if it they were back loaded. We had sub 0 cold and multiple snow events with a +NAO/+AO due to the massive -EPO.

 

 

It keeps going and gets into even better position at the end of the run.

 

[Carvers Gap]

7 minutes ago, John1122 said:

I'm well pleased with them tbh. Because of this. We had potent winters in 2013-14/2014-15 because of this. Even if it they were back loaded. We had sub 0 cold and multiple snow events with a +NAO/+AO due to the massive -EPO.

It keeps going and gets into even better position at the end of the run.

Yeah, the Canadian cold is still there.  If we could manage a -epo, that would potentially enable direct discharge of that cold into our area instead of going west and modifying.

 Man, Jeff is banging the cold drum.  Has me all out of sorts.  Lol.  Now, if Mr. Bob comes in and says we stay cold for a while...I know I have entered a parallel dimension.  

[Daniel Boone]

Yeah John. Those 2 were late great ones but, the feb. '15 was rare. There have been other years(mid-50's and mid 70's) with that setup that had a strong se ridge and never eventually set up a snowy pattern in the se.Se ridge was so strong. The west, Ohio valley and upper ma Maryland northward cashed in.

Not meaning to be pessimistic here just honest because of many years experience. I never like seeing a trough dig into the west without upstream blocking . Sure, a strong tnh connection like feb. 2015 with a +nao can deliver for those of us above 35 lat... but how likely is that exact pattern to repeat ? Just a slightly watered down version would allow for the snow to be further north and west. We got hammered then but Johnson City didn't as they had just rain during much of that time and wound up with just 10-11" the entire winter.

[John1122]

8 minutes ago, Daniel Boone said:

Yeah John. Those 2 were late great ones but, the feb. '15 was rare. There have been other years(mid-50's and mid 70's) with that setup that had a strong se ridge and never eventually set up a snowy pattern in the se.Se ridge was so strong. The west, Ohio valley and upper ma Maryland northward cashed in.

Not meaning to be pessimistic here just honest because of many years experience. I never like seeing a trough dig into the west without upstream blocking . Sure, a strong tnh connection like feb. 2015 with a +nao can deliver for those of us above 35 lat... but how likely is that exact pattern to repeat ? Just a slightly watered down version would allow for the snow to be further north and west. We got hammered then but Johnson City didn't as they had just rain during much of that time and wound up with just 10-11" the entire winter.

I believe KTri recorded 14 inches in February 2015. I know some of the areas around there got a lot more.  A +EPO usually causes a GOA low and that floods Pacific air over Canada and our source cold isn't that cold. A -EPO allows cross polar flow to set up and dump into Canada. Historically a -EPO is the second most common correlation to cold in the East with a -AO being 1st. 

[Daniel Boone]

Yeah John, I know about those indices but, it doesn't always pay off snowwise in this area and points south if a deep western trough is established. I hope it does as I'm like most here in that I love snow.

  Ktri received more than Johnson city that winter. Kingsport more than ktri as carver can attest . Sharp gradient then.

 

[John1122]

24 minutes ago, Daniel Boone said:

Yeah John, I know about those indices but, it doesn't always pay off snowwise in this area and points south if a deep western trough is established. I hope it does as I'm like most here in that I love snow.

  Ktri received more than Johnson city that winter. Kingsport more than ktri as carver can attest . Sharp gradient then.

 

In most winters the Western trough usually sets up early and gradually the trough will establish itself further East. That's why December is the snowiest month until March/April in the Rockies. If I had a choice, I'd always take the EPO on my side vs having it working against me.

[Carvers Gap]

12z. EPS mean has a -EPO d10 and loses it within five days and goes warm.  The mean does support the operational by muting the second cold shot.  I think that is a possible solution.  The models have been spitting out warm solutions in the LR about 50% of the time.  The LR JMA is warm weeks 3-4.  Seems like the more reasonable solution is a back and forth cold/warm pattern that would match a normal December with much colder temps over the GL and Ohio Valley.   The cold has shown a tendency to dive south and that matches Nina climo.  But definitely, the 12z OP and EPS have my attention with potential warmth in the future.  One run.  It may well be different next run.

[Carvers Gap]

Jeff, those weeklies look exactly like your last post.   You are a ninja.  Minus a ten day break, they are pretty cold at 850 and the 500 mb pattern looks very good weeks 1-2 and 4-6.5.  Trough is centered in the East after d28-46.  Looks like a -EPO and -NAO to boot in January.  Cold over the Plains, especially northern.  SE has to fight the SER which isn't all bad w blocking.  Couldn't ask for a much better look this far out.  

[jaxjagman]

http://www.tropicaltidbits.com/analysis/models/?model=gfsp

 

Post it here,Tidbits added the GFS PARA

[John1122]

Wow, that run of the GFS gives East Tennessee 14-16 inches of rain topped off by a major ice storm from the Plateau west. 

[John1122]

Insane. 

[John1122]

The cold hangs up from the Plateau west that run for something crazy like 5 days straight. the last 60 hours of the run the western 2/3rds of the valley is getting an ice storm. Nashville is -10+ from normal while Johnson City is +10 or more above. As weird as that run was, that kind of storm actually happened in the area and I believe it was in December. Nashville got buried in snow and ice, as did Memphis, while it rained and was mild in Knox, Nooga and Tri. 

[Carvers Gap]

0z Euro has returned to a cold solution for d6-8.  It has delayed and blunted the northward extent/overall strength of the warmup. Strong -epo on the run seems to be adjusting the trough eastward.  Very different run than 12z yesterday.  Would appear by d10 that the energy in the southwest is digging too much w that -epo.  Either way, it should kick that trough east.  Would have enjoyed seeing the next 72hrs.

[Carvers Gap]

0z GEM is interesting as well.  It also has the second shot of cold air where at 12z it had lost it.  The GEM does not bury the trough in the West late in the run.

[Carvers Gap]

GEFS and GEM ensembles at 0z are quite warm at 850 during the second half of their runs.  Big SERs.  EPS is quite warm after d10.   It may potentially be in error as it somehow manages to leave a trough out West with a strong -EPO.  The NAO is positive and that may be the driver for that, but it looks very wonky.

[jaxjagman]

On 12/2/2016 at 11:14 PM, jaxjagman said:

There some signals for some severe weather mid month.The Control which did rather well in the long range with the last outbreak has been showing it now for several runs as well as the CFS and even the teleconnections.Not saying it will happen or even the same magnitude as the last,just something to watch