GaWx

With every case being different, how confident do you feel that 2023 tropical WPac SSTs will rebound as quickly as they did in 2019 and why? Though Nov of 2019 was cold, 2019-20 was a mild winter overall in the E US going all of the way through March though it was only warm neutral ENSO vs El Niño for 2023-4.

Yes, 180 to 260 degrees for 180-100W. Also, choose “seasonal average” if you’re looking at only a certain month or months as opposed to all of Jan-Dec. For analysis level, choose “monolevel variables” to do SSTs.

I’m talking specifically about the area of the tropical W Pacific W of Nino 4 and N of Australia from 120E to 160E, 15N to 15S. This is an area that meteorologist Brad Harvey has been focusing on for W Pacific forcing that had previously been at or near record highs for much of the last three years. He believes that the warmth of this area has likely been a major contributing factor toward recent years’ winter warmth in the E US/increased domination by the infamous “SE ridge” by focusing tropical convection N of Australia, thus leading to both a tendency for increased duration/amplitude of warmer winter MJO phases and tropical forcing from that area to dominate even when the MJO wasn’t officially in warm phases. Here is a link that calculates that tropical WPac area’s SSTs for Septembers back to 1948: 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=1&mon1=8&mon2=8&iarea=0&typeout=1&Submit=Create+Timeseries Below is the image of that area’s SSTs for Septembers going back to 1948. It shows the 0.7C to 0.8C cooling in 2023 vs 2020-2 along with the cooling that I assume was associated with the aforementioned fall 2019 IOD event. It isn’t quite as cool as the 2015 Nino Sept (0.108C warmer than Sept 2015) although it is 0.133C cooler than the 2014 Nino Sept and is 0.231C cooler than the 2009 Nino Sept:

It is from here: https://psl.noaa.gov/cgi-bin/data/timeseries/timeseries1.pl I was told about this site by a pro-met, who closely follows tropical WPac SST anomalies via this site. The following post has animation that also shows the tropical WPac cooling:

I don’t know if it is just for the short term or not, but a large portion of the tropical W Pac (15N to 15S, 120-160E) is actually significantly cooler than the last 3 years at this time (~0.7 to 0.8C cooler) while the central and E eq Pacific is much warmer as we know.

For some reason, OISST is stuck on Oct 3rd.

Regarding the continued cooling of WPac SST anomalies N of Australia (120-160E, 15N to 15S), I asked meteorologist Brad Harvey this: “Hey Brad, It looks like even further cooling of this WPac area you've been watching when looking at September of 2023 vs prior Septembers (cooler Sep 2023 anomaly vs anomaly for Aug 2023). When keeping in mind the much warmer Nino 4 just to its east in Sept vs prior Septembers, does this imply an increased chance for a colder E US winter vs recent winters?” This is his response: “For the WPac. Yes, appears to be cooling quite a bit. At face value, this could have a colder implication for the Eastern US in winter, as tropical convection is not over warm MJO phases around Indonesia but could be farther east near or to the east of the International Dateline which tends to be a colder position. That said, 2015-16 is a good example of a full basin strong El Nino with cooler waters in the west Pacific than we have now, and that was a record warm winter.”

Here’s something else I posted regarding relationship between Oct and winter during ENSO, this one addressing an apparent partial correlation regarding BN temperatures in Oct and in DJF in the SE: During El Niño in the SE, there’s evidence of a partial correlation between a BN Oct and a BN DJF. Check out these 9 KSAV BN (more than 2 BN) Nino Octobers for example: - 1876, 1885, 1930, 1957, 1958, 1976, 1977, 1987, 2006 Of these nine, seven (78%) of the subsequent winters were BN at KSAV: 1876-7, 1885-6, 1930-1, 1957-8, 1976-7, 1977-8, 1987-8 The other two (22%), 1958-9 and 2006-7, were NN None (0%) were AN. These 11 El Niño Octs were AN at KSAV -1884, 1911, 1918, 1919, 1939, 1941, 1951, 1969, 1986, 2002, 2018 Subsequent winters: 3 (27%) BN: 1939-40, 1969-70, 2002-3 6 (55%) NN: 1884-5, 1911-2, 1918-9, 1919-20, 1941-2, 1986-7 2 (18%) AN: 1951-2, 2018-9 So after BN Octs El Niño winters were 78% BN, 22% NN, and 0% AN. Thus, BN El Niño winters have been favored after BN Octobers. So after AN Octs El Niño winters were 27% BN, 55% NN, and 18% AN. Thus, NN El Niño winters have been favored over each of the other categories after AN Octobers. All 7 El Nino Octobers colder than 65F were followed by BN winters.

Are you referring to this that I posted recently? 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. That’s important to note because the monthlies average ~twice the amplitude of the dailies’ average. ———————— Recent GEFS PNA 2 week progs have been increasingly suggesting a +PNA for Oct as a whole. Keep in mind that the absolute value of the corresponding monthly amplitude averages ~twice as high as what the dailies would suggest. 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. I could even extend this sweet spot to ~+1.15 when considering the +1.14 of Oct of 1965, which was followed by a cold winter in the SE. My concern is that it is going to end up possibly well over +1.15.

I was just going to respond with this link to monthly NAO back to 1950. I’ve already back tested it and have found there’s been no correlation of a -NAO in Oct to a -NAO in the subsequent DJF. Anyone could look at this data and determine this quickly. If one would look in the table, they’d see many examples of a -NAO in Oct followed by a neutral NAO or +NAO in DJF. This is similar to the lack of correlation between a summer -NAO and the subsequent winter -NAO. Of course there being no correlation of Oct -NAO and DJF -NAO doesn’t at all mean there can’t be a -NAO for DJF. It just means that having a -NAO in Oct doesn’t at all increase that chance.

That’s what I thought. Hoping the trend is wrong, which is quite possible since model accuracy this far out is limited for all models.

Where are you saying that the model trended colder? Please be more specific. My take is that you’re correct for most of the W half of the CONUS, but not for most of the E half, which actually appears to me to be warmer per this new run. Of course, this is just a model prog, which has limitations on accuracy. As one who’d prefer the coldest centered in the E US, I hope the model trend on this run turns out to be wrong, which I feel is a reasonable hope, especially considering how cold OCT may end up in the SE US (looking at past chilly Octobers).

I look at it differently. We all have different takes, preferences, etc. Here’s mine: 1. I prefer BN in all seasons. 2. I don’t believe so much in the idea of “saving” BN as in some cases it is actually the opposite: there’s a correlation and thus BN may predict subsequent BN. 3. During El Niño in the SE, there’s evidence of a partial correlation between a BN Oct and a BN DJF. Check out these 9 KSAV BN (more than 2 BN) Nino Octobers for example: - 1876, 1885, 1930, 1957, 1958, 1976, 1977, 1987, 2006 Of these nine, seven (78%) of the subsequent winters were BN at KSAV: 1876-7, 1885-6, 1930-1, 1957-8, 1976-7, 1977-8, 1987-8 The other two (22%), 1958-9 and 2006-7, were NN None (0%) were AN. These 11 El Niño Octs were AN at KSAV -1884, 1911, 1918, 1919, 1939, 1941, 1951, 1969, 1986, 2002, 2018 Subsequent winters: 3 (27%) BN: 1939-40, 1969-70, 2002-3 6 (55%) NN: 1884-5, 1911-2, 1918-9, 1919-20, 1941-2, 1986-7 2 (18%) AN: 1951-2, 2018-9 So after BN Octs El Niño winters were 78% BN, 22% NN, and 0% AN. Thus, BN El Niño winters have been favored after BN Octobers. So after AN Octs El Niño winters were 27% BN, 55% NN, and 18% AN. Thus, NN El Niño winters have been favored over each of the other categories after AN Octobers. All 7 El Nino Octobers colder than 65F were followed by BN winters.

If the 12Z GEFS suite were to verify pretty closely, the SE would have a decent shot at one of the coldest Octobers of the last few decades. Let’s say possibly 90% percentile cold in relation to the last 30 years or so. Going to be interesting to see if this model is onto something.

I don’t know what the 0% significance means on any of the maps. I got these maps from this website: https://www.daculaweather.com/4_mjo_phase_forecast.php#thumb

Bastardi said in his most recent Saturday Summary that the best shot for a cold E US winter would be for 3.4 anomalies to be higher (central) than that for Nino 1+2 (east) but also higher than 4 (west). He implied that forcing centered on Nino 4 would favor MJO phase 6, which is one of the three warmest phases in DJF overall in the E US (see maps in image below) whereas forcing centered on Nino 3.4 would favor colder E US phases (8 and 1). It looks to me like Nino 4 could also favor phase 7, which isn’t as warm in the E US as phase 6 though it still favors mildness:

For the 2nd month in a row after being mainly the other way around for awhile, ERSST came in slightly warmer than OISST in Sep (+1.59 vs +1.53). For Aug/Sep, ERSST came in 0.05/0.06 warmer than OISST.

Though it is mathematically possible based on the past for a rapid enough rise to allow for a neutral to slightly +PDO averaged out for DJF, especially with it being a solid El Niño, a more realistic possibility is only rising to the -0.50 to -1.00 area. But that would still mean a rapid PDO rise between Sep and DJF to only a modest -PDO, which would appear to be enough to correlate more with higher cool to cold E US winter chances than mild or warm E US winter chances. I don’t feel a rise to a neutral or +PDO would be what’s required.

In your outlook, you said: “I've decided to take a blend of 1952-1953, 1956-1957, 1972-1973 & 2009-2010.” Also, following that, the three maps you showed included 1956-7 instead of 1957-8 (H5, temperatures, and precip) in the Nov-Mar blend calculation. Obviously, you meant 1957-8 (strong CP El Niño), which I see you mentioned earlier several times, instead of 1956-7 (cold neutral).

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: