Winter 2014-2015 Medium-Term Discussion

[donsutherland1]

As AmericanWx has typically had a thread devoted to medium-term discussion for the winter season, I'm starting such a thread.

 

Already, there have been a few not so subtle whispers that the coming winter could be a generous one. Two early highlights:

 

1. September 10-11 saw accumulating snow blanket parts of South Dakota

2. October 31-November 3 saw storms bring heavy snow to a portion of the Southeast and then parts of New England

 

The development of a weak El Niño still appears to be on course with the ENSO Region 3.4 anomaly at +0.6°C for the week centered around October 29. That outcome could provide for a more active subtropical jet.

 

October saw the Arctic Oscillation (AO) average an estimated -1.024. Past winters with an October AO of -1 or below included: 1960-61, 1966-67, 1968-69, 1974-75, 1979-80, 1981-82, 2002-03, 2006-07, 2009-10, and 2012-13. In addition, the October Pattern Index (OPI) was -2.12. If past experience with many of those earlier cases proves relevant and the OPI proves relatively accurate, the upcoming winter could feature frequent periods of blocking, some of which could be strong. Coupled with a weak El Niño, at least parts of North America could look forward to opportunities for above normal snowfall if everything plays out.

 

Already, the latest GFS ensembles are hinting at a period of renewed blocking down the road. Such blocking could usher in a pattern change (DT is already discussing the possible pattern change here: http://www.americanwx.com/bb/index.php/topic/44804-rapid-pattern-change-developing/).

 

In short, the upcoming winter does not appear to resemble a 2011-12 "non-winter" scenario. Instead, a more promising evolution seems to be in the early stages of getting underway.

 

Finally, while we still await winter's arrival and look forward to any previews the approaching winter has to offer--some of which have been noted above--a thought to consider from English novelist John Boynton Priestley to help pass the time:

 

The first fall of snow is not only an event, it is a magical event. You go to bed in one kind of a world and wake up in another quite different, and if this is not enchantment then where is it to be found?

[Quixotic1]

My favorite seasonal thread.  Have been looking forward to this.  Thanks, Don. 

[GaWx]

Don, thanks for the thread.

1) I'm already on the record within the SE subforum as being more optimistic than ever about the combination of both cold potential for the SE and a good bit heavier than average wintry precip. for at least the bulk of the well inland SE US fwiw. Even though the 2009-10 winter was quite impressive for much of the SE, I wasn't this optimistic in advance of it (partially due to less knowledge then). The combo of a solid +PDO (now almost a lock for DJF averaged per analogs with +1+ Sep. PDO per Univ. of Washington), a solid -AO (supposedly very likely averaged over DJF due to the 3rd highest SAI since 1973 as well as the quite negative OPI and sub -1 October AO), and the very likely weakish El Nino is per analogs a very hard combimation to beat if one wants the best shot at a solidly cold DJF in the SE as well as much of the E US. I think we could end up with a winter that at least matches 2009-10 in many respects. In addition when looking at November, I've come to the conclusion for the SE US (at least) that a near normal or cold November would be an additional good indicator though I'd still expect a cold winter in the now extremely unlikely event that November were to somehow turn out warm.

 

2) Per 500 mb wx maps back to 1948, that 11/1 snow producing very strong upper low likely was the strongest one on record for so early in the season as far south as SC and surrounding areas by a good margin!

[Bob Chill]

Glad to see you start this thread, Don. I always look forward to your analysis. I made a post in the MA forum this morning about what models are advertising down the line and some similarities to 02-03. Figured I'd post it here as well. 

 

Last couple days of Euro ensembles and the GEFS have been quite similar. Usually when you see that in the d10-15 range it means some clarity is being seen in the otherwise volatile long range. 

 

This d10-15 mean looks very similar to Nov 02

 

 

 

 

 

Oct 02 features a similar anomalous blocking event as this year:

 

 

Unlike some of the other high SAI warm enso years, 02-03's blocking period set in from Nov all the way through the end of Jan with only 1 notable break. 76 and 09 both featured a later start (Dec) to the anomalous period

 

 

Way too early to know whether this year will feature similar behavior but some early signs are emerging. 

 

Before I get jumped on for using 02-03 and the obvious snowy year it was, I'm only using it in regards to the behavior of the high latitudes.

 

Also, ORH and Coastal have made some great posts in their forum about Siberian strat temps @ 50mbs in November and what it could imply down the line. 06 was a big bust for blocking and there seems to be some connection with the strat temps in Nov and why blocking didn't develop. Right now the forecasts are looking pretty favorable for warm strat temps over the right areas of Siberia. Another good sign that we are moving in the right direction. 

 

 

 

 

 

[uncle W]

I can't think of a better person to start this tread than Don...You know the season has started when he posts about it...I've been optimistic ever since the AO went -4 in October...it seems like every storm is a coastal / noreaster... big winters along the east coast have many coastal storms...the more chances you get the better the odds of getting a big one...Hopefully this pattern continues...

[ncwxlvr]

Any thoughts on that impact of recurving Super Typhoon Nuri?

[JBG]

I can't think of a better person to start this tread than Don...You know the season has started when he posts about it...I've been optimistic ever since the AO went -4 in October...it seems like every storm is a coastal / noreaster... big winters along the east coast have many coastal storms...the more chances you get the better the odds of getting a big one...Hopefully this pattern continues...

I second that. Don is quite the "un-Joe Bastardi." Quiet,dispassionate and scientific.

[Met1985]

Thanks for starting this thread Don! Cannot wait to get into the depths of winter. Have already had an early season snowstorm.

[Rjay]

2) Per 500 mb wx maps back to 1948, that 11/1 snow producing very strong upper low likely was the strongest one on record for so early in the season as far south as SC and surrounding areas by a good margin!

I think this was out the the Charleston, SC (CHS) NWS office...(Bluewave posted this)

..500 HPA TEMPERATURES ARE

FORECAST TO DROP IN THE -22 TO -26C RANGE WITH 850 HPA TEMPERATURES

FALLING TO -2 TO -5C. IT SHOULD BE NOTED 850 HPA TEMPERATURES OF

THIS MAGNITUDE FOR EARLY NOVEMBER ARE ABOUT 12 STANDARD DEVIATIONS

BELOW NORMAL--CERTAINLY A TESTAMENT TO HOW COLD THIS AIRMASS WILL BE.

[GaWx]

I think this was out the the Charleston, SC (CHS) NWS office...(Bluewave posted this)

..500 HPA TEMPERATURES ARE

FORECAST TO DROP IN THE -22 TO -26C RANGE WITH 850 HPA TEMPERATURES

FALLING TO -2 TO -5C. IT SHOULD BE NOTED 850 HPA TEMPERATURES OF

THIS MAGNITUDE FOR EARLY NOVEMBER ARE ABOUT 12 STANDARD DEVIATIONS

BELOW NORMAL--CERTAINLY A TESTAMENT TO HOW COLD THIS AIRMASS WILL BE.

 

Rjay,

 Thanks for reposting this tidbit. Wow, 12 SD's! That along with the fact that I saw nothing even close to the low 500 mb heights that occured with this at CHS through 11/5 going back to 1948 tell me that this could easily have been at least a once in several hundred year event there for early Nov.

[Harry]

I can't think of a better person to start this tread than Don...You know the season has started when he posts about it...I've been optimistic ever since the AO went -4 in October...it seems like every storm is a coastal / noreaster... big winters along the east coast have many coastal storms...the more chances you get the better the odds of getting a big one...Hopefully this pattern continues...

 

 

Not really and i doubt it will be either. Typically mod/stronger nino's and drier ( Sept/Oct-especially with a weak nino ) out this way brings that sort of thing and we have none of it. YES there will be coastals but as well systems tracking to the eastern lakes etc as well.

[donsutherland1]

Thanks all for the kind words.

 

FWIW, some of the winters that saw strong blocking develop toward mid-November included 1995-96 and 2002-03. This list is not all-inclusive. The important point is that some notable winters experienced an evolution of blocking similar to what is currently forecast. Moreover, given the ongoing evolution of events and forecast evolution on the ensembles, the current CFSv2 idea of warm anomalies for December across virtually all of North America doesn't appear to be a high probability outcome. I suspect that given where things currently stand and how they are forecast to evolve, there will be a fairly expansive area of cold anomalies. Placement remains uncertain, though the PDO+ signal may indicate a predominant PNA+ setup to coincide with possible Atlantic blocking. If so, the eastern half of North America (except for northern Ontario, northern Quebec and Atlantic Canada) into central Canada might be somewhat more favored for the cold anomalies.

 

For now, let's see if the blocking actually develops. That outcome could offer yet another signal related to the character of the upcoming winter. In a few weeks, one should have a better idea about December. For now, I don't think one should automatically assume a widespread warm scenario especially in light of the evolving synoptic pattern and forecast evolution.

[NJwinter23]

Clearly look to be heading for a longer term -AO period here in early winter. What 2002 proves to us though is that it still can get warm in Dec for a meaningful period of time across much of the CONUS, if the Pacific breaks through... After a significant arctic shot early Dec 02 it warmed up pretty nicely, and the CONUS finished the month above normal on average with a pretty classic Nino Dec look (it was cold on the East Coast though, more so than your average Nino Dec). In short, I'm not sold on the Midwest either way, but I'd be cold East Coast in Dec. 

 

[Quakertown needs snow]

Nice thread Don, thank you.

Hopefully we can add some nice snow photos to your archives.

[donsutherland1]

Nice thread Don, thank you.

Hopefully we can add some nice snow photos to your archives.

Thanks Andy. I certainly hope that this will be a memorable winter.

[wildweatherman179]

Glad to see this thread. Also glad to see you talking about winter again Don.

[Yanksfan]

My thoughts on the upcoming winter… with all the teleconnections seemingly wanting to line up in our favor, not to mention the developing El Nino and extreme snow cover over eurasia, I think it is not that far fetched to make a run at the all time season of 1995-96. Of course to achieve those extreme snow totals, there are obstacles to endure like timely phasing, mixing issues, and occasional pattern relaxing. Is this wishful thinking on my part? Perhaps, but you can't ignore the obvious- the pattern in the weeks and months ahead is screaming potential.

[InstantWeatherMaps]

Monster storm in the Bering coming up...

[The_Global_Warmer]

My God.

 

 

 

 

 

[donsutherland1]

Another day has passed and the CFSv2 continues to forecast warm anomalies across almost all of North America for December. Even as it is too soon to really try to hone in on a December idea, the forecast evolution of the teleconnection indices argue against that idea. Just for a quick illustration, I took some partial teleconnection cases (similar to where they were during the end of October with a similar evolution afterward through mid-November for the 1981-2010 base period).

 

If one takes a look at the 500 mb anomalies shown at 360 hours on the GFS ensembles and considers a modest degree of retrogression in those anomalies, something not dissimilar to the composite 500 mb anomalies based on those partial teleconnection cases would result. (Top Chart).

 

The temperature anomalies would be quite different from what the CFSv2 is currently showing for December (Bottom Chart).

 

Therefore, while I make no guesses for December right now, I am wary of the CFSv2's expansive warm scenario at this point in time.

 

[Srain]

Thanks for starting our Medium-Term Discussions for the Main Page Don. The 12Z parallel GFS is suggesting the extratropical storm Nuri will usher in a significant pattern change across North America. It will be interesting to see if the improvement made will offer a reasonable look for the sensible weather we can expect beyond the 3 to 5 day range. The departures suggested by the parallel GFS are most impressive by mid November standards well south into Texas and Mexico. The 2 meter temperature profiles approach the -30 to -35 degree range if verified.

 

 

[usedtobe]

I posted this discussion in the Mid Atlantic thread but could fit here just as easy.

http://www.washingtonpost.com/blogs/capital-weather-gang/wp/2014/11/06/d-c-to-be-dealt-a-dose-of-winter-in-about-a-week-and-it-may-stick-around/

The stratsophere is interesting. Adria Lang wrote this about it.

There has been much discussion of the forecasted recurvature of Nuri and the re-intensification of Nuri as an extratropical cyclone. There are, as highlighted by many on this list, implications of this extratropical transition process on North American weather and it is linked to the downstream propagation of wave energy along the tropopause waveguide. Something that most of you probably are not looking at are impacts of this Nuri-induced wave activity on the stratospheric polar vortex.

In the recent (0600 UTC 5 Nov) GFS forecast, the wave train associated with Nuri is responsible for two notably large ridge building events, one in the N. Pacific and one linked to an explosive cyclogenesis event in the N. Atlantic. These ridges pinch the Arctic cold pool, creating an amplified wavenumber 2 pattern in the troposphere by forecast day 7 and the return of a lobe of the 'polar vortex' to the US.

The amplified tropospheric wavenumber-2 pattern in the forecast is associated with the amplification of the stratospheric wavenumber-2 pattern. By forecast day 15 (shown below), this wave amplification leads to a stratospheric warming event and the initial splitting of the stratospheric polar vortex. Of course this is a 15 day forecast during a lower predictability period, but for what its worth, in the extended range we are generally talking about planetary scale features. If this forecast holds true, it would be (to my knowledge) the earliest vortex splitting event on record (most occur in Jan-Feb).

If the stratospheric vortex splitting event were to occur as forecast, it would also have substantial implications on the evolution of the vortex for the rest of the winter season. The last time we had a weak stratospheric vortex near this magnitude this early in the winter season was Nov 1996 (linked to the re-intensification of TC-Dale as an extratropical cyclone and a vortex displacement event). By late December 1996 the stratospheric portion of the vortex recovered and by March 1997 we had the coldest Arctic stratosphere observed in the satellite era (associated with low Arctic ozone and cold European temperatures).

This could be an interesting winter!

Andrea

[SnoSki14]

So given the article above; does that mean our potentially record early vortex split would actually lead to a cold Arctic stratosphere by mid winter, which would essentially lead to a mild winter?

[usedtobe]

So given the article above; does that mean our potentially record early vortex split would actually lead to a cold Arctic stratosphere by mid winter, which would essentially lead to a mild winter?

I don't know but that would fit Balwin and Dunkerton as the negative AO generally runs for 2 to 3 months. Strongly during the 1st 2 and then wekaly part of all of the next.

[Joe Vanni]

So given the article above; does that mean our potentially record early vortex split would actually lead to a cold Arctic stratosphere by mid winter, which would essentially lead to a mild winter?

I don't think it would make our winter mild overall, but I'm sure we'll have a couple warmer periods; but even a lot of our great winters have that. But I wouldn't compare this winter to 1996-1997 as our entire background state is different. ENSO, PDO, SAI/SCE, solar state, and even the QBO was already starting to rise toward neutral/positive by late winter at 30 mb.

[usedtobe]

I don't think it would make our winter mild overall, but I'm sure we'll have a couple warmer periods; but even a lot of our great winters have that. But I wouldn't compare this winter to 1996-1997 as our entire background state is different. ENSO, PDO, SAI/SCE, solar state, and even the QBO was already starting to rise toward neutral/positive by late winter at 30 mb.

[/quo

You amke a good point about the background state being much different.

[IntenseBlizzard2014]

This means that 60% of December could be above average of most of CONUS.

Basically, the CFS v2 is actually on to something.

[Srain]

There are some impressive analog dates in the updated CPC Day 8+ forecast.

[Ginx snewx]

There are some impressive analog dates in the updated CPC Day 8+ forecast.

610analog.off-5.gif

8-14 is similar and Euro weeklies are in the freezer too. Get out your woolies SteveO

[Ginx snewx]

I don't know but that would fit Balwin and Dunkerton as the negative AO generally runs for 2 to 3 months. Strongly during the 1st 2 and then wekaly part of all of the next.

Dec and Jan will be pretty special and then Feb the snows , looking pretty sweet.

 

Wes I posted a visual of the beginning of disruption of the PV

 

http://www.americanwx.com/bb/index.php/topic/43733-2014-2015-winter-outlooks-and-discussions/?p=3113248