2015-16 Winter Pattern Discussion

[Stormcatt]

I'm patiently waiting for January. 

Gonna be waiting till at least mid january. Patterns like this don't just flip , it's gonna take a while. And with no sign on the horizon of that even starting we very well could be looking at the last two weeks of January before we are in a " better " pattern

[BristowWx]

at least Christmas eve and day temps look seasonal..nothing says full on torch like this weekend at this point...one positive I suppose

[Supercane]

Warning: Raleigh-centric post but with implications for the entire region...

 

Over recent years, I've noticed an interesting tendency at RDU. During neutral/cool ENSO winters, we tend to get more snow when QBO is westerly or weakly easterly through Nov-Feb (-10 and above) vs. when it is strongly easterly in at least one of those months (-10 and below). Curiously, I've noticed the exact opposite tendency when ENSO is warm.

 

So I decided to run some numbers on this based on years from 1955-2015 when the QBO dataset is reliable (hat tip to Jon for the snowfall archive link). Below are the stats I found for RDU's seasonal snowfall and the attached Dec-Mar 500mb heights. 

 

Neutral/Cool ENSO + Westerly/Weak Easterly QBO

 

1954-55: 16.8

1955-56: 2.0

1959-60: 18.7

1961-62: 14.8

1964-65: 13.5

1966-67: 10.6

1967-68: 5.7

1971-72: 7.7

1973-74: 5.7

1975-76: 3.0

1978-79: 18.3

1980-81: 5.7

1985-86: 0.9

1988-89: 12.0

1995-96: 14.6

1999-00: 25.8

2001-02: 10.8

2008-09: 7.1

2010-11: 9.0

2013-14: 5.8

 

Average Snowfall: 10.4"

Median Snowfall: 9.8"

 

 

Neutral/Cool ENSO + Strong Easterly QBO

 

1956-57: 0

1960-61: 3.8

1962-63: 8.3

1970-71: 5.9

1974-75: 0.6

1981-82: 6.6

1983-84: 6.9

1984-85: 4.1

1989-90: 2.7

1996-97: 0.4

1998-99: 0

2000-01: 2.6

2005-06: 0

2007-08: 0.5

2011-12: 0.9

2012-13: 0.7

 

Average Snowfall: 2.8"

Median Snowfall: 2.2"

 

 

The difference in the pattern between the above two datasets seems to be mostly in the Pacific. The westerly QBO years yield more northward-displaced Gulf of Alaska ridge centered in the Aleutians, whereas the easterly years have the high well south of Alaska and more ridging nosing into the SE.

 

Now for the warm ENSO years...

 

Warm ENSO + Westerly/Weak Easterly QBO

 

1957-58: 7.9

1963-64: 3.5

1969-70: 2.0

1977-78: 10.6

1982-83: 11.8

1987-88: 7.9

1990-91: 0

1992-93: 2.5

1993-94: 4.4

1994-95: 2.2

1997-98: 2.4

2002-03: 7.4

2004-05: 0.9

2006-07: 1.6

 

Average Snowfall: 4.7"

Median Snowfall: 3.0"

 

 

Warm ENSO + Strong Easterly QBO

 

1958-59: 13.5

1965-66: 11.8

1968-69: 12.0

1972-73: 11.3

1976-77: 3.6

1979-80: 18.3

1986-87: 10.8

1991-92: 0

2003-04: 14.9

2009-10: 8.0

2014-15: 7.9

 

Average Snowfall: 10.2"

Median Snowfall: 11.3"

 

 

Here, the difference in pattern seems to be mostly related to the NAO. The easterly QBO years yield a robust negative NAO pattern, whereas there is little NAO signal at all in the westerly years. For the record, this winter fits in the westerly QBO group. So I'd err on the low side in predicting snowfall this year, though the potential for big totals isn't entirely zero (see 1982-83). 

 

Obviously I only looked at snowfall for a specific location, but as you can see the differences in snowfall based on the 4 ENSO/QBO combinations seem to be related to broader modifications in the pattern. I'd be very interested to see how snowfall in other locations correlate with these combinations, or why exactly the QBO might impact the pattern in very different ways depending on the ENSO.

[mackerel_sky]

A local met that I think is one of the best around on our local stations ( ch4 Chris Justus) just put out a short write up about our winter. He says dont let the warm fool you, winter will be here in Jan and February ! He says the mountains and the piedmont areas will still likely see above normal snow for the season!! The only thing that concerns me greatly is, he is basing this on the NAO becoming and staying negative , and we all know that doesn't happen anymore!

It's on wyff.com, for anyone interested!

[Cold Rain]

Good info, Supercane! Thanks for taking the time to put that together. Not the best configuration for us, but it shouldn't be too shocking.

[BlueRidgeFolklore]

A local met that I think is one of the best around on our local stations ( ch4 Chris Justus) just put out a short write up about our winter. He says dont let the warm fool you, winter will be here in Jan and February ! He says the mountains and the piedmont areas will still likely see above normal snow for the season!! The only thing that concerns me greatly is, he is basing this on the NAO becoming and staying negative , and we all know that doesn't happen anymore!

It's on wyff.com, for anyone interested!

 

Definitely one of the best. He puts so much time into giving us a forecast unlike most TV mets.

 

https://www.facebook.com/ChrisJustusMeteorologist/posts/875937775836914

[RubiksDestroyer]

Supercane,

Interesting concept! However, while I realize there aren't very many El Nino years, I feel that you used many weaker El Nino years in your composite that may've skewed it slightly, because in weaker El Ninos it's much easier for other patterns to overrule its impacts. I decided to use your data, but limit it to only moderate+ years:

 

Moderate+ Warm ENSO + Westerly/Weak Easterly QBO:

 

1957-58: 7.9

1963-64: 3.5

1982-83: 11.8

1987-88: 7.9

1997-98: 2.4

2002-03: 7.4

Average: 6.8

Moderate+ Warm ENSO + Strong Easterly QBO:

 

1965-66: 11.8

1972-73: 11.3

1986-87: 10.8

1991-92: 0

2009-10: 8.0

Average: 8.38

 

While the stronger easterly QBO have more 10"+ years, it appears that the difference between the two patterns is much smaller. The main difference I see are the much stronger heights over the Hudson Bay area for the stronger eastern QBO, which is something I feel would be preferable to have this winter.

 

Of course, this data size could be further limited, however by that point the sample size would be too small to show any true correlations. In the end, I think you're right about this correlation, but as I stated earlier, it is much harder for stronger El Nino and La Nina patterns to be impacted by external forces like the QBO.

[BullCityWx]

If you roll forward to next friday using MOS temps, the average December temp will be at 53 for Charlotte which would tie 1956 as the second warmest December of all time. 1956-1957 would end up having only a trace of snow and the 5th warmest winter of all time. 

[Supercane]

Good info, Supercane! Thanks for taking the time to put that together. Not the best configuration for us, but it shouldn't be too shocking.

 

We can hope that the strong El Nino is enough to deliver for us anyway, as it did in 1982-83. But 1997-98 is in the same group, so with such a small sample size it's difficult IMO to say if a strong El Nino is truly more advantageous than a weaker one.

[Supercane]

 

Supercane,

Interesting concept! However, while I realize there aren't very many El Nino years, I feel that you used many weaker El Nino years in your composite that may've skewed it slightly, because in weaker El Ninos it's much easier for other patterns to overrule its impacts. I decided to use your data, but limit it to only moderate+ years:

 

Moderate+ Warm ENSO + Westerly/Weak Easterly QBO:

 

1957-58: 7.9

1963-64: 3.5

1982-83: 11.8

1987-88: 7.9

1997-98: 2.4

2002-03: 7.4

Average: 6.8

 

Moderate+ Warm ENSO + Strong Easterly QBO:

 

1965-66: 11.8

1972-73: 11.3

1986-87: 10.8

1991-92: 0

2009-10: 8.0

Average: 8.38

 

 

While the stronger easterly QBO have more 10"+ years, it appears that the difference between the two patterns is much smaller. The main difference I see are the much stronger heights over the Hudson Bay area for the stronger eastern QBO, which is something I feel would be preferable to have this winter.

 

Of course, this data size could be further limited, however by that point the sample size would be too small to show any true correlations. In the end, I think you're right about this correlation, but as I stated earlier, it is much harder for stronger El Nino and La Nina patterns to be impacted by external forces like the QBO.

 

 

Thanks for breaking down this even further. However, how are you determining what is a moderate+ El Nino? Since you included 1963-64 and 2002-03, I'm not following how 1994-95 and 2006-07 (which had very similar ONI values) are kept out.

[Cold Rain]

Let's see if we've made any improvement:

 

 

Nope, apparently not.

[NCSNOW]

If you roll forward to next friday using MOS temps, the average December temp will be at 53 for Charlotte which would tie 1956 as the second warmest December of all time. 1956-1957 would end up having only a trace of snow and the 5th warmest winter of all time. 

Unfortunately I could see history repeating itself. This all time strongest Nino we are expierencing is gonna take a long time before it fades enough to quit influencing the pattern the way it is. I hope Im wrong but I'm very skeptical  that this pattern changes in time to make a difference before time runs out. Hopefully as we roll through the next week or so we can start to see some indications on Long range. I'm still at zero on model forecasted fantasy snow this year and it's mid December. Those warm SST's piled up in the central to eastern areas of the pacific scream for a trough to hang out forever along  the west coast.

 

I know  Brickster is happy. Haven't had the luxury of seeing one post from him complaining about the cloudy& rainy / Colld & Dry weather

[NCSNOW]

We can hope that the strong El Nino is enough to deliver for us anyway, as it did in 1982-83. But 1997-98 is in the same group, so with such a small sample size it's difficult IMO to say if a strong El Nino is truly more advantageous than a weaker one.

 

A weaker El Nino is ALWAYS way more advantageous for us verse a strong elnino. Strong El nino's are crap for the SE.

[Jon]

A weaker El Nino is ALWAYS way more advantageous for us verse a strong elnino. Strong El nino's are crap for the SE.

Depends on your definition of crap...Strong El Niños average more snow in the SE than weak El Ninos, Neutral, or La Niña patterns.

[FallsLake]

I'm only out past day 5 on the 12 GFS and it actually looks good for that time period. Nice ridging on the west coast with cold air spilling towards the SE. Not sure what it will show after this, but does it really matter...

[Cold Rain]

I'm only out past day 5 on the 12 GFS and it actually looks good for that time period. Nice ridging on the west coast with cold air spilling towards the SE. Not sure what it will show after this, but does it really matter...

 

Will be a modified and transient cold air mass.  More energy crashing into the west coast.  At least it won't be torching after the front for a couple of days!

[RubiksDestroyer]

Thanks for breaking down this even further. However, how are you determining what is a moderate+ El Nino? Since you included 1963-64 and 2002-03, I'm not following how 1994-95 and 2006-07 (which had very similar ONI values) are kept out.

I used this websitem which defines moderate as an ONI above 1.0: http://ggweather.com/enso/oni.htm

 

Looking at the graph/table on that link, 2006-2007 and 1994-1995 were just below the requirements needed.

[FallsLake]

Will be a modified and transient cold air mass.  More energy crashing into the west coast.  At least it won't be torching after the front for a couple of days!

I'm out to day 7 and it does look to not have much staying power. I do like the high coming down from Canada. Just wish it was farther west. I would post an image but I have limited computer access right now.

[calculus1]

Let's see if we've made any improvement:

 

Nope, apparently not.

 

Looks to me like the AO and NAO are heading toward negative territory at the edge of the graph.

[Jon]

Thanks for breaking down this even further. However, how are you determining what is a moderate+ El Nino? Since you included 1963-64 and 2002-03, I'm not following how 1994-95 and 2006-07 (which had very similar ONI values) are kept out.

 

I used this websitem which defines moderate as an ONI above 1.0: http://ggweather.com/enso/oni.htm

 

Looking at the graph/table on that link, 2006-2007 and 1994-1995 were just below the requirements needed.

Yeah, it states that those years were moved down from Moderate to Weak because of ERSSTv4 update by the CPC for the calculation of SST's. It's kinda up to the person on whether to include the years they want, some people (webberweather for example) are working on adjusted ONI's based on newer more accurate data, but he told me a few days ago he won't have final numbers until next year. So basically you decide whether to include or leave them out, shouldn't make too much of a difference though. That's why it's good to compare only strong Ninos to see the variability.

 

Check out this post by Joe D'Aleo (now with weatherbell) back in 2009 http://www.intellicast.com/Community/Content.aspx?a=213

 

"Research by Barnston, Livesey and Halpert at the CPC and then others suggested ENSO (both El Nino and La Nino) is modulated by the QBO, a quasi-biennial oscillation of the winds high up over the tropical Pacific which goes through alternating phases of west and east anomalies. Ming Cai at the University of Maryland found a tendency for enhanced potential vorticity in east QBO years in lower mid-latitudes and colder temperatures across much of the US in DJF along with northeast Canada blocking. Westerly QBOs tend to produce more of a positive PNA pattern with a western North America ridge and eastern trough. It is cold in east QBOS in Siberia and warmer in west QBOs."

 

 

I'll note it's interesting comparing patterns with regard to snowfall...as you wouldn't think the above eastern QBO map would produce....the El Nino West QBO years map looks a lot like Weatherbell's "Pioneer" model, if we do get above average snow with the heights in western Canada it will be most likely due to a +PNA working in concert with a -NAO...in my research the only thing I saw definite for above snowfall was a west based -NAO or baffin block, but that shouldn't undermine the importance of a nice +PNA.

[Cold Rain]

Looks to me like the AO and NAO are heading toward negative territory at the edge of the graph.

 

They always are.  In fact, they should just hard code the lines to go down at the end of the period, since they do all the time anyway.  Trouble is, when the end of the period becomes the beginning of the period, we're still hoping that the lines will go down from where they are at the beginning of the period.

[pcbjr]

I'm somewhat at a loss here - are we east or west based QBO?

[mackerel_sky]

Warm oceans, cold continents ,

Warm oceans, cold continents,

Repeat!

[RubiksDestroyer]

 

I'm somewhat at a loss here - are we east or west based QBO?

 

West.

 

Also:

 

[Supercane]

I used this websitem which defines moderate as an ONI above 1.0: http://ggweather.com/enso/oni.htm

 

Looking at the graph/table on that link, 2006-2007 and 1994-1995 were just below the requirements needed.

 

I see. So they're factoring in longevity of the 1.0+ values in the fall and winter, rather than just, say, the ONI value for DJF. Seems fair enough.

 

The snowfall average of your narrowed stronger El Nino + westerly/weak easterly QBO list is slightly above our long-term average -- noticeably better than the weak El Nino + westerly/weak easterly QBO years (which yields an average of 3.0"). For the strong easterly years, El Nino strength doesn't seem to be a big factor, which is interesting. Based on this, I guess the moral of the story is that for moderate+ El Ninos, a westerly/weak easterly QBO is slightly worse, and for weak El Ninos, a westerly/weak easterly QBO is much worse.

[RubiksDestroyer]

I see. So they're factoring in longevity of the 1.0+ values in the fall and winter, rather than just, say, the ONI value for DJF. Seems fair enough.

 

The snowfall average of your narrowed stronger El Nino + westerly/weak easterly QBO list is slightly above our long-term average -- noticeably better than the weak El Nino + westerly/weak easterly QBO years (which yields an average of 3.0"). For the strong easterly years, El Nino strength doesn't seem to be a big factor, which is interesting. Based on this, I guess the moral of the story is that for moderate+ El Ninos, a westerly/weak easterly QBO is slightly worse, and for weak El Ninos, a strong easterly QBO is much worse.

I think so too. We could be better, but it's still likely we'll end up above average for snowfall (at least, at RDU).

[BullCityWx]

While I'd love that 12z GFS LR panel to verify, that's nothing but cold chasing moisture. There could be some upslope though and maybe some flurries across the cumberland plateau in tennessee. 

[Supercane]

I think so too. We could be better, but it's still likely we'll end up above average for snowfall (at least, at RDU).

 

Edited because I meant to say a westerly/weak easterly is much worse, but I think you got what I meant.

[FlatLander48]

While I'd love that 12z GFS LR panel to verify, that's nothing but cold chasing moisture. There could be some upslope though and maybe some flurries across the cumberland plateau in tennessee. 

From what I've heard, it's not as much as cold chasing moisture as you would think. There's supposed to be a stalled front and low pressure is supposed to ride up the front, and those that are west of the stalled front should be ok. 

[Jon]

While I'd love that 12z GFS LR panel to verify, that's nothing but cold chasing moisture. There could be some upslope though and maybe some flurries across the cumberland plateau in tennessee. 

The cold source is over South Dakota, so I agree classic cold chasing moisture haha...It's ok we have another threat to watch hour 384 

 

Anything we get at the end of the month in the way of cold, even seasonable cold, is a bonus. A cold Christmas would be amazing.