GaWx

The CFS ONI forecasted peak has been bouncing back recently and is now back up to ~+1.73/+1.75 for NDJ/DJF, vs +1.59/+1.56 in NDJ/DJF as of 10-14+ days ago. The Jan 3.4 forecast is now back up to ~+1.98, which is near its latest forecast for Nino 3. For Jan, it now has 1+2 (which it has been way too cool with for many months) at ~+1.25 and Nino 4 at ~+1.1. So looking strictly at anomalies, the latest CFS has a cross between an EP and CP El Niño this winter. Latest CFS forecast of ONI: peak +1.75 DJF

I follow the SAI and it has since 2014 actually been a reverse indicator of the winter AO vs what it used to indicate. So, if the trend of the last 9 years were to continue into the winter of 2023-4, the AO may actually end up negative despite the lower than average SAI so far this month. Also, we still don’t have the final 2023 SAI. I hope it stays below average based on what has occurred since 2014.

The OHC anomaly has finally been rewarming recently although only gradually to just over +1.0 C, i.e. nothing to write home about and still well below the mid June and late August peaks:

The re-drop on the WCS PDO chart continues and it was at -0.81 yesterday after hitting a high of ~-0.15 on 10/21. The momentum will probably take it down at least to ~-1.00. The drop over the last week is no surprise following the tremendous 20 day rise of 2.45 from way down at -2.60. This is a correction of sorts. What I’ll be watching for is where equilibrium is reached and ends the current drop. Hopefully this won’t be much below -1.00 and it resumes a rise, which is supported by the current strong El Niño. Just a reminder: the NOAA monthlies have been more negative than what these WCS charts have been showing. NOAA daily is probably ~~-1.25 to -1.50 now:

So, even more reason to forecast either a neutral NAO or +NAO for this winter overall. (I’m still leaning -NAO in Feb). But what about a -AO this winter? Since 1979-80, we’ve had more -AO winters without a -NAO (9) than -AO/-NAO winters (6). Five of the last 14 El Niño winters have had a -AO (1979-80, 1986-7, 1997-8, 2002-3, 2009-10) vs only two of the last 14 having a -NAO (1986-7, 2009-10). What I feel confident about is a +PNA this winter. A whopping 12 of the last 14 El Niño winters had a +PNA.

Based on the last 44 winters, there have been for unknown reason(s) many more -AO (defined as sub -0.50) winters than -NAO (defined as -0.25) winters. These 9 winters had a -AO but no -NAO: 1979-80, 1985-6, 1997-8, 2000-1, 2002-3, 2003-4, 2005-6, 2012-3, 2022-3 At the same time, no winters since 1979-80 have had a -NAO but no -AO. Since 1979-80, there have been 15 -AO winters but only 6-NAO winters. OTOH during 1950-1 through 1978-9 there were 15 -AO winters and 16 -NAO winters. Only two of these winters had a -AO and no -NAO: 1950-1 and 1952-3. And three had a -NAO but no -AO: 1958-9, 1963-4, and 1970-1. So, something has changed over the last 44 years to make it way more difficult to get a -NAO winter than a -AO winter despite an increase in summer -NAOs. So, based on this, I’m giving it a significantly higher chance that 2023-4 will have a -AO vs a -NAO. During the last 44 winters, only these 6 had a -NAO: 1984-5: (NAO -0.70) (moderate La Niña) headed down in cycle 21 with limited sunspots averaging only 20/month; this was 20 months before the minimum of Sept 1986 1986-7: (NAO -0.30) (moderate El Niño) very early in cycle 22 four months after the Sept 86 minimum with very limited sunspots of only 6/month 1995-6: (NAO -0.62) (moderate La Niña) headed down in cycle 22 with limited sunspots of only 12/month nine months before Sept 1996 minimum 2009-10: (NAO -1.67) (strong El Niño) one year into cycle 24 at 13 months after the Dec 2008 minimum just starting to head upward but with still limited sunspots of only 22/month 2010-11: (NAO -0.68) (strong La Niña) two years into cycle 24 at 25 months after the Dec 2008 minimum headed further up but still low at 33/month 2020-1: (NAO -0.42) (moderate La Niña) early into cycle 25 at 13 months after the Dec of 2019 minimum just starting to head up but still with limited sunspots of only 14/month So, there has been no winter of the last 44 with a -NAO averaged out over the winter along with DJF sunspots above 33/month. With us now in an active part of the sunspot cycle, that’s even more reason for me to feel it is going to be a challenge to get a -NAO this coming winter. So, a -AO combined with a neutral NAO or +NAO looks to me more likely this winter than a -AO/-NAO. However, even with that, I’m leaning toward a -NAO Feb.

I don’t subscribe. This is from the link posted above. After such a sharp rise, the current decline back to -0.7 from -0.2 is totally expected (reverse dead-cat bounce). What’s not known is how much further this reverse dead-cat will go. Per the current trajectory, it going back below -1 at least for a short period wouldn’t surprise me. Also, the monthly NOAA PDOs have been a good bit more neg than the ones calculated from WCS dailies. If there were a NOAA daily reported, I’d guess it would be ~-1.25 to -1.5. Regardless, Oct will almost certainly come in much less negative than Sep on both. I’m wild guessing ~-1.75 for Oct NOAA vs -2.94 in Sep. That would mean a rise of ~1.19, which is quite significant. We’ll see whether the overall momentum of rising continues into Nov. I’m leaning that way based on the huge rise (on the posted graph) earlier this month along with it being a strong Nino. My hope as a cold preferrer is that we end up with a DJF PDO higher than -1 and preferably higher than -0.75 (I’m talking about how NOAA table measures it). Analogous El Niño SE winters following sharp Sep to Nov rises are 1876-7 (cold), 1880-1 (cool), 1884-5 (cool), 1969-70 (cold), 1986-7 (normal), and 2002-3 (cool). It is important that the rise continues through at least Nov.

https://s2s.worldclimateservice.com/climatepanel/

It was -.70 yesterday per below though the NOAA PDO runs more negative and is thus likely ~-1.25:

I guess it depends on one’s definition of atmospheric coupling.

Not only has the SAI not shown a positive correlation to a winter -AO during the last 10 years, it has actually shown a significant negative correlation during that period!

2023’s ASO SOI looks to come in near -11. To compare: 2018: -4 2015: -19 2014: -8 2009: -5 2006: -12 2004: -4 2002: -10 1997: -16 1994: -12 1991: -12 1987: -10 1986: -2 1982: -21 1979: -2 1977: -11 1976: -7 1972: -11 1969: -9 1968: -1 1965: -12 1963: -8 1958: +1 1957: -6 1953: -10 1951: -10 - The six moderate El Niños since 1951-2 averaged -7 with a range of -1 to -12. - The 10 weak ones also averaged -7 (with a range of +1 to -12). - The four strong ones averaged -8 (range -5 to -12). - The five super-strong averaged -16 (range -11 to -21). Based on the above: whereas 2023’s -11 ASO SOI isn’t “representative” of a super-strong, it is easily representative of strong (actually border between strong and super) and thus solidly translates to that form of atmospheric coupling during ASO imho.

Tammy has quickly become tropical again and is now a TS.

The significantly warm biased Euro, especially in spring, has been noted before. However, the Australian (BoM) average bias of zero during the 10 years prior to 2023 in May runs’ ONI peak forecast had also been noted though it was also mentioned that there were rather significant swings from too warm to too cool. So, whereas BoM average bias was near zero during 2013-22, the accuracy wasn’t necessarily anything to write home about. It had a pretty good sized average error but it was just that that error was evenly balanced between too warm and too cool. This year of course will end up way too warm barring an unforeseen sudden upcoming rapid warming.

Here’s why I feel the SAI, which is supposed to predict the winter AO, has for some unknown reason(s) not come through during the last 9 years in general: SAI per this graph (in msq): top 4 (mean 11.5) -2018 SAI 14: winter AO +0.2 -2016 SAI 14: winter AO +1.0 (2nd strongest +AO since 2014) -2015 SAI 13.5 winter AO 0.0 -2019 SAI 12.5 winter AO +2.1 (strongest +AO since 2014) The two winters since 2014 with the strongest -AO by far had these SAIs and AOs: -2020 SAI 11 -1.8 -2022 SAI 10 -0.6 So, the two most -AO winters since 2014 (2020 and 2022) were both preceded by a below mean SAI. Also, none of the top 4 SAIs of the last 10 had a -AO winter and two of them were the strongest +AOs since 2014! So, when I said that the SAI in recent years could be used as a reverse indicator, this is the evidence. AO monthly: https://www.cpc.ncep.noaa.gov/products/precip/CWlink/daily_ao_index/monthly.ao.index.b50.current.ascii.table

Of the 6 listed El Nino autumns with large PDO rise, 5 of the 6 subsequent winters were cold in the E US: 1876-7, 1880-1, 1884-5, 1969-70, 2002-3 The only one that wasn’t was 1986-7, which was near normal. So, there have been no mild E US El Niño winters on record back to the 1870s that had a preceding rapidly rising autumn PDO. Also, the projected Oct 2023 PNA looks to favor a chilly E US, especially SE, per El Niño analogs. OTOH, strong +IOD El Niño autumns have generally been the opposite with mild to near normal subsequent winters dominating in the E US. So, in summary, we have mixed indicators.

Update: My rough guess based on Oct 1-24 is for the WCS Oct PDO to end up near -1.05. Based on that, NOAA’s Oct PDO should come in somewhere within -1.4 to -2.1 with the best guess near -1.7. This would mean a substantial rise from Sept’s -2.94 along with the prospect for another substantial rise for the Nov PDO, when there’s a chance NOAA could even come in >-1.0 based on current trends. If it did, that would mean a rise of 1.95+, the largest NOAA PDO rise from Sept to Nov for the last 55 El Niños going back to the 1850s: Largest NOAA PDO increases Niño Sep to Nov 1986: 1.71 1969: 1.65 1876: 1.44 1884: 1.42 1880: 1.37 2002: 1.29 NOAA monthly PDO back to 1854: https://www.ncei.noaa.gov/pub/data/cmb/ersst/v5/index/ersst.v5.pdo.dat

Indeed, a strong vortex is on the way for early to mid Nov. However, the Euro weeklies continue to suggest a drop to neutral near the end of Nov along with a continued fall to a little weaker than average in early Dec:

The good news is that the SAI hasn’t been successfully predicting the winter AO ever since I discovered it ~10 years ago. It may have even become a contra-indicator, which if true would mean that bottom feeder SAI would actually favor a -AO winter.

DMI, which is apparently the same thing per this: Dipole Mode Index (DMI) Intensity of the IOD is represented by anomalous SST gradient between the western equatorial Indian Ocean (50E-70E and 10S-10N) and the south eastern equatorial Indian Ocean (90E-110E and 10S-0N). This gradient is named as Dipole Mode Index (DMI). When the DMI is positive then, the phenomenon is refereed as the positive IOD and when it is negative, it is refereed as negative IOD. As the original provider has changed how they update the index, we have decided to calculate it here using the HadISST1.1 SST dataset for the entire time period. Climatology is currently 1981-2010. Time Interval: Monthly Time Coverage: 1870 to present Update Status: Periodically updated https://psl.noaa.gov/gcos_wgsp/Timeseries/Data/dmi.had.long.data

Please provide a link if you have it because I’ve looked hard and can’t find any other comparable table that goes that far back. The table I use has these for 1965, 1968, and 1977: 1965 OND: +0.017, -0.224, -0.290; Avg -0.166 (moderate negative) 1968 OND: -0.531, -0.454, -0.213; Avg -0.399 (moderate to strong negative) 1977 OND: +0.245, -0.127, -0.020; Avg +0.033 (neutral)

1. Regarding Oct-Dec, 1963 was moderate +IOD, but 1965 (moderate -IOD), 1968 (moderate to strong -IOD), and 1977 (neutral IOD) weren’t +IOD per this table: https://psl.noaa.gov/gcos_wgsp/Timeseries/Data/dmi.had.long.data 2. I’m looking strictly at temperatures and not at all at snowfall or precip. Precip has averaged significantly heavier in the E US following +IOD autumns vs -IOD autumns. In the NE US, that may be a bigger factor for snowfall whereas temperatures are much more crucial in the much warmer SE. 3. NAO/AO will likely be very crucial this winter like it often is but perhaps moreso a factor this winter than others due to mixed indicators. For example, the Oct PNA is now looking to come in ~+0.85-+1.15, which tends to correlate with chilly winters, especially in the SE.

What I make out of it is that a strong +IOD El Nino autumn like what we now have has had a notably significant correlation to a mild E US El Niño winter. This is something I knew nothing about til last week. But even notably significant is still nowhere near a 100% correlation, which is the case for practically any index.

As per the above for El Niño in the E US, solid +IOD Oct-Dec have had on average warmer subsequent winters vs the winters following solid -IOD Oct-Dec as well as winters following neutral Oct-Dec IOD, both of which averaged similarly cool in the SE. Thus as one desiring BN winters and now that I’ve learned this, I’ll be rooting against strong +IOD autumns during future El Nino’s to allow for a better chance for a BN winter. The coldest winters on average in the NE US have followed neutral Oct-Dec IOD: Winters following strongest +IOD Oct-Dec: averaged mild Winters following neutral IOD Oct-Dec: averaged cool Winters following strongest -IOD Oct-Dec: averaged cool SE to normal NE IOD monthly history: https://psl.noaa.gov/gcos_wgsp/Timeseries/Data/dmi.had.long.data

The very long -SOI streak finally ended on 10/24 at 65 days. Only two streaks in 1997-8 and one in 2015 (that one barely) exceeded 65 days since June of 1991. The streak started way back on August 20th!