Fall 2017 Great Tennessee Valley Outlook

[John1122]

Looks like a long term pattern shift inbound. Trough in the West with BN temps and mountain snow, which gives AN temps East of the Rockies in the 6-15 day range. We'll see if this is progressive and only lasts a week or two or becomes a longer term feature after being almost exactly opposite of this pattern for most of late July-Early Sept.

 

[Carvers Gap]

Can't see today's Weeklies yet...but the Weeklies from last TR had a transient northwest weeks 2-3 trough w somewhat slightly BN heights continuing in the SE long term after that.  I think Jeff sees Monday's Weeklies early.  Maybe he could give us a hint.  If not, they will roll within a couple of hours.  Will try to check back then.

[Carvers Gap]

12z EPS today definitely looked like a pattern change.  I bet that -QBO won't let that hold though....it is tanking.  It was -14.42 for August.

[nrgjeff]

Euro weeklies are warm next week through end of Sept. Right as the month changes, October resumes a cool look here. Mild North so no early polar pigs. Leaves should continue ahead of schedule all elevations.

Chattanooga winds of 25 mph gusting to 40 mph. Basically it is like any March day in Kansas but with rain. Could be a little higher toward 02Z but I'm thinking my lights stay on. Higher elevations could be more tricky. Low clouds are really screaming and Doppler radar confirms. 

[jaxjagman]

34 minutes ago, nrgjeff said:

Euro weeklies are warm next week through end of Sept. Right as the month changes, October resumes a cool look here. Mild North so no early polar pigs. Leaves should continue ahead of schedule all elevations.

Chattanooga winds of 25 mph gusting to 40 mph. Basically it is like any March day in Kansas but with rain. Could be a little higher toward 02Z but I'm thinking my lights stay on. Higher elevations could be more tricky. Low clouds are really screaming and Doppler radar confirms. 

Marker on my Radar shows 44mph at the Chatty airport

[nrgjeff]

Euro weeklies showed a little consistence for once. Weeks 1-2 are still shown warm. Weeks 3-4 are closer to normal. CFS goes cooler those weeks. Euro might be missing a cold front or two.

Despite the La Nina watch I would not give up on winter yet. The deeper we get into Nina, of course the warmer the signal. However the QBO will be fighting it. I am watching the North Pacific SSTs. If those cool anomalies make it to the West Coast then I might throw in the towel. 

Confidence will be better in about a month. Let's see how September averages out and how October starts. Cool Aug. Sept. Oct. correlate with cold winter. Though causation is not guaranteed in cookbook meteorology, it is still another valid tool.

[Carvers Gap]

I can live w a weak Nino and -QBO.  We go moderate amd another warm winter is prob on tap.  The ENSO graph had been slightly positive (if I rem correctly).  The recent month of BN temps and cool, rain days reflected that.   Fortunately this Nina appears tp be weak.  Those can be good winters.  John, what do your family records show regarding -QBO and weak Nina winters?   I think we will be ok as we are not fighting a huge hangover from the Super Nino...maybe just fighitng a lingering headache.

[Carvers Gap]

And truly, winter patterns are fickle.  I have seen great signals for winter result in cold, rainy winters.  I have seen winters w marginal signals do very well.  Like I said above, moderate-strong Ninas or super Ninos...almost always result in warm winters. I am no fan of nadas either. Need a weak enso driver either way IMO.  Also, we won't know how blocking will look for a couple of more months.  Have to think the -QBO will help there.  It has a very decent correlation to recrent, good winters.  Also, John, we had kicked around the idea that warm winters seem to come in 2s or 3s here...wondering how that idea might factor as well?  Jeff, great write-up BTW... The rest of you need to jump-in as well.  Nobody holds anyone accountable for seasonal forecasts because they are so tough to get correct.

[John1122]

17 hours ago, Carvers Gap said:

I can live w a weak Nino and -QBO.  We go moderate amd another warm winter is prob on tap.  The ENSO graph had been slightly positive (if I rem correctly).  The recent month of BN temps and cool, rain days reflected that.   Fortunately this Nina appears tp be weak.  Those can be good winters.  John, what do your family records show regarding -QBO and weak Nina winters?   I think we will be ok as we are not fighting a huge hangover from the Super Nino...maybe just fighitng a lingering headache.

I'll check into the years of -QBO and weak Nina in a day or two. We do seem to have pairs of warm winters followed by normal to cold winters for a couple of years and last winter was the 2nd in a row above normal. I'll look closer at that too.

[Carvers Gap]

Been doing a bit of digging w La Niña winters, weak to moderate.  Their are some very decent analogs.  I would suspect they correlate well with a -QBO and when also coming off a Nino-ish "bounce."  With that in mind I am actually optimistic that this winter will be a good one.  

http://ggweather.com/enso/oni.htm

[jaxjagman]

Wondering if we see some tropical genesis the end of the month into the first of the month of Oct.It's rare to see Mid Tn feel the effects of any tropical system 2 times much less 3 times which could be possible.Guess we'll see

[jaxjagman]

8 hours ago, Carvers Gap said:

Been doing a bit of digging w La Niña winters, weak to moderate.  Their are some very decent analogs.  I would suspect they correlate well with a -QBO and when also coming off a Nino-ish "bounce."  With that in mind I am actually optimistic that this winter will be a good one.  

http://ggweather.com/enso/oni.htm

You're not going to find any great analogs with past winters with a -QBO and Nina.We generally see the QBO fall off into the winter months,not always but in general it does.In 2000 which is closer in modern day era there was a severe drought in North America at this time also in 2000 the tropics were nothing but dead,not like this season

[jaxjagman]

US National Weather Service Nashville Tennessee

17 hrs · 

This sudden re-emergence of summer isn't how we had planned autumn's overture. It was all humming along nicely until about 3 days ago when the sun finally re-emerged after Hurricane Irma's remnants and then summer released all that pent-up heat. Looking out 240 hours, which is as far out as the GFS & European models will take us, we don't see any pattern change. There are currently two hurricanes in the Atlantic, foremost of which is Jose, and he has not been playing nice. As long as he's around, the atmospheric circulation that affects us is in sort of a holding pattern. There is a ridge of high pressure running along the Appalachians, and a trough of low pressure stuck over the Great Plains, and as long as that trough stays to our west, there is no available mechanism to affect an air mass change. So that means above normal temperatures for at least the next 10 days. From tomorrow through Sunday, Nashville's predicted highs range from 85-89°, and our lows will run 65-68°. Granted, these aren't exactly oppressive temperatures, but normal high for today is 82° and normal low is 60°, so you have to conclude that we're being shafted. One could point out that the first half of September was well below normal, and there's that whole law of averages thing. But the law of averages also owes us a pleasant, placid and prolonged autumn followed by about 100 inches of snow this winter, and a list of other things. (We meteorologists have grievances, too.) Trust me, we at the NWS aren't happy about this turn of events, but it is what it is.

[Carvers Gap]

The Weeklies revert back to a cooler pattern after week one.  By week's 5-7, all of NA is pretty much AN.  Weeklies go into early November.

[Carvers Gap]

Just looking at the 15 day EPS....cool down in the middle, but overall a very warm/dry pattern beginning to build d10-15.  Some hints, though nothing definitive, that our cool pattern has one more gasp, and then the pattern flips warm and stays warm.  

[jaxjagman]

Jamstec,IMME and NMME all show AN precip in D,J,F.

[nrgjeff]

October is a tricky time for the weeklies. If we get a quick cool-down followed by warm, esp with a GOA, I will start becoming skeptical of much in the way of winter. If a western North America ridge can re-establish I'll be more optimistic about some sort of winter. ENSO forecasts are not really solid yet either. How strong of a La Nina? In four weeks many of these questions will clear up. Winter will still be up in the air, but at least we will get some better signals. For now, enjoy football even though it's baseball weather. 

[Daniel Boone]

Drought worries and forest fire possibilities are back, I'm afraid. Better pray for for a major nhem pattern change, imo. Ironically, this area could use some tropical system influence. Just under an inch and a half rain here for the month thus far. Not too bad at this juncture but, rest of month doesn't look promising. 

[John1122]

I think we're okay on the drought/fire aspect of things. There soil moisture is completely restored in the region and not a single county in the entire Valley region is even abnormally dry. The sun angle/lack of heat will keep things from drying out to the extent they did last year when we baked in summer. There could be flash fires still, as always in autumn, but last years fires burned deep into the soil and root systems. That's why they were so hard to extinguish.

[jaxjagman]

Mt.Agung is on high alert

 

 

https://magma.vsi.esdm.go.id/press/view.php?id=95

 

Edit:You have to translate the article,just saying.I use Goggle Chrome,not sure how other servers will work

 

[nrgjeff]

Mt Agung or thermo-nuclear war both present possible complications to MJO forecasting in the Pacific. Otherwise, La Nina looks strong enough to be a SER signal. The now solid -QBO should break it up occasionally. Northeast Pacific may be the deciding factor between mild-variable and another blowtorch. My colder optimism is fading quickly.

[Carvers Gap]

The Weeklies are a pattern flip and leave almost no room for doubt,. They have trended this way for the past few runs.  Trough in the West and a mid-summer like heat ridge over the forum area.  Wow.  Crazy how quick that flipped.  Even next week's "cool down" is basically poof.  As the ENSO switched so did our wx pattern.  Went from a wet/cool Nino-ish pattern to a hot/very dry Niña-ish pattern.  And that Weeklies look, along w being a torch, is also dry.  For those of us who love winter....not much positive to extrapolate from that.  The QBO will have to save us...

[Carvers Gap]

On 9/17/2017 at 0:32 PM, Carvers Gap said:

Been doing a bit of digging w La Niña winters, weak to moderate.  Their are some very decent analogs.  I would suspect they correlate well with a -QBO and when also coming off a Nino-ish "bounce."  With that in mind I am actually optimistic that this winter will be a good one.  

http://ggweather.com/enso/oni.htm

Scratch that post...LOL.  

[PisgahNCWeather]

Where is Nibiru when you need her?

[tnweathernut]

18 hours ago, Carvers Gap said:

The Weeklies are a pattern flip and leave almost no room for doubt,. They have trended this way for the past few runs.  Trough in the West and a mid-summer like heat ridge over the forum area.  Wow.  Crazy how quick that flipped.  Even next week's "cool down" is basically poof.  As the ENSO switched so did our wx pattern.  Went from a wet/cool Nino-ish pattern to a hot/very dry Niña-ish pattern.  And that Weeklies look, along w being a torch, is also dry.  For those of us who love winter....not much positive to extrapolate from that.  The QBO will have to save us...

Well, we have "it's not winter yet" still going for us.  There is still time, but several indicators obviously trending in the wrong direction. 

[Windspeed]

This pattern looks more like a hot and dry July than October. Fortunately, we had a normal Summer with regards to precipitation so we're not in significant drought conditions yet. Irma was our last significant rainfall in NETN/SWVA however. It is getting bone dry fast and the recent ECMWF/GFS runs look to keep things that way through next week. Every shortwave gets swiftly ejected NE off the Canadian Maritimes without so much as touching the Tennessee Valley. Look at the 500mb ridging parked over the easterrn CONUS and high surface pressures over the southern Apps late in the model run. Not likely we could get in on any tropical action out of the Gulf/W. Carib with that behemoth block.

[John1122]

Not a terribly unusual fall pattern, October is the driest month of the year. As for winter, I've given up on trying to predict anything. Some of us were buried in snow 2 seasons ago with a rampaging super warm death Nino. Last year all the analogs suggested we'd be below normal and the atmosphere behaved exactly the opposite of normal. I'd be surprised if we are as warm and snow free as we were last year.

[Carvers Gap]

5 hours ago, tnweathernut said:

Well, we have "it's not winter yet" still going for us.  There is still time, but several indicators obviously trending in the wrong direction. 

No doubt.  At this range it is a crap shoot for sure.  Just depends on what pattern develops.  We usually get a few chances up this way no matter how bad the pattern.  Just crazy to see ENSO flip to a less than optimal state.  I am definitely riding the -QBO as I think we see more blocking.  But that modeled western trough looks locked.  Just following the very broadbrushed rule that most patterns last 4-7 weeks, we might see a change around December, considering that patterns recently have tended to be more stable and long lasting.  The eastern trough pattern that we have been experiencing was due to change IMO.  Maybe the silver lining is that the current, developing pattern might be due to change around the time of winter's onset.  But yeah, like John said....seasonal prognostications have not been exactly stellar lately.  Windspeed, that is a heat ridge.  Ya'll, I just want some cold night normal for fall.  I believe we are quite a ways from that being a consistent feature.

[Windspeed]

3 hours ago, Carvers Gap said:

Windspeed, that is a heat ridge.  Ya'll, I just want some cold night normal for fall.  I believe we are quite a ways from that being a consistent feature.

It looks like a summer heat ridge. After the shortwave ejects off the Mid-Altantic and NE, the Euro builds heights from 120 hr to 5940dcm at 192hr, Texas to Ohio, with a 1031mb surface ridge over us. Anyone up for some temperature records next week? I realize it's medium range. Tonight's 00z GFS is again showing the same behemoth. See if it that evolves again on the 00z ECWMF and both keep the trend.

I'm totally with you on wanting a cool Autumn. I'm ready for crisp nights, frosty mornings and fresh air. Yearning to break out some bourbon around ye olde fire pit on a cool night.

[nrgjeff]

South winters are always like a power hitter: many strike-outs with a possible home run. I continue to think AN temps; however, it only takes one system. Background seems to favor SER. However every 4-6 weeks I expect 1-2 weeks of colder weather. That West ridge occasionally likes to pop up which would deliver some cold. West ridge appears to be the secondary pattern behind the primary SER pattern. Wish I had colder thoughts. Still time to change thinking if October verifies colder than current forecasts.