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Wanna correct a mistake, I said the La Nina event this winter should look like a weaker, shorter event in my last post. I later found out that both the ONI and MEI of 1954 have been already the exact same as 2020 so far.1954 reached the first peak as early as ASO with an ONI around -0.9 and a MEI of -1.045 in ND.

This year we’ve already had a rough -1 MEI for JA, and a ONI of -0.6 in JAS. With the upcoming multiple rounds of easterlies burst, I’d like to go with a ONI in the range of -1.0 to -1.4 for NDJ or DJF, so it maybe far more stronger than the first peak of 1954 La Nina event and looks very close to the strength of 2007 or 1995.But here’s some other things looks interesting to me, almost every climate models continuously predicting a sharp rising of Nino3.4 values in late winter and spring in 2021, this doesn’t often happen when a mature, modoki-like, moderate or strong La Nina in its decaying stage. Usually a Nina which goes into the moderate or strong range often has a double peak, even multiple peak in next year. Just like how 1954,1955; 1995,1996;2007,2008 evolve. The situation may shift away from 1955,1996,2008, these cold-neutral of double peak event. So It’s pretty wise for raindancewx to put 1964 as an analog cuz 1964 Nina decaying quickly and transitioning into a Nino in early 1965 just like the what climate models are predicting for next year.I’m not saying 2021 would be another Nino, but if the rapid warming in Nino 3.4 verifies, 1964-1965 could be the only best analog in nearly 70 years.

7a18a8cdf0cbf8572c7b317247e12225.png

-58f1bb26237d30137525a5f81439b7b8.png

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The Euro is showing a brief pressure pattern reversal by Darwin, Australia and Tahiti in two days. Relatively high pressure by Darwin and relatively low pressure should crash the SOI. Would likely dump a storm into the SW later in October. The rule is, ten days after the SOI crashes by 10 points in one day, there is a low between Los Angeles and Dallas, somewhere between 30-38N. It works around 90% of the time locally in Oct-May, and then doesn't work at all once the highs prevent any storms from entering this part of the country in Summer.

The new Jamstec should be out soon. Some of the models have fairly high amplitude MJO phase five now for a while. Hope we see that again in Nov, Dec, Jan - can be quite cold in the SW later on. 

Image

 

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2D442DB1-286C-4CFB-9974-9742598BCEC8.thumb.jpeg.6b67a04fd42be73e8e831c9ef559fc36.jpeg

Strong/persistent Niña standing wave now and that NMME mean is impressive. Should probably note the rapid decay of the Niña in the new year might be problematic if it decays from east to west. A couple of previous studies have identified a link between a positive state of the Trans Nino Index (TNI), with colder waters in Nino 4 versus 1.2, and increased potential for tornado outbreaks especially east of the Plains in spring.

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               Nino1+2      Nino3        Nino34        Nino4
 Week          SST SSTA     SST SSTA     SST SSTA     SST SSTA
 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
 23SEP2020     19.6-0.8     23.6-1.2     25.7-1.0     28.1-0.5
 30SEP2020     20.1-0.5     23.8-1.1     25.6-1.1     27.9-0.7
 07OCT2020     19.5-1.2     23.4-1.5     25.5-1.2     27.8-0.8

Still like a blend of 1995/2007 on the weeklies. The 1999/2011 events are close at the moment too. Way stronger/colder than 2017, 2005, 2008 at this point. Somewhat stronger than 2016 at this point, but that event peaked in November. Way warmer than 2010 still.

 10OCT2007     18.8-1.9     23.3-1.6     24.9-1.8     27.7-1.0
 04OCT1995     19.6-1.0     23.9-1.0     25.6-1.1     28.1-0.5

The subsurface actually looks like it is plateauing. Fall 2012 actually looks pretty similar to this Fall so far too, which makes me wonder if the low-sea ice cold-ENSO signature is showing itself again. The Sandy like system depicted to hit the NE in the BS range on the GFS is kind of a hint at that too. Pretty sure Canada had a late hit in 2011 too.

Oct-Subsurface-20209-1-to-10-9-2020

These are the closest SST matches for September for the four Nino zones. I put the temperature pattern locally to the right of the matches. You can see it gets pretty cold in Dec/Jan in a lot of them. Colder air is coming into the NW in the coming days, ala 2007 and various others, despite arriving a bit late. But a lot of these years actually do have the hot West October: 1978, 1988, 1952, 1999, 1950/1959/1966/1967 sort of have it but without the expansiveness/severity of the heat. It is interesting to me to see 1959, 1978, and 1988 show up - those are three of the only cold ENSO years in the last 90 years to follow two El Nino winters in a row. 

Sept-2020-Matches

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Intuitively, the modeled strengthening Nina doesn't correlate to other things. We'll see, I guess. Even if the Nina strengthens, my guess is there will be lack of -PNA-strong, or PNA descending. 

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On 10/11/2020 at 2:32 PM, raindancewx said:

The Euro is showing a brief pressure pattern reversal by Darwin, Australia and Tahiti in two days. 

The new Jamstec should be out soon. 

Date Tahiti (hPa) Darwin (hPa) Daily Contribution 30 day Av. SOI 90 day Av. SOI
14 Oct 2020 1012.74 1010.20 -2.26 12.44 8.84
13 Oct 2020 1014.49 1010.00 10.31 12.58 8.77
12 Oct 2020 1014.54 1009.90 11.28 12.34 8.52
11 Oct 2020 1014.50 1009.75 11.99 12.18 8.26
10 Oct 2020 1015.51 1010.40 14.31 11.82 8.15

Yay. Euro/GFS now have some rain down here sometime around 10/24. This is similar to when the dry spell in Fall 2007 broke up here, if it verifies.

The Jamstec has a very warm/dry winter nationally. Still not 100% on the strong La Nina. Then it has an El Nino in 2022.

Jamstec-Oct-2020

The forecast for the US is actually pretty similar to what it forecast in 2016, when it was actually quite cold in the NW.

Jamstec-October-2020-2

 

 

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For what its worth:

SOI -

Oct 12-15 10.7, -0.2, -5.5, -6.3 in 2007

Oct 13-16 10.3, -2.3, -7.9,        in 2020

Really close. In 2007, southern CO had precip 10-days after the crash. ABQ did not. But you have almost identical magnitude/timing for the crash if nothing else

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5 hours ago, raindancewx said:

For what its worth:

SOI -

Oct 12-15 10.7, -0.2, -5.5, -6.3 in 2007

Oct 13-16 10.3, -2.3, -7.9,        in 2020

Really close. In 2007, southern CO had precip 10-days after the crash. ABQ did not. But you have almost identical magnitude/timing for the crash if nothing else

Just going off of memory, but I think 10/2007 was very mild around these parts....pretty benign autumn until the switch got flipped about 12/3.

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Pretty healthy La Nina with the warm version of the -PDO in September.

Image

I'd really like to see more of the North Pacific cool off with this event. This is probably the best shot at that for the next few years. The AMO actually cooled a fair bit in September, still very high AMO value though. We're almost in a warmed up -AMO, -PDO configuration, if you assume the oceans would be ~0.2C colder than now without the slow warming since 1981-2010. The Atlantic would look pretty cold with that extra 0.2C gone.

Image

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11 hours ago, raindancewx said:

Pretty healthy La Nina with the warm version of the -PDO in September.

Image

I'd really like to see more of the North Pacific cool off with this event. This is probably the best shot at that for the next few years. The AMO actually cooled a fair bit in September, still very high AMO value though. We're almost in a warmed up -AMO, -PDO configuration, if you assume the oceans would be ~0.2C colder than now without the slow warming since 1981-2010. The Atlantic would look pretty cold with that extra 0.2C gone.

Image

Nina still looks pretty east-based.

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12 hours ago, raindancewx said:

Pretty healthy La Nina with the warm version of the -PDO in September...I'd really like to see more of the North Pacific cool off with this event.

Yes...yes. It seems that is what needs to happen to get quality severe weather in the central CONUS again.

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2 hours ago, 40/70 Benchmark said:

Nina still looks pretty east-based.

Yes.  It will end up being classified as east-based or hybrid/mix.  If it were west-based (Central Pacific), the max cool anomalies would be centered roughly along 160W thru the fall/winter.

6iBTrQA.gif

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1 minute ago, griteater said:

Yes.  It will end up being classified as east-based or hybrid/mix.  If it were west-based (Central Pacific), the max cool anomalies would be centered roughly along 160W thru the fall/winter.

6iBTrQA.gif

Its interesting that this hasn't transitioned as quickly west as I had thought.....good sign for the eastern US IMO.

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On 10/15/2020 at 8:49 AM, 40/70 Benchmark said:

Just going off of memory, but I think 10/2007 was very mild around these parts....pretty benign autumn until the switch got flipped about 12/3.

that was an extreme latitude based winter with the quick transition in extreme SNE.  I remember your predictions for that winter were spot on, going with similar for this winter?

10/07 had the latest 90 I have ever seen on the south shore of Long Island.

 

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On 10/14/2020 at 7:39 PM, raindancewx said:
Date Tahiti (hPa) Darwin (hPa) Daily Contribution 30 day Av. SOI 90 day Av. SOI
14 Oct 2020 1012.74 1010.20 -2.26 12.44 8.84
13 Oct 2020 1014.49 1010.00 10.31 12.58 8.77
12 Oct 2020 1014.54 1009.90 11.28 12.34 8.52
11 Oct 2020 1014.50 1009.75 11.99 12.18 8.26
10 Oct 2020 1015.51 1010.40 14.31 11.82 8.15

Yay. Euro/GFS now have some rain down here sometime around 10/24. This is similar to when the dry spell in Fall 2007 broke up here, if it verifies.

The Jamstec has a very warm/dry winter nationally. Still not 100% on the strong La Nina. Then it has an El Nino in 2022.

Jamstec-Oct-2020

The forecast for the US is actually pretty similar to what it forecast in 2016, when it was actually quite cold in the NW.

Jamstec-October-2020-2

 

 

2007-08 and 2016-17 were very different here, the latter was a really good backloaded winter with heavy snow in March and April.  2007-08 was pretty much a noshow winter here outside of one 6-8 inch event in February (a SWFE that didn't changeover.)

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I went with 2012 and 2007 as the main analogs in my forecast because those events were colder east in the Nino zones in Fall, and they have very low sea ice. But the cold in the Nino zones spreads out later on. The cold core below the surface has been about 140W for a while, so it doesn't really fit into any of the three blends listed above. My sense is the average departures for the four zones in winter may be pretty consistent against the 1951-2010 averages, probably around -1.0 overall, despite the possibility of a colder peak than that between now and December in Nino 3.4. I'm a believer in some form of the storm depicted for the NE later in the month - I've been expecting that for a while. I lean toward it being a strong Nor'easter that originates over relatively warm water rather than a hurricane or Perfect Storm type of deal.

SOI - still amazingly similar for this brief negative period. 2007 has not been a good match for October so far, but to me that's an MJO thing, not because the La Nina is that different. 

Oct 12-15 10.7, -0.2, -5.5, -6.3 in 2007

Oct 13-16 10.3, -2.3, -7.9, -6.1  in 2020

The coming period with the cold dump in the middle of the country is similar to October 2012. Several of the cold-ENSO years following two El Nino winters are also pretty similar to this October so far - notably 1978 and 1988. 1959, another cold ENSO following two El Nino winters is also showing up a lot in the CPC 6-10 and 8-14 analogs.

October may end up looking a lot like a blend of 1978, 1988, and 2016, all years following two-cold ENSO years. The model depictions with Montana and other areas of the NW, 5-10 above normal in October look wrong now with the highs in the 30s in the coming day for places like Billings (88 a few days ago - I live in a desert and we haven't topped 87 here this month for reference).

This is my forecast for anyone who missed it. So far, close to 300 people have read it. Pretty happy with that actually. 

https://www.scribd.com/document/479516526/Winter-2020-21-Outlook

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On 10/16/2020 at 1:59 PM, LibertyBell said:

that was an extreme latitude based winter with the quick transition in extreme SNE.  I remember your predictions for that winter were spot on, going with similar for this winter?

10/07 had the latest 90 I have ever seen on the south shore of Long Island.

 

I didn't do winter outlooks back then...I started in the fall of 2014. You mean my feelings leading up to storms? 

My outlook wil be out in a few weeks, but will have one more interim update this week. The gradient may not be too dissimilar to that season, though I would hesitate to predict 130" in central NH again.

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The SOI has been pretty negative for a few days now. I don't think this La Nina is super well connected to the atmosphere yet. That said, the weeklies look like they may drop below 25.0C in the Fall at some point - that's about as cold as it can get in Nino 3.4 in Oct-Feb. Strong La Ninas are below 25.0C in DJF.

               Nino1+2      Nino3        Nino34        Nino4
 Week          SST SSTA     SST SSTA     SST SSTA     SST SSTA
 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
 23SEP2020     19.6-0.8     23.6-1.2     25.7-1.0     28.1-0.5
 30SEP2020     20.1-0.5     23.8-1.1     25.6-1.1     27.9-0.7
 07OCT2020     19.5-1.2     23.4-1.5     25.5-1.2     27.8-0.8
 14OCT2020     19.6-1.2     23.6-1.3     25.3-1.4     27.8-0.9
 17OCT2007     18.6-2.2     23.5-1.4     25.3-1.4     27.9-0.7

The subsurface and weekly data is still very similar to 2007. The coldest reading on record for October in Nino 3.4 (1950-2019) is 24.41C in 1955. So still a way from that. If we finish at 25.3C in October that would be 8th coldest October from 1950-2019.

2007-v-2020-subsurface-October

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Putting together an analog for a moderate-strong Nina winters since the 1980s, based in the Eastern Pacific extending into the entire basin:

b27dc031-b0b1-41de-806a-0db326c706c6.png
  • Troughing/low pressure in the Eastern Indian Ocean and over Maritime Continent, certainly goes with the idea of a strong tropical standing wave over Maritime Continent. 
  • Strong Aleutian Ridge, supports snowfall and cold in Northern America and Canada. Less North Pacific Jet extensions, less atmospheric rivers.
  • A very weak -NAO and more obvious Scandinavian blocking, which may help support snowfall and cold in Southern Europe/UK.
  • Decent troughing of east of Japan versus strengthened Siberian blocking, which supports Japanese snowfall.

 

2 hours ago, raindancewx said:

The SOI has been pretty negative for a few days now. I don't think this La Nina is super well connected to the atmosphere yet.

20201020025556-7590f52748859347ba384f756f48a967989b4bba.thumb.png.62f5b24ee7ed6b5e34af7b642b89036d.png

We certainly see ECMWF go with a positive Equatorial Southern Oscillation, that matches with an atmospheric Nina going forward. So there is a case for seeing a proper atmospheric Nina....

 

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I haven't looked in a few hours, but the SOI looked like it would see a few more substantially negative days by the end of the month on the European MSLP depiction. 

On the subsurface data, for 100-180W, most of the stronger La Ninas have had far stronger peaks than the current La Nina. Some of the weaker events (by ONI) have too. These are the subsurface peaks (by month), on a July-June basis for the La Ninas in the subsurface data (1979-2019). We'll likely beat some of these peaks in October, November or December but we're just approaching -1 now on the monthly data.

1998    -2.46
1983    -2.25
1988    -2.04
2010    -1.93
1999    -1.55
2007    -1.50
2008    -1.44
2011    -1.26
1995    -1.20
2005    -0.97
2017    -0.97
2000    -0.96
1984    -0.93
 

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9 hours ago, Snowy Hibbo said:

Putting together an analog for a moderate-strong Nina winters since the 1980s, based in the Eastern Pacific extending into the entire basin:

b27dc031-b0b1-41de-806a-0db326c706c6.png

  • Troughing/low pressure in the Eastern Indian Ocean and over Maritime Continent, certainly goes with the idea of a strong tropical standing wave over Maritime Continent. 
  • Strong Aleutian Ridge, supports snowfall and cold in Northern America and Canada. Less North Pacific Jet extensions, less atmospheric rivers.
  • A very weak -NAO and more obvious Scandinavian blocking, which may help support snowfall and cold in Southern Europe/UK.
  • Decent troughing of east of Japan versus strengthened Siberian blocking, which supports Japanese snowfall.

 

20201020025556-7590f52748859347ba384f756f48a967989b4bba.thumb.png.62f5b24ee7ed6b5e34af7b642b89036d.png

We certainly see ECMWF go with a positive Equatorial Southern Oscillation, that matches with an atmospheric Nina going forward. So there is a case for seeing a proper atmospheric Nina....

 

1996 was marginal...okay, but by what metric was 2001 a moderate la nina? It was weak by all accounts, as far as I'm concerned.

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On 10/18/2020 at 6:55 PM, 40/70 Benchmark said:

I didn't do winter outlooks back then...I started in the fall of 2014. You mean my feelings leading up to storms? 

My outlook wil be out in a few weeks, but will have one more interim update this week. The gradient may not be too dissimilar to that season, though I would hesitate to predict 130" in central NH again.

My memory must be going but I remember that you brought up 1970-71 as an analog in 2007-08 and it ended up being spot on for how the winter played out.  I dont know if it was an outlook per se or if you were just sharing your thoughts about similar winters from the past, but I do remember you said you thought it would be a frontloaded winter like that.

 

 

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9 hours ago, LibertyBell said:

My memory must be going but I remember that you brought up 1970-71 as an analog in 2007-08 and it ended up being spot on for how the winter played out.  I dont know if it was an outlook per se or if you were just sharing your thoughts about similar winters from the past, but I do remember you said you thought it would be a frontloaded winter like that.

 

 

Yes, I did say that...along with Will. I never laid my thoughts out, though.

Big difference between the two winters was the NAO.

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The forecast lows in Albuquerque in the mid-20s with the 10/25-10/27 storm add confidence to my idea of at least semi-regular cold dumps making it into the Southwest for the winter. Long-term, the coldest temperature in October is highly correlated with total lows at or below 32F from October to May. A low of 25 or 26 in October, would imply something like ~98 lows <=32F for Oct-May, even accounting for the urban heat island and global warming effects locally.

The MJO looks like it will start November in phase six. That's warm nationally, but seven is a lot colder. I'm kind of expecting something like high amplitude 6, then weaker 7-8 for November. Still early though, the models don't seem to have a great idea on the MJO for the next ten days at the moment. If you get a 6-7-8 transition in early November, that's a lot like 2016.  The 1999 and 2007 transition was 5-7 in November, about two weeks behind reaching phase six compared to 2020. In 1998, the transition is 5-6 in November. 1996 went all the way from 5 to 1. Not really a lot of years that go 6-8 in November. Hopefully the models will depict a different outcome, but this is probably what the CFS sees right now. I don't really expect November to be this warm though.

MJO-6-7-8-in-Nov-2020

 

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Some La Ninas I don't like and some I do:

Dislike:

2010 - the entire North Pacific is cold east of 150W. This year? Not so much. Atlantic is opposite too - cold east this year, warm east in 2010. Even the waters by Greenland are different. The IOD is pretty canonically negative in 2010 too, unlike this year. Nino 4 is also way colder than this year.

Oct-2020-v-Oct-2010

2017-18 developed late and was still very weak in October. The Atlantic is much warmer. The warmth west of Australia this year is not there in 2017 at all. So it's close to a positive Indian Ocean Dipole, which we don't really have this Fall. 2005 is kind of similar, developed late, but it was stronger in by South America at this point.

Oct-2020-v-Oct-2017.png

Like:

1988 is similar in the Nino zones. Colder North Atlantic/North Pacific, but similar structurally. It followed two El Ninos too. It's a strong La Nina that didn't completely take over the North Pacific. 

Oct-2020-v-Oct-1988.png

2007 has the ring of warmth around the strong La Nina look, with the cold eastern Atlantic. It's not perfect, but it's the best match of recent La Ninas (1990-)

Oct-2020-v-Oct-2007.png

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On 10/16/2020 at 12:31 PM, griteater said:

Yes.  It will end up being classified as east-based or hybrid/mix.  If it were west-based (Central Pacific), the max cool anomalies would be centered roughly along 160W thru the fall/winter.

6iBTrQA.gif

I've bee looking at la nina structure a lot this week. Its interesting because your winter forecast composite looks much more like a CP, west-based la nina.

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On 10/14/2020 at 1:05 PM, StormchaserChuck! said:

Intuitively, the modeled strengthening Nina doesn't correlate to other things. We'll see, I guess. Even if the Nina strengthens, my guess is there will be lack of -PNA-strong, or PNA descending. 

I agree with this from what I have been looking at....my finished product should be out in a couple of weeks.

How is your NAO formula this season? Positive?

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