GaWx

0Z ICON just like 18Z ICON heads to S FL Sun night. That would be going against almost all of the W basin headings of the entire season.

18Z ICON at 120 hrs N Bahamas 998 mb TS moving W at ~15 mph

What are the longitudinal and latitudinal boundaries of the area in the W Pacific that you follow? I follow 120-160E, 15N-15S: 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 According to the table generated, it doesn’t have either Aug or Sep of 2023 or the combo of both as the warmest on record for a developing Nino: Year…….…….Aug…………..Sep 2023……….27.959……….28.096 2018………..27.946……….28.170 2014…………27.953……….28.229 2009…………28.098..…….28.327 So, per this, the average of Aug and Sep in 2023 was cooler than that for 2018, 2014, and 2009. This is especially the case vs 2009, when the globe was notably cooler. Aug-Sep of 2023 came in 0.185C cooler than that for 2009. So, on a relative basis to global temperatures, Aug-Sep of 2023 was significantly cooler than Aug-Sep of 2009 in the area that I monitor to the N of Australia.

12Z UKMET changes its mind and doesn’t bring Tammy back W like prior 3+ runs: HURRICANE TAMMY ANALYSED POSITION : 21.4N 64.2W ATCF IDENTIFIER : AL202023 LEAD CENTRAL MAXIMUM WIND VERIFYING TIME TIME POSITION PRESSURE (MB) SPEED (KNOTS) -------------- ---- -------- ------------- ------------- 1200UTC 23.10.2023 0 21.4N 64.2W 1004 37 0000UTC 24.10.2023 12 22.3N 63.7W 1002 42 1200UTC 24.10.2023 24 23.0N 62.8W 1001 38 0000UTC 25.10.2023 36 23.7N 61.5W 998 41 1200UTC 25.10.2023 48 24.6N 60.3W 997 42 0000UTC 26.10.2023 60 26.9N 58.1W 993 53 1200UTC 26.10.2023 72 29.5N 57.9W 993 47 0000UTC 27.10.2023 84 30.3N 59.1W 993 46 1200UTC 27.10.2023 96 31.1N 61.0W 996 43 0000UTC 28.10.2023 108 31.9N 62.9W 995 43 1200UTC 28.10.2023 120 33.0N 63.3W 998 35 0000UTC 29.10.2023 132 33.6N 62.4W 995 36 1200UTC 29.10.2023 144 34.2N 60.4W 998 38 0000UTC 30.10.2023 156 33.9N 58.6W 1002 32 1200UTC 30.10.2023 168 33.3N 56.9W 1006 29

The -SOI streak is still going and is now up to 65 days. This is a classic form of atmospheric coupling to the ocean of El Niño. Going back to June of 1991, this is the 4th longest streak with only the 1997-8 streaks of 100 and 72 days, respectively, as well as the 66 days of 2015 exceeding it. However, I think per model progs that today is going to turn out to be the last -SOI day of this streak: Longest -SOI streaks in days since June 1991: 100: Days 3-102 of 1998 72: Days 195-266 of 1997 66: Days 248-313 of 2015 65: Days 232-296 of 2023 55: Days 191-245 of 2015 46: Days 268-313 of 1997 46: Days 6-51 of 2010 43: Days 175-217 of 1994

0Z GFS/CMC: keep it well OTS from Bahamas/CONUS 0Z ICON: after initially going NE turns west and goes into S FL at 180 as a weakening low 0Z UKMET: similarly to at least last two runs it first goes NNE and later turns WSW at 10 mph making it to 150 miles E of the N Bahamas at 168 while then weakening: HURRICANE TAMMY ANALYSED POSITION : 20.3N 63.8W ATCF IDENTIFIER : AL202023 LEAD CENTRAL MAXIMUM WIND VERIFYING TIME TIME POSITION PRESSURE (MB) SPEED (KNOTS) -------------- ---- -------- ------------- ------------- 0000UTC 23.10.2023 0 20.3N 63.8W 999 47 1200UTC 23.10.2023 12 21.7N 64.5W 1001 37 0000UTC 24.10.2023 24 22.3N 63.5W 999 39 1200UTC 24.10.2023 36 22.9N 62.8W 998 37 0000UTC 25.10.2023 48 23.5N 61.6W 997 36 1200UTC 25.10.2023 60 24.9N 60.0W 993 43 0000UTC 26.10.2023 72 26.7N 58.6W 988 57 1200UTC 26.10.2023 84 28.9N 58.1W 992 44 0000UTC 27.10.2023 96 29.8N 59.5W 997 48 1200UTC 27.10.2023 108 29.9N 62.1W 1000 41 0000UTC 28.10.2023 120 30.0N 65.8W 998 46 1200UTC 28.10.2023 132 30.3N 67.9W 1001 36 0000UTC 29.10.2023 144 29.5N 70.3W 1001 34 1200UTC 29.10.2023 156 28.0N 72.6W 1003 31 0000UTC 30.10.2023 168 27.2N 74.7W 1006 30

For those such as myself hoping for a -AO in Dec, hopefully the Nov AO doesn’t end up +0.5+. The reason is that out of 18 +0.5+ AO (what I consider to be a +AO) Novembers since 1950, only 3 (1/6) of the subsequent Decembers had a -AO (sub -0.5): 2020, 2001, and 1978. Four of the 18 -AO Novembers were followed by a neutral Dec. About 1/3 (23) of Novembers have had a -AO vs the 18 with a +AO. About 1/3 (26) of Decembers have had a -AO.

The last few Euro weeklies’ mean (thickest blue line) have shown a stronger than normal Nov SPV, suggesting that a +AO would be favored, along with a weakening to a near normal SPV in early Dec fwiw:

Preliminary indications are that the Oct PNA will likely end up within the +0.85 to +1.15 range. If so, that would put it in the upper part of the most common range of past El Niño Oct PNAs preceding cool to cold SE winters: 1965: +1.14 cool 1977: +0.98 cold 1986: +0.92 cool 2014: +0.89 cool 1963: +0.69 cold

1. I have OND of 2009 as neutral IOD (barely positive) and definitely not negative per this: https://psl.noaa.gov/gcos_wgsp/Timeseries/Data/dmi.had.long.data 2. DJF 2009-10 was only one year after the prior deep minimum and thus sunspots were still very low.

The Oct 2023 MJO averaged out is going to end up weak in magnitude. Because of a partial correlation of Oct magnitude to the subsequent winter magnitude, there’s a better than average chance for a weak MJO averaged out this winter. During the winter periods when weak has dominated for a long enough time, especially near or inside the COD, they have tended to average colder (BN) for much of the E US, especially SE, during El Niños compared to when the MJO has been stronger as I’ve posted about. So, when you say you’re expecting the MJO to be weak, I (as one who’d prefer a BN winter) like what you’re saying.

12Z UKMET: similar to 0Z run with a W heading 108-168 at ~10 mph slightly N of 0Z run: HURRICANE TAMMY ANALYSED POSITION : 18.9N 62.6W ATCF IDENTIFIER : AL202023 LEAD CENTRAL MAXIMUM WIND VERIFYING TIME TIME POSITION PRESSURE (MB) SPEED (KNOTS) -------------- ---- -------- ------------- ------------- 1200UTC 22.10.2023 0 18.9N 62.6W 998 50 0000UTC 23.10.2023 12 20.2N 63.8W 1000 38 1200UTC 23.10.2023 24 21.4N 63.7W 1001 42 0000UTC 24.10.2023 36 22.2N 63.3W 1000 42 1200UTC 24.10.2023 48 22.6N 62.9W 1001 38 0000UTC 25.10.2023 60 22.8N 62.6W 1001 30 1200UTC 25.10.2023 72 23.7N 61.4W 999 36 0000UTC 26.10.2023 84 25.0N 59.7W 996 54 1200UTC 26.10.2023 96 26.7N 59.1W 995 49 0000UTC 27.10.2023 108 27.2N 61.0W 997 43 1200UTC 27.10.2023 120 27.7N 64.0W 998 45 0000UTC 28.10.2023 132 27.7N 67.7W 995 39 1200UTC 28.10.2023 144 27.5N 69.8W 997 36 0000UTC 29.10.2023 156 27.6N 71.5W 1000 37 1200UTC 29.10.2023 168 27.2N 73.4W 1003 33

The 0Z UKMET at the end (168) has a 590 dm H5 ridge centered over the GOM and a trough dipping down into the SW US (see image below) moving very slowly E with TS Tammy blocked in and thus then moving just N of due W at just under 10 mph. It is hard to tell what she would do after this point had the maps gone out further although a subsequent continued W heading would be most likely at first although soon after I would think it would start to recurve as the blocking high eventually weakens and gives way:

Maybe not so soon to be forgotten? The 0Z UKMET has a mainly westbound to WNW moving Tammy hours 120-168: HURRICANE TAMMY ANALYSED POSITION : 17.5N 61.5W ATCF IDENTIFIER : AL202023 LEAD CENTRAL MAXIMUM WIND VERIFYING TIME TIME POSITION PRESSURE (MB) SPEED (KNOTS) -------------- ---- -------- ------------- ------------- 0000UTC 22.10.2023 0 17.5N 61.5W 999 48 1200UTC 22.10.2023 12 18.7N 62.4W 1003 45 0000UTC 23.10.2023 24 19.8N 63.5W 1003 41 1200UTC 23.10.2023 36 20.8N 63.7W 1004 39 0000UTC 24.10.2023 48 21.7N 63.8W 1004 36 1200UTC 24.10.2023 60 22.1N 63.5W 1004 37 0000UTC 25.10.2023 72 21.2N 64.2W 1004 29 1200UTC 25.10.2023 84 21.4N 63.3W 1003 30 0000UTC 26.10.2023 96 21.7N 62.2W 1001 31 1200UTC 26.10.2023 108 23.5N 61.7W 999 37 0000UTC 27.10.2023 120 24.9N 61.7W 999 41 1200UTC 27.10.2023 132 25.9N 63.7W 999 39 0000UTC 28.10.2023 144 26.6N 66.8W 998 40 1200UTC 28.10.2023 156 26.2N 69.4W 997 36 0000UTC 29.10.2023 168 26.4N 71.2W 1000 37

Followup: Let’s say Oct PDO ends up at -1.5, which would mean a rise of 1.44 from Sep and would easily be the third strongest PDO rise in Oct for El Niño since the 1850s. The following five Nino autumns had a PDO rise of 1+ from Sep to Oct along with these E US winters to follow: 1969: 2.02 (weak); cold winter w/PDO +1.07 1880: 1.79 (weak); cool to cold winter w/PDO -0.23 1876: 1.08 (moderate); cool to cold winter w/PDO -0.15 2006: 1.08 (weak); normal winter w/PDO -0.61 1986: 1.03 (moderate); normal E US winter w/PDO +1.55 So, none of these five were mild. If the winter PDO were to be above -1 and especially above -0.75, I’d think that the PDO wouldn’t likely be a mild influence. The odds of a sub -1 Nino winter PDO are low considering there has been a mere two of the last 50 (4%) at sub -1 (1994-5 and 1951-2). *Edited for correction to add 1951-2

Whereas SST charts near Japan suggest a significant PDO rise has occurred, which I strongly believe, I still would recommend caution before accepting this from WCS as accurate, especially after a rise of 2.3 in just 2.5 weeks. WCS appears to be a private co. as opposed to governmental fwiw. I use this from NOAA for monthly PDO: https://www.ncei.noaa.gov/pub/data/cmb/ersst/v5/index/ersst.v5.pdo.dat Looking at the monthlies, WCS has been much less negative than NOAA: -Jan is ~-0.75 per WCS graph while NOAA is -1.25 -Feb is ~-0.8 per WCS vs -1.65 per NOAA -Mar is ~-1.3 per WCS vs -2.45 per NOAA. -Apr ~-2 WCS vs -3.07 NOAA. -May/Jun ~-1.5 WCS vs -2.42/-2.53 NOAA. -Jul ~-1.75 WCS vs -2.52 NOAA -Aug ~-1.6 WCS vs -2.46 NOAA -Sep ~-2.25 WCS vs -2.94 NOAA So, on average, WCS has been coming in at ~63% of NOAA. But they have been mostly moving in the same direction from month to month. Thus, NOAA has very likely also risen substantially so far this month and thus it wouldn’t shock me if it comes in near -1.5 for Oct vs Sept’s -2.94.

Going back to 1951-2, I can’t find a single El Niño analog to the upcoming moderate+ El Niño, -QBO (30mb), and +IOD winter. The closest may be 1972-3 as it was a moderate+ with +IOD. It had a -QBO that was still solid in Dec but it rose rapidly and was already neutral by late Jan.

Way down here on the SE coast, it can never be too cold from my perspective. I mean hopefully the 1-2 F BN on the model isn’t going to end up colder than what verifies because the model has been a good bit too cold in the past at times.

Regardless of the details, it is highly likely that the Oct-Dec IOD will be near or at the highest on record for El Niño. I’m betting heavily that it will be amongst the warmest IOD Oct-Dec periods for El Niño, which are in order from strongest 1997, 2018, 1972, 2006, 1994, and 2015. Even 1997 looks to be challenged. Edit: I should add that with IOD averages tending to increase somewhat in recent decades vs earlier that there probably is a GW influence that warms the IOD somewhat despite it being a dipole. Look no further than the non-Nino of fall of 2019! But regardless, the current IOD is very impressive.

1. I’m willing to bet that a typical +2+ ONI peak of past El Nino events would have had at least a small area of +3+ nearer to the equator. Even a high +1+ ONI could possibly support a narrow +3+ area there since the center portion is always significantly warmer than the ONI level. 2. Do you know what climo base is used for the 2m temp anomalies by JAMSTEC? 3. Hopefully this run isn’t too cold in the SE as it has been significantly too cold before. I’d sure love a 1-2 F BN DJF, the coldest on the entire map!

Every month of June-Oct have had a +PNA despite the very strong -PDO during the same period. Are there any implications?

Showing an area >+3.0 SSTS isn’t as absurd as it seems because it is only a small area. It goes only between 1.5N and 2S latitude at its widest point, which stretches only across ~15 degrees of longitude centered on 120W, the middle of Nino 3 and the far E end of Nino 3.4. Keep in mind that Nino 3 and 3.4 stretch from 5N to 5S, a 10 degree swath. So, the +3+ covers only ~1/3 of this at its widest, which stretches only across ~15 deg of longitude vs Nino 3’s 60 degrees of longitude or 1/4 of it. So, the +3+ area covers not much more than 10% of the entire Nino 3 and well <10% of Nino 3.4. Even the +2+ area covers <50% of Nino 3/3.4 meaning the +1 to +2 area covers 50%+ of Nino 3/3.4. So, Nino 3 likely averages only in the low +2’s at most on this map and Nino 3.4 is probably only ~+2 at most. For reference, TAO is already ~+2.5 in a portion of 120W and a little warmer than that just to the east.

Looking at the ONI chart, it barely missed a triple. Also, 2018-9 to 2019-20 barely missed a double. https://origin.cpc.ncep.noaa.gov/products/analysis_monitoring/ensostuff/ONI_v5.php

That’s actually likely since most peak in Oct or Nov. So, that wouldn’t change the equation.

There appear to be some questionable classifications in this per the IOD source I use: - 1987, 2002, and 2009 don’t belong in the -IOD column as Oct-Dec averaged positive for all three years - 1986 doesn’t belong in the +IOD column since Oct-Dec IOD averaged negative - 2018 (+), 2014 (+), 1976 (-), 1969 (-), and 1953 (-) were all left out - Note that the presented graphs were for NDJ rather than DJF - However, for the E US even after making these adjustments/additions/change from NDJ to DJF, the avg precip for +IOD still comes out AN/much wetter than that for -IOD while the avg temperature for +IOD still comes out significantly warmer than that for -IOD. You learn something new every day but this isn’t what I wanted to see for upcoming winter BN temp. chances. Thus, next El Niño I’ll be rooting for a -IOD. My monthly IOD source: https://psl.noaa.gov/gcos_wgsp/Timeseries/Data/dmi.had.long.data