Winter Speculation 17/18 -December Thread

[Bango]

For those of us in knoxville to ktri, what should we be looking for in the euro model (or any other descent model run for that matter) to root for a sag south? Is it a case of timing, where as the cold air needs to arrive a tick earlier? Or do we need the energy to eject sooner?  

Edit: answered by carver thanks!

[John1122]

There's an incredible warm nose over the eastern 2/3rds of the valley at 6pm Christmas eve evening. The snow level is less than 1000 feet across most of West Tennessee and it's above 8500 feet over the rest of the area. 

The ground freezing line is Middlesboro, Ky to Tazewell to Norris to the Cumberland Co/Roane Co line. SW down the plateau into Northwestern Alabama. All points west of there are sub freezing.

Freezing rain is falling in those areas and Memphis has switched to snow.

[Carvers Gap]

And to add to John’s comments which were excellent...the bias of the models might be to not have the cold far enough SE. The cold was stalled due to interaction w the cutoff....I don’t think it can be ruled out that the cutoff might come out as well.  But the odds of a winter storm across the southern Plains and Upper South are increasing.   

[John1122]

The front appears to be draped over the Apps. It's 50 degrees in SW NC and 34 in Maryville at 6 pm on Christmas eve. By 6 am Christmas morning the precip is about to exit but Knoxville has finally fallen below freezing and is getting freezing rain. Still rain at the Tri-Cities. The freezing line is around Hancock County by that point. The back edge of the precip is along the plateau.

[Carvers Gap]

1 minute ago, Bango said:

For those of us in knoxville to ktri, what should we be looking for in the euro model (or any other descent model run for that matter) to root for a sag south? Is it a case of timing, where as the cold air needs to arrive a tick earlier? Or do we need the energy to eject sooner?  

Edit: answered by carver thanks!

I think it is one of many solutions...but many seem to be clusters over western TN.  But this cutoff low in the southwest(looking like it may be an actual feature) is playing havoc with every model run.  Once that feature is closer to NA, I expect better accuracy.  Still about 80ish hours from being in a decent spot to get sampled I believe.  The other feature is the trough near HI.  Afternoon runs very slightly moved the trough westward by a nudge.  When that trough is slightly east, it pushes that cutoff into the NA pattern and it is progressive in nature.  

[John1122]

Santa arriving on skates? 

Keep in mind, this is a time to know your micro climate. The models can ony have a general idea about where things will set up. Know how you do in these set ups. How does your back yard usually fare. I've personally found from observing East Tennessee weather is that you can often slide the line where this sets up 25-50 miles south and east, Especially north of 40.  The two screen shots are Christmas eve evening at 6 cst and Christmas at midnight cst. Keep also in mind the many and significant changes that can and likely will happen between now and then. I wouldn't be surprised if this sets up over the central plains or over the North Carolina coastal plain or doesn't happen at all. But models seem to be keying in on this time frame for mischief and we may or may not be in the cross hairs.

 

 

[John1122]

As for totals, buy candles, flashlights etc if this forecast comes to pass. 1-2 inches of qpf falls as freezing rain in the freezing rain areas. The QPF that falls as snow shows dollops of 1.2 inches in Western Tennessee. It's hard to find an actual snowfall map that doesn't include ice in it's totals. There are spots of 1.5 near Clarksville that falls as snow with that being more common across a streak just below Lexington, Ky.

[nrgjeff]

John you forgot the liquor, lol. Seriously non-perishable food that does not require cooking is necessary in a winter kit also. All of this action is still about 10 days out so I would not worry. Just being prepared never hurts. 

Odds favor the surface cold front making it through the 500mb ridge. Remember though low press waves giveth and taketh away. Front will sag behind them; but, front may surge ahead of them. Southwest flow is a whip to forecast. Plus MOS is horrible both directions. Did I mention I hate ice?

Looking way out, still appears the 16-20 day will be colder than normal. However I'm not sure how much longer it will last. Alaska ridge crashes in weeks 4-6. Hints of higher heights over Greenland could introduce new cold though. I'd look for a mid-January thaw and then more variability. 

[PowellVolz]

John you forgot the liquor, lol. Seriously non-perishable food that does not require cooking is necessary in a winter kit also. All of this action is still about 10 days out so I would not worry. Just being prepared never hurts. 

Odds favor the surface cold front making it through the 500mb ridge. Remember though low press waves giveth and taketh away. Front will sag behind them; but, front may surge ahead of them. Southwest flow is a whip to forecast. Plus MOS is horrible both directions. Did I mention I hate ice?

Looking way out, still appears the 16-20 day will be colder than normal. However I'm not sure how much longer it will last. Alaska ridge crashes in weeks 4-6. Hints of higher heights over Greenland could introduce new cold though. I'd look for a mid-January thaw and then more variability. 

I just picked up a bottle of Buffalo Trace...... well for this weekend. LOL


.

[PowellVolz]

18z GFS looking a little better state wide. Not sure how much of this is sleet though.




.

[jaxjagman]

This should be our system coming off Mongolia and China headed into North and South Korea.We should be looking at a potential storm just after New Years.There is a phoon headed into/around the Philippines and going into around VietNam,this shouldn't effect us being so far south.

The SOI as odd as it is has been in a more Nino pattern the last five days.The Equatorial Temperature anomaly still shows cold water at depth,Nina should hang on until around spring time and beyond possibly.IMME shows it lasting possibly into summer now.

The IMME shows a wet Jan-March Valley,maybe a early severe season like last year?Gotta love the wet look though,we just need things to time right with the cold if you want winter,if not, time it right for severe,i like both

 

[jaxjagman]

Cant get a better ice storm look than this,or then again,severe

[BlunderStorm]

The 0z GFS clown expands upon the last run with quite the mess for Christmas!

[1234snow]

 0z GFS handles the trough a little differently and has a similar look to today’s Euro. Snowstorm for KY and snow to ice to rain for TN. 

[John1122]

0z drops the hammer before warming from snow to ice to rain for especially 40 and north. HP is perfect for snow and for some reason it beats it out of the way and lets rain arrive. Usually there's some kind of kicker coming down in the midwest to kick a HP out like that. But this one is just being replaced by another big high.

 

 

[John1122]

The Canadian is a cutter with a 35 degree temp difference than the GFS. First cutter solution I've seen in a few runs.

[John1122]

The Euro went way east with a rain to snow scenario. Thumps the Eastern areas with 4-12 inches of snow per the clown map.

Basically N Alabama to Chattanooga, the Mountains and far eastern valley areas get 5-10 inches with 2-4 on the Plateau and Knox area down to around 1 inch from Cookeville to Corinith Miss. Nashville to Memphis are too far NW as is all but extreme SE Ky. The individual members are much more centered around what is shown on the 12z run with far NW areas getting the big snow hit. One or two have all of Tennessee being too far North and show something similar to what happened last week. 

The big difference this run is that it's rain to snow with very little freezing rain and the system arrives faster, on the eve of Christmas eve.

0z Euro 6PM Cst Dec 23rd The changeover has happened plateau and mountains. It starts changing over in the highest spots on the N Plateau 6 hours before this. By midnight CST on the 24th moderate snow has overspread N. Alabama into the Eastern Valley.

 

[franklin NCwx]

0z euro says merry Christmas east Tennessee! 

[Carvers Gap]

Great overnight discussion.  The 0z Euro and EPS...both press cold further east more quickly than previous runs.  Tough to know if it is a blip in doing that or a trend.  Anytime something is coming in at that angle, the slightest variation can change the entry point in the Valley.  Seems like the Euro and EPS both bring the cutoff out and let the trough absorb it.  There is still some residual cutoff, but far weaker.  The weaker that cutoff, the stronger the trough in the East as JB would say.  So, that is an example of what happens when the cutoff is weaker and ejected.  Most runs on most models bury it in the southwest.  So, going to have to see several more runs before buying the newer solution.   That said...the 0z Euro is the one that makes the most sense vs sending a cutoff to Baja under a massive -EPO ridge.  I suspect the precip shield will be larger and cold more expansive.  The real question is where the boundary sets up.  It is likely models are underestimating how far SE this makes it.  It is growing more likely that a winter event will occur somewhere in the forum area around Christmas.  Big change from last year. 

[Carvers Gap]

10 hours ago, jaxjagman said:

Cant get a better ice storm look than this,or then again,severe

 

Nothing quite like convection into sub 32 air.  LOL.  Yeah, the ice set-up is there.  Said this several posts back....this  looks like one of those old school 70s/early-mid 80s winter storms.

[Carvers Gap]

So Cold Rain in the SE forum stated that Webber is mentioning that the GFS might be mishandling a typhoon in the western Pacific...and that might be causing issues w the rest of its run. Packer posted maps of the differences.  Give it a look. The Euro does not have this feature.  If I have to factor the Fujiwhara effect into my thinking... 

[jaxjagman]

5 minutes ago, Carvers Gap said:

So Packer in the SE forum stated that Webber is mentioning that the GFS might be mishandling a typhoon in the western Pacific...and that might be causing issues w the rest of its run. The Euro does not have this feature.  If I have to factor the Fujiwhara effect into my thinking... 

Euro has  the phoon going into the ridge on the 0Z,but that ridge in/around the Phillippine Sea should keep that storm S,ridge looks pretty stout.Something to keep an eye on,Webber knows his stuff though,maybe that ridge isn't as strong?

[PowellVolz]

Anyone having issues with Tapatalk app for American Weather? It won’t let me login but I’ve got other boards on that app and I can look at them just fine. 

[AMZ8990]

12 minutes ago, PowellVolz said:

Anyone having issues with Tapatalk app for American Weather? It won’t let me login but I’ve got other boards on that app and I can look at them just fine. 

The whole site is jacked up right now, it's been like this since some time last night.  It's pretty annoying!!

[PowellVolz]

Just now, AMZ8990 said:

The whole site is jacked up right now, it's been like this since some time last night.  It's pretty annoying!!

That sucks but at least it’s not my problem like I thought it was. 

[franklin NCwx]

1 hour ago, Carvers Gap said:

Great overnight discussion.  The 0z Euro and EPS...both press cold further east more quickly than previous runs.  Tough to know if it is a blip in doing that or a trend.  Anytime something is coming in at that angle, the slightest variation can change the entry point in the Valley.  Seems like the Euro and EPS both bring the cutoff out and let the trough absorb it.  There is still some residual cutoff, but far weaker.  The weaker that cutoff, the stronger the trough in the East as JB would say.  So, that is an example of what happens when the cutoff is weaker and ejected.  Most runs on most models bury it in the southwest.  So, going to have to see several more runs before buying the newer solution.   That said...the 0z Euro is the one that makes the most sense vs sending a cutoff to Baja under a massive -EPO ridge.  I suspect the precip shield will be larger and cold more expansive.  The real question is where the boundary sets up.  It is likely models are underestimating how far SE this makes it.  It is growing more likely that a winter event will occur somewhere in the forum area around Christmas.  Big change from last year. 

The eps has for several runs in a row now has trended weaker with the SE ridge. Hopefully that continues.  We are insideal 10 days now for Christmas so the ensembles have decent skill at the range. As usual op models will be all over the place.

[Carvers Gap]

10 minutes ago, franklin NCwx said:

The eps has for several runs in a row now has trended weaker with the SE ridge. Hopefully that continues.  We are insideal 10 days now for Christmas so the ensembles have decent skill at the range. As usual op models will be all over the place.

I "think" it is correcting its problem w the southwest bias that it has.  I think all models like a cutoff.  The problem w the Euro is that it does not need much encouragement to stall a low over the Four Corners....like an infinite loop in programming it seems to have no reasonable way of getting it out of there once it is there.  Interesting, the other major models have the same problem which makes it tough to discount.  It is not unusual for a tall -EPO or PNA ridge to get undercut.  It is very unusual IMO for it to get undercut by a system moving in from the east and then stalling.  If that cutoff does not stall...the east coast better lookout.

[AMZ8990]

7 minutes ago, Carvers Gap said:

I "think" it is correcting its problem w the southwest bias that it has.  I think all models like a cutoff.  The problem w the Euro is that it does not need much encouragement to stall a low over the Four Corners....like an infinite loop in programming it seems to have no reasonable way of getting it out of there once it is there.  Interesting, the other major models have the same problem which makes it tough to discount.  It is not unusual for a tall -EPO or PNA ridge to get undercut.  It is very unusual IMO for it to get undercut by a system moving in from the east and then stalling.  If that cutoff does not stall...the east coast better lookout.

I've got a bad feelIng that I'm gonna get screwed on this storm.  Murphy's law always likes to sock it to me!!

[bearman]

8 minutes ago, AMZ8990 said:

I've got a bad feelIng that I'm gonna get screwed on this storm.  Murphy's law always likes to sock it to me!!

I think that is the sentiment that we all have in Tennessee valley.

[John1122]

12 minutes ago, AMZ8990 said:

I've got a bad feelIng that I'm gonna get screwed on this storm.  Murphy's law always likes to sock it to me!!

I honestly like your position better currently than mine. As I mentioned, out of the 50 ens members more were similar to the 12z run yesterday with the western areas near the threat than the far eastern areas. At this range the signal is strong that a storm is going to happen. Think of it like a hurricane cone. I'd say St Louis to Charlotte at minimum are still in the window of it's potential path.