Tennessee Valley 2019 Fall Speculation/Forecasting

[Carvers Gap]

10 hours ago, Mr. Kevin said:

Carver, i am not sure its a good thing to see it real cold this early. I live in Arkansas, but that may not make any difference. It was cold last November and in 2011 and the following winters blowtorched. Alot of interesting signs already. 

A big snowstorm in NE TN in late October is the kiss of death here.   Cold Novembers, as John has documented, generally favor cold winters.  Last winter was an exception to that rule.  As Jeff noted as well, probably want to see some strong cold fronts then - the winter will remember what happens in November.  However, I really don't like seeing snowstorms in October - though I don't really have a choice in the matter so I just enjoy it anyway.  LOL.  I definitely think there is always a danger that sometimes cold source areas get emptied of cold and then it takes them some time to rebuild.  Though, I am sure there is a line of thinking that cold sources can replenish quickly.

[Daniel Boone]

I can remember October 1976 being one of the coldest on record as was November and the Winter became the famed frigid Winter of 77.  The following Winter had an early severe cold blast that brought snow to even the lower elevations on the 13th of October.  However, the rest of the month was rather mild as was early November . Things changed abruptly after the 20th and Dec thru mid March was cold and snowy. 

So, there are exceptions to the cold October =mild winter, cold November =cold winter rule. Of course, we are in a different era climate wise now and of all the years of record, odds favor the cold November cold Winter rule .

[John1122]

It snowed here several times in October 1995, one about 3/4ths of an inch. Didn't slow winter of 1995-96. Also had 3 inches Halloween 1993, January 1994 was brutal. 

[Daniel Boone]

 I remember those well too John. Had those recorded in my records of which got misplaced during relocation. Don't know why those didn't come to mind. Only snowed once here oct. 95 . Recorded 1.5" Halloween 93 with about 2" the 1st of Nov. . Jan. 94 was cold here but only received 1 significant snow. 7 inches. 95-96 ; 52 inches.

[Carvers Gap]

Pretty good illustration of the hemispheric pattern where the wavelengths are really shortened up likely due to the season change.  Finally have the term I was looking for earlier in the thread - wave.  So, wave3 and wave4 patterns are fairly stable IMHO with w4 patterns being very common during winter(correct me if I am wrong on that).  The wave6 pattern below is probably not sustainable for very long.  What becomes the stable pattern once this(if it even verifies) reverses back to a wave4 or wave3 pattern is debatable.  Pattern could revert back to the most recent warm pattern or form something new.  IMHO, sort of like spinning the wheel on the old Price is Right.  The wheel is gonna eventually stop...but can we win a new car is the question?  Also note this is waaaay out there and may not verify...but this also might explain why the GFS is so cold - cause it might be wrong.  LOL.  Anyway, I thought it was a interesting look even if it didn't verify.  

 

 

[nrgjeff]

High numbers sell subscriptions. Carvers is right, reality is 3 or 4 is actually more impressive. Oh well. Wx Twitter is awful. Wake me up in May?

Oops this is not Banter, I have to say something other than biting cynicism. Hour 360 EPS is nearly unanimous still cold. 15 days out is not too reliable; but, the consistency is notable. Can it carry to mid-Novie?

[Carvers Gap]

I actually like wx twitter...just have to filter out the blah.  I literally only follow like twenty people total on Twitter.   For me, pics use up a ton of my AmWx storage, so just easier to use a Tweet.  Point is the with Tweet above, though we are about to enter a normal to BN pattern...tough to extrapolate that too far out as the 6wave pattern is likely not sustainable - need to have a more stable wave pattern.  That will likely break down fairly quickly.  For those saying there will be a quick return to warmth, that pattern probably supports that - meaning it will break down.  That 6wave pattern is fairly progressive and won’t allow heat to build over one area for long.  But once it breaks down heat will possibly build under either a western or eastern ridge.   

[nrgjeff]

Oh yeah I totally agree with you Carvers. Also understood your skepticism with the tweet. Good posts. 

Some Wx Twitter is great, like Anthony, Grit and others. Also some Strato experts and Climo scientists I follow. Somehow, even with a good follow list, retweets sometimes get thru. Even if they are making fun of it, I still get high blood press.

Anyway the GFS and GEFS are still frozen out to Day 15. EPS usually does not bounce around a lot. Figure it will stay cold. Occasionally has 8-10% cluster a little warmer SE. However the rest are full-on full-latitude trough. Looks cold end of Oct.

Back to the busy hemispheric pattern, jury is out of November. Fingers crossed.

[Holston_River_Rambler]

Speaking of the Euro and cold, the end of last nights OP run looked pretty nippy for late Oct.  I'll throw the gif out for fun, but just the precip. one since the temps don't actually look all that bad lol, but maybe my standards for cold are too high:

Isobars running from Baffin island to Iowa. I imagine if this verified it would be hard freeze time once that front clears us. 

I know it is just one run, but the GFS has spit out some pretty cold solutions in the Halloween time frame.  The question now seems to be, as y'all say above, will this be a cold outbreak before a pattern shake up? 

 

[AMZ8990]

Looks like the -NAO is trying to show back up on modeling.  If what is being showed happens in reality ( not just on modeling) then that probably  ups the chances of it happening again, due to feedback loops.  We haven’t been in that type of flow in a few years so I’m excited to see how this progresses!

[PisgahNCWeather]

Would be nice to see. Naysayers are already out in force saying the Euro is developing another SE ridge at the same time. I guess we will see once again.

[AMZ8990]

1 hour ago, PisgahNCWeather said:

Would be nice to see. Naysayers are already out in force saying the Euro is developing another SE ridge at the same time. I guess we will see once again.

Time will tell, doesn’t surprise me though given how stubborn the SE ridge has been to us in recent memory.  The next 10-15 days should give us some clarity. 

[jaxjagman]

4 hours ago, PisgahNCWeather said:

Would be nice to see. Naysayers are already out in force saying the Euro is developing another SE ridge at the same time. I guess we will see once again..

We'll have to wait and see what happens,right now.The pattern we are in right now with the MJO being stuck MORE into the western IO due to the low into the eastern IO that seemingly that is not going to end anytime soon .The MJO signal right now is warm but yet unstable,this could be one of the best severe falls we've seen in some time,seemingly right now

[Carvers Gap]

6 hours ago, PisgahNCWeather said:

Would be nice to see. Naysayers are already out in force saying the Euro is developing another SE ridge at the same time. I guess we will see once again.

Definitely a weak trend long term to slide a SER in south Georgia and the coastal Carolinas.  With that cold water off of South America, does not surprise me at all.  I continue to think a back-and-forth pattern is likely with cold building in the northwest and surging SE w/ arm air surging in between cold air masses...and significant(but temporary) heat at that.  Sometimes with ensembles, the average/mean shows up and the average or mean is not the actual weather.  That SE ridge is going to be significant in front of incoming cold fronts, and I wonder if maybe that is why it is showing up.  The GEFS nor GEPS have this, but the overall long wave pattern over NA is fairly similar among all global ensembles - GEFS would have a SER if it backed up a few hundred miles.  The Euro does a good job in detecting that SE ridge early.   Now, the Euro bias is also to hold cold air back in the SW.  However, it has been correct about this for months on end, but sometimes it misses because of this.  I think with it being shoulder season, we are just going to see an unsettled pattern.   This past week is probably a great example.  Lots of conflicting signals out there, and I am sure it is playing havoc with LR modeling including along with the changing wavelengths of the season.  Lots of moving parts.  

[nrgjeff]

Naysayer warning, hatched 15%! Indeed ECMWF and now GFS are slowing down and weakening fronts into the Southeast. Believe the cold SSTs off SA have something to do with it. Also wavelength issues associated with split MJO convection. Japan's Himarwari satellite shows it so well. Convection crossing the Date Line would be a cold signal. Ooops! Got new blowing up in the Indian Ocean too.

This winter is going to be a headache. Believe we'll get a couple legit shots and a lot of false alarms. I'm looking forward to forecasting it like I look forward to a root canal. Otherwise mild, I can't help it.

[Carvers Gap]

Not a ton this AM that hasn't already been discussed.  Sometimes that EPO ridge can bee too much of a good thing.  Looks like the Euro is correctly placing energy into the Southwest sort of underneath that big ridge.  We have seen that many times during past years.  Cold is forecast for the East and the model corrects by dropping it into the West underneath a big West Coast, coastal high.  Fortunately, I wasn't totally bought into the cold Eastern solution quite yet.  I do think it is a situation where the trough still eventually goes into the East.  The GEFS has corrected towards the EPS solution this AM which is of no surprise at all.  I actually like the 6z GEFS run as I suspect that might be how it evolves at 500.  Energy hangs back and then kicks out...and the eastern trough reforms for a time.  My money is on a big warmup next weekend into early next week.  Would not surprise me to see some record highs fall, though I have not looked at them recently.  I made a mental note a few weeks ago that there were some low-hanging fruit record highs in late October.   This week should be pleasant with seasonal to slightly BN.  The 12z runs will be interesting to see if the the GEFS and EPS continue to move towards each other.  Some say the recurving typhoon over Japan is responsible for the bouncing around of the EPS over the weekend.  I think it is just fall, and well within what normally happens...which means LR ensembles are notoriously fickle at this time of year.  I still think the overall pattern is one where cold builds out West and then surges eastward with big fronts.  Warm surges behind those fronts on return flow.  Wash, rinse, repeat.  Pretty classic fall pattern.  In other words, fairly progressive pattern where nothing really holds yet.  

[Carvers Gap]

Just tagging onto my earlier post.  I think that 6z GEFS(10.21.19) run still looks like a good compromise.  Looks like the 12z GEFS and EPS have their act back together...at least for this run.  Very similar runs and placement of features.  Looks like both moved towards each other.  About the only thing different from a few days ago(looked super quick...so don't consider this a scientific statement with loads of rigor) is a cut-off that will dive into the southwest.  "Looks" like the Euro has resolved leaving the low in the Southwest versus just dumping every subsequent cold shot there.  IMHO, that is just normal bias working itself out.  My main concern, is that has sort of been the actual solution(cold dumping West and staying) for about ten months so I am definitely gun shy.  Basically a progressive pattern with warm and cold dispersed fairly evenly.  Weeklies will run off a very warm run...bet they would have looked different if derived from the 12z. 

[nrgjeff]

You should see the Euro, Canadian and UKMet for the weekend low coming out of Texas. They all strongly agree with each other, and the GFS is an outlier. Probably go warmer Euro next week. Now the 11-15 day period they are all cold. That case, GFS might be better for intensity.

Interesting follow up to the conference I attended a couple weeks ago. While a -EPO is cold here a strong --EPO actually buckles the flow too much. Trough dives into West/Plains first and pops a SER. Even with a slight -NAO the SER oozes up. Can't really share pics but we've all seen it plenty the last year or two. Super blocking may be too much of a good thing.

More examples of extremes disappointing compared to moderate. We like Alaska and Greenland together; but, too much too strong and the snow is Deep South, leaving us dry cold. Severe wx indices pegged off the chart normally ends up too much convection for chasing. How about the Miller A that pulls in too much warm air vs a Miller B slider?

In the past I wrote about a weak source region; however, I think that's not all. West/Plains had some serious cold when we missed. I think it's the over-buckling of the jet stream. Wavelength shortens a little and SER forms. With all this super-blocking early strato warming, probably too much. Just go mild. (Ducks for cover)

Honestly think it'll be variable mild, but with some cold shots. Eventually the shallow cold air oozes in if a couple short-waves chip away at the SER. Midwest cutters of course fail. Should be a challenging mix this winter. 

[Carvers Gap]

3 hours ago, nrgjeff said:

You should see the Euro, Canadian and UKMet for the weekend low coming out of Texas. They all strongly agree with each other, and the GFS is an outlier. Probably go warmer Euro next week. Now the 11-15 day period they are all cold. That case, GFS might be better for intensity.

Interesting follow up to the conference I attended a couple weeks ago. While a -EPO is cold here a strong --EPO actually buckles the flow too much. Trough dives into West/Plains first and pops a SER. Even with a slight -NAO the SER oozes up. Can't really share pics but we've all seen it plenty the last year or two. Super blocking may be too much of a good thing.

More examples of extremes disappointing compared to moderate. We like Alaska and Greenland together; but, too much too strong and the snow is Deep South, leaving us dry cold. Severe wx indices pegged off the chart normally ends up too much convection for chasing. How about the Miller A that pulls in too much warm air vs a Miller B slider?

In the past I wrote about a weak source region; however, I think that's not all. West/Plains had some serious cold when we missed. I think it's the over-buckling of the jet stream. Wavelength shortens a little and SER forms. With all this super-blocking early strato warming, probably too much. Just go mild. (Ducks for cover)

Honestly think it'll be variable mild, but with some cold shots. Eventually the shallow cold air oozes in if a couple short-waves chip away at the SER. Midwest cutters of course fail. Should be a challenging mix this winter. 

Definitely watching the weekend system as the marching band is heading to Virginia for another big regional competition.  Pretty amazing to see the GFS is handling that system totally different.  Lots of rain on Saturday w the GFS where the non-GFS models take the same system into the Plains.  Hoping the non-GFS suite wins this battle, even if it means dealing with a SE ridge for few more days!!!   Watching the 12z suite closely. 

[Carvers Gap]

And sure as heck...the Euro trended eastward for the weekend system.  LOL.  Not quite in Virginia yet, though.....

[tnweathernut]

2 minutes ago, Carvers Gap said:

Definitely watching the weekend system as the marching band is heading to Virginia for another big regional competition.  Pretty amazing to see the GFS is handling that system totally different.  Lots of rain on Saturday w the GFS where the non-GFS models take the same system into the Plains.  Hoping the non-GFS suite wins this battle, even if it means dealing with a SE ridge for few more days!!!   Watching the 12z suite closely. 

Definitely leaning toward the non-us modeling.  Selfishly I'd like to see it dry for Friday night football and the TN SC game Saturday.  Pretty amazing to see the wide spread between the GFS with the system.  Heck, the GFS has very limited rains west of I-65.  Some of the other modeling has most of the rain much further west.  

[tnweathernut]

2 minutes ago, Carvers Gap said:

And sure as heck...the Euro trended eastward for the weekend system.  LOL.  Not quite in Virginia yet, though.....

Well, that's great.  Glad I could post without checking first..... lol  

Per the 12z Euro, the Friday night games in middle Tennessee (north) might stay dry for Friday and the TN SC game might be "workable" too, with some drying and warmer temps ahead of the front.  Would probably be breezy and warm in Knoxville if that run comes to fruition.

[Carvers Gap]

19 hours ago, tnweathernut said:

Well, that's great.  Glad I could post without checking first..... lol

I think we are still OK for Friday night football in E TN as is...maybe not west.  UT game is OK as is...but the rain trending more quickly eastward I don't like.  LOL.  Hey, I posted without looking at the 12z Euro either.  I was like...maybe I better go look.  I don't think the slp track is that much different which is basically eastern Oklahoma to Chicago.  However, the precip on the east side is much more robust and moving more quickly eastward.  The Euro still looks much different than the GFS, but not so sure it didn't blink just a tad.  Besides, a rainy game Saturday might be in the Vols' best interest with our QB situation, just not great for the fans!

[Carvers Gap]

Just when we think it is time to go back in the water...the 12z Euro operational flips much cooler.   The handling of the weekend system does seem to be a lynchpin to the short range pattern that occurs after.  One can definitely see that big EPO ridge.  It certainly plays a key roll as Jeff spoke about in his earlier post.  The EPS tamps it down a bit.  Even the control has changed the configuration a tad, ie weakens it w vortices rolling into it and strengthens it at other times when compared to the previous run.  Still is a big, big ridge that seems semi-constant.   I really have no idea if the Euro continues by kicking out the undercutting trough, splitting the troughs rolling down the front range,  or if it returns to the Southwest during subsequent runs.  None of those would be a surprise and well within the norm of energy diving into the West.  That tuck has been a stubborn feature of for many months/years.  In a year not named 2018 or 2019, I would say it is normally an error by the Euro, but sometimes verifies as cutoff lows in the Southwest are not that rare.  That said, Euro guidance did surprisingly move towards the GFS at 12z.  If that trough tucks in under that EPO ridge intermittently during the next few months, going to be nearly impossible to know when it tucks and or when it is in error.   Do I believe any particular model at this point?  Nope.  Though it would be interesting if the GFS is actually correct about the energy coming through TX over the weekend... 

[John1122]

The Euro is extremely wet, especially for the southern valley where the drought has been the worst. It's spitting out some 5-8+ inch rain totals over the next 10 days in Northern Alabama. 2-4 pretty wide spread over the rest of the region except for Memphis/Eastern Arkansas where it's closer to 1-2 inches. GFS is way drier and only gets Nashville East basically with it's heaviest rains being far Eastern areas and Western NC.

[John1122]

GFS stepped towards the Euro, no more open wave that just blows through the area. It bullseyes Chattanooga with 5 or so inches of rain this weekend. 2-3 for most of the rest if the Valley. 

[PowellVolz]

GFS stepped towards the Euro, no more open wave that just blows through the area. It bullseyes Chattanooga with 5 or so inches of rain this weekend. 2-3 for most of the rest if the Valley. 

UT football game looks wet


.

[PowellVolz]

UT football game looks wet


.

Actually (LOL) now it looks dry as the down sloping is set up nice to shadow the valley most of Saturday


.

[Greyhound]

I think this is just all a preview of what to expect for winter:  GFS doing it's own thing while every other model is in step with each other..........only to have downsloping make everyone look silly once again for having the slightest amount of hope.  

[Carvers Gap]

It is shoulder season right now, and models are notorious for misses during this time of year.  Last year, the Euro was all-in on a warm November and missed badly - me included.  Then the Euro and its Weeklies(and seasonal runs) whiffed on the winter pattern.  The JMA for last winter was truly bad.  The GFS has done reasonably well in at least signaling cold outbreaks in NA where the Euro had none at all.  Problem with the GFS and the Euro as well, is the are struggling with the MJO which is causing havoc in downstream forecasts, ie ridge and trough placement.  I think the Euro has been a little more consistent though it did a huge flip over the weekend with the ridge/trough alignment over North America.  The good thing is that if each model's bias is taken into account...they have been serviceable.  For example, the Euro was a bit too wound up with the Plains system and pulled the precip field back too far.  The GFS was too progressive.  The Euro moved about a 1/3 of the way to the GFS and then the GFS backed up 2/3 of the way.   

As for upcoming ten days, likely plenty of back-and-forth temps.  The past week at TRI has been slightly BN - thankfully!!!!  I think the next ten days will be similar.  D10-15 seem to indicate an eastern trough with AN heights building underneath.  That can create forecasting headaches if true.  EPS troughs in the d10-15 seems to actually verify much stronger.  Conversely, ridging is much stronger.  I think once we get into the second week of November, we might see temps move to tolerable AN values with cold shots building in the Rockies and surging eastward.   Still looks like the same pattern that we are in, but slightly warmer - that is not set in stone!

Honestly, the current October and November pattern reminds of the spring pattern with the SER present just enough which allows for precip to come into play - not talking flooding, just the pattern.  Thankfully, Virginia looks rain free for Saturday!!!  Last marching band competition of the season.  These temps have been a welcome relief to all of the HS and college sports teams who have had to practice outside.  It has been truly pleasant.   

Lastly,  the leaves are now changing in earnest in this area.  These cool nights and plentiful precip of late have really hurried things along.  Not sure my garden will ever produce again at the level it has this fall regarding cool season crops.  The shorter days combined with warm weather has made for nearly perfect conditions to grow some of those crops.  My scallions and garlic are just coming up.  They really don't like to poke through the soil until the cooler temps of fall show up.  Over the next three weeks, the early season cool crops will die back and the late season cold crops of garlic and scallions will take over.  Interesting fact....Scallions are multiplier onions.  This means that you can put one in the ground and it will form a large clump of onions similar to planting just a single potato.  Garlic will be harvested late next spring or early summer.  Scallions will likely be ready during spring.  I have heard that cold winters make garlic have more flavor, as if it needed it!  Honestly, garlic is one of the few things in my garden that doesn't taste much different than what is purchased in the store.  I grow it because, it looks cool and I also know that it has been grown in mostly organic soil.  Most things from the garden taste much better than store-bought, because one can pick them while ripe thus preserving the sugars found in them.  Things that taste notably better than store-bought:  carrots, salad greens, tomatoes, squashes, beans, potatoes(all varieties), onions, and herbs to name a few.  Best thing about garden food is that you know how they were grown.