griteater

In the polar cap north of 60N, it looks like the significant water vapor anomalies didn't kick in until the start of January (2023). We'll have to see what happens this Oct-Nov. Hopefully we don't see an ice cold stratosphere develop in that timeframe.

Playing around with some data again. Some of this was previously covered, but some not. Criteria 1: 1) El Nino Winters, 2) Winters with-QBO at 40mb on Jan 1, 3) Winter Solar Cycle Phase (Sunspots) = Minimum, Ascending, or Maximum (Descending winters excluded due to known propensity for +NAO...those excluded were 72-73 and 14-15, which both ended up being +AO/+NAO winters) Table Results...21 of 32 months with -AO/-NAO combo, 7 of 8 with official SSWs (3 of those with multiple SSWs) 500mb Pattern Composite Results: Split Flow / West-Based -NAO Removing the 2 Weak El Nino winters (58-59, 79-80) yields the following...similar pattern, but with sharper anomalies: Criteria 2: All El Nino winters in Descending portion of the Solar Cycle Phase (Sunspots) Table Results...6 of 32 months with -AO/-NAO combo, 3 of 8 with official SSWs 500mb Pattern Composite Results: +AO/+NAO, big ridge over the conus (I couldn't include 2016 in the composite per that webpage) Removing the 3 weak El Nino winters (04-05, 06-07, 14-15) yields the following...similar idea, but with big Gulf of AK low given the high-end Super Nino influence: Will the Hunga Tonga volcano wreck the Criteria 1 composite ideas above (same criteria as this winter) like Pinatubo potentially did in 91-92? Pinatubo was a particulate emitting volcano / Hunga Tonga emitted water vapor, but both (particulate / water vapor) are believed to be cooling agents in the stratosphere (+AO favored). We don't really have to speculate about how the excess water vapor is moving around in the earth's stratosphere because we can monitor it in real-time. First image here shows the presence of higher than normal water vapor in the upper and middle stratosphere (3mb down to 30mb) at 75N (in the Northern Hemisphere Polar Cap), with the plus water vapor anomaly maximized at 10mb: Second image shows the presence of higher than normal water vapor at 10mb in both the Northern and Southern Hemisphere (image covers 75 N to the Equator to 75 S for the 10mb level in the stratosphere) That is all.

That PDF Corrected CFS is on crack. It has Sep at like +1.2. Today's daily value on UKMO is +1.7 (+1.68)

Feb 2015 as well, of course

First look at JMA Seasonal for winter is in (Dec-Feb). -EPO/+PNA ridge. West Coast split flow. Weak West-Based -NAO JMA has bluewave forcing (west of dateline), similar to 14-15, which spawns W Canada ridging. JMA 3.4 SST Mean maxes out at +2.1 in the month of Dec JMA SST Nino base has a basin-wide look overall for Dec-Feb, though it is a tick east of 15-16 Source: Ensemble Model Prediction / TCC (jma.go.jp)

3.4 SSTs don't seem to care about what's going on all around it and continue their slow and steady climb. Up to +1.66 on UKMO data, highest this year. Here is a quick 2 image subsurface loop for Aug 27 > Sep 6. Downwelling ripple working east to 120 W

OK, that 10-day VP image you posted makes a lot more sense to me. Looking back at Dec 2015 in 10-day increments, there was Dateline to E Pac uplift in early Dec, then MC to Dateline uplift in mid-Dec (your image), then back to Dateline uplift in late Dec. But yeah, it looks like that amplified MJO wave was at least partially to blame with wrecking things in Dec 2015. Here is what that 10-day period looks like on the JMA images... The main idea in that paper (at least in the Intro I read) is that in a Super Nino, you wouldn't expect the MJO to be active and influential...and rather, you'd expect a Super Nino to moreso be fully in control of influencing the pattern. In contrast, the weaker the ENSO, the more influence you'd expect coming from the MJO. OK, we'll have to see how it shakes out this winter. For periods of E U.S. winter interests, we want to see the low frequency uplift stay closer to the Dateline and not be overwhelmingly strong, and not extend too far east into the E Pac (or too far west)...and we don't want to see big amplitude MJO making a run thru Indonesia.

You could be right, but I'm not ready to throw in the towel on El Ninos altogether. Since the 2009-2010 winter, we've either had Weak El Ninos (14-15, 18-19) which have tended to be highly variable and not as cold post-1980 <OR> a super El Nino (15-16) which tends to be +AO/+NAO and warm. Here's a comparison of note...the VP pattern seen in Dec 2015 matches up favorably to the VP pattern from mid-Jan to mid-Feb in 2010 with the -VP extending back west to 150E, yet, the resulting 500mb patterns for each were vastly different, as you know. I realize that dateline forcing, on average, affects the pattern a little differently in December compared to Jan-Feb, but it's not wildly different...and the overall point is, let's see what happens when we get a more favorable El Nino strength (moderate or strong, and not plowing forcefully into super...and also with a weaker MEI/RONI), and then roll the dice and see how much the Maritime Continent and West Pacific waters influence the pattern. Maybe the MJO is higher amplitude than normal in a robust El Nino, and it does influence the pattern heavily again...but maybe this year's version of El Nino takes on a different route given its strength and makeup.

But there is more at play this year as the Atlantic Ocean temperatures are by far the warmest in these records back to 1982. SSTs aren't everything with hurricanes, but all else equal, it does promote more and stronger storms.

CANSIPS all in on active southern stream in split-flow

Here it is... Source: ECMWF | Charts

Here is what the composite for the SST Base Best Match years looks like. East-biased Aleutian Low / Split-Flow along the West Coast / Classic West-Based -NAO

Updated El Nino SST Base Chart with Best Match years with August data now in

Euro Seasonal Sep update on NAO index. Dec moved more positive this run (+NAO). Jan stayed the same (-NAO). Feb moved more negative (-NAO). -NAO in Mar as well

September Euro Seasonal update is in. Ensemble mean at the surface has a KU low pressure anomaly for Jan-Mar lol (2nd image). Aleutian Low anomaly is well west

Corrected a few dates due to Labor Day... Approximate Schedule of Upcoming ENSO Monitoring Events (lol): 8/31 (Aftn): September CANSIPS Update on Twitter 8/31 (Evening): September CANSIPS Update on Tropical Tidbits 9/3 to 9/8: September Update for JMA 3-Month Forecast (1st Look at Dec Forecast) 9/3 to 9/8: September JMA Winter Seasonal Forecast (1st Look at Dec-Feb Forecast) 9/5: JJA ENSO ONI Update from NOAA 9/5: JJA ENSO RONI Update from NOAA 9/5: September Update for ENSO SST Base E vs C Index 9/5: September Update of Euro Seasonal Forecast 9/8: September MEI Update 9/10: September Update of Copernicus C3S Ensemble Seasonal 9/10 to 9/20: September Update of JAMSTEC Seasonal

Regarding the PDO, the averaged value for August appears to be something around -1.60 on this chart. Trend loop of the last 3 runs of the CANSIPS seasonal for Nov-Jan shows a trend toward maintaining the healthy -PDO. I would think this gives credence to the idea that we won't have a big Aleutian Low parked in the North Pacific. Rather, expect variability in the N Pac pattern.

I get your point about not wanting to see MC forcing (Nina like), but historically, the +IOD autumns haven't been a good omen for winter with respect to high latitude blocking (winters that had +IOD autumns shown below). Given the strength of this Nino, I would think we'd keep a good amount of subsidence in the MC even with the increased Indo-Pacific warm pool influence in recent years. "AO+NAO" below is a combined AO/NAO index value

George added a poll for this year's max El Nino strength if you haven't seen it: What strength will the El Niño peak at in 2023-2024? - Weather Forecasting and Discussion - American Weather (americanwx.com)

My prediction: Oct: 1.8 Nov: 2.0 Dec: 2.0 Jan: 1.9 Max Tri-Monthly ONI: 1.97 rounded to 2.0 for NDJ I voted for "Super (>2.0)", but that's with considering Super as "2.0 and higher" instead of "higher than 2.0" (I know, I'm not playing by the rules). In addition, I consider an official SST Super Nino not just one tri-monthly reaching 2.0, but 3 tri-monthlies reaching 2.0 <OR> the average of the 3 highest tri-monthlies being 2.0 or greater...got this from the way Jan Null designates ENSO strength, which I like: Source: El Niño and La Niña Years and Intensities (ggweather.com) "The Oceanic Niño Index (ONI) has become the de-facto standard that NOAA uses for classifying El Niño (warm) and La Niña (cool) events in the eastern tropical Pacific. It is the running 3-month mean SST anomaly for the Niño 3.4 region (i.e., 5oN-5oS, 120o-170oW). Events are defined as 5 consecutive overlapping 3-month periods at or above the +0.5o anomaly for warm (El Niño) events and at or below the -0.5 anomaly for cool (La Niña) events. The threshold is further broken down into Weak (with a 0.5 to 0.9 SST anomaly), Moderate (1.0 to 1.4), Strong (1.5 to 1.9) and Very Strong (≥ 2.0) events. For the purpose of this report for an event to be categorized as weak, moderate, strong or very strong it must have equaled or exceeded the threshold of the highest category for at least 3 consecutive overlapping 3-month periods."

You'll never really know how hard forecasting is until you put actual pen to paper and publish it for all to see

This is the million dollar question. Does the low frequency -VP hold near the dateline and does the +VP hold in S America

The ENSO paper from Anthony Barnston et al. in 1997 became the defacto standard for designating the occurrence and strength of El Nino and La Nina. This is why Nino 3.4 is widely used. Regarding Super Nina, we simply haven't witnessed a year with those types of extreme SST numbers on the cool ENSO side in Nino 3.4 like we've seen with warm ENSO, but maybe one occurs in the future. Although Nino 3.4 is widely used, there is no exact standard for which all use for determining Nino / Nina occurrence and strength...as you mentioned, there are multiple ENSO SST regions, and you have RONI / MEI / SOI / Equatorial SOI. One advantage with using SSTs is that there are a multitude of models that predict future SSTs, whereas, I don't know of any models that predict explicit MEI & SOI numbers (though values could be inferred). Paper: Documentation of a highly ENSO‐related sst region in the equatorial pacific: Research note (tandfonline.com) "A new ENSO SST index is documented that is strongly correlated to thé core ENSO phenomenon. The SST anomaly in much of the east-central and eastern tropical Pacificis closely related to ENSO. However, thé anomaly from approximately thé centre of thé eastern half of the equatorial Pacific westward to near thé dateline is suggested to be most strongly ENSO-related when data spanning thé most récent several décades are used. This is thé case both with respect to (l) strength of association with other oceanic/atmospheric ENSO-related anomalies (both simultaneously and as a time-delayed predict and), and (2) impact on remote Worldwide climate anomalies. This observational insight was lacking in thé early 1980s when thé four "Nino" régions were developed. While a firmer dynamical foundation for this régional préférence still needs to be established, thé région straddling Nino 3 and Nino 4 may be regarded as an appropriate général SST index of thé ENSO state by researchers, diagnosticians and forecasters. A dataset of this index, called "Nino 3.4"(5°N-5°S, 120-170°W), is maintained on thé Internet, shown in thé Climate Diagnostics Bulletin, and provided in thé Appendix of this note."

In fairness, the Nino 3.4 climb has been steady state, and I don't see a good reason why that would change going forward (unfortunately). If things keep progressing along a similar course between the warmer 97-98 / 15-16, and the cooler 02-03 / 09-10, we end up with this peaking in the +2.1 to +2.2 range in the dailies in Nov or Dec, but it's unlikely to be a quick spike and fall type curve if these comparison lines are valid in the end.

Approximate Schedule of Upcoming ENSO Monitoring Events (lol): 8/31 (Aftn): September CANSIPS Update on Twitter 8/31 (Evening): September CANSIPS Update on Tropical Tidbits 9/3 to 9/8: September Update for JMA 3-Month Forecast (1st Look at Dec Forecast) 9/3 to 9/8: September JMA Winter Seasonal Forecast (1st Look at Dec-Feb Forecast) 9/4: JJA ENSO ONI Update from NOAA 9/4: JJA ENSO RONI Update from NOAA 9/4: September Update for ENSO SST Base E vs C Index 9/5: September Update of Euro Seasonal Forecast 9/8: September MEI Update 9/10: September Update of Copernicus C3S Ensemble Seasonal 9/10 to 9/20: September Update of JAMSTEC Seasonal