2016-2017 Great Tennessee Valley Winter Discussion

[Carvers Gap]

Some changes in the 12z GEFS and GEPS in the LR.  AK ridge is connecting to the Scandanavian ridge.  In turn, it is adjusting the western trough eastward.  This supresses the eastern trough.  Other than that, very boring look past few days.  I don't want to be "that person" ths complains every run looks awful.  So, just been sitting back watching for new trends...

[rbowman]

I apologize in advance. This is in the wrong thread I know, but not sure how to let the mods know if a problem to report to the Amwx tech folks. Access to the forums via tapatalk is totally jacked up. When you enter any subforum it tells you there are no topics available. That includes the best subforum on American weather - the Tennessee Valley!

If someone in authority can report this. I'd be most appreciative!

 

[Carvers Gap]

2 minutes ago, rbowman said:

I apologize in advance. This is in the wrong thread I know, but not sure how to let the mods know if a problem to report to the Amwx tech folks. Access to the forums via tapatalk is totally jacked up. When you enter any subforum it tells you there are no topics available. That includes the best subforum on American weather - the Tennessee Valley!

If someone in authority can report this. I'd be most appreciative!

 

Might not hurt to send a pm to Mr. Bob, stormtracker or wow.   They probably would like to know.

[John1122]

Looking more and more like cold and bone dry as the clipper parade isn't looking as likely due to trough orientation. Still have a decent amount of winter left but barring a major turn around this is going to be a severely below average snow winter in my area.

After 3 above in a row I figured one was due. It's amazing that it's either feast or famine the last decade or so, with not a lot of middle ground. I'm at maybe 10-15 percent of normal this year with around 2 inches. Was 125-175% of normal the prior 3 years. Finished at 15-25% of normal the two years before  those three, finished at 175-225% of normal the two before that and finished at 20-25 percent of normal the two before that. 

[Met1985]

1 hour ago, Carvers Gap said:

Some changes in the 12z GEFS and GEPS in the LR.  AK ridge is connecting to the Scandanavian ridge.  In turn, it is adjusting the western trough eastward.  This supresses the eastern trough.  Other than that, very boring look past few days.  I don't want to be "that person" ths complains every run looks awful.  So, just been sitting back watching for new trends...

Yeah the trends are pronounced and are not good. It's a lackluster of a look on both the euro and gfs. Looks like the same crap we have been dealing with after a short cold shot.

[weathertree4u]

29 minutes ago, Met1985 said:

Yeah the trends are pronounced and are not good. It's a lackluster of a look on both the euro and gfs. Looks like the same crap we have been dealing with after a short cold shot.

Yea, I feel like we are seeing a repeat of what year was it, 2011/2012, where it always looked like there was going to be a pattern change but it never really transpired? Looks like the extended is just if anything seasonal and wet, which is good, cant complain about getting the water table back up.

[Carvers Gap]

3 minutes ago, weathertree4u said:

Yea, I feel like we are seeing a repeat of what year was it, 2011/2012, where it always looked like there was going to be a pattern change but it never really transpired? Looks like the extended is just if anything seasonal and wet, which is good, cant complain about getting the water table back up.

Yeah, great to get rain.  In terms of needs and wants, rain is a need and snow is a want in this area.  I am going to withhold judgement until March.   There are models out there that would end winter such as the EPS.  The 12z GEFS and GEPS suggest Feb might be interesting.  The EPS has corrected a little more eastward w its western trough after d15 during the last few runs.  I would not call it a cave but it seemed to consider the possibility.  I still suspect the western trough is not a permanent feature but less certain than say a week ago.   The EPS is more on its own today w its look of a western trough and eastern ridge.  I suspect the trough will largely be in the East, but I am less than excited about that look as well.  PV seems too far north near Hudson Bay and just doesn't press far enough to prevent AN heights to build below it.  This has more of a 89-90' feel to it for me.  A pattern that was cold in Dec left and never returned.  But I also think there is some 95-96' in there as well, meaning when it got cold it snowed.  But to be clear, I am not enthused at all.  There is enough out there to build a case that winter is over south of the Mason-Dixon Line.   There is enough evidence to convince many that winter still has life.  The debate right now is this...Are we entering a pattern change or is it just a relaxation of the pattern that has dominated this winter?  And is the potential new pattern any better than the old pattern?  That last question is the biggest concern and question for me.

[Carvers Gap]

The MJO will verify w the upcoming cold.  But it illustrates the conundrum.  Drops into the circle of death where it has less influence and other drivers take over.  But what will those drivers be?

 

 

[Carvers Gap]

So, I will try to analyze a fairly meh pattern that follows the first cold shot.  I will use this frame of the 18z GEFS as it resembles much of what is modeled on the GEPS and EPS.  I have labeled the NH map w ten features that are important IMO.

1.  The AN heights connecting AK to Scandinavia.  That is normally a good thing, because it can trap part of the vortex and potentially force it south.

2.  AN heights over the Bering Straights.  IMO, for us to have colder wx we need those centered directly over AK or in the GOA to build a strong -EPO.

3.  BN heights in the Pacific need to be in areas ten and nine.

4. BN heights need to be over southern HB. (Biggest problem which if solved could counter many other factors)

5. +NAO trending less amplified as such. (Second biggest problem as even a neutral state could help.)

6.  Slightly AN heights build under the low height center over northern HB.  

7. Western Europe has AN heights which do not correlate to cold in the East.

8.  Is that trough transient or permanent?  Depends on which model and which run you look at...

9.  Generally a trough east of Hawaii is a plus.

10.  Looks like a neautral to positive WPO.

Not all of these need to be perfect or will ever be perfect....but we need more factors in our favor than we have modeled.

[Met1985]

2 hours ago, weathertree4u said:

Yea, I feel like we are seeing a repeat of what year was it, 2011/2012, where it always looked like there was going to be a pattern change but it never really transpired? Looks like the extended is just if anything seasonal and wet, which is good, cant complain about getting the water table back up.

Yeah we need the rain. I'll take any precipitation currently. It seems like for the past 3 to 4 winters we are scrapping buy on whatever can transpire.

[John1122]

2 hours ago, Carvers Gap said:

So, I will try to analyze a fairly meh pattern that follows the first cold shot.  I will use this frame of the 18z GEFS as it resembles much of what is modeled on the GEPS and EPS.  I have labeled the NH map w ten features that are important IMO.

1.  The AN heights connecting AK to Scandinavia.  That is normally a good thing, because it can trap part of the vortex and potentially force it south.

2.  AN heights over the Bering Straights.  IMO, for us to have colder wx we need those centered directly over AK or in the GOA to build a strong -EPO.

3.  BN heights in the Pacific need to be in areas ten and nine.

4. BN heights need to be over southern HB. (Biggest problem which if solved could counter many other factors)

5. +NAO trending less amplified as such. (Second biggest problem as even a neutral state could help.)

6.  Slightly AN heights build under the low height center over northern HB.  

7. Western Europe has AN heights which do not correlate to cold in the East.

8.  Is that trough transient or permanent?  Depends on which model and which run you look at...

9.  Generally a trough east of Hawaii is a plus.

10.  Looks like a neautral to positive WPO.

Not all of these need to be perfect or will ever be perfect....but we need more factors in our favor than we have modeled.

Excellent analysis. GEFS is much better at 500 than the OP in the days 5-13 range. I'm wanting to get into that time frame and see if we can cash in some snow while it's cold. The OP goes crazy with the ridge in the west and sharpens the eastern trough and shoves it east. The GEFS has a much more broad trough and shows some potential for southern stream involvement. It even had an area of snow between Houston and San Antonio at one point.  

[jaxjagman]

4 hours ago, Carvers Gap said:

Might not hurt to send a pm to Mr. Bob, stormtracker or wow.   They probably would like to know.

I'M having other problems with tapatalk on my cell phone when i try and use it.Keep seeing porn ads.I deleted it thinking i might have a virus and reloaded it and seen the same ad'.Then went on my laptop and put in keyword "tapatalk" and put in americanwx and once again see porn ads.Not at all happy with this

[bigdog660]

2 hours ago, jaxjagman said:

I'M having other problems with tapatalk on my cell phone when i try and use it.Keep seeing porn ads.I deleted it thinking i might have a virus and reloaded it and seen the same ad'.Then went on my laptop and put in keyword "tapatalk" and put in americanwx and once again see porn ads.Not at all happy with this

I haven't seen any porn ads, when I try to view a topic, I keep getting asked for my L/P even though I'm signed in. Entering my L/P does nothing, and I get asked again for my L/P. Wierd. Also only one of the topics shows up for me.

[John1122]

00z GFS OP was very warm. But it's in complete disagreement with it's ensembles. At hour 336 the OP is 30+ degrees warmer over the midwest than it's ensembles. Almost never see that much disagreement between a model and it's members.

 

[weathertree4u]

2 hours ago, John1122 said:

00z GFS OP was very warm. But it's in complete disagreement with it's ensembles. At hour 336 the OP is 30+ degrees warmer over the midwest than it's ensembles. Almost never see that much disagreement between a model and it's members.

 

Seems like we go through this more often than not the last few years. We will mention how looks like it is going to get cold according to the MJO and other indicators, then when we get to the time period or close to it it is actually warm or seasonal, not personally speaking of you course, but just wonder when we can actually get an honest Winter, this will be another like '11/'12 if we honestly end up with just the four days of actual cold in January by the end of the season and if you look at the latest GFS at 06Z, we just might. Especially around here, by the time you get into mid and latter February it is just harder to get a good snow because sun angle and averages are just increasing so much on a daily basis. What do we think about next Winter or more importantly, anyone have any ideas about the severe weather season this year in the TN Valley?

[John1122]

GFES will give us about a week of cold from the 27th to the 3rd or so, then we may warm up for a short time with another shot of cooling back down. At the end of the 06z run the OP is rebuilding the PNA ridge and trough in the east. Some blocking may even be showing up in the Atlantic/Greenland area but I'll dismiss that.

If we can get this.

To turn into this in the next few frames, we'll only have a 2-3 day warm up before cold reestablishes itself. The image below was the December 1989 cold outbreak. There's not even any good Atlantic blocking on the map, the NAO was negative early month, but was neutral to mildly positive when we had highs in the single digits and lows in the 10s below zero late month.  When a +PNA connects with strong Alaska and Siberia ridging, which is close on the 06z GFS, it gets really really cold really far south.  The eternal question will of course be, is this something that is actually going to happen or not? Hopefully the models can be a little more consistent at 500 after this major storm passes and the initial colder air works it's way east.

[John1122]

ENS are usually going to be more muted than the OP, but the 06z GEFS is trying to build some ridging back in the west, has great over the top blocking, building heights over the entire Arctic region. That would send cold south as well.  If we could get the ridging over Alaska to be 300 miles East we'd get a major trough in the east, or if we could get that ridging in the SW to look more like the OP we would as well.

[Carvers Gap]

6 hours ago, weathertree4u said:

Seems like we go through this more often than not the last few years. We will mention how looks like it is going to get cold according to the MJO and other indicators, then when we get to the time period or close to it it is actually warm or seasonal, not personally speaking of you course, but just wonder when we can actually get an honest Winter, this will be another like '11/'12 if we honestly end up with just the four days of actual cold in January by the end of the season and if you look at the latest GFS at 06Z, we just might. Especially around here, by the time you get into mid and latter February it is just harder to get a good snow because sun angle and averages are just increasing so much on a daily basis. What do we think about next Winter or more importantly, anyone have any ideas about the severe weather season this year in the TN Valley?

The MJO will most likely verify this time.  At no point did it signal prolonged cold...just a flip.  The duration and where we go after that are unanswered questions w trends for answers that are not encouraging.  What is prob incorrect were the weeklies several runs back that signified long term cold which it seems now is unlikely.  I have already noted that error.  We also talked about the QBO which is not in our favor and is strongly positive.   It seems like it is one of those programs on a computer that runs in the background and just gums up the works.  It may turn out to be "the" driver this winter.  At this latitude there are more things working against us regarding winter weather than for us.  Our window for snow is basically an iffy eight weeks.  In other places like Maine and Montana it might be twenty weeks where climo easily supports it.  We have fo have several things be correct as I posted yesterday...not all of them but several.  So one always stands a pretty good chance if they say the cold won't last here or will not be as prolonged or severe as forecast.  We live near the northern sections of the subtropics.  We can only get better at our hobby if we try to use the many forecast tools out there.  But the best forecast tools will always be climo and indices that deal with the state of our oceans as they cover vast areas of our planet.  Thus measures like the MJO, ENSO, PDO, AMO, SOI, WPO, and the NAO are important. They are not full proof but are often our best tools.  To loop back to leaning warmer than the models portray, it is prob not bad advice.  There is a reason MRX and other NWS offices undercut snow totals and won't go out on a limb...but here we can take chance and risk being wrong.  They have people depending on their forecasts so they rightfully should be conservative and will most likely be right.  This forum is like batting practice.  You can only get better if u take a swing.  

[Carvers Gap]

This is the EPS @ 500 for d15.  It does not correlate all that well w colder surface temps in the northwest and warm temps in the SE.  However, it does show the significant shift in the atmosphere that has happened at 500.  This is after the ridge rolls through.  Trough in the eastern half of NA vs the west.  It also illustrates that sometimes an eastern NA trough does not equal cold in the SE as there is a slight ridge under the trough.

[Carvers Gap]

4 hours ago, John1122 said:

ENS are usually going to be more muted than the OP, but the 06z GEFS is trying to build some ridging back in the west, has great over the top blocking, building heights over the entire Arctic region. That would send cold south as well.  If we could get the ridging over Alaska to be 300 miles East we'd get a major trough in the east, or if we could get that ridging in the SW to look more like the OP we would as well.

Great info this AM...Seems like some decent model trends during the past few runs meaning the western trough after d10 might just roll through without locking-in.  What is the link for creating analog packages?  

[John1122]

The 12z managed to show an even more favorable 500mb set up than 06z.

The GEFS also stepped that way with better ridging beginning to build off the west coast, it would be much better if it were a little more east like the op. If this happens it's still a 2-3 day or so warm up and then we head back below normal. As you can see the flow is more NW than the EPS map Carver posted, which features SW/Zonal flow here. Thus the warmth.

[John1122]

The Canadian Ens show the great over the top blocking and too. This is close to a -EPO/-AO/-NAO look. Even though heights are higher than normal over us, we're still below normal on temps at this hour. A piece of the polar vortex is slowly working it's was S into Canada. 

[Carvers Gap]

Great disco, John1122.  I was just looking through the 12z suite.  Looks a lot like the progression from the last TR's Weeklies.  Trough wk2, ridge wk3, trough wk4 in the East.  The Weeklies do keep a mean trough but w AN temps after wk4.   But the 500 maps looked good.  Seeing that trough in the GEFS/GEPS ensembles not hold in the northwest between d10-15 gives me better confidence that we are indeed leaving the old pattern and heading for a new one...and not just a relaxation.  Nice to see a -NAO show up on the GEPS....might prevent that PV from rotating back out.  Not sure on that one yet.  For those reading and not posting, I am not saying the new pattern holds more winter...but it stands a better chance than the mid-60s we have seen during the past two weeks in the 60s.  The 12z Euro does have a weak impulse that impacts northeast areas of the forum between d5-10.

[BristowWx]

53 minutes ago, John1122 said:

The Canadian Ens show the great over the top blocking and too. This is close to a -EPO/-AO/-NAO look. Even though heights are higher than normal over us, we're still below normal on temps at this hour. A piece of the polar vortex is slowly working it's was S into Canada. 

That's a nice look.  But blocking has proved elusive

[Carvers Gap]

12z EPS showing nice improvement.  The control is about perfect.  Too bad it will change next run as it usually does at that range.  The mean looks very consistent w what is on the GEFS and GEPS...maybe a day or so slower.  Ridge rolls through after the second cold snap and is in the process of being replaced by a broad nation-wide trough.  Good trends.  

[BristowWx]

What I find so curious is how dry it is in the LR.  Days of no precip.  Across the US no storms.  Hard to believe it's winter.  

 

[weathertree4u]

42 minutes ago, BristowWx said:

What I find so curious is how dry it is in the LR.  Days of no precip.  Across the US no storms.  Hard to believe it's winter.  

 

Been plenty wet near me around Nashville, would just love to actually see some cold though in the long range hold to the short range and at least one good snow this year not seeing it in the next two weeks

[Carvers Gap]

We often use the word "torch" too liberally in the weather hobby community.  But w a +10.5 departure so far for Jan @ TRI....that is a torch.  And yet, 3+" of snow recorded at the airport.  Snow and overall temps for a given winter month do not always correlate.  We often gripe during cold patterns that we often don't score.  We had one chance at TRI this month and hit it.  And before folks climb out of the woodwork saying this was not seen...go back and look at everyone's posts.  It was well documented that it would be bad. 

[Carvers Gap]

The EPS and major ensembles flat out nailed this upcoming pattern flip. It may not get as cold as we would have liked, but pretty incredible.  I was going back and looking at some of our posts in this thread around Jan 8/9/10.  The switch was projected around Jan 25th w the beginning of the flip beginning around the 22nd w the ridge being undercut. Looking at today's MRX forecast..NWS high on Jan 26th is forecast to be 44.  To hit a switch 15 days out is pretty incredible.  Jax, tnweathernut, john1122, others...some really good posts.  We all knew the torch was coming and were looking for a way out...very little complaining in our forum.  No matter where winter goes after the cold snap...that was some decent work.

[BlunderStorm]

3 hours ago, BristowWx said:

What I find so curious is how dry it is in the LR.  Days of no precip.  Across the US no storms.  Hard to believe it's winter.  

 

plenty of precip in SWVA