Fall 2017 Great Tennessee Valley Outlook

[Carvers Gap]

So the UKMET is now showing a Niña...it looks like almost like a moderate one.  First the trend was a nada (slightly plus side), then a nada(slightly negative side), then a weak Niña....man, that UKMET looked like a borderline moderate Niña.  As dry and warm as it is...I probably wouldn't even need to see the graph to know what the current ENSO state is.  This is looking more and more like the run-up to last winter minus the pattern flip.  So what could help us?

1.  The negative QBO...it could help w more high latitude blocking.  It will likely mute the almost wall-to-wall warm winter that we had last year.

2.  We are not following a Super Nino.

3.  As tnwxnut stated...it is not winter yet.   We will have to see how strong the cold fronts are this winter.  No way to no that now.  Sometimes even during the winter's with the worst signals...a decent pattern can show at the best time for climatology and we get a nice but relatively short winter pattern.  But right now, this pattern could potentially produce some incredibly warm temps(relative to norms) this fall.  After a pleasant last half of summer...the high temps of fall may rival some of the warmest stretches of summer.  The only thing keeping them from being worse will be the decline in daylight.  Thankfully we have not returned to a drought...yet.  We have had very little rain in weeks at TRI.  We only have .99 for the entire month of September w our last significant rain falling on September 5.

What are the negatives?

1.  If the Niña goes moderate, we are toast IMO.  

2.  The pattern flip right now looks about as locked-in as I have seen a pattern since...well, last winter.  The eastern ridge that is modeled is allowing almost no BN heights to even budge it.   Looks more like a summer heat ridge instead of just a SER.  If we had seen that during summer, we would have had the summer of 2016 redux.  

3.  It is almost October, so things could change by December as most normal patterns grow stale after 4-7 weeks.  The warm pattern last winter though was very stable and lasted almost the entire winter season.  That pattern began the previous spring.  What concerns me about this upcoming Niña is the pattern flip that just happened looks (as modeled) very stable as well...almost no variability, no back and forth temp swings.

 

Either way...looks like a very warm start to the fall season through at least October.

[Stovepipe]

I've already had to run the sprinkler more on the fall garden than I did all summer.  I suppose the upside to another torch winter is excellent camping weather! 

[Carvers Gap]

I would add that a couple of other things in our favor are the low solar min and whatever volcano deal happens.  Volcanoes take a few years to impact global wx in terns of cooling or heating, right? In other words, an eruption would not help this winter?

Stovepipe, having to water my yard like crazy.  I did get some monster sweet potatoes that I will try to post.  

[Carvers Gap]

...and if we have a cold, snowy winter...you can thank me for the earlier posts.

[John1122]

It seems like a -QBO may not be the best thing for us regarding winter. Some of the warmest/worst winters regarding snowfall we've had since 1979 featured the -QBO.  1985 looks like the outlier, as it was -8 during January of 85. 

Deeply negative QBO periods happened in the winter of 07-08, which was a blowtorch winter. It was almost -10 in Jan-March of 1990 and that was a torch. 2005-06 was an extremely mild winter with a very negative QBO. The average low in Crossville was above freezing for the entire month of January 2006. This with an average low of 23 for January in Crossville. 2012-2013 was a negative QBO winter. It was mild overall as well. 

The QBO was positive 1993-94 which was a cold/snowy winter. Positive during 95-96 which was extremely cold and snowy. Positive during 2009-10 which is one of the most consistently cold/snowy winters of my life. Positive during 10-11 which was also very cold/snowy. Positive during 13-14 which was frigid/snowy here. Positive during 15-16 which was mild but very snowy across the northern areas of the valley/SWVA and Southern Ky. 

[Windspeed]

I posted this in the Atlantic tropical thread. Would absolutely love this to play out next week with regards to rain either by Canadian trough or tropical moisture feed from the Gulf. We sure need it. And some cooler temperatures next weekend would be an awesome reprieve after the heat ridge next week.

The second disturbance that the models try to develop out of the W. Carib surface trough later next week is being driven up the eastern Gulf right into the Tennessee Valley. Heights crash. That's a huge shift in pattern. The ECMWF is also crashing heights over the eastern CONUS but doesn't show any particularly strong tropical vorticity coming that far north.

 

[Windspeed]

I posted this in the Atlantic tropical thread. Would absolutely love this to play out next week with regards to rain either by Canadian trough or tropical moisture feed from the Gulf. We sure need it. And some cooler temperatures next weekend would be an awesome reprieve after the heat ridge next week.

The second disturbance that the models try to develop out of the W. Carib surface trough later next week is being driven up the eastern Gulf right into the Tennessee Valley. Heights crash. That's a huge shift in pattern. The ECMWF is also crashing heights over the eastern CONUS but doesn't show any particularly strong tropical vorticity coming that far north.

 

I guess I need to be carefully optimistic as the EPS geospatial is still quite different from the ECMWF op.

[Carvers Gap]

6 hours ago, John1122 said:

It seems like a -QBO may not be the best thing for us regarding winter. Some of the warmest/worst winters regarding snowfall we've had since 1979 featured the -QBO.  1985 looks like the outlier, as it was -8 during January of 85. 

Deeply negative QBO periods happened in the winter of 07-08, which was a blowtorch winter. It was almost -10 in Jan-March of 1990 and that was a torch. 2005-06 was an extremely mild winter with a very negative QBO. The average low in Crossville was above freezing for the entire month of January 2006. This with an average low of 23 for January in Crossville. 2012-2013 was a negative QBO winter. It was mild overall as well. 

The QBO was positive 1993-94 which was a cold/snowy winter. Positive during 95-96 which was extremely cold and snowy. Positive during 2009-10 which is one of the most consistently cold/snowy winters of my life. Positive during 10-11 which was also very cold/snowy. Positive during 13-14 which was frigid/snowy here. Positive during 15-16 which was mild but very snowy across the northern areas of the valley/SWVA and Southern Ky. 

I am reading 09-10 winter as negative.....95-96 as well...93-94 as well...and 07-08 featured a QBO that broke positive late which was a quickly rising QBO where by March it was positive.  Seems like our best winters were a failing QBO(that has just flipped negative) into negative territory.  The significance of a QBO drop has a decent correlation to cold wx here.  I just don't like the forecast Nina ENSO state.  

https://www.esrl.noaa.gov/psd/data/correlation/qbo.data

[Carvers Gap]

Not to sound like a broken record...Weeklies are very warm and very dry.

[jaxjagman]

Rare to see a Nina develop so late in the year.Ninas usually develops in the late spring and summer time.1984 was the latest ever on the tri-monthlies on the ONI (S-O-N)

Though you could count 1974 as well, but this was a drop in between two Nina's.Close to being a historic Nina time

1973	1.7	1.2	0.6	0	-0.4	-0.8	-1.0	-1.2	-1.4	-1.7	-1.9	-1.9
1974	-1.7	-1.5	-1.2	-1.0	-0.9	-0.8	-0.6	-0.4	-0.4	-0.6	-0.7	-0.6
1975	-0.5	-0.5	-0.6	-0.6	-0.7	-0.8	-1.0	-1.1	-1.3	-1.4	-1.5	-1.6
1976	-1.5	-1.1	-0.7	-0.4	-0.3	-0.1	0.1	0.3	0.5	0.7	0.8	0.8

[John1122]

4 hours ago, Carvers Gap said:

I am reading 09-10 winter as negative.....95-96 as well...93-94 as well...and 07-08 featured a QBO that broke positive late which was a quickly rising QBO where by March it was positive.  Seems like our best winters were a failing QBO(that has just flipped negative) into negative territory.  The significance of a QBO drop has a decent correlation to cold wx here.  I just don't like the forecast Nina ENSO state.  

https://www.esrl.noaa.gov/psd/data/correlation/qbo.data

It's odd, the CPC site I got the QBO index from has completely different values than the ESRL side you provided.  January 1996 is +2.52 on the CPC and -5 on the ESRL. Not sure what the deal is there.

[Carvers Gap]

6 hours ago, John1122 said:

It's odd, the CPC site I got the QBO index from has completely different values than the ESRL side you provided.  January 1996 is +2.52 on the CPC and -5 on the ESRL. Not sure what the deal is there.

I am not seeing too much variation between the two sites.  93-94, 95-96, and 09-10 are negative QBOs on CPC.  Not only are they negative, but they are falling like now,  07-08 is a rising QBO late in winter.  Based on that I think a -QBO is probably a very good thing.  I still don't like the ENSO.  

Edit:  Looks to me like you are using the 50 mb values.  So, we are talking apples and oranges.  I think in general, when folks talk about a reversal in the QBO, it involves measurements at 30mb.  

http://www.cpc.ncep.noaa.gov/data/indices/qbo.u30.index

[Carvers Gap]

From ERSL...

"Quasi-Biennial Oscillation*. Calculated at PSD (from the zonal average of the 30mb zonal wind at the equator as computed from the NCEP/NCAR Reanalysis)."

....The CPC also adds 50 mb as a measure.  Either way that you look at it, the QBO is in a better place than last winter, much better or even ideal.  

[Carvers Gap]

Here is an older article from the State Climate Office of NC that I use when looking at the QBO....some folks will say correctly that the data sample is very small when trying to find specific QBO matches.  This article is a forecast for the 14-15 winter which was quite snowy here in NE TN. I started looking at the QBO because Isotherm(think that is correct) has nailed the last two winter forecasts with it.  I ignored it last winter and got burned.  Seems like when it is negative there is more high latitude blocking that helps in the East. FTR, I a, not saying 14-15 is a good match.

http://climate.ncsu.edu/climateblog?id=106

[Carvers Gap]

Here is Isotherm's forecast for last winter....great discussion utilizing the QBO.  This is why I won't ignore that index again.  Generally, then ENSO state trumps all for me.  This year the -QBO and La Niña are juxtaposed to each other.  That is why I am less certain that the -QBO will trump.  But it does seem like we will see some high latitude blocking in terms of a -NAO which may or may not help given the Niña.

 

[nrgjeff]

Regarding the October 5-10 period, occasional operational models try to lower Southeast heights but for totally different reasons. GFS plays the tropical card. 00Z Euro drops in a mid-latitude closed low. Curve balls are something to watch, but both sets of ensembles totally reject the ideas of their op runs attm.

If we can just keep humidity in check I do not mind warm days and cool nights. Lower sun angle, if low humidity, should keep even much above normal temps comfortable.

Euro weeklies are pretty warm. CFS introduces a mid-October cold front, separate from and later than the Oct. 5-10 question. CFS has caught swings better than the Euro. Punting additional seasonal thoughts until next week.

[John1122]

5 hours ago, Carvers Gap said:

From ERSL...

"Quasi-Biennial Oscillation*. Calculated at PSD (from the zonal average of the 30mb zonal wind at the equator as computed from the NCEP/NCAR Reanalysis)."

....The CPC also adds 50 mb as a measure.  Either way that you look at it, the QBO is in a better place than last winter, much better or even ideal.  

I was looking at the 50mb measure. It's vastly different for whatever reason.

[John1122]

To me the weather drivers here in winter are the PDO/PNA/AO/NAO primarily. Then other factors like Nina/Nino.  We've seen the northern Pacific conditions completely overwhelm the ENSO state in recent years both for good and bad. It even overwhelmed the +AO/NAO. These two haven't been particularly favorable in almost 10 years now but we've had several very good winters, driven by a favorable north Pacific.

I do hope you are right about the QBO. I just watched a video and in the person who made it's mind, there just isn't enough correlation between QBO and any observed weather to make any definitive statement. They pointed out a general lack of analog years to draw any conclusions, as Jax mentioned earlier. They mentioned a couple of years where there were similar atmospheric/solar conditions and a negative QBO where winters were the exact opposite in the East with one being cold/snowy and the other being very mild.

[Coach B]

3 hours ago, nrgjeff said:

 

If we can just keep humidity in check I do not mind warm days and cool nights. Lower sun angle, if low humidity, should keep even much above normal temps comfortable.

Totally agree! I'm a big fan of the Fall blowtorch. Great time of year to be outside in our part of the country. As long as we can keep it below the mid 80s and we don't have major fire problems I say get out and enjoy it. There is plenty of cold, dark, and dreary to come in winter even in bad years. 

[Carvers Gap]

2 hours ago, John1122 said:

To me the weather drivers here in winter are the PDO/PNA/AO/NAO primarily. Then other factors like Nina/Nino.  We've seen the northern Pacific conditions completely overwhelm the ENSO state in recent years both for good and bad. It even overwhelmed the +AO/NAO. These two haven't been particularly favorable in almost 10 years now but we've had several very good winters, driven by a favorable north Pacific.

I do hope you are right about the QBO. I just watched a video and in the person who made it's mind, there just isn't enough correlation between QBO and any observed weather to make any definitive statement. They pointed out a general lack of analog years to draw any conclusions, as Jax mentioned earlier. They mentioned a couple of years where there were similar atmospheric/solar conditions and a negative QBO where winters were the exact opposite in the East with one being cold/snowy and the other being very mild.

I am not stating the QBO is the driver this winter, just that 30mb is the level that is used to say the QBO is negative or not.  Really, they are just measuring a prevailing wind about fifteen miles up near Singapore that has some correlation to high latitude blocking.  I think it is similar to the MJO in that it is more useful during some winters than others.  I do find it interesting that our string of above normal months was broken as the QBO flipped negative.  And I did note that some forecasters do not like to use the index. Like I said, I think the ENSO states trumps the pattern.  Isotherm, a meteorologist, used the +QBO to nail the last two warm winters...he actually was one of the lone warm winter forecasters for whichever year everyone said it would be cold.  I ignored it last winter and vowed never to ignore it again.  I think with anything in the weather, one can easily be humbled if they don't take into account multiple drivers.  Even then, there is no magic wand that makes forecasting easy as we all know. That is why I say seasonal forecasts should never be held against a forecaster.  Some years are easier, especially if the Nino or Niña is strong.  But this winter is a bit more sketchy.  The Nino hangover is basically over.  We are coming off a weak positive state.  The solar min us approaching.  The QBO just flipped negative.  And that falling -QBO corresponds to some great Tennessee winters.  It correlates very well to the winters that you listed.  I had already looked at those before making my initial statements.  Had to do a double take when you showed the 50mb numbers.  If this Niña goes moderate, we are in trouble IMO.  However, weak Ninas combined with a dropping -QBO have been a good combo.  What I don't like is the LR model trend to strengthen the Niña.  Now, I have seen some recent info that states that a few regions are not dropping as quickly as forecast and have even risen in temps slightly.  Jax can keep us updated.  All of that said, I do not like the pattern flip in light of the ENSO evidence.  The atmospheric reaction in NA is similar to a Niña that is moderate to strong, and a Niña generally correlates to a warm SE.   But like Jeff said...really going to have to get to the end of October before anything definite can be said.  A weak Nino is our best driver in E TN, but that is not true for the entire forum I realize.  Next would be a weak Niña.   I am not to the point where I can say that a -QBO will trump the ENSO state.  But the -QBO does correlate very well to some great winters in the eastern Valley.  But I would think the tone of my earlier posts would indicate that I am not overly enthused....but like the weather, that could change.  After suffering through a miserable fall last year, I just want normal weather.  

Also, for those of you who suffered through that long post stormchaserchuck has a great post on the NAO and Niña on the main discussion forum.  It really is outstanding and would be encouraging to those of you who want a -NAO....

[Carvers Gap]

And as for things correlating.  Sometimes studies lead us to believe that things correlate when they don't.  Event still, correlation does not always imply causation.  Snowfall in Siberia, anyone?  Here is a great link to some numerous correlations.  About the best correlation that we can use are oceans because they cover so much of the planet.  The very best forecasters use them for seasonal forecasts.  I just hope the UMass game does not correlate the way that I think it will to the UGA game...

http://www.dailymail.co.uk/sciencetech/article-2640550/Does-sour-cream-cause-bike-accidents-No-looks-like-does-Graphs-reveal-statistics-produce-false-connections.html

[jaxjagman]

The jury is still out what kind of Nina we will have if we do even have one.Right now a Upwelling Kelvin Wave moving around the equatorial Pacific looks even stronger than a few days ago

[Carvers Gap]

On 9/28/2017 at 3:36 PM, Windspeed said:

I posted this in the Atlantic tropical thread. Would absolutely love this to play out next week with regards to rain either by Canadian trough or tropical moisture feed from the Gulf. We sure need it. And some cooler temperatures next weekend would be an awesome reprieve after the heat ridge next week.

 

 

You have been killing it in the Tropical thread.  Good posts.  

[Carvers Gap]

Vanuatu is currently erupting.

[John1122]

Mt Agung which is close by is also getting very close to erupting. Mt. Agung last erupted in 1963. It caused a .5 C drop in global temperatures. Temps are effected more globally with further south volcanoes. Two factors on why Mt St Helens, which was a sizeable eruption, didn't effect climate more were that it was as far north as it was and that it blew out sideways instead of up.

[nrgjeff]

I am warming my winter forecast for work. Evidence for normal is fading.

Before diving into reasoning, I will agree the -QBO does not hurt but it does not at all mean cold South  It may deliver cold into North America, but other ingredients are needed down South. PDO/PNA/AO/NAO have greater correlation but even they do not act in a vacuum. 

September concluded like August, near normal temps when averaged over our entire region. Any cold Aug/Sept cold winter correlation is tossed, since neither month was cold. What about warm North October? Regardless of how our own temps turn out, warmest October anomalies are forecast North. Southeast could turn cooler than normal in November. Theory goes that deeper into winter the wavelengths become longer. Unfortunately, by December it has the Plains warmth expanding into the Southeast. Yeah that hurts.

While I will concede a cooler than normal November in the Southeast under a mild North, I have to go warmer for December and January just about everywhere. Maybe another chance of cold in February. Well, that's a good time for cold considering our snow climo. Think positive. 

[Carvers Gap]

2 hours ago, nrgjeff said:

I am warming my winter forecast for work. Evidence for normal is fading.

Before diving into reasoning, I will agree the -QBO does not hurt but it does not at all mean cold South  It may deliver cold into North America, but other ingredients are needed down South. PDO/PNA/AO/NAO have greater correlation but even they do not act in a vacuum. 

September concluded like August, near normal temps when averaged over our entire region. Any cold Aug/Sept cold winter correlation is tossed, since neither month was cold. What about warm North October? Regardless of how our own temps turn out, warmest October anomalies are forecast North. Southeast could turn cooler than normal in November. Theory goes that deeper into winter the wavelengths become longer. Unfortunately, by December it has the Plains warmth expanding into the Southeast. Yeah that hurts.

While I will concede a cooler than normal November in the Southeast under a mild North, I have to go warmer for December and January just about everywhere. Maybe another chance of cold in February. Well, that's a good time for cold considering our snow climo. Think positive. 

Thanks for the post.  Yeah, my enthusiasm has definitely been tempered w the recent pattern flip.  The -QBO is one of the few signals not pointing towards a warm winter.  The ENSO state is just not good, and it is my personal trump card.  Hope it stays weaker.  LR modeling really likes a western trough as a base pattern.  Maybe we can beat the odds for once.   But realistically, there are plenty of reasons to go warm.  

[Carvers Gap]

8 hours ago, John1122 said:

Mt Agung which is close by is also getting very close to erupting. Mt. Agung last erupted in 1963. It caused a .5 C drop in global temperatures. Temps are effected more globally with further south volcanoes. Two factors on why Mt St Helens, which was a sizeable eruption, didn't effect climate more were that it was as far north as it was and that it blew out sideways instead of up.

Agree.  Hate it for the folks near the volcano, but indeed, that is a wild card...

[Windspeed]

Models may score us a nice tropical feed next week. Both majors are still trying to bring whatever becomes of the tropical disturbance in the W. Caribbean through the GOM and as far northeast as the southern Appalachians. Obviously, timing and track of the future cyclone and the longer trough digging into the eastern CONUS are all major players for increased chance of significant precipitation that we so desperately need. Obviously not wishing any landfalling hurricane on the northern Gulf Coast, but chances of a good rain event is increasing.

 

[Carvers Gap]

Thanks, John, for letting us hijack your fall thread to talk winter.  Now, back to mid-range discussion.  Like Windspeed stated....looks like a tropical connection is possible late this weekend and into early next week depending upon your model preference.  I don't want to get my hopes up too much.  Looks like this will impact the eastern side of the forum area.