And we begin

[Mallow]

Don't need to. We are a lot higher today. But why did you pick 2007?

Probably to show a sea ice comparison to the previous lowest-on-record year.

[MillzPirate]

Don't need to. We are a lot higher today. But why did you pick 2007?

We're actually lower today by a good bit

[tacoman25]

We're actually lower today by a good bit

He was referring to snowcover, not ice extent.

[weathafella]

Let's compare 9/17, the day this thread started to today.

9/17:

9/20: Not much difference in ice yet and of course snow waxes and wanes this time of year still.

This post will auto update the current picture so we'll see from day 1 to the present as we roll forward in one post.

[Ed Lizard]

This. The fact is, the SAI is better correlated to the winter AO than the SCE. Whatever the reasons, that's just what the data shows. It's not a perfect correlation, so there are exceptions (of course), but unless you can show me your own index based on, say, southern Siberian snow cover that has an even better correlation than the SAI, I'm sticking with the SAI. So, yes, I am rooting for low snowcover anomalies at the beginning of October, and high at the end.

In other words, we don't fully understand the physics, but we have the statistics. So unless you understand the physics well enough to discriminate such details (and beat the statistics), you're not going to convince me to go against the statistics.

I fully respect going off the empirical data, best fit data is best fit data, just trying to wrap my mind around why the rate of change would be even more important than the actual snowpack in influencing the atmosphere. This approaches HM territory (mountain torques and GLAAM and strat warms), where things happen and can be useful predictors, but w/o a met education, its hard to understand why.

[Mallow]

I fully respect going off the empirical data, best fit data is best fit data, just trying to wrap my mind around why the rate of change would be even more important than the actual snowpack in influencing the atmosphere. This approaches HM territory (mountain torques and GLAAM and strat warms), where things happen and can be useful predictors, but w/o a met education, its hard to understand why.

I don't know why. But that doesn't mean there isn't a valid physical explanation. Maybe, for example, the change in wavelengths through the month of October means that you want to have the opposite forcing early in the month compared to later to get the same effect over the Arctic or Greenland? I mean, there are obviously quite a few possible explanations.

[Roger Smith]

It should be noted that the open water boundary in the arctic is not as far north as in 2007 on the Siberian side, but is further north on the European side. Back in 2007 the boundary was around 84N at 150E ... and the outcome that winter (2007-08) was for anomalous snow cover in east Asia and parts of eastern North America. Having the ice anomaly tilted further towards Europe this time around is no great guarantee of a "better" outcome for any region of North America in relative terms to 2007-08.

There is also the tipping point factor to consider. Long-term, you would tend to associate ice-free arctic with milder winters in general. The route to a rebound or opposite signal effect is a complex one and it should not be assumed that a rebound will have to occur. We may just be looking at a signal for a stronger polar vortex.

I have the feeling that the net result will favour high variability this winter, in other words, not the exact opposite of last winter but a greater mixture of flow patterns that may remain rather zonal but high amplitude, so not the best possible outcome for northeast U.S. cold or snow, but unlike last winter, not the worst case scenario. For reasons unrelated to the ice anomaly I have come up with late January as the most favoured part of the winter for snow in the northeast U.S. ... and it appears likely to be a good lake effect winter, but February could turn much warmer.

[donsutherland1]

Thank you Don. And thank you for teaching all of us again and again. I hope you are well and perhaps this year there can be some nic additions to the digital snow museum.

Thanks Jerry. I'm well. An infant keeps me busy. I'm trying to work on his sleep patterns so that he will wake up around the times the 0z Euro and 6z GFS come out, giving me additional reason to check the models. Hopefully, we won't see another winter like the last one for a long time to come.

[weathafella]

Thanks Jerry. I'm well. An infant keeps me busy. I'm trying to work on his sleep patterns so that he will wake up around the times the 0z Euro and 6z GFS come out, giving me additional reason to check the models. Hopefully, we won't see another winter like the last one for a long time to come.

Congratulations on having a new baby! I must have missed the announcement. You'll be a great father. Get him out in the snow asap. All of my kids have some wx weenie in them....

And being a good husband, you can graciously offer the overnight duty particularly when the pattern is active.

[Damage In Tolland]

Thanks Jerry. I'm well. An infant keeps me busy. I'm trying to work on his sleep patterns so that he will wake up around the times the 0z Euro and 6z GFS come out, giving me additional reason to check the models. Hopefully, we won't see another winter like the last one for a long time to come.

Don congrats on the new addition.. I thought you were like 60..lol

[Mr Torchey]

Congrats Don.

[SVT450R]

2011 vs 2012 If anyone is looking for any other comparison let me know.

[Met1985]

Thanks Jerry. I'm well. An infant keeps me busy. I'm trying to work on his sleep patterns so that he will wake up around the times the 0z Euro and 6z GFS come out, giving me additional reason to check the models. Hopefully, we won't see another winter like the last one for a long time to come.

Congrats! I feel ya about the sleep patterns trying to do the same with my newborn. Also great thread Jerry! Learning stuff all the time on this board!

[Ground Scouring]

I am also in concurrence with the people who do not believe that a lower snow cover in Greenland / N Canada this year necessarily portends a milder winter in the lower 48 states...as the AAM this year will likely be higher than in previous weak Niño cycles (like 2006-2007) due to the likelihood that the PDO will likely trend more + over the course of October and November. Latest SSTA and subsurface data show this trend, which would aid temperature contrast and cyclogenesis over the Aleutians region and tend to pump up the W NAM ridge later in November-December. In this sense the Siberian pattern would favor ridging and enhanced snowcover there, thereby increasing Rossby amplifications downstream as ENSO warms--but only slightly before leveling out--and the atmosphere responds by mid-October. In conjunction with a persistent + NAO, this trend should be good news for those wanting higher snow cover in the Great Lakes region, which has missed out on large Miller A / B events alike in recent years.

[tacoman25]

I am also in concurrence with the people who do not believe that a lower snow cover in Greenland / N Canada this year necessarily portends a milder winter in the lower 48 states...as the AAM this year will likely be higher than in previous weak Niño cycles (like 2006-2007) due to the likelihood that the PDO will likely trend more + over the course of October and November. Latest SSTA and subsurface data show this trend, which would aid temperature contrast and cyclogenesis over the Aleutians region and tend to pump up the W NAM ridge later in November-December. In this sense the Siberian pattern would favor ridging and enhanced snowcover there, thereby increasing Rossby amplifications downstream as ENSO warms--but only slightly before leveling out--and the atmosphere responds by mid-October. In conjunction with a persistent + NAO, this trend should be good news for those wanting higher snow cover in the Great Lakes region, which has missed out on large Miller A / B events alike in recent years.

In regards to the PDO...this past summer featured the most negative PDO ever for a +ENSO year. There is a very high correlation between very -PDO summer and -PDO the following winters, so while we very well may see the -PDO rise some this fall, a -PDO winter is quite likely.

[mitchnick]

on a related note.....meh

http://www.ijis.iarc.uaf.edu/en/home/seaice_extent.htm

[weathafella]

on a related note.....meh

http://www.ijis.iarc.uaf.edu/en/home/seaice_extent.htm

Quick ramp up on that graph in the past week or so. Will be interesting to see where it goes in October.

[QVectorman]

In regards to the PDO...this past summer featured the most negative PDO ever for a +ENSO year. There is a very high correlation between very -PDO summer and -PDO the following winters, so while we very well may see the -PDO rise some this fall, a -PDO winter is quite likely.

I crunched the numbers earlier in August using July PDO numbers and came up with this....appears that for July when the PDO is below -1.00 historically 87% of the time it stayed neg. for DJF. And 53% of the time it went lower than -1 for DJF. If PDO is below -1.5 for July...71% of the time it stayed negative..smaller sample size. Also...it seems that a PDO value of -1.20 or lower for DJF is when the PDO correlated height anomalies really show up and exert themselves.

Two years that the PDO flipped or was "neutral" was 1904 and 1933. Of course ENSO states aren't available for those years.

Winter of 52-53 and 78-79 were the only years ENSO flipped to weak nino in winter while July PDO was still <-1.

I also color labeled the years by ENSO for events greater than -.5 or .5 for DJF

**Side note...did this using August numbers and it becomes pretty jumbled.

[GaWx]

Two years that the PDO flipped or was "neutral" was 1904 and 1933. Of course ENSO states aren't available for those years.

1904 was another weak Nino that followed La Nina. That's one reason I'm still going with a 1 in 3 chance for the PDO to flip in time for the DJF avg. However, it will likely need to start rising in earnest within the next month or so. 1933 was a moderate Nina.

Edit: 1939-40, another weak nino that followed a Nina, is another reason I'm still giving the PDO a 1 in 3 shot to flip by DJF. The 1939 PDO was still solidly - in Oct. before it rose rapidly to a very solidly + DJF PDO.

[tacoman25]

I crunched the numbers earlier in August using July PDO numbers and came up with this....appears that for July when the PDO is below -1.00 historically 87% of the time it stayed neg. for DJF. And 53% of the time it went lower than -1 for DJF. If PDO is below -1.5 for July...71% of the time it stayed negative..smaller sample size. Also...it seems that a PDO value of -1.20 or lower for DJF is when the PDO correlated height anomalies really show up and exert themselves.

Two years that the PDO flipped or was "neutral" was 1904 and 1933. Of course ENSO states aren't available for those years.

Winter of 52-53 and 78-79 were the only years ENSO flipped to weak nino in winter while July PDO was still <-1.

I also color labeled the years by ENSO for events greater than -.5 or .5 for DJF

**Side note...did this using August numbers and it becomes pretty jumbled.

I don't have the numbers on me, but I ran the correlation between JJA PDO of -1 or lower and the following DJF awhile back, and the vast majority of those winters had -PDO, with a good percentage quite -PDO.

In a -PDO phase like we are currently in, it usually takes a significant Nino to flip to +PDO. And the signs that this is coming almost always show up by July/August (as happened in 2009, though 2009-10 only weakly +PDO).

As it is, I would give the following odds for the DJF PDO:

-1.5 or lower: 25%

-1 or lower: 50%

Neutral (-.5 to .5): 40%

+1 or higher: 10%

[GaWx]

I don't have the numbers on me, but I ran the correlation between JJA PDO of -1 or lower and the following DJF awhile back, and the vast majority of those winters had -PDO, with a good percentage quite -PDO.

In a -PDO phase like we are currently in, it usually takes a significant Nino to flip to +PDO. And the signs that this is coming almost always show up by July/August (as happened in 2009, though 2009-10 only weakly +PDO).

As it is, I would give the following odds for the DJF PDO:

-1.5 or lower: 25%

-1 or lower: 50%

Neutral (-.5 to .5): 40%

+1 or higher: 10%

Your %'s look pretty reasonable to me and pretty much agree with my 1 in 3 chance for a DJF +PDO. Keep in mind the pretty strong flips that occurred during three weak Ninos that followed Ninas: 1904-5, 1939-40, and 1976-7. 1904 still had a -1.53 in June and a -1.58 in July although it admittedly wasn't in a negative phase like the current one. 1939-40 also wasn't within a strong negative phase like the current one, but it did have a very strong and quick reversal: Sep/Oct/Nov were -1.10, -1.31, and -0.88, respectively. Yet, look at how + was the DJF PDO, one of the stronger ones. 1976-7 was coming out of a strongly -PDO phase. Look at how fast it flipped from solid -PDO spring to solid +PDO autumn with a strong +PNA at that time. I still wonder about the chicken-egg relationship of the +PNA and +PDO.

[SVT450R]

No big changes from yesterday so another comparison with last year.

[tacoman25]

Your %'s look pretty reasonable to me and pretty much agree with my 1 in 3 chance for a DJF +PDO. Keep in mind the pretty strong flips that occurred during three weak Ninos that followed Ninas: 1904-5, 1939-40, and 1976-7. 1904 still had a -1.53 in June and a -1.58 in July although it admittedly wasn't in a negative phase like the current one. 1939-40 also wasn't within a strong negative phase like the current one, but it did have a very strong and quick reversal: Sep/Oct/Nov were -1.10, -1.31, and -0.88, respectively. Yet, look at how + was the DJF PDO, one of the stronger ones. 1976-7 was coming out of a strongly -PDO phase. Look at how fast it flipped from solid -PDO spring to solid +PDO autumn with a strong +PNA at that time. I still wonder about the chicken-egg relationship of the +PNA and +PDO.

Yeah, none of those years were at a similar point in a -PDO phase as we are now. 1976-77 is when we flipped to a +PDO phase, and we saw a large rise in the PDO summer 1976. Very different than where we are at now.

[Isotherm]

1952-53 is an interesting case - one would think it was a decent winter given the data indicates a -NAO,-AO, and +PNA, in conjunction w/ the weak Nino. But this was a classic case of the north pacific pattern being crucial -- the +EPO induced Alaskan vortex can trump favorable -NAO/AO signalling when strong enough.

Note the DJF H5 composite anomalies:

Blocking evident in the NW Atlantic/Greenland, but the massive low height anomaly in the Gulf of Alaska yielded a powerful hose of mild Pacific air, aimed into the United States. Thus temp anomalies looked like this:

Torcherama.

Hence, even if we look good for NAO/AO/PNA values, there is concern that the strong -PDO may create a bit of repeat scenario in the north pacific (as we saw last winter). The weaker the Nino (or if its neutral ENSO) the higher the chance for a dud winter.

[GaWx]

1952-53 is an interesting case - one would think it was a decent winter given the data indicates a -NAO,-AO, and +PNA, in conjunction w/ the weak Nino. But this was a classic case of the north pacific pattern being crucial -- the +EPO induced Alaskan vortex can trump favorable -NAO/AO signalling when strong enough.

Note the DJF H5 composite anomalies:

Blocking evident in the NW Atlantic/Greenland, but the massive low height anomaly in the Gulf of Alaska yielded a powerful hose of mild Pacific air, aimed into the United States. Thus temp anomalies looked like this:

Torcherama.

Hence, even if we look good for NAO/AO/PNA values, there is concern that the strong -PDO may create a bit of repeat scenario in the north pacific (as we saw last winter). The weaker the Nino (or if its neutral ENSO) the higher the chance for a dud winter.

This is tricky. According to the newest ONI classification table, 1952-3 has been changed from a neutral positive to a late starting weak Nino. I still am calling it a neutral positive because I'm still using the prior table's classifications for all of the past years going back to 1950. All of my prior analyses have used that prior table for 1950+ and I see no reason to change it. For example, I'm still calling the warm 1951-2 a weak Nino.

Based on the overall history of weak Ninos following Ninas, I do feel that the category of weak, overall, is the best shot at a cold winter and that a neutral fall/winter peak (or fewer than five trimonths in a row of +0.5+) would mean higher chance for a dud.

[The_Global_Warmer]

1952-53 is an interesting case - one would think it was a decent winter given the data indicates a -NAO,-AO, and +PNA, in conjunction w/ the weak Nino. But this was a classic case of the north pacific pattern being crucial -- the +EPO induced Alaskan vortex can trump favorable -NAO/AO signalling when strong enough.

Note the DJF H5 composite anomalies:

Blocking evident in the NW Atlantic/Greenland, but the massive low height anomaly in the Gulf of Alaska yielded a powerful hose of mild Pacific air, aimed into the United States. Thus temp anomalies looked like this:

Torcherama.

Hence, even if we look good for NAO/AO/PNA values, there is concern that the strong -PDO may create a bit of repeat scenario in the north pacific (as we saw last winter). The weaker the Nino (or if its neutral ENSO) the higher the chance for a dud winter.

I remember last winter in my region where cold fronts came in with quick moving troughs but even worse was the W. WNW winds coming off or over the Rockies where the ground was bare the downsloping effect would eat right into the cold coming out of Canada during transitions like a fire hose so to speak.

I don't recall such a consistent winter in recent history with that effect so far off the E. MTN slopes so quickly.

[QVectorman]

I don't have the numbers on me, but I ran the correlation between JJA PDO of -1 or lower and the following DJF awhile back, and the vast majority of those winters had -PDO, with a good percentage quite -PDO.

In a -PDO phase like we are currently in, it usually takes a significant Nino to flip to +PDO. And the signs that this is coming almost always show up by July/August (as happened in 2009, though 2009-10 only weakly +PDO).

As it is, I would give the following odds for the DJF PDO:

-1.5 or lower: 25%

-1 or lower: 50%

Neutral (-.5 to .5): 40%

+1 or higher: 10%

I agree with your numbers it looks like we're on the same page. I did notice that a couple years that flipped from - to + ENSOs during DJF ended up having -1<PDO<-.5. So I might have to lean more towards the chances of a PDO btwn -1 to -.5.

Then from the years I have looked at with PDO btwn -1 to -.5 the PDO height anomaly correlations begin to get lost and you get patterns like Isotherm pointed out where the vortex positioned over the GofA rather than Western Can. and you don't get a ridge off the Aleutians and the US temp pattern ends up being drastically different than when the PDO is less than -1.2. Of course looking at years with PDO's of -.8 to 0 it seems the whole pattern over AK and western Can becomes extremely unpredictable as to where ridge and trough set up. So I think with PDO btwn -1 to -.5 as I personally am leaning towards for this DJF I think we will see a mix EPO for the winter...I know...way to narrow it down! But I don't think all hope is lost from the maps I've looked at to see a few time frames where a nice ridge sets up over w. Can. and dumps some cold air into the US.

1904 was another weak Nino that followed La Nina. That's one reason I'm still going with a 1 in 3 chance for the PDO to flip in time for the DJF avg. However, it will likely need to start rising in earnest within the next month or so. 1933 was a moderate Nina.

Edit: 1939-40, another weak nino that followed a Nina, is another reason I'm still giving the PDO a 1 in 3 shot to flip by DJF. The 1939 PDO was still solidly - in Oct. before it rose rapidly to a very solidly + DJF PDO.

Thanks for the data to fill in missing holes! I was looking at the overall PDO graph and it appears that 1904 and 1933 took place in +PDO decadal cycles. So since we are heading into a -PDO I am leaning toward the chances of the PDO going into + range for DJF to be pretty slim just on gut feeling. As much as I wish it would go + and hopefully encourage a -EPO config.

[tacoman25]

I agree with your numbers it looks like we're on the same page. I did notice that a couple years that flipped from - to + ENSOs during DJF ended up having -1<PDO<-.5. So I might have to lean more towards the chances of a PDO btwn -1 to -.5.

Then from the years I have looked at with PDO btwn -1 to -.5 the PDO height anomaly correlations begin to get lost and you get patterns like Isotherm pointed out where the vortex positioned over the GofA rather than Western Can. and you don't get a ridge off the Aleutians and the US temp pattern ends up being drastically different than when the PDO is less than -1.2. Of course looking at years with PDO's of -.8 to 0 it seems the whole pattern over AK and western Can becomes extremely unpredictable as to where ridge and trough set up. So I think with PDO btwn -1 to -.5 as I personally am leaning towards for this DJF I think we will see a mix EPO for the winter...I know...way to narrow it down! But I don't think all hope is lost from the maps I've looked at to see a few time frames where a nice ridge sets up over w. Can. and dumps some cold air into the US.

Thanks for the data to fill in missing holes! I was looking at the overall PDO graph and it appears that 1904 and 1933 took place in +PDO decadal cycles. So since we are heading into a -PDO I am leaning toward the chances of the PDO going into + range for DJF to be pretty slim just on gut feeling. As much as I wish it would go + and hopefully encourage a -EPO config.

Oh absolutely, there are definitely different variations of -PDO patterns, and -EPO can certainly be included. I know people have 2011-12 still on their minds, but there have been many -PDO winters, especially ones with weak ENSO, where nice blocking episodes occurred.

[tacoman25]

1952-53 is an interesting case - one would think it was a decent winter given the data indicates a -NAO,-AO, and +PNA, in conjunction w/ the weak Nino. But this was a classic case of the north pacific pattern being crucial -- the +EPO induced Alaskan vortex can trump favorable -NAO/AO signalling when strong enough.

Note the DJF H5 composite anomalies:

Blocking evident in the NW Atlantic/Greenland, but the massive low height anomaly in the Gulf of Alaska yielded a powerful hose of mild Pacific air, aimed into the United States. Thus temp anomalies looked like this:

Torcherama.

Hence, even if we look good for NAO/AO/PNA values, there is concern that the strong -PDO may create a bit of repeat scenario in the north pacific (as we saw last winter). The weaker the Nino (or if its neutral ENSO) the higher the chance for a dud winter.

It's interesting you bring up 1952-53...that winter was actually only very weakly -PDO. Not surprising considering it was a second year +ENSO winter.

If we just look at weakish +ENSO winters in the last -PDO phase that came on the heels of -ENSO events, we only have 1951-52 and 1968-69. Not a great sample size, obviously, but I'd favor either of those winters as analogs over 1952-53.

Other years include 1976-77, 1990-91, and 2006-07. But none of those were in a similar PDO state.

[Isotherm]

It's interesting you bring up 1952-53...that winter was actually only very weakly -PDO. Not surprising considering it was a second year +ENSO winter.

If we just look at weakish +ENSO winters in the last -PDO phase that came on the heels of -ENSO events, we only have 1951-52 and 1968-69. Not a great sample size, obviously, but I'd favor either of those winters as analogs over 1952-53.

Other years include 1976-77, 1990-91, and 2006-07. But none of those were in a similar PDO state.

You're right, 52-53 was only weakly negative. 1951 has been one of my primary analogs through this past summer and it looks like it may be a good one going forward. The august PDO value is more strongly negative than last month, which isn't good news:

http://jisao.washing.../pdo/PDO.latest

This puts 12-13 closest to 51-52 PDO wise if we have a weak nino. I can see the PDO warming over the next few months, but usually by September we see some indication of reversal, and we've gone the wrong direction. Going to have to hope for NAO/AO magic this year I'm thinking.