GaWx

I can now add pre-1950 latest Lesser Antilles TS+ hits on record. What’s odd is that while there are none on record for Oct 10+ for the years 1899-1942, there are a whopping 7 just during the 12 year period of 1887-1898, including three during El Niño! Starting from latest: - Dec 7, 1887, TS Windwards *during weak El Nino* - Nov 27-9, 1896, TS Windwards to Leewards *during strong El Nino* - Nov 27-8, 1878, TS Leewards - Nov 1-2, 1888, TS Windwards to Leewards *during superstrong El Nino* - Oct 29, 1867, 110 knots cat 3 H Leewards - Oct 27, 1898, TS Leewards - Oct 15, 1895, TS Windwards - Oct 12, 1891, TS Windwards - Oct 11-12, 1894, H (cat 1?) Windwards to Leewards - Oct 11, 1943, TS Windwards

Going back to 1950, here are the latest TS+ hits from the east on the Lesser Antilles: - Alice of 1954 was cat 1 H in Leewards Jan 2 moving WSW: https://en.m.wikipedia.org/wiki/Hurricane_Alice_(December_1954) - Tomas of 2010 was 100 mph cat 2 H in Windwards Oct 30: https://en.m.wikipedia.org/wiki/Hurricane_Tomas - Helena of 1963 was TS in Leewards Oct 26-7: *During El Nino* https://www.meteo-tropicale.fr/en/detail-du-systeme-meteo/?Storm=AL091963 - Jose of 1999 was cat 1 H in Leewards Oct 20: https://en.m.wikipedia.org/wiki/Hurricane_Jose_(1999) - Joan of 1988 was TS in Windwards Oct 15: https://en.m.wikipedia.org/wiki/Hurricane_Joan–Miriam - Gonzalo of 2014 was cat 1 H in Leewards Oct 13: *During El Nino* https://en.m.wikipedia.org/wiki/Hurricane_Gonzalo

Regarding the above, the last couple of GFS and EPS runs for late month are suggesting there’d be virtually no chance for a BN October (2+ BN) in most of the E US. That period is still far enough away for a decent level of uncertainty to remain, but the current trend isn’t at all favorable to a cold late month with too much mild Pacific flow as opposed to cold Canadian flow. What I was hoping for and what I’m now seeing are not at all matching up. Just being real. I hope it changes. Any other opinions?

That would require a rise similar to the period of the fastest rise of this event so far, Aug 4-24. Not impossible but highly unlikely imo. We’ll see!

Indeed, what per Eric Webb’s tables is the strongest El Niño on record took place in 1877-8. It peaked at +2.9 both in NDJ and in DJF: https://www.webberweather.com/ensemble-oceanic-nino-index.html

To clarify regarding the latest versions of ONI peak for each major model, only the BoM (+2.43 in DJF) and MeteoFrance (~+2.3 in NDJ) have a super Nino now. Eric is showing Dec, alone. He has ~+2.75 for MeteoFrance. I see only ~+2.45 for Dec, which is from here: https://climate.copernicus.eu/charts/packages/c3s_seasonal/products/c3s_seasonal_plume_lfpw?area=nino34&base_time=202310010000&type=plume Here’s the summary of the latest runs: BoA: +2.43 vs +2.87 a month ago (DJF) MetFrance: ~+2.3 vs ~+2.5 a month ago (NDJ) Euro: ~+1.98 vs +2.24 a month ago (NDJ) UKMET: ~+1.90 vs +1.96 a month ago (DJF) JMA ~+1.90 vs +2.06 a month ago (NDJ) CFS ~+1.60 (DJF) vs +1.83 a month ago (NDJ) AVG ~+2.02 (NDJ/DJF) vs +2.29 a month ago (NDJ) Median ~+1.94 (NDJ/DJF) vs 2.15 a month ago (NDJ)

Regarding the idea of a partial correlation of BN temperature in Oct in the E US with BN in the following winter in the E US during El Niño, I did a rough estimate of where Oct 1-18 will be for RDU and NYC and came up with right at normal for RDU and +1 at NYC. So, for a BN full Oct (2 BN or colder), RDU would need to be ~5 BN for Oct 19-31 and NYC would need to be ~6BN for Oct 19-31 assuming those Oct 1-18 estimates verify pretty closely. That’s going to be quite a challenge. Areas further south than RDU would probably have an easier time to end up BN for the month.

Does anyone here follow GLAAM? “State Of The Atmosphere: El Niño, Positive India Dipole And Negative GLAAM” “The Earth’s atmosphere and oceans have a certain amount of natural rotation or spin, which is called angular momentum. This spin affects weather patterns. Normally, GLAAM is positive when the Trade Winds reverse blowing warm waters (arrow) from west to east. So positive GLAAM is most present during roughly 75% of all El Niño events. Currently, GLAAM is negative, which means less torque or rotation along the equator. This could potentially weaken the warm waters blowing from west to east. If it does, a cold, snowy northern Hemispheric winter would be the rule.” https://www.barchart.com/story/news/21017728/how-different-el-nino-events-affect-winter-weather-and-natural-gas-prices

Summarizing the major models I follow, this month cooled on all of them for ONI peak vs last month’s run: BoA: +2.43 vs +2.87 a month ago (DJF) MetFrance: ~+2.3 vs ~+2.5 a month ago (NDJ) Euro: ~+1.98 vs +2.24 a month ago (NDJ) UKMET: ~+1.90 vs +1.96 a month ago (DJF) JMA ~+1.90 vs +2.06 a month ago (NDJ) CFS ~+1.60 (DJF) vs +1.83 a month ago (NDJ) AVG ~+2.02 (NDJ/DJF) vs +2.29 a month ago (NDJ) Median ~+1.94 (NDJ/DJF) vs 2.15 a month ago (NDJ)

Looking at the very telling actual output for the new JMA, it cooled notably for a second month in a row and is no longer forecasting a super. Based on eyeballing, I have it (NDJ peak) no warmer than ~+1.90 vs +2.06 last month and +2.22 two months ago. It is easy to see that all months Oct-Feb cooled with January having cooled the most (see two images below). Just place a ruler along the +2 line on each and it is easy to see that it cooled. Jan is no higher than +1.7 after having been ~+1.9 last month and ~+2.05 two months ago: Sept 1st run: NDJ +2.06 Oct 1st run: NDJ ~+1.90

This means that the BoM model’s ONI peak in DJF dropped from 2.87 a couple of runs ago to 2.77 on the 9/23 run to only 2.43 in this latest run. It will almost certainly keep dropping.

The MJO is forecasted to end up weak for October of 2023 as a whole. Looking back at the 16 prior El Niños back to 1976-7, I found these 6 (38% of them) with weak MJO Octobers: 1977, 1982, 1987, 1997, 2002, and 2014 What did they have in common? - Peak ONI strength? No as two were weak, one was moderate, one was strong, and two were super strong - Average amplitude of winter MJO? Not really as only two of the six (1982-3 and 1997-8) stayed weak (mainly inside or just outside COD) all winter. 2002-3 was close as it was weak in J and F but it was strong prior to that in D. 1977-8 was the reverse of 2002-3 as it was weak in D but J and F were strong. 2014-5 was moderate through all of DJF. 1987-8 was moderate in D and J followed by strong in F. So, to summarize the subsequent winter MJO amp for these 6 weak Oct MJO cases: -D was weak 3 times, moderate twice, and strong once. -J was also weak 3 times, moderate twice, and strong once. -F was weak 3 times, moderate once, and strong twice. ——————— **Edit: Now I’ll add an analysis of moderate Oct MJOs: 8 cases 1976, 1986, 1991, 1994, 2004, 2009, 2015, 2018: again a mix of ONI peak strengths -D weak once (2004), moderate 5 times, strong twice -J also weak once (1977), moderate 5 times, strong twice -F also weak once (1977), moderate 5 times, strong twice So when comparing weak Oct MJO to moderate Oct MJO, the moderate Oct tend to keep it moderate in winter vs being weak more often than moderate during winter following a weak Oct MJO. So, there’s a tendency for some carryover. —————— Strong Oct MJOs: only 2 cases 1979, 2006 -Both had weak ONI peak -1979-80 MJO was weak through DJF -2006-7 MJO was moderate through DJF

Thanks for posting. Wow, you’ve put a lot into this! It is well thought out. 1. Do you use 1991/2020 for normals or do you use another base period? 2. Have you made a DJF NAO or AO forecast? 3. I know you said Oct would be cooler/warmer in the E/W than the Oct 1-7, 2023 temp map you posted. However, you also said that the full month would retain the look where the E is warmer than the W relatively speaking. Based on the Euro weeklies and other model output showing a BN/AN last 3 weeks of the month for much of the E/W US, I wonder about this, especially for the SE vs the W but also even for areas further N like the Mid-Atlantic states. If there are 3 weeks of AN in the W, wouldn’t a lot of the W end up AN?

Raindancewx has spoken but it has been met with a lot of silence. Are folks in shock? Meanwhile the new Euro weeklies have also spoken and this is the 2nd run in a row with a BN E US for 10/23-30, with this run having more widespread BN. In addition, 10/30-11/6 is NN on this run vs AN on the prior run.

@roardog and others: 12Z GFS suite is another run supporting another Canadian shot deep down into the E US the last week of Oct. Thus,BN October chances for much of E US continue to increase. Euto Weeklies will be out a little later.

I’d love to see it that cold in some of the SE! But did you mean to post the warmer 150 hour instead? Although the next chilly snap is still looking impressive, this GFS run isn’t calling for SE highs as low as the 40s outside of the mountains. It is more like mid 50s to mid 60s for that and nearby days, which itself would be great. Now toward end of month could be a different story in the extreme since it is so far out. And more and more evidence on the models is supporting another chilly shot then! This would also be good news from the perspective of BN full Octobers partially correlating to BN winters during El Nino.

If you still think that, then there’s no reason to not stick with it. So, in your mind, you’re probably not going down with the ship because otherwise you wouldn’t have said you still expect super.

To not admit that 3.4 is very much underperforming vs model consensus and my own earlier expectations, especially at a very crucial time like this, wouldn’t be being objective/honest. The 3.4 anomaly on Oct 10th is the same as it was WAY back on Aug 16th, when it first made this level. Back then, it was warming rapidly and forecasts for a super strong ONI were looking good to me. That is no longer the case, period. A super peak is going to be very hard to attain based on the latest. I’m now back to a high end strong (~+1.7 to +1.9) like I was earlier.

The SOI is now up to 52 straight negative days. Looking at the models, it could easily end as early as tomorrow. We’ll see as I’ve been too early ending the streak in recent predictions. Regardless, a 52 -SOI day streak is impressive. Going back to 1994-5, only 2015-6 and 1997-8 had longer -SOI streaks though they their longest were well above 52 days (two were much longer in 1997-8 with 72 and 99 days and 2015-6 had both a 66 and a 55 day -SOI streak).

I’m confident that Oct 2023 won’t be nearly as cold as Oct of 1976. But regarding 2009, the cold was more intense in the C US than in the E US. Oct of 2023 has a very good chance as it looks now to end up colder in the SE and even a decent shot at as cold or colder up into the Mid Atlantic states vs 2009. And Oct looks to have a decent shot at being about on par in the E US with 1957, 1965, and 1977, especially if yesterday’s Euro weeklies were to verify well.

I agree with you about the SE. But even further N at BWI, there appears to be a decent chance. BWI is for Oct 1-9 down to +4.8 or 43 cumulative degrees above normal, consistent with the map you posted having BWI within +3 to +6. The latest Euro weeklies, which actually have had more tendency to be too warm rather than too cool per my memory, have BWI BN for each of Oct 9-16, Oct 16-23, and Oct 23-30. This is the first time it has a BN E US for Oct 23-30. IF this Euro run were to verify well, that 43 cumulative degree surplus could very easily be much more than erased. If these 3 weeks were to average, say, -5 (which from what I’m seeing is a reasonable possibility) that would be enough to put Oct 1-30 at a cumulative -62 degrees or an average of -2 per day, which is my threshold for a BN month.

There is a partial correlation between BN E US Octobers and BN subsequent winters during El Niño. That’s one reason I’ve been rooting for a BN E US October (besides my preferring BN during all seasons), which as @roardogjust implied is looking increasingly likely. Check out the map I included in the following post showing how cold it was in the E US during Octobers of 1957, 1965, 1976, 1977, 1987, and 2009:

But COD MJO (especially W half of COD) during El Niño correlates more to cold than warm in the E US. Most of the highlighted periods within the 15 MJO charts I posted had majority COD. So, that’s actually very good news for those hoping for a cold E US that you’re talking about COD possibly being frequent this winter.

These JMA maps for Jan and Feb look much more -EPO than +PNA to me with the lowest ht anomalies centered in the Lakes to NE and not in the SE and the highest H5 anomalies centered Alaska and NW Canada instead of further E from N Idaho northward. Regardless, I take these seasonal predictions of models with a huge grain, especially this far out due to limited accuracy.

Looking at the indices: despite a solid +PNA, there was a strong +AO and +NAO. Also, Jan MJO was strongly concentrated on the warm right side. Now, Feb was a cold month though despite no AO/NAO blocking.