GaWx

Essentially, almost analogous to constructive and destructive interference in sound. Another relationship, from the University of Alaska, Fairbanks webpage The Pacific Decadal Oscillation also asserts that -One thing the severely -PDO isn’t interfering with is the solid -SOI of the last 2 months -A sub -2 Sep PDO has been followed by several cool to cold E US winters: - 1892-3: DJF PDO rose to -0.77 - 1894-5: DJF PDO rose to -0.89 - 1916-7: (cool NE): DJF PDO still down at -1.96 - 1933-4: DJF PDO rose to -0.32 (very cold Feb NE US) - 1950-1: DJF PDO rose to -1.26 (cool Mid Atlantic/SE) - 2010-1: DJF PDO still down at -1.77 - 1920-1: near normal; DJF PDO -1.11 - 1955-6: near normal; DJF PDO -2.25 - 1999-0: near normal; DJF PDO -1.80 - 2011-2: warm; DJF PDO -2.20 - 2012-3: mild; DJF PDO -1.28 - 2022-3: warm; DJF PDO -1.70

The Sep ERSST based PDO came in at a whopping -2.94. This is the 3rd lowest Sep PDO on record going way back to 1854! The only lower Sept ones were the -2.99 of 2012 and the -2.97 of 1933. Both rose rapidly in Oct and Nov and reached -0.66/-0.49 in November: https://www.ncei.noaa.gov/pub/data/cmb/ersst/v5/index/ersst.v5.pdo.dat

It is a combo of the +2 PNA (peaking on that day) and a -1 NAO coinciding.

GEFS is still suggesting high chance for a +PNA for October as a whole with a likely +2+ peak in the dailies coming early next week. Hoping Oct doesn’t come in with too high of a +PNA, however:

Actually, in addition to Sep of 2004, it is Sep of 2015 rather than 2014 although 2014 is close behind. Also, Sep of 1987 is very close.

The comparison of the following two graphs of September SSTs 1948-2023 shows how much the equatorial region N of Australia has cooled in September of 2023 vs recent Septembers while at the same time Nino 4 directly to its E has warmed in September of 2023 vs recent Septembers. I assume this bodes well for increased chances of a colder winter for the E US vs recent ones assuming this relationship holds into winter: Much cooler equatorial area N of Australia Sep: Much warmer Nino 4 September:

Not surprisingly based on the animation, the anomalies for the equatorial W Pac area that I’ve been watching (120E to 160E, 15N to 15S) cooled even further from Aug to Sep allowing Sep of 23 to be a whopping 0.8C/0.7C/0.7C cooler than Sep of 22/21/20. This area had been very warm in recent years: https://psl.noaa.gov/cgi-bin/data/timeseries/timeseries.pl?ntype=1&var=SST&level=2000&lat1=15&lat2=-15&lon1=120&lon2=160&iseas=0&mon1=0&mon2=11&iarea=0&typeout=1&Submit=Create+Timeseries

Looking more closely: - During the first 7 weeks of your 11 week elapsed period of animation: the far E Nino portion cooled slightly while the remaining Nino areas warmed between 0.4 to 0.7. -But since then (subsequent 4 weeks): while the far E Nino continued to cool, the remaining Nino areas either remained steady (Nino 4) or cooled slightly (Nino 3 and 3.4). -So, since all Nino areas either cooled or remained steady during the last 4 weeks of your animation, it may make it seem like no Nino areas warmed during the 11 week interval. This is almost like a visual recency bias of sorts. And the far E portion (Nino 1+2) did actually cool during the 11 week interval.

During that time (week centered on 7/12 to week centered on 9/27), the indices’ anomalies went from: Nino 1+2: +3.4 to +2.8 Nino 3: +1.6 to +2.0 Nino 3.4: +1.1 to +1.5 Nino 4: +0.7 to +1.1 ———— Also, I can see in that animation how much the anomalies for the equatorial area of the WPac area that I follow (120E to 160E, 15N to 15S) cooled from July to Aug and how much the southern half of this area continued to cool from Aug to Sep. even while Nino 4 to its E kept warming. Much of the area between New Guinea and Australia has anomalies that cooled 1.25 to 1.75 C from the July 12th week to last week: —————— Weekly Nino anomalies: https://www.cpc.ncep.noaa.gov/data/indices/wksst9120.for

The Sep SOI came in at -13.9. How does this compare to the Sep of the 49 prior El Niño events dating back to 1876-7? -Of the 49, these 12 had more negative Sep SOIs: 2015, 1997, 1994, 1991, 1982, 1972, 1940, 1923, 1914, 1902, 1896, and 1877. So, 2023 comes in more negative than ~75% of the others. -Of those 12 with stronger Sep negatives, five were super strong El Niño events (2015, 1997, 1982, 1972, and 1877). These had a range of -14.1 (1997 and 1972) to -20.0 (1982). The super strong 1965’s Sep was at -13.5 while the super strong 1888’s Sep was only down to -8.8. - Regarding the other seven Septembers with a sub -13.9, four were strong El Niño events (1991, 1940, 1902, and 1896) with a range of -16.2 to -18.8. Seven strong Septembers (2009, 1987, 1957, 1930, 1925, 1918, and 1899) were less negative or even positive in one case (2009’s +3.6). - The remaining three were moderate El Niño events (1994, 1923, and 1914) with a range of -14.1 to -16.2. - Five of the 49 El Niño events came in with a +SOI in Sept: 2009 (+3.6/strong), 1979 (+1.7/weak), 1904 (+0.5/moderate), 1887 (+5.2/weak), and 1880 (+8.1/weak).

As of Oct 1, the -SOI streak reached 43 days. Although the streak may end at any point soon because it is so close to zero, I’m now leaning to it continuing through day 49 and then ending on Oct 8. Assuming the 49 days were to verify, how would that stack up to the longest streak of prior El Niño events back to 1994-5 (as far back as dailies are readily available)? Only the two super strong events of 2015-6 and 1997-8 would exceed 49 days. They both had max streaks well above that. But 2018-9, 2014-5, 2009-10, 2006-7, 2004-5, 2002-3, and 1994-5 didn’t. Of course, there’s always the chance that there will be a longer than 49 day streak later in this event: https://data.longpaddock.qld.gov.au/SeasonalClimateOutlook/SouthernOscillationIndex/SOIDataFiles/DailySOI1887-1989Base.txt

The Sept 100-180W OHC came in at +1.03, down slightly from last month’s +1.09 and well below the June peak of +1.40. This drop was the last thing I had earlier expected for Sep. (though I realized Sep could easily come in lower once I saw it fall way back) and the clock is ticking. Unless this does something extreme like the sometimes considered analog of 2009, when it suddenly warmed 0.99 from Sep to Nov to 1.75 after having fallen back from an initial high point in June of +1.13 to a temporary low point of only +0.76 (similar to the 2023 pattern); or like 1991, when after sputtering between April’s +0.80 and Sept’s +0.60 it suddenly warmed 0.81 to Oct’s +1.41 and then another 0.30 to Dec’s +1.71; it will not ever get to the high 1 area that I had earlier thought had a good chance to occur: https://www.cpc.ncep.noaa.gov/products/analysis_monitoring/ocean/index/heat_content_index.txt

Nino 4 at 29.87 is likely the warmest on record for 10/1 at least back to 1982. Also, when comparing to other Nino regions at the same time, it is very impressive! But considering GW, including how much warmer the globe has been this year, is it the most impressive for 4 for 10/1? Compare to 29.0 in 82, 29.1 of 86/87, 29.2 of 91, 29.6 of 15.

The August PDO was way down at -2.47. There have been 15 other sub -2 Aug PDOs since 1854 with only 1876 during El Niño. This is how the E US subsequent winters went including PDO: 1876 (only other Nino): winter cold mainly due to Dec, PDO -0.15 (rose 2.01, the third sharpest rise of the 15 from Aug to DJF), snowy NYC in DJ, major snowstorm Atlanta in D 1881: winter NN NE, warm SE, PDO -1.51 1883: winter cold NE, NN SE but very cold J, PDO -1.80, snowy NYC in D; wintry ATL in J 1892: winter cold, PDO -0.77 (rose 2.08, the 2nd sharpest rise of the 15 from Aug to DJF), heavy SN JF Boston/NYC, one of heaviest SN on record Atlanta in J 1909: winter cold, PDO -1.72, very cold/wintry ATL in D 1916: winter cool NE, NN SE, PDO -1.96, snowy NYC 1920: winter NN, PDO -1.11, heavy SN Boston F 1921: winter cool NE, mild SE, PDO -0.40, Knickerbocker SN NC/Mid Atlantic in J preceded by historic ZR SE coast 1933: winter very cold NE mainly due to Feb, NN SE, PDO -0.32 (rose 2.60, the sharpest rise of the 15 from Aug to DJF), heavy SN DFM NYC/Boston, major SN ATL in F 1950: winter mild NE, NN SE, PDO -1.26, wintry ATL D 1955: winter NN, PDO -2.25, very heavy SN M NYC/Boston 2010: winter cool NE, cold SE, PDO -1.77, very snowy winter Boston/NYC/ATL 2011: winter warm, PDO -1.87 2012: winter mild, PDO -1.28, very heavy SN FM Boston/NYC 2022: winter very warm, PDO -1.70 - 53% of the winters were cool to cold in the NE but only 27% were in the SE. - 27%/33% of winters were mild to warm in the NE/SE, including the last 3 - Active winters NE/SE when PDO rose sharply Monthly PDO back to 1854: https://www.ncei.noaa.gov/pub/data/cmb/ersst/v5/index/ersst.v5.pdo.dat **Edited due to typo as it’s Aug to DJF, not Oct to DJF, sharpest rises I’m referring to

Today’s GEFS based PNA is saying a daily peak of +2+ is likely near Oct 10th. The following Octs since 1950 peaked at +2+ with these peak dates and these full Oct PNAs: 1953: 10/6 Nino +1.91 1963: 10/12 Nino +0.69 1965: 10/5 Nino +1.14 1969: 10/8 Nino +0.35 1979: 10/1 Nino +1.53 1980: 10/4 +2.45 1984: 10/8 -0.63 1987: 10/3 Nino +0.53 2003: 10/6 +0.97 2008: 10/3 +0.86 2010: 10/2 +1.80 2011: 10/2 +0.63 2015: 10/10 Nino +1.78 - All 13 peaked within Oct 1-12 just like 2023’s prog. El Niños were the most favored ENSO for these through 1979. - All but one of these Octs had a monthly PNA of +0.53+. Seven of these 13 were within +0.53 to +1.14. All but one of the 13 cool to cold E US El Niño winters since 1950 were preceded by Octobers with a PNA of +0.16 to +1.14 fwiw. So, as one who’d prefer a cool to cold winter, I’ll be hoping for an Oct PNA within that range. - As @George001just reminded me though, the PDO was sub -2 in August, which itself doesn’t bode well if one is hoping for a neutral PDO or +PDO in DJF. More about that in my next post.

The colder map’s 8 cases include 7 +PNAs. Nearly all of the coldest E US El Niño winters had a +PNA in Oct (mainly weak to moderate). The 9/30 0Z GEFS suddenly switched to a strong +PNA for the first half of Oct. I’ll be following this closely as Oct appears to a canary in the coal mine for El Niño winters.

Iceland minus Azores SLP anom difference (correlates to -NAO) -Dec went from ~+4 mb (~-0.25 NAO) on the prior run to ~+0.5 mb (~-0.05 NAO) on this one -Jan went from ~+3 mb (~-0.2 NAO) to ~+4.5 mb (~-0.3 NAO) -Feb went from ~+6.5 mb (~-0.55 NAO) to ~+9 (~-0.75 NAO) So, DJF NAO went from ~-0.33 to ~-0.37

El Niño Oct PNA: Strong +PNA: 53, 65, 79, 15 Mod +PNA: 63, 76, 77, 86, 87, 14 Weak +PNA: 57, 68, 69, 09 Neutral PNA: 51, 58, 94, 18 Weak -PNA: 97 Mod -PNA: 82, 02, 06 Strong -PNA: 72, 91, 04 SE US from coldest to warmest Nino winters 57, 63, 65, 69, 76, 77, 09: cold 68, 86, 87, 02, 14: cool 58, 72, 79, 82, 04: NN 94, 97, 06: mild 51, 53, 91, 15, 18: warm ——————— Correlation of Oct PNA to SE US winter for Nino -25% of the 4 strong +PNA (+1+) in Oct followed by cool to cold SE winter - A whopping 100% of the 10 weak to moderate +PNA (+0.25 to +0.99) in Oct followed by cold to cool SE winters - None of the 4 neutral PNA (-0.24 to +0.24) in Oct followed by cool to cold SE winter - 14% of the 7 -PNA (<-0.24) in Oct followed by cool to cold SE winter - So, only 13% of the 15 Octs that had either strong +PNA, neutral PNA, or -PNA followed by cool to cold SE winters - So, sweet spot by far for best shot at cool to cold SE Nino winters is Oct PNA of +0.25 to +0.99. Needless to say after just today discovering this, I’ll be rooting very hard for a +0.25 to +0.99 PNA in Oct! ** The data I’m basing this on is from the monthly PNA table seen at the 1st link below as opposed to the dailies (2nd link). That’s important to note because the monthlies average ~twice the amplitude of the dailies’ average. ———————— Today’s GEFS PNA prog for Oct 1-14 based on dailies is ~+0.6. However, keep in mind that the absolute value of the corresponding monthly amplitude averages ~twice as high as what the dailies would suggest. So, in this case, the equiv for the first half of Oct could easily be ~+1.2. That bodes very well for the chances of this full Oct’s PNA coming in as a +PNA when the monthly is released. But hopefully it would come in within the +0.25 to +0.99 interval so as to hit the sweet spot for the chances of a cool to cold winter: Monthly PNA (higher amp vs avg of dailies): https://www.cpc.ncep.noaa.gov/products/precip/CWlink/pna/norm.pna.monthly.b5001.current.ascii.table Daily PNA (lower amp vs monthly): https://ftp.cpc.ncep.noaa.gov/cwlinks/norm.daily.pna.index.b500101.current.ascii

Today’s GEFS PNA prog for Oct 1-14 based on dailies is ~+0.6. However, keep in mind that the absolute value of the corresponding monthly amplitude has averaged ~twice what the average of the dailies would suggest. So, in this case, the equiv for the first half of Oct could easily be ~+1.2. That bodes very well for the chances of this full Oct’s PNA coming in as a +PNA when the monthly is released. From what I’ve just learned about the relationship between Oct PNA and the following winter during El Niño per data going back to 1950, that alone might bode well for the rare shot at a cool to cold E US winter assuming a monthly +PNA actually does verify as long as it isn’t 1+. The stats suggest an Oct PNA sweet spot of +0.25 to +0.99 for the highest cool to cold E US winter chances with +0.5 to +0.75 most preferred.

@snowman19is full of knowledge, provides a lot of useful info, and has helped make this thread as lively as anyone has. That’s all greatly appreciated. The thread wouldn’t be the same without him/her. However, there’s much room for improvement regarding objectivity imo. Then again, he/she is far from the only one with much room for improvement in this regard imo. It isn’t easy to keep one’s biases from influencing the nature of one’s posts.

El Niño Oct PNA: Strong +PNA: 53, 65, 79, 15 Mod +PNA: 63, 76, 77, 86, 87, 14 Weak +PNA: 57, 68, 69, 09 Neutral PNA: 51, 58, 94, 18 Weak -PNA: 97 Mod -PNA: 82, 02, 06 Strong -PNA: 72, 91, 04 ———————— Nino Oct: +PNA: 56%, Neutral PNA: 16%, -PNA: 28% Non-Nino Oct: +PNA: 48%, Neutral PNA: 13%, -PNA: 40% So, Oct +PNA moderately more favored in Nino vs non-Nino E US from coldest to warmest Nino winters 69, 76, 77: cold 14, 02: cold NE, cool SE 58: cold NE, NN SE 63, 09: cool NE, cold SE 68: cool 57, 65: NN NE, cold SE 86, 87: NN NE, cool SE 79, 04: NN 18: NN NE, warm SE 72, 82: mild NE, NN SE 06: mild 94, 97: warm NE, mild SE 51, 53, 91, 15: warm ——————— Correlation of Oct PNA to E US winter for Nino - Only 0%/25% of the 4 strong +PNA (+1+) in Oct followed by cool to cold NE/SE winters - A whopping 70%/100% of the 10 weak to moderate +PNA (+0.25 to +0.99) in Oct followed by cold to cool NE/SE winters - Only 25%/0% of the 4 neutral PNA (-0.24 to +0.24) in Oct followed by cool to cold NE/SE winters - Only 14% of the 7 -PNA (<-0.24) in Oct followed by cool to cold NE/SE winters - So, only 13%/13% of the 15 Octs that had either strong +PNA, neutral PNA, or -PNA followed by cool to cold NE/SE winters - So, sweet spot by far for best shot at cool to cold NE/SE Nino winters is Oct PNA of +0.25 to +0.99. Needless to say after just today discovering this, I’ll be rooting very hard for a +0.25 to +0.99 PNA in Oct! ** The data I’m basing this on is from the monthly PNA table seen at the 1st link below as opposed to the dailies (2nd link). That’s important to note because the monthlies average ~twice the amplitude of the dailies’ average. Monthly PNA (higher amp vs avg of dailies): https://www.cpc.ncep.noaa.gov/products/precip/CWlink/pna/norm.pna.monthly.b5001.current.ascii.table Daily PNA (lower amp vs monthly): https://ftp.cpc.ncep.noaa.gov/cwlinks/norm.daily.pna.index.b500101.current.ascii

-Note that all were between 7/3 and 10/1. -9/1/2021: post Ida interacting with front -9/4/1913: not directly from TC that moved W into SE US 9/3-4 -7/28/1913: frontal -7/3/1930: offshore frontal low -7/12/1937: frontal low -10/1/1913: frontal low that moved offshore and later became H that hit SC 10/8 -8/10/2006: frontal -8/21/2021: from nontropical event well ahead of Henri/not directly from it -9/8/2004: post Frances interacting with front -So, none directly from TC but some indirect or post TC

OHC hasn’t warmed back any as of ~9/23 per the following image. I had said I expected the start of rewarming by around that date per the most recent@so_whats_happeninganimation but it still hasn’t happened on this (clock is ticking):

Based on data since 1950, this summer’s strongly -NAO itself isn’t at all predictive of a -NAO for the upcoming winter. The factors leading to summer -NAOs, which have become much more frequent since 2007 (2/3 of those summers vs only 1/5 of summers 1950-2006), don’t necessarily continue into winter, which has had much less frequent -NAOs in recent decades. Here are years with sub -0.50 summer NAO followed by the subsequent winter’s NAO (data goes back to 1950): * = El Niño winter -2023: -1.27/????* -2019: -1.23/+1.27 -2016: -1.28/+0.65 -2015: -1.34/+1.31* -2014: -0.82/+1.66* -2012: -1.61/+0.02 -2011: -1.38/+1.37 -2010: -0.82/-0.68 -2009: -1.18/-1.67* -2008: -1.27/-0.08 -2007: -0.68/+0.65 -1998: -1.07/+0.64 -1993: -1.22/+1.22 -1987: -0.71/+0.70* -1989: -1.01/+0.69 -1974: -0.51/+0.49 -1963: -0.61/-1.43* -1962: -0.72/-1.47 -1958: -1.56/-0.30* -1957: -0.82/-0.49* -1956: -0.67/+0.42 -1954: -0.92/-0.76 Anal. of 21 DJF NAO after sub -0.5 NAO summers: - Subsequent winter: 57% (12) +NAO, 10% (2) neutral NAO, 33% (7) -NAO - There have been 11 sub -1.00 NAO summers since 1950 (excluding 2023). Of these 11, 64% (7) of the subsequent winters had a +NAO. - Of the last five of these sub -1.00 summer NAOs (2019, 2016, 2015, 2012, 2011), four were followed by a +NAO winter, including 3 of the 4 strongest +NAO winters (2019, 2015, 2011). - However, for the 7 El Niño winters, alone: 43% (3) were +NAO and 57% (4) were -NAO despite a -NAO occurring during only one of last four El Niño winter cases (2009). - Of the 7 -NAO winter cases, 4 were during El Niño Conclusions: - No correlation is suggested in general between summer -NAO, even if sub -1.00, and following winter -NAO. - Summer -NAOs have become much more frequent recently even while winter -NAOs have been less frequent in recent decades. - But 2023 being El Niño MIGHT help -NAO chances somewhat for upcoming winter. - However, El Niño sample size pretty small and most recent two El Niño cases (2015 and 2014) had two of the three strongest +NAO winters. - There have been only 6 -NAO winters during the last 44 and those all had low (~30 or fewer) sunspots. In contrast, the upcoming winter sunspot # is expected to be very high (~150+). - Based on all the above, I’m maintaining my earlier prediction that despite this summer’s strong -NAO that the upcoming winter NAO will not average sub -0.25 (my def of -NAO) though I’m currently leaning -NAO for February. Monthly NAO: https://www.cpc.ncep.noaa.gov/products/precip/CWlink/pna/norm.nao.monthly.b5001.current.ascii.table

I’m not a big Bastardi fan these days due to what I feel is a serious lack of objectivity and apparent hidden agendas, but I suspect that many here will agree with this at least to some extent (sounds like a RONI better indicator than ONI idea, which I think has merit):