Winter 2014-2015 Thread

[Bob Chill]

Millwx, please come here and post often. You answered a burning question about timing. Last year there were a bunch of discussions about whether Sept could throw a wrench into the Oct increase calc. Those italian guys had us all scared. In their defense, the Dec +AO verified but other factors worked in concert to offset what would normally be an abysmal month with an AO reading that high on the means. Personally, I don't want to take that chance again. 

 

Wes and I have discussed the Dec AO signal at length over the last 2-3 years. At our latitude, a -AO is incredibly important. It's part of why we are so darn paranoid about what happens in Dec. Wes did an awesome scatter plot of 4"+ snows and the state of the AO/NAO. It's pretty obvious that we do far better in a -AO regime.

 

 

 

The NAO is a funny beast. We talk all the time about how bad we want a -NAO. But in reality what we want is an active NAO. The phase changes are much more telling than just wishing for a -4 NAO. That's for a different discussion though. 

 

I dug up a bunch of stats on anomalous + & - December AO's. A lot of folks here have seen this stuff already but I think putting them side by side in this post will help folks understand early signals and which way to hedge once they show their face. Of course there are no guarantees because outliers can always happen in any regime. But playing the odds is always better than praying for the needle threader or perfectly timed event in an otherwise hostile pattern. 

 

Anomalous positive AO's in December on the means are pretty clearly an omen of wasting precious winter weeks. We only have 12 and losing the front 6-8 makes a weenie's skin crawl. Going back 64 years, here's the list of Decembers with a rounded AO of +1 or higher and the subsequent months and DC snowfall for the season.

 

 

 

There are no blockbusters and plenty of duds on the list. Interestingly, the 2 of the 3 best winters had a notable flip to an -ao in January. 82-83 had an anomalous Feb -AO and piled up 21" of snow during that month. 79-80's best month was Jan (8.6") and the seasonal total was saved by 6" in March. 

 

Dec +1 AO's greatly increase our odds of a warm winter. Here's the seasonal composite.

 

 

 

-1 Dec AO's paint a much happier picture. There are certainly some duds in the mix but the odds of a decent snow year look a lot better. 

 

 

 

And the seasonal temps are what would be expected with starting off cold. 

 

 

 

There's some compelling evidence that anomalous AO's in Dec are a good indicator of what the personality of winter will be on the whole. 

 

One thing I picked up on when looking at the + outlier years is that they all had a +AO in November as well. Anomalous periods seem to have a general 45-60 day period before breaking down. I'm certainly not smart enough to know why the outlier years broke down but from a simpleton view it appears at least plausible that they simple ran out of gas during a typical cycle. I suppose timing of when the anomalous period starts should at least be taken into consideration. 

 

The short story of this tl;dr post is that we are incredibly paranoid about ANY indication, index, pattern, size of acorns, and fatness of squirrels that Dec is favoring AN temps and a +AO. Please come in here often as October progresses and tell us why a -AO is favored in Dec. lol

[mitchnick]

Millwx, please come here and post often. You answered a burning question about timing. Last year there were a bunch of discussions about whether Sept could throw a wrench into the Oct increase calc. Those italian guys had us all scared. In their defense, the Dec +AO verified but other factors worked in concert to offset what would normally be an abysmal month with an AO reading that high on the means. Personally, I don't want to take that chance again. 

 

Wes and I have discussed the Dec AO signal at length over the last 2-3 years. At our latitude, a -AO is incredibly important. It's part of why we are so darn paranoid about what happens in Dec. Wes did an awesome scatter plot of 4"+ snows and the state of the AO/NAO. It's pretty obvious that we do far better in a -AO regime.

 

 

 

The NAO is a funny beast. We talk all the time about how bad we want a -NAO. But in reality what we want is an active NAO. The phase changes are much more telling than just wishing for a -4 NAO. That's for a different discussion though. 

 

I dug up a bunch of stats on anomalous + & - December AO's. A lot of folks here have seen this stuff already but I think putting them side by side in this post will help folks understand early signals and which way to hedge once they show their face. Of course there are no guarantees because outliers can always happen in any regime. But playing the odds is always better than praying for the needle threader or perfectly timed event in an otherwise hostile pattern. 

 

Anomalous positive AO's in December on the means are pretty clearly an omen of wasting precious winter weeks. We only have 12 and losing the front 6-8 makes a weenie's skin crawl. Going back 64 years, here's the list of Decembers with a rounded AO of +1 or higher and the subsequent months and DC snowfall for the season.

 

 

Dec +AO.JPG

 

There are no blockbusters and plenty of duds on the list. Interestingly, the 2 of the 3 best winters had a notable flip to an -ao in January. 82-83 had an anomalous Feb -AO and piled up 21" of snow during that month. 79-80's best month was Jan (8.6") and the seasonal total was saved by 6" in March. 

 

Dec +1 AO's greatly increase our odds of a warm winter. Here's the seasonal composite.

 

+AO Dec Seasonal Temps.JPG

 

 

-1 Dec AO's paint a much happier picture. There are certainly some duds in the mix but the odds of a decent snow year look a lot better. 

 

Dec -AO.JPG

 

 

And the seasonal temps are what would be expected with starting off cold. 

 

-AO Dec Seasonal Temps.JPG

 

 

There's some compelling evidence that anomalous AO's in Dec are a good indicator of what the personality of winter will be on the whole. 

 

One thing I picked up on when looking at the + outlier years is that they all had a +AO in November as well. Anomalous periods seem to have a general 45-60 day period before breaking down. I'm certainly not smart enough to know why the outlier years broke down but from a simpleton view it appears at least plausible that they simple ran out of gas during a typical cycle. I suppose timing of when the anomalous period starts should at least be taken into consideration. 

 

The short story of this tl;dr post is that we are incredibly paranoid about ANY indication, index, pattern, size of acorns, and fatness of squirrels that Dec is favoring AN temps and a +AO. Please come in here often as October progresses and tell us why a -AO is favored in Dec. lol

Bob, great research and info. Maybe because I just have a Cubs fan mentality, but looking beyond 95/96 and 09/10 on your -AO December list, the next 11 years were downright lousy or average at best.....and then you hit 02/03. Frankly, looking at it from another point of view, the -AO is great as long as you have other factors lining up with it. I mean, 02/03 and 09/10 had the west based NINOs and 95/96 was similar to last year where the PAC ruled the roost. IOW, I think we need -AO periods during the winter in these parts to greatly increase the chances of snow, but -AO winters (or Decembers) don't make a whole lot of difference if other factors are not in our favor.

[T. August]

Great posts, everyone.

 

Very deep and informative discussion, but all I can comment on are acorns. They have to do with previous years' precipitation.

[EastCoast NPZ]

Great posts, everyone.

 

Very deep and informative discussion, but all I can comment on are acorns. They have to do with previous years' precipitation.

 

Then next year I won't have any.

[Bob Chill]

Bob, great research and info. Maybe because I just have a Cubs fan mentality, but looking beyond 95/96 and 09/10 on your -AO December list, the next 11 years were downright lousy or average at best.....and then you hit 02/03. Frankly, looking at it from another point of view, the -AO is great as long as you have other factors lining up with it. I mean, 02/03 and 09/10 had the west based NINOs and 95/96 was similar to last year where the PAC ruled the roost. IOW, I think we need -AO periods during the winter in these parts to greatly increase the chances of snow, but -AO winters (or Decembers) don't make a whole lot of difference if other factors are not in our favor.

 

Absolutely, Mitch. There is no single answer...ever. These are just anomalous Dec years and nothing more. If this Dec isn't anomalous then everything I posted is irrelevant. The way I look at it is if we have an anomalous +AO this December we are likely going to have to sit and wait for a while. If it's the other way around, we have to hope we can actually time precip with cold air. Cold doesn't mean snow in these parts. That's for sure. 

 

Here's a list of 10" snowfalls in DC and the corresponding indicies

 

 

 

You can throw out the vet day storm. That thing was an absolute freak on so many levels. The 79 storm was on the heels of a prolonged period of a very anomalous -NAO (bottoming out @ -4.3 in late Jan. The big dump came right as it was going +). There are a lot of examples of snow coming on phase changes one way or another with the NAO. I would have no problem if the daily NAO chart this winter looks like the peaks and valleys in central NV. lol

[T. August]

Then next year I won't have any.

That's what I've read, however, last year there was plenty of precipitation, but this year there aren't many acorns. So I'm not entirely sure that's accurate.

[millwx]

Millwx, please come here and post often. You answered a burning question about timing. Last year there were a bunch of discussions about whether Sept could throw a wrench into the Oct increase calc. Those italian guys had us all scared. In their defense, the Dec +AO verified but other factors worked in concert to offset what would normally be an abysmal month with an AO reading that high on the means. Personally, I don't want to take that chance again. 

 

Wes and I have discussed the Dec AO signal at length over the last 2-3 years. At our latitude, a -AO is incredibly important. It's part of why we are so darn paranoid about what happens in Dec. Wes did an awesome scatter plot of 4"+ snows and the state of the AO/NAO. It's pretty obvious that we do far better in a -AO regime.

 

 

 

The NAO is a funny beast. We talk all the time about how bad we want a -NAO. But in reality what we want is an active NAO. The phase changes are much more telling than just wishing for a -4 NAO. That's for a different discussion though. 

 

I dug up a bunch of stats on anomalous + & - December AO's. A lot of folks here have seen this stuff already but I think putting them side by side in this post will help folks understand early signals and which way to hedge once they show their face. Of course there are no guarantees because outliers can always happen in any regime. But playing the odds is always better than praying for the needle threader or perfectly timed event in an otherwise hostile pattern. 

 

Anomalous positive AO's in December on the means are pretty clearly an omen of wasting precious winter weeks. We only have 12 and losing the front 6-8 makes a weenie's skin crawl. Going back 64 years, here's the list of Decembers with a rounded AO of +1 or higher and the subsequent months and DC snowfall for the season.

 

 

Dec +AO.JPG

 

There are no blockbusters and plenty of duds on the list. Interestingly, the 2 of the 3 best winters had a notable flip to an -ao in January. 82-83 had an anomalous Feb -AO and piled up 21" of snow during that month. 79-80's best month was Jan (8.6") and the seasonal total was saved by 6" in March. 

 

Dec +1 AO's greatly increase our odds of a warm winter. Here's the seasonal composite.

 

+AO Dec Seasonal Temps.JPG

 

 

-1 Dec AO's paint a much happier picture. There are certainly some duds in the mix but the odds of a decent snow year look a lot better. 

 

Dec -AO.JPG

 

 

And the seasonal temps are what would be expected with starting off cold. 

 

-AO Dec Seasonal Temps.JPG

 

 

There's some compelling evidence that anomalous AO's in Dec are a good indicator of what the personality of winter will be on the whole. 

 

One thing I picked up on when looking at the + outlier years is that they all had a +AO in November as well. Anomalous periods seem to have a general 45-60 day period before breaking down. I'm certainly not smart enough to know why the outlier years broke down but from a simpleton view it appears at least plausible that they simple ran out of gas during a typical cycle. I suppose timing of when the anomalous period starts should at least be taken into consideration. 

 

The short story of this tl;dr post is that we are incredibly paranoid about ANY indication, index, pattern, size of acorns, and fatness of squirrels that Dec is favoring AN temps and a +AO. Please come in here often as October progresses and tell us why a -AO is favored in Dec. lol

 

Great post, Bob.  A few points...

 

1) I know you weren't disputing what I was saying, so, to be clear... I'm not arguing back, lol.  I just think it's worth clarifying in my original post.  The odd disconnect between the snow correlating to AO versus temperatures (and whether you want to look at SAI or just the raw extent numbers) in no way undermines the desire for a negative AO.  In fact...

 

2) My point was largely just that the SAI (or at least the delta in the weekly Eurasian snow extent values... I shouldn't outright crucify the SAI itself, as that is not PRECISELY the data they're using... but it should be similar) does NOT correlate well to temperatures despite correlating well to AO.  ...which likely indicates that it's pulling a lot of "bad -AO" seasons.  BUT, if you simply look at extent, you get good correlations on both sides - on both the AO and temps (Week 42 peaks for the temperature correlation; Week 43 peaks for the AO correlation... I have no idea why the lag, but the correlation differences appear sufficient enough to be "real", not just noise - so, I'd have to think about the mechanics there).  So, to be crystal clear... I completely agree with you... -AOs are very good for snowfall, especially if you're in a temperature sensitive region (Mid-Atlantic up the coastal plain to NYC and probably even - but to a lesser extent - NYC and BOS).  All I'm saying is that the Eurasian snow increase appears to do a fine job of hitting the outlier seasons (-AO, but warm).

 

3) You're also absolutely correct on the -NAO.  It's the change that matters.  That said, the most favorable phase, as documented pretty extensively by KU, is when you're swinging out of a good -NAO.  As such, you have to at least have periods of -NAO.  And since the seasons do tend to have a favored sign, I do think it is at least fair to say you want to see, when just looking broadly at seasonal expectations, a -NAO.  A persistently +NAO is not going to afford you many opportunities.  So, you're right... change in NAO is most important... but it's also correct that you want -NAO dominated.  You want to swing out of it, get your blockbuster then quickly head back into it, so you can line up for blockbuster #2 ...in a perfect world.  So, in the mean, that'd still be pretty solidly negative.

[millwx]

...to follow-up on my own post above, I just checked out the individual seasons.  The best (still poor) correlation between Eurasian snow increase and AO does include a number of AO-neutral or even AO-negative warm years.  That correlation with the AO peaks at a stout -0.5472 in Week 43 minus Week 39.  The top snow-change years in that list are:

 

Year, SnowChng, WinterAO, WinterHDDAnom ("warm", "cold" or "normal", since there are variant calculations on this)

1976, 21.78, -2.26, cold

2012, 16.29, -1.12, warm

2009, 15.62, -3.42, normal

2003, 14.65, -0.98, warm

2004, 14.02, +0.11, warm

1970, 13.81. -0.33, cold

1968, 13.80, -2.27, cold

2006, 13.51, +1.00, warm

2011, 13.47, +0.66, warm

1972, 13.20, +1.59, cold

 

Those are the top ten snow-increase seasons.  The majority of them have a negative AO winter (6 of 10), while a plurality of them have warm winter (5 of 10).  You get a good correlation on the AOs because, even though it's only 6 of 10, the negative ones are much more strongly negative than the positive ones are positive.  So, there's a heavy negative lean here.  The average is -0.72 ...not bad for a full seasonal average when four of six seasons are positive.  But that's an atrocious record on cold-vs-warm.  The only reason there's any positive correlation to cold is because of the severity of 1976 and 1978 (which isn't on the list but was just off of it).

 

Now if you just list those peak snow cover Week 42 seasons, you get a list with only four similar seasons.  Here's the top 10:

 

1976, 18.39, -2.26, cold

1978, 16.99, -1.08, cold

1966, 15.76, +0.07, normal

2006, 14.81, +1.00, warm

2002, 14.34, -0.65, cold

1972, 14.25, +1.59, cold

2013, 13.53, +0.18, cold

1985, 13.31, -1.28, warm

2000, 13.15, -0.92, cold

1970, 13.00, -0.33, cold

 

The addition of 1985 on that list is a bit of a bite (one of those warm -AO seasons), but for the most part, this is a much better list... The same 6-4 split in -AO to +AO winters, but this time there are SEVEN cold winters to only two warm; and the normal winter, 1966-67, tilted cool on the East Coast. (And this is achieved with a weaker mean AO signal... the 10 years average out to only -0.37... the snow increase list was almost twice that magnitude, -0.73.)

 

Note that with a negative AO, for the total period of record that we have the snowfall data to compare with (since 1966), there are 24 winters with a negative AO (that's all, even marginal ones).  17 ended up cold, 6 warm, 1 normal.  They're cold 71% of the time.  They're warm only 25% of the time.

 

It's a TREMENDOUSLY small sample, but the snow increase list chalked up two -AO warm winters of its six -AO winters... a rate of 33%.  The raw snow cover list only had 17% (1) of its -AO seasons come in warm.  Granted, that's a ludicrously small sample (2-of-6 versus 1-of-6).  BUT, it is backed up by the correlation data.  And, interestingly (coincidental?  ...or are there other forcing mechanisms at work?), the raw snow cover list had 50% of its +AO winters end up cold, and 75% were normal or cold; the "snow increase" list had 75% of its +AO winters end up warm.  I'd reiterate... small samples on these lists.  So, I'm not sure I'd call them statistically valid.  But, as the correlations ARE statistically valid, and these examples back up those correlations... I'd say you can consider them to be valid anecdotal examples.

 

Bottom line, the Eurasian snow increase may be a fair indicator of what AO signal you'll get for the winter.  But it's pegging to some bad AO examples (more than its share of -AO warm winters).  What you really want to track is just the standard snow cover.  Not only does it show the more expected AO-to-temperature relationship but it even hints that it can help cold winters be achieved in +AO winters.

[WinterWxLuvr]

That's what I've read, however, last year there was plenty of precipitation, but this year there aren't many acorns. So I'm not entirely sure that's accurate.

I have them by the bushel.

[DTWXRISK]

 IT SUCKED  MOOSE  DICK LAST YEAR...

  seriously... it  was positive lot of the time  BUT  every time  the PV came  south  the   AO  went neutral then negative... followed by an arctic outbreak and   2 or 3   Moderate  east coast snow event

 

Since you all are talking AO, and it's almost October. How well did that "October Pattern Index" do last year?

 

Here's the relevant threads from last year:

 

http://www.americanwx.com/bb/index.php/topic/41379-october-pattern-index-predicting-winter-ao-from-october-with-90-accuracy/

http://www.americanwx.com/bb/index.php/topic/41639-seasonal-winter-20132014-forecast-based-on-opi-index/

[DTWXRISK]

BOB       100% FABULOUS   post . REALLY

Millwx, please come here and post often. You answered a burning question about timing. Last year there were a bunch of discussions about whether Sept could throw a wrench into the Oct increase calc. Those italian guys had us all scared. In their defense, the Dec +AO verified but other factors worked in concert to offset what would normally be an abysmal month with an AO reading that high on the means. Personally, I don't want to take that chance again. 

 

Wes and I have discussed the Dec AO signal at length over the last 2-3 years. At our latitude, a -AO is incredibly important. It's part of why we are so darn paranoid about what happens in Dec. Wes did an awesome scatter plot of 4"+ snows and the state of the AO/NAO. It's pretty obvious that we do far better in a -AO regime.

 

 

 

The NAO is a funny beast. We talk all the time about how bad we want a -NAO. But in reality what we want is an active NAO. The phase changes are much more telling than just wishing for a -4 NAO. That's for a different discussion though. 

 

I dug up a bunch of stats on anomalous + & - December AO's. A lot of folks here have seen this stuff already but I think putting them side by side in this post will help folks understand early signals and which way to hedge once they show their face. Of course there are no guarantees because outliers can always happen in any regime. But playing the odds is always better than praying for the needle threader or perfectly timed event in an otherwise hostile pattern. 

 

Anomalous positive AO's in December on the means are pretty clearly an omen of wasting precious winter weeks. We only have 12 and losing the front 6-8 makes a weenie's skin crawl. Going back 64 years, here's the list of Decembers with a rounded AO of +1 or higher and the subsequent months and DC snowfall for the season.

 

 

Dec +AO.JPG

 

There are no blockbusters and plenty of duds on the list. Interestingly, the 2 of the 3 best winters had a notable flip to an -ao in January. 82-83 had an anomalous Feb -AO and piled up 21" of snow during that month. 79-80's best month was Jan (8.6") and the seasonal total was saved by 6" in March. 

 

Dec +1 AO's greatly increase our odds of a warm winter. Here's the seasonal composite.

 

+AO Dec Seasonal Temps.JPG

 

 

-1 Dec AO's paint a much happier picture. There are certainly some duds in the mix but the odds of a decent snow year look a lot better. 

 

Dec -AO.JPG

 

 

And the seasonal temps are what would be expected with starting off cold. 

 

-AO Dec Seasonal Temps.JPG

 

 

There's some compelling evidence that anomalous AO's in Dec are a good indicator of what the personality of winter will be on the whole. 

 

One thing I picked up on when looking at the + outlier years is that they all had a +AO in November as well. Anomalous periods seem to have a general 45-60 day period before breaking down. I'm certainly not smart enough to know why the outlier years broke down but from a simpleton view it appears at least plausible that they simple ran out of gas during a typical cycle. I suppose timing of when the anomalous period starts should at least be taken into consideration. 

 

The short story of this tl;dr post is that we are incredibly paranoid about ANY indication, index, pattern, size of acorns, and fatness of squirrels that Dec is favoring AN temps and a +AO. Please come in here often as October progresses and tell us why a -AO is favored in Dec. lol

[DTWXRISK]

WOW   another  great   post

 

Thnx all.  I should add that the correlation between Week 39 (the current week) and Week 42 snowfall is NOT high... but it is positive and significant (0.243).  Further proof that late September snowfall matters (easier to retain above normal snowpack if you start early... I don't think there's anything magical in that... I don't think late September snow magically creates early to mid-October snow; more likely it's just related to a dominant pattern which would favor both).

 

Also, that correlation increase to 0.412 in Week 40 (10/1 - 10/7) and to 0.670 in Week 41 (10/8 to 10/14).

 

And the correlation suffers due to scatter.  If you're merely curious as to whether or not the weeks "match" (e.g., how often does Week 39 above normal snow cover couple with above or below normal Week 42 snow cover).  Well, in just being directionally predictive - which is ultimately what matters - Week 39 has the same signal as Week 42 60% of the time.  Week 40 has the same signal 66% of the time.  Week 41 matches Week 42, as you might expect, a whopping 80+% of the time.  So, by Week 41 (2nd week in Oct) we should have a solid idea what signal this providing.  And right now, we already have some "clues".

[DTWXRISK]

MILLWX

 if you go back to last winter I argued the    EXACT  same thing ...   SEE THE   text in  RED .

I know  no one  remembers  but I said it HERE  many times  and on the FB page and on the web site .  I  never got around  to  looking up the data like you did  but   I know   bull**** when I hear it   and that  SAI argument is   like you said    just plain old  bravo Sierra 

 

If you believe some of the previous discussions on this board, this is irrelevant.  And, in fact, it may actually be a bad thing.  Why?  Because it's TOO soon.  It is only the gains in October that matter.  I've even heard some (attempt to) attribute some physical processes as to why late September snowfall doesn't matter.

 

Frankly, it's bull, and you are correct to point it out.  This snow cover is a good thing.  I've run the numbers myself.  I admit, I'm kind of a data nerd, lol.  But I just get skeptical trusting other's analyses when we have all the data we need on hand.  Snow data is readily available online, as is the AO data.  I've run it all myself...

 

It is true, as the SAI promoters suggest, that the highest correlation between Eurasian snow cover and the AO is on the advance of the snow cover, NOT on an absolute value.  However, that correlation (-0.5472) occurs on the delta between Week 43 and Week 39.  Week 39 is 9/23 - 9/30.  So, the argument that last September snowfall is "too soon" or irrelevant is just total b.s.  Mother Nature doesn't look at a calendar and flip a switch on October 1st.  And the numbers hold to that.  Mind you, the correlation using the delta between Week 43 and 40 (Week 40 starts at 10/1) isn't much lower (-0.5217), but it IS lower.  This late September snow advance is relevant and it is good.  Arguably, since we're IN week 39 and looking at the delta, maybe we don't want Week 39 to be high yet (don't want to subtract off a large number), but just AFTER... which could imply that what I'm saying is wrong and, in fact, we don't want to start watching until Week 40.  BUT... I've done the correlations on all of the week pairings, and I can tell you that even Week 43 minus Week 38 (9/16 - 9/22) has a higher correlation (-0.5373) than Week 43-40.  Bottom line... late September matters... unquestionably.

 

Moreover, while I said that the correlations support the SAI proponents, I'm not totally sold on the increase being most important anyway.  The correlation between AO and just the total snow cover in a given week (not the increase) barely comes in under the peak increase correlation.  The top correlation to raw snow cover values is -0.5259 (in Week 43 ...not coincidentally, I'm sure, the end-week on the peak increase correlation... indicating that the first week that you're subtracting off is of almost negligible importance).

 

Furthermore, the AO is not a perfect harbinger of U.S. winter temps anyway.  The correlation between Eurasian snow cover and population-weighted U.S. temperatures (which is what we use in my industry... but the population in the U.S. leans heavily to the East... so, this is VERY relevant to this board) actually does NOT peak on a snow increase value.  It peaks on an absolute snow cover value.  And, in fact, it's not even remotely close.  The highest correlation you get between U.S. winter temps and Eurasian snow increase is a putrid +0.1673 (correlation is positive because it's on U.S. heating degree days, not temperature)... that's on Week 43 minus Week 37.  But whatever... that's a pretty poor correlation.  The BEST correlation is on the absolute snow cover value... NOT on the increase!  The top correlation (still modest, lower than the AO correlation itself, but MUCH better than the HDD correlation with the snow increase), is +0.3024.  That is the correlation of the U.S. winter temps with Week 42 (10/15 - 10/21).

 

So, for U.S. (mainly Eastern U.S.) temperatures what matters most in Eurasian snow cover is the absolute amount by mid or mid-to-late October.  It's really as simple as that.  Sometimes I think we over-complicate matters.  If Eurasian snow cover is high in mid-October, that's a positive sign for a cold winter (not a guarantee... a 0.3 correlation is far, far from a home run... just a good indicator).  Simple as that.  (And, as an aside, if the GFS ends up even in the rough ballpark of correctness, snow cover by mid-Oct should be above normal... but that's pretty far out there... and it's the GFS... so, we'll see.)

[DTWXRISK]

 wrong. 

and last year  showed it 

 

Booo.  We don't want snowcover now. 

[DTWXRISK]

CORRECT .... 90% of the time  Dr Cohens forecast would of   verified nicely...

+TNH  pattern   was a   Freak event / pattern  that showed up in 1993-94  and in both cases ...1993-94  and  2013-14...
caused by the    appearance /  build up of warm  water in the Northern Pacific / Gulf of Alaska  in NOV of 2013

Most winter forecasts  came out in sept and october  and they busted

 

1) last year, the snow cover expanded rapidly at the end of September and look what happened

2) Cohen's forecast last year for the winter based upon the lack of snow cover in Siberia in October was a huge fail

http://www.nsf.gov/news/special_reports/autumnwinter/predicts.jsp

 

I'll take as much buildup of snow around the Pole as soon possible

[mattie g]

I have a headache.

[DTWXRISK]

 those  european     forecasters/ research team ... the one from last year ...still around ?

[DTWXRISK]

ANDREW  doesnt  know his  arse from a hole in the ground.    
anyone  seen the   record el nino this summer he was talking about? 

and that LRC   stuff...  

 

Andrew from the Weather Center blog isn't a big fan of the JAMSTEC forecast, doesn't think it will fully verify:

 

http://theweathercentre.blogspot.com/2014/09/jamstec-model-predicting-harsh-winter.html

[DTWXRISK]

um    that is not   what t   happened.  
Yes the   +AO did  verify  BUT it was part   of the  +TNH   Pattern....

and once it sets   in   + TNH  patterns stay around for   months

 

 

 

 

 

 

The +ao verified in Dec last year. We should all count our blessings that it didn't bleed well into Jan. Maybe it broke down because it went big + during Nov. Maybe the epo overwhelmed and took control.

There is solid data supporting the fact that a stout +ao in December is terrible here. The snowcover stuff is not perfect. Do we want to test it again? I sure don't.

[mitchnick]

CORRECT .... 90% of the time  Dr Cohens forecast would of   verified nicely...

+TNH  pattern   was a   Freak event / pattern  that showed up in 1993-94  and in both cases ...1993-94  and  2013-14...

caused by the    appearance /  build up of warm  water in the Northern Pacific / Gulf of Alaska  in NOV of 2013

Most winter forecasts  came out in sept and october  and they busted

 

boy, am I glad I was on the right side of this post!  

 

on a different note, I think I figured out your posting style Dave.......your space bar is broken!  

[WhiteoutMD]

I love when dt posts adds some spice to the board

sorry for the ot post

Sent from my iPhone using Tapatalk

[Amped]

DT has his preliminary winter outlook out.

[Redmorninglight]

His main points make sense to me. Glad I have a shat ton of firewood ready for the stove. Impressive analogs to say the least. I think 77-78 had cold but 78-79 had more snow. Looks like he is banking on niño to deliver the NAO.

[AvantHiatus]

His main points make sense to me. Glad I have a shat ton of firewood ready for the stove. Impressive analogs to say the least. I think 77-78 had cold but 78-79 had more snow. Looks like he is banking on niño to deliver the NAO.

It would be an ideal placement according to DT. Been a long time since i've seen 02-03 and 09-10 in the same analog set. I am concerned about dryness and don't think the recent coastals say anything about the upcoming winter.

 

Yeah, you don't want the cold to flood out into the mid-laditudes too early. A warm October may be a favorable signal in the long-haul. 

[AvantHiatus]

Long-range 12z Euro 850mb Temperatures, not very impressive...

 

 

[StudentOfClimatology]

What's "not impressive", exactly? That's a fantastic looking pattern. Aleutian low, good for SAI progress, and a nice PVA in S Canada. Plenty of nearby cold air as a result:

[AvantHiatus]

It looks good, but It appears the core of the cold would once again spill just a bit too far west. Height anomalies are rather high over Greenland suggesting a -NAO.

 

I read some earlier discussion about how a -NAO in October is bad. It has a warmer version of 2009-2010 vibe, wet-snow city. When is the El Nino going to take off? Color me skeptical.

 

Getting a 1899 or 2013 redux out of that 850mb pattern is unlikely. I'm just trying to make sure people's expectations are leveled off so they don't become disappointed. We should know by November, snowcover has to work harder than usual.

[StudentOfClimatology]

At one stage, there was an inverse correlation noted between the S/O/N NAO and the D/J/F NAO. However, that line of thinking hasn't worked too well in recent years. The correlation between the Aleutian Low/SAI and the winter AO still holds, however.

I never have through-the-roof expectations, living in this climate.

[AlaskaETC]

It looks good, but It appears the core of the cold would once again spill just a bit too far west. Height anomalies are rather high over Greenland suggesting a -NAO.

 

I read some earlier discussion about how a -NAO in October is bad. It has a warmer version of 2009-2010 vibe, wet-snow city. When is the El Nino going to take off? Color me skeptical.

 

Getting a 1899 or 2013 redux out of that 850mb pattern is unlikely. I'm just trying to make sure people's expectations are leveled off so they don't become disappointed. We should know by November, snowcover has to work harder than usual.

 

[WinterWxLuvr]

I think most would take an 09-10 wet snow city again