2016-2017 Great Tennessee Valley Winter Discussion

[John1122]

Also, read the extended forecast discussions each afternoon around 4 pm Mon-Friday when the 6-10/8-14 day outlooks are posted. Not surprisingly, the forecasters have a higher pattern verification score than any of the models.

[Matthew70]

6 minutes ago, John1122 said:

In addition to that AO forecast, there's this.

 

 

Thanks John & Jag for posting.  I will believe a -NAO when it is happening.  I cannot remember what one was during the winter months. Just another reason to be very cautiously optimistic about the upcoming pattern.

[John1122]

The following indexes are forecast to go in our favor. The PNA stays negative, which would normally work against us, but due to the EPO  working with Atlantic blocking, it just allows most of the country to be over spread by Arctic air and the Pacific sw flow is still blocked from overwhelming the nation.

AO

 

NAO

 

EPO

 

WPO

 

 

[Carvers Gap]

The Euro has a great set-up late in its 12z run.  Still a long ways out there, but in that time frame that many other operationals are providing interesting looks.

[Met1985]

4 minutes ago, Carvers Gap said:

The Euro has a great set-up late in its 12z run.  Still a long ways out there, but in that time frame that many other operationals are providing interesting looks.

With the arctic high and the SER there is a squeeze play but currently we look to be on the positive side.

[Carvers Gap]

22 minutes ago, Met1985 said:

With the arctic high and the SER there is a squeeze play but currently we look to be on the positive side.

Interestingly, the 12z GEFS has several members that impact this forum region and then also you guys up at elevation in western Carolina.

[Met1985]

2 minutes ago, Carvers Gap said:

Interestingly, the 12z GEFS has several members that impact this forum area and then also you guys up at elevation in western Carolina.

Yeah I like look today especially.  The ensembles have been inching better and better daily.

[Met1985]

Shoot I'm excited about our little event coming Thursday night through Friday. The 12z was spitting out some 3 to 5 inch totals.

[John1122]

It's all about the pattern, if we can get it to actually verify, we're gonna have our shots. I don't pay so much attention to any individual threats in that range, more so what the atmosphere is showing and what should happen when it's set up like that. The longer range GFS will often show things at the surface that defy the actual upper atmosphere pattern it is showing.

[Carvers Gap]

4 minutes ago, Met1985 said:

Yeah I like look tod especially.  The ensembles have been inching better and better daily.

If anything, I like that the pattern could support this instead of trying to thread the needle for 18 more Euro runs.  LOL.  I am sure there will be changes but having that block looking like an upside down omega(with the base near our latitude) is supportive of winter somewhere in our region.  

edit:  Ha!  John with the ninja move.  Beat me to it.  I agree.  

[tnweathernut]

Where do we sign up?  12z EPS hour 216

[tnweathernut]

Pretty strong signal for continued EPO help in the long range....

[Met1985]

26 minutes ago, tnweathernut said:

Pretty strong signal for continued EPO help in the long range....

That's a great sign. That will offset the PNA.

[John1122]

18z op tries to scoot the -NAO out. GFES says it stays. Keep in mind in my experience models are often way too fast to remove blocking. In the great -EPO driven winter of 2014 it continually tried to break that down but it persisted for a month.

[John1122]

00z loses the ice box way out in fantasy land, but from 180 on it gets really really frigid for multiple days in a row. Highs in the 20s and lows in the singles at times. 

[Carvers Gap]

For kicks and giggles. I rarely post 384....The 500mb pattern reloads.  Nothing verbatim at all from this range, but that is some seriously cold air rotating to this side of the planet, and that begins well before d16.  This is just where the run stops.  Blocking at high latitudes does not seem to want to leave the trough in the West.  The 0z GFS seemed to change a bit at 500mb, but there is a ridge in the west w weakish heights in the East around 300.  Really, IMO there is a trough throughout after d10.   There is a brief relaxation, the jet buckles, and the whole mass of cold begins to head south at the end of the run.  Cold just pinwheeling southward in waves.

[Carvers Gap]

0z GEM @ 240.  Nice look at 500mb.

[Carvers Gap]

The 0z GEFS has some chances centered over the forum area....Also, great discussion during the past several days.

[John1122]

It's impressive that the mean is for 2-4 inches over the entire state. 

[jaxjagman]

14 minutes ago, Carvers Gap said:

The 0z GEFS has some chances centered over the forum area....Also, great discussion during the past several days.

[John1122]

I've not re-fired my Euro sub anywhere yet. But this should be producing for areas where the 850s are good.

 

[John1122]

Euro ends with us in the icebox, great blocking and a 1054 HP sliding SE out of Alaska bringing another shot of cold down the middle of the two blocks.

[1234snow]

The 0z GFS was really different this time with the evolution of the trough in the 100-186 hour timeframe. Doesn't stick it in the west at all. A midwestern snowstorm idea is back and further south for those folks. Powerful cold front sweeps thru for us around hours 180-192 and the whole forum doesn't get back above freezing until hour 360 and like Carver says the pattern could reload after that.

I will say that this might not actually be the best case for us to get a snowstorm as this was a case of the Nina cold and dry on the GFS. I think our best case is to get a front to stall to our se and have a wave move along it. The past several runs of the GFS showed this nicely while this run moved away from it and into the icebox scenario.

[tnweathernut]

5 hours ago, John1122 said:

I've not re-fired my Euro sub anywhere yet. But this should be producing for areas where the 850s are good.

 

You are correct. Kind of silly to look at specifics this far out, but I will try and paint a picture anyway for those interested (0z Euro)

The entire state of TN has over 2 inches, with the exception of extreme southeast TN. Verbatim, it's a 6-8" snowstorm for the I-40 corridor. Lollipop amounts closer to 10" exist around and just north of Memphis and the mountains of northeast TN. 7-8" in Nashville, 7" Jackson and Knoxville. 7" for Tri-Cities too.

the lower half of KY also scores 2"+, with far SE KY over 6" and generally 5" across the entire southern border.

honorable mentions - western Arkansas 6-8" amd a general 3-5 just north and south of....and all of southwest VA is 6-8". Far northwest MS gets 2 inches and a dusting to an inch in northern AL.

[JayCee]

1 hour ago, tnweathernut said:

You are correct. Kind of silly to look at specifics this far out, but I will try and paint a picture anyway for those interested (0z Euro)

The entire state of TN has over 2 inches, with the exception of extreme southeast TN. Verbatim, it's a 6-8" snowstorm for the I-40 corridor. Lollipop amounts closer to 10" exist around and just north of Memphis and the mountains of northeast TN. 7-8" in Nashville, 7" Jackson and Knoxville. 7" for Tri-Cities too.

the lower half of KY also scores 2"+, with far SE KY over 6" and generally 5" across the entire southern border.

honorable mentions - western Arkansas 6-8" amd a general 3-5 just north and south of....and all of southwest VA is 6-8". Far northwest MS gets 2 inches and a dusting to an inch in northern AL.

Thanks for the detailed snapshot!  Sounds like a snow lover's dream storm.  Border to border. 

 

[tnweathernut]

11 minutes ago, JayCee said:

Thanks for the detailed snapshot!  Sounds like a snow lover's dream storm.  Border to border. 

 

No problem. Probably has no basis in reality (lol), but always fun to hear totals from a model showing something, especially when it's the Euro.  This event starts just beyond day 8 and it has been on and off in some fashion since day 10-11 so all in all things are looking decent at this stage, if you are looking for something to track.  

I see several people cliff diving in other forums, but the EPS (I refuse to look much beyond day 10) keeps the -EPO and the -NAO in the long range (through day 10) with a bowl shaped trough in much of the US.  Sure, there is a SE ridge, but without that feature everyone would likely go cold and dry (which is possible).  Basically all options are on the table between something that goes just north and gives the mid-south rain, a winter event, and cold and dry.  We always have to walk a tight rope in the south so it's not really worth getting worked up over.  

In a nutshell, I don't see much of a reason to be discouraged this morning.  We are entering our "prime" part of winter and there is cold coming per the forecast maps.  Better than a mega death heat ridge with no end in sight, right?

[Met1985]

6 minutes ago, tnweathernut said:

No problem. Probably has no basis in reality (lol), but always fun to hear totals from a model showing something, especially when it's the Euro.  This event starts just beyond day 8 and it has been on and off in some fashion since day 10-11 so all in all things are looking decent at this stage, if you are looking for something to track.  

I see several people cliff diving in other forums, but the EPS (I refuse to look much beyond day 10) keeps the -EPO and the -NAO in the long range (through day 10) with a bowl shaped trough in much of the US.  Sure, there is a SE ridge, but without that feature everyone would likely go cold and dry (which is possible).  Basically all options are on the table between something that goes just north and gives the mid-south rain, a winter event, and cold and dry.  We always have to walk a tight rope in the south so it's not really worth getting worked up over.  

In a nutshell, I don't see much of a reason to be discouraged this morning.  We are entering our "prime" part of winter and there is cold coming per the forecast maps.  Better than a mega death heat ridge with no end in sight, right?

Great post. I think the euro and eps have a much better handle on the upcoming pattern than the gfs has.

[tnweathernut]

Just now, Met1985 said:

Great post. I think the euro and eps have a much better handle on the upcoming pattern than the gfs has.

We probably don't realize a stout -NAO that connects to the ridging from Alaska trapping the cold underneath, but what is shown would certainly do with the amount of cold that should be entering the US.  I suppose the next trough into the west could be a little quicker and the NAO fades to neutral or even slightly positive (that has happened many times in the last several years).  The quicker trough would help pump the SE ridge and with a lack of blocking could help aid the more northerly solution providing more rain, but at this point I don't see that scenario as more likely than something that would give the southeast and midsouth an opportunity at a winter event.  As always, time will tell.........

[Met1985]

9 minutes ago, tnweathernut said:

We probably don't realize a stout -NAO that connects to the ridging from Alaska trapping the cold underneath, but what is shown would certainly do with the amount of cold that should be entering the US.  I suppose the next trough into the west could be a little quicker and the NAO fades to neutral or even slightly positive (that has happened many times in the last several years).  The quicker trough would help pump the SE ridge and with a lack of blocking could help aid the more northerly solution providing more rain, but at this point I don't see that scenario as more likely than something that would give the southeast and midsouth an opportunity at a winter event.  As always, time will tell.........

Yeah we are in the battleground. Sometimes that's good, sometimes that's bad.

[tnweathernut]

5 minutes ago, Met1985 said:

Yeah we are in the battleground. Sometimes that's good, sometimes that's bad.

I hope that is the neighborhood we find ourselves in around day 8.  You have to be close to the rain to get the best snows.....