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Happy snowy September 9th from the Southwest. In NM, the snow got down to about 7,000 feet. Only fell to 41 in Albuquerque unfortunately (although the record for September is 35 since 1931). All it took to go from 90-100 degree readings to snow was six hours of 40-70 mph winds in most places. Who knew?

Believe it or not, some of the years with similar ENSO setups that I like do actually have fierce cold shots as a feature of the pattern in the SW in the second week of September. One of the more interesting years to look at is 1936, although I'm not going to use it as analog. 1995 actually had fairly intense cold dump into the SW in September. I'm getting a little concerned that there may be some very intense (although 1-3) dumps of cold into the West this winter. It's increasingly looking to me like the PDO is going to be the most negative it's been in a long time for one thing, I think below -1.0 is possible for Nov-Apr.

Red River at 8,600 feet had it's earliest snow on a July-June basis since at least 1906, they have reliable weather records there for 1906-2014 in that town. It's not uncommon to snow there in September, but getting more than four inches is rare in September, and the prior earliest snow had been 9/17.

Image

Outside Santa Fe - 

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Los Alamos - 

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38469EFB-882C-4800-9E0C-BBADBFA1947E.thumb.png.87bc800a2a107555d5075e6fa3388cca.png

September run of the NMME is getting pretty aggressive with the strength of the Niña come winter, with the majority of members reaching moderate strength. Getting rather concerned about a very active cool season severe weather pattern given the drought conditions in the SW supporting efficient EML advection east of the Plains and the La Niña supporting SE/W Atlantic ridging.

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1 hour ago, andyhb said:

38469EFB-882C-4800-9E0C-BBADBFA1947E.thumb.png.87bc800a2a107555d5075e6fa3388cca.png

September run of the NMME is getting pretty aggressive with the strength of the Niña come winter, with the majority of members reaching moderate strength. Getting rather concerned about a very active cool season severe weather pattern given the drought conditions in the SW supporting efficient EML advection east of the Plains and the La Niña supporting SE/W Atlantic ridging.

The big red flag to me is that the majority of the models end the La Nina (whatever intensity it is) as central to west-based as we head through late winter and toward spring.  That sets up a significantly positive TNI pattern.  You know all about what that means, in conjunction with the La Nina itself and a -PDO that is already -1.25 as of August (it peaked at -1.75 last winter and didn't get to -1.25 until after Christmas)...

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image.thumb.png.696ffe6c4d08a71bb0f2b93dc44b8579.png

Should probably add the obvious Nina standing wave pattern showing up now in the 850 hPA zonal wind Hovmollers. Strong, sustained trades across most of the basin.

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17 minutes ago, Fred Gossage said:

The big red flag to me is that the majority of the models end the La Nina (whatever intensity it is) as central to west-based as we head through late winter and toward spring.  That sets up a significantly positive TNI pattern.  You know all about what that means, in conjunction with the La Nina itself and a -PDO that is already -1.25 as of August (it peaked at -1.75 last winter and didn't get to -1.25 until after Christmas)...

Yet Plains chasers aren't optimistic, as the general consensus seems to be that La Nina leads to drought and excessive capping for their region.

It seems to be a mixed bag for here in the upper Midwest. We can get very active years like 2008 where there was pretty much sustained severe weather and tornado activity from the 4th week of May through the first two weeks of June. However every year after 2015 has pretty much been a total dud in this region, apart from sneaky overachieving events on low-key risk days at random times of the year (the latest being the 8/10 derecho).

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2 minutes ago, CheeselandSkies said:

Yet Plains chasers aren't optimistic, as the general consensus seems to be that La Nina leads to drought and excessive capping for their region.

It seems to be a mixed bag for here in the upper Midwest. We can get very active years like 2008 where there was pretty much sustained severe weather and tornado activity from the 4th week of May through the first two weeks of June. However every year after 2015 has pretty much been a total dud in this region, apart from sneaky overachieving events on low-key risk days at random times of the year (the latest being the 8/10 derecho).

First-year La Ninas coupled with a -PDO tend to be unkind to Dixie Alley, and often times, there is enhanced drought in the Plains.  However, even then, there can still be big events out there.  May 24, 2011 and May 3, 1999 come to mind.  There was decent drought in the Southern Plains in the fall of 1998 as we went into that La Nina.  By the time we were rolling into the summer of 1999, some areas of Oklahoma were apparently above average in precipitation.  You will find that most (definitely not all) Plains chasers are a very knee-jerk reaction and Plains inactivity = no activity anywhere at all type of crowd.

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@andyhb, do you believe early spring 2021 will be similar to or perhaps even more violent than early spring 2020 (the Easter outbreak and I believe another one close to that timeframe)?

Will that translate into a similarly lackluster chase season for the Plains/Midwest, or is it impossible to make that connection at this point?

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Just now, CheeselandSkies said:

@andyhb, do you believe early spring 2021 will be similar to or perhaps even more violent than early spring 2020 (the Easter outbreak and I believe another one close to that timeframe)?

Will that translate into a similarly lackluster chase season for the Plains/Midwest, or is it impossible to make that connection at this point?

That's impossible to know for now. I'd lean towards a quieter than normal chase season though.

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Latest MEI value is -1.0, which is the same as the previous bi-monthly value. 

Closest resemblance to this year based solely on the MEI value is 2007. The JA MEI value was already -2.4 back in 2010 as the Nina peaked in the Fall as I noted in my previous post. 1998-99 Nina isn't the greatest analog in my opinion as it came off the heels of a very strong El Nino and were much colder than 1995-96.

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I do like 2007, and I'm going to use it as one of my winter analogs but to me, there are still a couple problems with it.

That said here is what I like about it:

- La Nina with a relatively low-ACE Atlantic (currently the ACE is near average for 9/8, but the little tropical storms out there now only add around 1 point a day). Historically, the half way point for ACE is 9/13. So it's definitely becoming harder, fast, for a very active (~160+) ACE season to develop. 

- La Nina with a low-ACE NE Pacific - the NE Pacific is well below average. It's not real common to have both basins below average in a La Nina, but 2007 had both.

- A lot of the recent La Ninas (1995-96, 2000-01,  2005-06, 2016-17, 2017-18, as well as cold Neutral 2013-14) had weakly positive or flat out positive PDO configurations Nov-Apr. I don't see that this year. The PDO could actually be the most negative it has been in 30 years for Nov-Apr from what I'm seeing. Will rival 1990-91, 1999-00, 2007-08, 2008-09, 2011-12 for a top five spot anyway in the last 30 years.

- 2007 followed a 27.3C El Nino in winter 2006-07. A La Nina this year would follow a 27.1 El Nino in 2019-20.

- 2007-08 was near the solar minimum. This is actually a bit of a wildcard since solar activity has been rising, slowly, since early 2020.

- You did have pretty low sea-ice in September 2007, like this year. A lot of the recent La Ninas had higher sea ice (relatively). The cold ENSO years when sea ice drops below 4.3 million square km seem to be better in the West (2007, 2012, 2016) than those that don't (2010, 2013, 2017), with 2011-12 (4.3m) on the border, as it was cold in NM/TX but not elsewhere.

The issues with 2007-08 are still substantial to me though:

- I don't think this La Nina will be as strong as 2007-08, especially in Nino 4.

- The QBO isn't a big factor for me, but I don't like the fact that it is near opposite of this year. The 2007-08 La Nina was very negative, trending up. This winter should be positive, trending up. If the trend matters more than the positioning, it is fine, but if the positioning (negative v positive) matters more, than it is a problem.

- The Atlantic is warmer than 2007. 

- The 2007-08 La Nina continued into 2008-09. I'm not super convinced this will be a two year event, especially if it comes in a lot weaker than 2007-08 in Nino 4.

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Euro seems to like a -1.0C La Nina, with a somewhat warmer Nino 4. I'd probably go warmer on both. I use the colder 1951-2010 basis anyway, and on those figures these are more like -0.8C / -0.3C anomalies anyway. CPC is going to switch to a 26.65C or so base line for 1991-2020 Nino 3.4 average next year (+0.08C from the current baseline), so there is little doubt this event will be classified as a La Nina at any rate.

Image

Image

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Using the 1951-2010 averages, Nino 4 has only been cooler than average for four months since mid-2012.

It has been tracking similarly to 2007 this year. Will be interesting to see if that can continue for a while. A much cooler Nino 4 in September means the US should be a lot warmer than last October in most places too.

2007 28.97 28.66 28.66 28.73 28.84 28.90 28.68 28.48 28.11 27.91 27.61 27.42
2020 29.16 28.97 29.07 29.15 29.00 29.09 28.89 28.50        
average 28.08 27.97 28.07 28.33 28.63 28.65 28.55 28.41 28.40 28.42 28.39 28.27

My sense is Nino 4 will have trouble falling below 28.0C this Fall-Spring. But we'll see. Still warm below Nino 4 after all.

Equatorial Pacific Temperature Depth Anomalies Animation

 

 

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I had kind of forgotten about this since it didn't apply last year, but La Nina after El Nino is a pretty consistent and reliable cold signal for the interior Northwest. In the last 10 cases, an area by Idaho, Wyoming, and Oregon is always either cold, or near average, even in cases when the US is mostly torching. If you look at the areas north of the San Francisco to SD-NE line, that zone is never completely warm in any of the ten most recent La Nina after El Nino winters.

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There is also a pretty strong warm signal for Texas - 7/10 years feature +3 or hotter winters somewhere in Texas. Even Florida and the Southwest don't have that. 

Image

The three composite looks that show up by month - cold interior West, cold Northwest, cold NW to Midwest - I actually have analogs that support all three to some extent. So it looks pretty reasonable to me. I think the January look is the closest to what will happen of the three months, but still want to see how the observations in September in the tropics pan out.

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My take is a weaker version of 2007 is the right idea. But I'm open to a stronger La Nina if the event can keep pace this month with 2007 in September. The bottom really fell out in 2007 in the Fall. That's the real test. The warm western Nino 4 subsurface was still there in 2007, even well into September -

figure5.gif

The models missed how strong it got: -1.5C ONI (forecasts were generally -0.5 to -1.0)

figure6.gif

I mentioned earlier, if you plot August subsurface against Dec-Feb SSTs in Nino 3.4, you get 25.75C as the estimated strength of the La Nina, give or take 0.75C, at about 80% certainty. So below 2007-08 (25.0C in winter in Nino 3.4) is pretty unlikely. But it wouldn't really be too shocking if it got close to that strong. My instinct is this event will be strongest in Fall, maybe as low as 25.5C or something in September, October or November given that week one of September was 25.8C on the weeklies.

Nino 4 and the PDO are both the coldest they've been in a while, which is almost like an indication that the system is less resistant to a stronger La Nina than it has been in a while. 

 

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                Nino1+2      Nino3        Nino34        Nino4
 Week          SST SSTA     SST SSTA     SST SSTA     SST SSTA 
 05AUG2020     19.8-1.2     24.6-0.6     26.3-0.6     28.4-0.3
 12AUG2020     19.9-0.9     24.8-0.3     26.4-0.5     28.3-0.4
 19AUG2020     19.5-1.1     24.3-0.7     26.0-0.8     28.4-0.2
 26AUG2020     20.0-0.6     24.2-0.7     26.1-0.7     28.6-0.1
 02SEP2020     18.9-1.6     23.6-1.3     25.8-0.9     28.4-0.3
 09SEP2020     19.5-1.0     23.4-1.4     25.7-1.0     28.5-0.2
 08AUG2007     19.3-1.6     23.8-1.3     26.2-0.7     28.6-0.1
 15AUG2007     19.7-1.0     24.0-1.0     26.3-0.6     28.6-0.1
 22AUG2007     19.2-1.4     23.8-1.2     26.1-0.7     28.5-0.1
 29AUG2007     18.4-2.1     23.7-1.3     26.1-0.7     28.4-0.2
 05SEP2007     19.4-1.1     23.7-1.2     26.0-0.8     28.3-0.4
 12SEP2007     18.6-1.8     23.6-1.3     25.8-1.0     28.0-0.6

Still almost identical in Nino 3 and Nino 3.4 to 2007. But Nino 4 has fallen behind. There was actually pretty substantial warming in Nino 1.2 too.  Nino 3.4 has also fallen a tiny bit relative to 2007 now too.

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It's been interesting trying to find a good match to the September 2020 US temperature pattern. It's pretty unusual to get a core of heat in the NW with a cold Central US look in September in a La Nina.

Some El Nino years are actually similar: 1953, 1957. 1987, 1991 aren't terrible either.

Neutral years 1966 and 1967 are both very hot in the NW, but very cold - way too cold - in the Southeast in September. 1974 also fits this description (probably near record heat NW but also record cold TX). 1975 too. 1993 is kind of the right idea, cold middle, warm east/west, but the cold is too far east. Same in El Ninos 2006, 2009.

La Nina years like 1933 and 2017 are actually near opposite - which I find encouraging as they are terrible Western winters - top five for heat and dryness in most places. The closest La Nina September is probably 1999. September 2008 is kind of the right idea, but not as extreme as this year. 2011 is like 1993, too far east.

A lot of the cold anomalies will burn off in the Rockies by the end of the month - so this may end up pretty close, especially if the South cools a bit with the wetness in the 6-10 day outlooks. You can see a lot of the same weird features - heat core in Oregon, SD/Kansas colder than Nebraska relatively. Summer 1999 was extremely cold in the Southwest, so I don't really think it's a good analog for winter, which gets at how strange this month is. Outside the Northeast, 1999 is almost opposite to 2020 for Summer, but similar in September.

Sept-2020-v-1953-1957-1999-1999-2008

1999-and-2020-1

We're definitely very different from 1933 & 2017 - cold core Oregon warm core Minnesota - exact opposite of this year for the western 2/3 of the US. 

1933-2017-and-2020-Sept

Anti 1933/2017 is fairly close (but too cold) to my winter idea at this point.

 

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                Nino1+2      Nino3        Nino34        Nino4
 Week          SST SSTA     SST SSTA     SST SSTA     SST SSTA 
 05AUG2020     19.8-1.2     24.6-0.6     26.3-0.6     28.4-0.3
 12AUG2020     19.9-0.9     24.8-0.3     26.4-0.5     28.3-0.4
 19AUG2020     19.5-1.1     24.3-0.7     26.0-0.8     28.4-0.2
 26AUG2020     20.0-0.6     24.2-0.7     26.1-0.7     28.6-0.1
 02SEP2020     18.9-1.6     23.6-1.3     25.8-0.9     28.4-0.3
 09SEP2020     19.5-1.0     23.4-1.4     25.7-1.0     28.5-0.2
 16SEP2020     20.0-0.4     23.6-1.3     25.9-0.8     28.2-0.4
 01AUG2007     19.6-1.5     24.1-1.2     26.4-0.6     28.7 0.0
 08AUG2007     19.3-1.6     23.8-1.3     26.2-0.7     28.6-0.1
 15AUG2007     19.7-1.0     24.0-1.0     26.3-0.6     28.6-0.1
 22AUG2007     19.2-1.4     23.8-1.2     26.1-0.7     28.5-0.1
 29AUG2007     18.4-2.1     23.7-1.3     26.1-0.7     28.4-0.2
 05SEP2007     19.4-1.1     23.7-1.2     26.0-0.8     28.3-0.4
 12SEP2007     18.6-1.8     23.6-1.3     25.8-1.0     28.0-0.6
 19SEP2007     18.5-2.0     23.6-1.2     25.8-0.9     28.0-0.7

Still pretty similar to 2007. Although Nino 1.2 is warming it looks like. Also, the Nino 4 readings are warmer than 2007. Way colder than 2017, 2016 at this point. Nino 3 is also a lot colder than 2011. All that said, still well behind how cold Nino 3.4 and 4 were in 2010 by this time. Looks substantially colder in some zones than 2000, 2005, 2008 too.

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Mathematically, I'd say for relevance, if you scored the 11 La Ninas for similarity to this year in the third weekly reading for September, you'd rank it like this, with Nino 1.2 difference multiplied by one, Nino 3 and 4 multiplied by two, and Nino 3.4 multiplied by three.

2005, 2010, 2016 are the worst matches, with 1995, 1999, 2000, 2007, 2011 the top matches. September does look a lot like 1999 at the moment. The models favor the La Nina becoming centered west of where it is now, which is consistent with current observations and how 2007 developed. My analogs look a lot like July, August and September nationally with the same kind of East core Fall to Central core Winter look the Jamstec/CFS show for the La Nina, so that's why I'll be riding 2007 fairly hard, even though it should be a weaker La Nina overall.

                Nino1+2      Nino3        Nino34        Nino4
 Week          SST SSTA     SST SSTA     SST SSTA     SST SSTA
 20SEP1995     20.2-0.2     24.0-0.9     26.1-0.7     28.4-0.3  (0.2) + (0.4 x 2) + (0.2 x 3) + (0.2 x 2) = 2.0
 23SEP1998     20.5 0.1     24.1-0.7     25.5-1.2     27.6-1.1  (0.5) + (0.5 x 2) + (0.7 x 3) + (0.6 x 2) = 4.8
 22SEP1999     19.3-1.2     23.8-1.1     25.8-0.9     27.9-0.7  (0.7) + (0.2 x 2) + (0.1 x 3) + (0.3 x 2) = 2.0
 20SEP2000     20.1-0.3     24.2-0.6     26.1-0.6     28.5-0.2  (0.1) + (0.6 x 2) + (0.2 x 3) + (0.3 x 2) = 2.5
 21SEP2005     19.6-0.9     24.7-0.2     26.8 0.1     28.9 0.3  (0.4) + (1.1 x 2) + (0.9 x 3) + (0.7 x 2) = 6.7
 19SEP2007     18.5-2.0     23.6-1.2     25.8-0.9     28.0-0.7  (1.5) + (0.0 x 2) + (0.1 x 3) + (0.2 x 2) = 2.2
 24SEP2008     21.3 0.8     25.1 0.2     26.4-0.4     28.1-0.6  (1.3) + (0.4 x 2) + (0.8 x 3) + (0.1 x 2) = 4.7
 22SEP2010     19.3-1.2     24.0-0.8     25.1-1.6     27.1-1.6  (0.7) + (0.4 x 2) + (0.8 x 3) + (1.1 x 2) = 6.1
 21SEP2011     19.8-0.6     24.3-0.6     25.9-0.9     27.8-0.9  (0.2) + (0.7 x 2) + (0.0 x 3) + (0.4 x 2) = 2.4
 21SEP2016     21.2 0.8     24.8-0.1     26.3-0.4     28.5-0.2  (1.2) + (1.2 x 2) + (0.4 x 3) + (0.3 x 2) = 5.4
 20SEP2017     19.3-1.1     23.9-1.0     26.3-0.4     28.7 0.0  (0.7) + (0.3 x 2) + (0.4 x 3) + (0.5 x 2) = 3.5
 16SEP2020     20.0-0.4     23.6-1.3     25.9-0.8     28.2-0.4

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5 hours ago, raindancewx said:

Mathematically, I'd say for relevance, if you scored the 11 La Ninas for similarity to this year in the third weekly reading for September, you'd rank it like this, with Nino 1.2 difference multiplied by one, Nino 3 and 4 multiplied by two, and Nino 3.4 multiplied by three.

2005, 2010, 2016 are the worst matches, with 1995, 1999, 2000, 2007, 2011 the top matches. September does look a lot like 1999 at the moment. The models favor the La Nina becoming centered west of where it is now, which is consistent with current observations and how 2007 developed. My analogs look a lot like July, August and September nationally with the same kind of East core Fall to Central core Winter look the Jamstec/CFS show for the La Nina, so that's why I'll be riding 2007 fairly hard, even though it should be a weaker La Nina overall.

                Nino1+2      Nino3        Nino34        Nino4
 Week          SST SSTA     SST SSTA     SST SSTA     SST SSTA
 20SEP1995     20.2-0.2     24.0-0.9     26.1-0.7     28.4-0.3  (0.2) + (0.4 x 2) + (0.2 x 3) + (0.2 x 2) = 2.0
 23SEP1998     20.5 0.1     24.1-0.7     25.5-1.2     27.6-1.1  (0.5) + (0.5 x 2) + (0.7 x 3) + (0.6 x 2) = 4.8
 22SEP1999     19.3-1.2     23.8-1.1     25.8-0.9     27.9-0.7  (0.7) + (0.2 x 2) + (0.1 x 3) + (0.3 x 2) = 2.0
 20SEP2000     20.1-0.3     24.2-0.6     26.1-0.6     28.5-0.2  (0.1) + (0.6 x 2) + (0.2 x 3) + (0.3 x 2) = 2.5
 21SEP2005     19.6-0.9     24.7-0.2     26.8 0.1     28.9 0.3  (0.4) + (1.1 x 2) + (0.9 x 3) + (0.7 x 2) = 6.7
 19SEP2007     18.5-2.0     23.6-1.2     25.8-0.9     28.0-0.7  (1.5) + (0.0 x 2) + (0.1 x 3) + (0.2 x 2) = 2.2
 24SEP2008     21.3 0.8     25.1 0.2     26.4-0.4     28.1-0.6  (1.3) + (0.4 x 2) + (0.8 x 3) + (0.1 x 2) = 4.7
 22SEP2010     19.3-1.2     24.0-0.8     25.1-1.6     27.1-1.6  (0.7) + (0.4 x 2) + (0.8 x 3) + (1.1 x 2) = 6.1
 21SEP2011     19.8-0.6     24.3-0.6     25.9-0.9     27.8-0.9  (0.2) + (0.7 x 2) + (0.0 x 3) + (0.4 x 2) = 2.4
 21SEP2016     21.2 0.8     24.8-0.1     26.3-0.4     28.5-0.2  (1.2) + (1.2 x 2) + (0.4 x 3) + (0.3 x 2) = 5.4
 20SEP2017     19.3-1.1     23.9-1.0     26.3-0.4     28.7 0.0  (0.7) + (0.3 x 2) + (0.4 x 3) + (0.5 x 2) = 3.5
 16SEP2020     20.0-0.4     23.6-1.3     25.9-0.8     28.2-0.4

I agree about this becoming a more modoki event...just blogging about that now, actually. Of course, a modoki la nina is the inverse Hadley cell configuration of el nino modoki....bad news bears for the east. Great for the west...specially NW.

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This is the updated subsurface comparison to 2007. To me it kind of looks like 2007 but everything happens 4-8 weeks later. So maybe the September flat-line in 2020 is the 2007 flat-line in August, and then the La Nina peaks in October? I guess we'll see. It's possible though that we really won't see much change in the subsurface for a while.

Subsurface-Sep-2007-2020.png

 

 

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On 9/9/2020 at 6:30 PM, frd said:

 

As many here already know, the QBO is currently positive and looks to continue to become more so in the months ahead.

There is some research that points out a tendency for a more poleward based and oriented North Pacific Ridge during  +QBO winters. HM mentioned that, along with a couple other mets as well. @griteater recently mentioned it  too in a detailed and revealing post. I found it so interesting as to share it here. Nice job with this ! 

Here is the post below :

The QBO is utilized in various ways with respect to seasonal forecasting, but IMO, it's best use with winter forecasting is not so much with the AO/NAO, but rather, with the configuration of the North Pacific High/Ridge that is common during La Nina winters.  A North Pacific ridge is almost certain to be present in the mean pattern during Cool ENSO / La Nina winters when the Jul-Oct averaged AAM is negative (which has been the case thus far for Jul-early Sep).

 

Anthony Masiello's findings from 2012 showed that more poleward north pacific ridges were favored during +QBO winters, while north pacific ridges that were suppressed to the south were more favored during -QBO winters.  A key element here is that the designation of the QBO for this purpose was in the lower stratosphere (roughly Nov-Feb averaged at 45mb) as opposed to the typical level used with QBO analysis which is at 30mb. 

 

While the QBO began to behave much more erratic than normal at the first part of 2020, it appears to have resumed with a more typical progression as the positive QBO has more firmly established itself in recent months in the middle stratosphere and descending into the lower stratosphere.  For the upcoming winter, I would anticipate the QBO to average positive for Nov-Feb averaged at 45mb - most similar to the winter of 2010-2011 when compared to other cool ENSO winters. 

 

See QBO Charts:

NASA QBO Chart

Free Univ of Berlin QBO Chart

 

Below is a list of what I have for the last 11 La Nina winters that followed El Nino, along with the Nov-Feb avg 45mb QBO, then the placement of the north pacific ridge averaged for Dec-Mar.

 

La Nina Winter That Followed El Nino Winter / Jan-Feb avg QBO at 45mb / Placement of North Pacific Ridge avg for Dec-Mar

2010-2011 / Positive QBO / north/poleward north pacific ridge (specifically, displaced to the NW)

2007-2008 / Negative QBO / south/suppressed north pacific ridge (specifically, displaced to the SW)

2005-2006 / Negative QBO / south/suppressed north pacific ridge (specifically, displaced to the SW)

1998-1999 / Negative QBO / south/suppressed north pacific ridge (specifically, displaced to the SW)

1995-1996 / Positive QBO / north/poleward north pacific ridge (specifically, displaced to the NW)

1988-1989 / Positive QBO / north/poleward north pacific ridge (specifically, displaced to the NE)

1983-1984 / Neutral QBO / no clear distinction overall in the north pacific

1973-1974 / Positive QBO / north/poleward north pacific ridge (specifically, displaced to the NW)

1970-1971 / Negative QBO / north/poleward north pacific ridge (specifically, displaced to the NW)

1964-1965 / Positive QBO / north/poleward north pacific ridge (specifically, displaced to the NW)

1954-1955 / Negative QBO / south/suppressed north pacific ridge (specifically, displaced to the SW)

 

Of the 11 winters, the only one that didn't follow the QBO/North Pacific Ridge placement theory was the winter of 1970-1971.

 

Here are 500mb Height / U.S. Temperature composites of the Positive QBO winters from the list: 

 

543070605_Sep9NinaPosQBO.png.b08d595893ad92d0f7876bd96c35464e.png

 

 

And here are 500mb Height / U.S. Temperature composites of the Negative QBO winters from the list (I left off the 70-71 winter):

 

795617113_Sep9NinaNegQBO.png.8098135465eea56fc7a9085a93bad00f.png

 

Clearly, the Positive QBO composite with the more poleward north pacific ridge offers more potential for cold air intrusion into the lower 48 east of the Rockies compared with the Negative QBO composite.

 

One other thing to look for is the Oct-Nov 500mb pattern over the NE Pacific / Alaska / NW Canada.  Winters with a more poleward north pacific ridge tend to be absent of negative height anomalies in the Bering Sea, Alaska, and NW Canada during Oct-Nov....while, winters with a more southward displaced north pacific ridge tend to contain solid negative height anomalies in the eastern Gulf of Alaska extending up into portions of the Bering Sea, Alaska, and/or NW Canada.

 

Bottom Line: I would expect the upcoming winter to exhibit a more poleward north pacific ridge in the mean pattern as long as: 1) the QBO progression continues in a more typical manner as seen in the past few months, and 2) the Oct-Nov averaged 500mb pattern doesn't contain negative height anomalies in the eastern Gulf of Alaska extending up into portions of the Bering Sea, Alaska, and/or NW Canada  

@raindancewx What are your thoughts on this research? +QBO in cool ENSO seasons favoring more N PAC ridging....

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The analogs I have look like the -QBO years because 2007 is the analog I trust most, even though it is still flawed. However, late winter and spring do look like the +QBO years on my blend for the winter.  2007-08 had a -QBO but it was rising, like this year. I find that the trend is about as reliable as the actual QBO anomaly for large areas of the country.

I'm skeptical to bet the farm on only ENSO/QBO DJF seasonal averages. To me 2010-11, 1995-96, 1988-89, 1973-74, 1964-65 are also very different winters. I actually don't consider 1995 a bad analog, but it's mostly for how similar the ENSO has been all year, not the surrounding stuff like the PDO or AMO. It's not going to be similar on hurricane activity either, we're at less than half the 1995 total ACE in the Atlantic to date even with 23 named systems.

Here is how these years looked for the QBO v. 2020, to me, they look very different with unusual tendencies in 2020 that would suggest erratic QBO behavior later on. I don't have QBO data at 45mb, but this is 30mb.

1964    3.94    5.26    5.46    5.94    6.32    2.23   -0.56   -0.57   -0.67    0.42    0.71    0.04
1973   -4.40    0.08    3.40    6.28    8.12    8.63    6.94    5.86    5.51    5.20    4.92    2.31
1988    7.81    6.17    5.86    6.59    5.46    0.42   -3.96   -2.58   -2.29   -1.53   -0.84   -2.42
1995    8.38    8.01    8.79   11.79   14.92   15.62   11.74    9.53    6.98    3.43   -0.77   -4.57
2010  -16.02  -16.98  -19.68  -23.57  -26.28  -25.05   -9.84    1.45    6.58   10.83   12.16   10.97
2020   -2.51   -3.20   -4.36   -5.03   -4.86   -2.78    0.34    4.78 -999.00 -999.00 -999.00 -999.00

64                              up             up              up             up           down          down       down        down     

73                              up            up              up              up             up             down       down      down

88                              down     down          up           down         down        down         up           up

95                             down        up              up            up             up             down        down      down

10                             down        down       down        down       up                up              up          up

2010                        down          down     down         up           up               up               up            up

You can see trend wise, 1964 is backwards (opposite) as is 1973. 1995 trended down mid-year, while we are trending up.

You do have the right idea for Jan-Aug in 2010, but the QBO looks to me like it will keep going up the rest of the year. It didn't in 2010. Does that matter? Maybe? The magnitudes seem like they could be pretty close in 2010 through Fall and then be very different in winter. If you care about the trend I think 2016 is probably better than 2010 as a match.

At a high level, I know 2010 and 1988 were both active monsoon years, without record setting heat in the West in the Summer. 1995 is closer in that regard too. To me, if the QBO was meaningfully similar through August, you wouldn't see something like a near all-time strong Western Monsoon in 1988 and a near all-time weak Western Monsoon in 2020. Some of that is solar driven, but the QBO is supposed to impact tropical weather and by extension subtropical weather like the monsoon. I think part of it is Nino 4 dropped much faster in 2010 and 1988 than this year. It had dropped like from 29.5 to 27.5 or something in 2010 January to August. It's only fallen 0.6 or so this year. My real issue with 2010 is you're talking about a ~3C year/year drop in Nino 3.4 We're not getting that this year, this isn't the La Nina version of 2015-16. Even 1988 had like a 2.5C drop. I'm looking for like a 1.6C drop y/y (27.1C to 25.5C).If you pulled up August 1964, it was super cold in the entire West - complete opposite this year. 1973 is warmer, but still nothing like this year. In 1995, you have a similar looking August and September nationally, with the slower decay of Nino 4 like in 2007 and this year.

1988-2010-2020

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