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2016-2017 Great Tennessee Valley Winter Discussion


John1122

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4 hours ago, nrgjeff said:

Glad you posted the picture! Yes the AO is exceptionally positive today, but I think the picture tells more than the index does. Low pressure bomb east of Greenland has spiked the AO, just a measure of pressure difference between the latitudes. Low press northeast of Siberia is also contributing to the index.

However right at the North Pole, temperatures are 50 degrees warmer than normal! That is not a typo. Actually wide swings can and do happen up there in winter due to low pressure bombs over the oceans. We can discuss the current sea ice and implications in the Climate Forum, but here we will just worry about the rest of this winter. 

While a +AO correlates with a mild start to January, it may not be so this year. Picture tells me the cold air is not bottled up at the pole. Way upstairs the stratospheric PV is tight right now, but may not remain so buttoned up in January. Then in between, the 500 mb pattern gets choppy in January with more high latitude ridging.

After a Florida like Christmas, a couple cold fronts are forecast New Year's weekend. However I'm not sure that is the change back to a colder pattern. Maybe give it until January 10-15? Hard to guess timing this far out, but we still have plenty of winter ahead of us.

Great info.  Way more commentary than I could have added.  Yeah, thought it was a good illustration of an interesting event.  I feel like that when those big lows impact the Arctic, the pattern gets shaken up.  Sandy and that typhoon a few years back caused early discharges of cold into our area during November.   Those are extreme examples.  I wonder if the same will be said of that big low?  If I remember correctly, the ensembles and operationals changed pretty quickly following those two storms.  I even think those big storms had far-reaching impacts into the winter season,  Obviously, this is occurring in a different part of the globe, and I have no idea what wx that a potential shake-up could cause.   But I felt like it was something of note.

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Long time lurker; first time poster.

What pic of NW Knox is crazy.  I live and teach near downtown and didn't even think that was in the realm of possibilities.  Just heard about possibly freezing fog.

Here's to much more of that stuff in January.



What school?


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2 hours ago, Carvers Gap said:

12z Euro, GEM, GFS....John, thoughts on that look?  I have to say they look encouraging.  -EPO.  Neutral to negative NAO.  +PNA.  The Euro seemed to want to hold that western ridge.   Honestly, I am a bit surprised in good way.  Though the GFS has been hinting at this for several runs.  

There's potential there but it's tough to trust anything in the LR. This year seems worse than normal in that regard once the warm/drought pattern finally broke. I wish something good could get established in the Pacific, we'd be in business because there's major cold nearby. 

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gfsp_z500a_nhem_51.png

 

System into the first week of Jan.Control mean is similar to the Para with the exception the closed off H5 is more towards the Aleutians into the Bearing Sea.The control shows a system quite like the last one we just saw.Severe threat,temps dropping sharply after the front,more ice than snow.Para,more snow,less ice.Long ways to go

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The GFS, Euro, GEM, and para GFS are advertising a much different pattern than they were.  The transition has happened during the last couple of days.  The question of where this is headed is a big one as the models are bouncing all over the place.  The SER is missing or muted on many of these model runs after d8 or so.  What appeared to be an extended warm-up is now showing potential bouts of very cold air due to an increasingly depicted -EPO.  At times the NAO is negative, but that seems to be transient.  However, it seems to be neutral as a mean after d8.  Each model has its own variation after d8.  (Jon has some great thoughts in the SE forum regarding the -EPO...so I won't go into great detail.). Most models show some type of Arctic cold shot(s).   It is a very similar pattern being depicted to what have just experienced, but if the EPO is negative it will make it more likely that the cold goes into the continent's mid-section instead of the West...then reach the Southeast as a colder airmass than its predecessors in early Dec.  To echo John, I am not convinced (as I was not convinced of the never ending warm pattern that was depicted) the pattern turns repetitively cold....but the past couple of days are modeling that to varying levels.  So, I am not speaking of the cold as the gospel but merely as model trends.  The 0z Euro is one option on the table.  The GEM is another.  The first moving to a great winter pattern and the other is transitory in nature.  Either way, the conversation is much more interesting than four or five days ago.   My guess is that we are looking at very cold air in Canada that is continuing to play havoc with the models.  It is my experience that the more the models vary (with those extremes present in Canada) the more likely the lower 48 is going to see that cold during that time frame or just after.  

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I like the cautious cold lean of our sub-forum. Yeah, we probably are the most level headed region. Nice AK ridge shows up in the 6-10 day. Oh but an equally nice SER is shown in the 11-15 day. Good forecast is 60 degrees one day 20 the next, repeat with a 40 drizzle day in between every other cycle. January looks volatile. 

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1 hour ago, nrgjeff said:

I like the cautious cold lean of our sub-forum. Yeah, we probably are the most level headed region. Nice AK ridge shows up in the 6-10 day. Oh but an equally nice SER is shown in the 11-15 day. Good forecast is 60 degrees one day 20 the next, repeat with a 40 drizzle day in between every other cycle. January looks volatile. 

Great posts between yours and the rest of the TN crew.  You guys are appreciated.  Level headed for sure.  Not to bash other sub forums but this one has fewer weenies and I Ike that. 

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16 minutes ago, LithiaWx said:

Great posts between yours and the rest of the TN crew.  You guys are appreciated.  Level headed for sure.  Not to bash other sub forums but this one has fewer weenies and I Ike that. 

Well, to be fair........................we have fewer people.  I am sure there is a correlation. haha

I like where we are going.  Looks changeable at the least.  Maybe we get lucky the first 10 days of January and score something minor.

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4 minutes ago, JayCee said:

Good news on the drought front.  The active weather is eating away at it, and this weekend's rains will only help further.  If we can keep the active weather train rolling, we'll eliminate most of the drought by spring. Good riddance!!

 

http://droughtmonitor.unl.edu/Home/StateDroughtMonitor.aspx?TN

Saw that earlier.  That is great news.  

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Watching the weeklies roll-in.  Not what would one expect after seeing recent operational trends.  Like the EPS they have a decent looking Pacific and a reasonable Atlantic at times(sometimes not)...and keep the cold in the West (for the mean) from d10 to d43.  At times, the weeklies have a double block and still do not move the cold East.  There seems to be a weak trough in the East at 500 and still no cold.  Weeklies don't bring winter to the East until the latter half of the first week of Feb.  It is usually a great tool, but I question that run...-EPO should put the trough in the East.  Come Feb, we are coming back to this run to see if it verifies.  Edit:. To add as well, the NAO does dip negative early in the period(between d10-20) and then rolls neutral or positive thereafter. Some of the biggest cold anomalies (late) circle the continent of Africa and Asia at the latitude of the Sahara.   By the end of the run the 850 temps across the globe are largely warm.  Weird, weird, run from a usually reliable tool that has a slight warm bias.  Some nice features on the map such as a -EPO but seems like the NAO wins the battle.  Not sure I am buying it as the weeklies have shown some difficulty in spotting cold during the past few winters, but I do give the weeklies significant weight even w the notable warm bias.  Head scratcher.  

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18 minutes ago, JayCee said:

Thanks for the info Carvers.  I think we are in for some interesting times ahead. It has to be better than last year's super Nino, at the very least;)

Strange that you mention the Sahara when it made the news today with the first snow in nearly 40 years. 

JayCee.  Yeah, man.  TRI was +12.7 for December last year.  Amazing!  Now that is a torch.  We are -1.1 this year.  I know most lean towards ensembles and for good reason past d10.  But I also follow the idea that operationals catch trends a little more quickly.  I have been encouraged by the trends recently.  Extreme cold seems to really cause issues for all models.  I think right now, as long as that cold is lurking in Canada, I am good.  I think back to several winters where we had a great storm pattern on the EC but no cold.  

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12 hours ago, Carvers Gap said:

JayCee.  Yeah, man.  TRI was +12.7 for December last year.  Amazing!  Now that is a torch.  We are -1.1 this year.  I know most lean towards ensembles and for good reason past d10.  But I also follow the idea that operationals catch trends a little more quickly.  I have been encouraged by the trends recently.  Extreme cold seems to really cause issues for all models.  I think right now, as long as that cold is lurking in Canada, I am good.  I think back to several winters where we had a great storm pattern on the EC but no cold.  

Even with Super Nino last year, we managed a cold spell or two, and had some decent snows.  Kentucky won the snow lottery.  With Nino gone, and Arctic air more accessible this year, I think we'll have some decent winter threats come January and February. 

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First glace it seems strange that the Op/Ens models are cold in the 11-15 day and then the weeklies go warm after that. Looking under the hood, some of the 11-15 day models show storminess approaching California. If it should come onshore, one might expect a short-wavelength SER downstream days 15-20. 

Such a development does not wreck January. The said pattern from California to the Southeast would be transient. I'm just trying to make sense of the data last night. Then weeks 3-4 are probably a crap shoot. I do not buy the trough west ridge east lock. Variability makes more sense with the return of baroclinicity.

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1 hour ago, JayCee said:

Even with Super Nino last year, we managed a cold spell or two, and had some decent snows.  Kentucky won the snow lottery.  With Nino gone, and Arctic air more accessible this year, I think we'll have some decent winter threats come January and February. 

Agree.  Will be interesting to see how this winter plays out.  That cold in Canada is wicked.  I think we face a continued threat for ice storms.  At some point, have to think that cold will not clear out quickly enough.  I think we have a decent chance at just a good, normal winter.  The extremes on either side exist which I am not always sure is true for every winter.  We are about to enter January with cold to our northwest, model uncertainty, and a weak La Niña.  Great time to be on the forum IMO.  Hopefully, we can get some new folks added to our forum.  Would really like to see Memphis have a nice storm.  Mempho is due a great storm out there.

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Hey PowellVolz:

Maynard Elementary - near downtown.  Originally from Texas.  Matter of fact, the tornado that hit Garland last year missed my parents' house by a few hundred yards.

 


I work for the HVAC department for the school. Maynard is one of my schools


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2 hours ago, Carvers Gap said:

Agree.  Will be interesting to see how this winter plays out.  That cold in Canada is wicked.  I think we face a continued threat for ice storms.  At some point, have to think that cold will not clear out quickly enough.  I think we have a decent chance at just a good, normal winter.  The extremes on either side exist which I am not always sure is true for every winter.  We are about to enter January with cold to our northwest, model uncertainty, and a weak La Niña.  Great time to be on the forum IMO.  Hopefully, we can get some new folks added to our forum.  Would really like to see Memphis have a nice storm.  Mempho is due a great storm out there.

Carver you convinced me.  Long time lurker here.  Great forum here.  Very level headed.  No gloom & doom.  Mr. Jeff & Carver & TN Wx Nut & John all have great posts.  Mr.  Jeff posts are great but man he brings you back to reality after seeing those weenie runs!  When he showed excitement last week I was like if he is excited so am I!   Everybody on here are great.  Very thorough discussions & repect for one another!  Really glad to have joined!

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