GaWx

The latest CFSv2 10 day mean prog for RONI for Oct is +2.5 and for Nov is +2.75. The current record high for any month since 1950 is the +2.5 of Jan of 1983. Judging by the blue lines all being at or below +2.75, this graph’s +2.75 mean for Nov is likely heading down in future 10 day runs. @40/70 Benchmark’s prediction for RONI is looking pretty good:

https://www.cpc.ncep.noaa.gov/data/indices/Rnino34.ascii.txt

23 hours ago, GaWx said:

Indeed as it on today’s Euro Weeklies gets down to +14 in early Nov, weakest run yet. Nothing earth shatteringly weak but interesting, regardless:

Today’s Euro Weeklies 10 mb zonal mean wind prog is even weaker than yesterdays, which had its lowest at 14 m/s, with it down to 12 m/s:

Today’s GEFS NAO forecast is even more positive than yesterdays, which itself was much more + than last week’s GEFS: 

Today: gets down to only -0.6 and then quickly rises to +0.5 followed by drop back to 0:

Yesterday:

Last week: 

23 minutes ago, roardog said:

Beating that record is not a slam dunk yet then. 

Agreed

 The most similar that I found to what the Euro Weeklies are forecasting late Oct-late Nov were 2016-7, 2009-10, and 1979-80 with the last two being El Niños:

2016 La Niña: similar late Oct/early Nov though late Nov weaker

2009 El Niño: not as weak late Oct/early Nov and weaker mid Nov vs 2026 (dip ~2 weeks later than 2026)

1979 El Niño: not as weak late Oct but early to mid Nov similar to 2026 although late Nov much weaker vs 2026

16 minutes ago, roardog said:

What’s the record RONI? I forgot now.

Are you asking for the record relative trimonthly 3.4? Or the record relative weekly 3.4?

Weekly record of relative 3.4 is +2.9 (12/29/1982)

Trimonthly RONI record is +2.40 in DJF 1982-3.

Yesterday’s NOAA official relative weekly SSTa update for last week had this: note the 0.3 cooling in Nino 4 to -0.1 and that 3.4 stayed at +2.4:

07OCT2026         4.4        3.4        2.4        0.2
 14OCT2026         4.4        3.5        2.4       -0.1

https://www.cpc.ncep.noaa.gov/data/indices/rel_wksst9120.txt

This is now Invest 93L.

 0Z UKMET almost gets to H strength:

TROPICAL STORM 93L ANALYSED POSITION : 35.0N 70.7W

ATCF IDENTIFIER : AL932026

LEAD CENTRAL MAXIMUM WIND
VERIFYING TIME TIME POSITION PRESSURE (MB) SPEED (KNOTS)
-------------- ---- -------- ------------- -------------
0000UTC 20.10.2026 0 35.0N 70.7W 1004 37
1200UTC 20.10.2026 12 35.2N 70.5W 998 40
0000UTC 21.10.2026 24 35.5N 69.8W 998 45
1200UTC 21.10.2026 36 36.2N 69.5W 995 40
0000UTC 22.10.2026 48 36.9N 69.7W 989 51
1200UTC 22.10.2026 60 38.1N 68.1W 982 52
0000UTC 23.10.2026 72 39.4N 63.9W 975 63
1200UTC 23.10.2026 84 42.8N 56.7W 975 57
0000UTC 24.10.2026 96 45.9N 51.6W 986 54
1200UTC 24.10.2026 108 46.7N 48.5W 992 45
0000UTC 25.10.2026 120 48.0N 42.4W 991 45
1200UTC 25.10.2026 132 54.1N 32.9W 980 40
0000UTC 26.10.2026 144 CEASED TRACKING

3 hours ago, MJO812 said:

Euro shows a stretched PV in the long range. We never had a very strong El Nino like this so no one knows what wil happen.

Indeed as it on today’s Euro Weeklies gets down to +14 in early Nov, weakest run yet. Nothing earth shatteringly weak but interesting, regardless:

 Look how much the forecasted mean GEFS NAO has risen from its Oct 13th forecast to today’s forecast!

Oct 13th: peaking at only +1.0 on Oct 15th and then plunging to -1/remaining down at -0.9 on Oct 27th:

Today’s prog (Oct 19th): peaked not til today way up at +1.73 and already after a dip to -0.8 back up to ~0 on Oct 27th:

 I’m assuming this drastic change is related to the actual strong storm offshore the E US that wasn’t even forecasted back on Oct 13th thus leading to lower actual SLP in Iceland today than progged 6 days ago.

Daily NAO: https://ftp.cpc.ncep.noaa.gov/cwlinks/norm.daily.nao.gefs.z500.120days.csv

 After a decent rise in last week’s release from +0.59 to +0.88, the latest weekly IOD update had no change. But that could easily just be a short-lived pause in the general upward trend since June 1st. Based on the history of IOD usually maxing out by Nov, I’m giving it another month to see if we get a very strong IOD peak this late autumn/early winter. One can see on this chart how much stronger was the +IOD in autumn 2023! At this time then, the IOD was already peaking way up at +1.91! Even in 2019 on this date it was way up at +1.94!

https://www.bom.gov.au/clim_data/IDCK000072/iod_1.txt?1791781094025

@snowman19

@LibertyBellasked me this:

“Are these similar to the naturally occurring doldrums at the horse latitudes that Columbus experienced?”

 ————
My answer: Good question. Quite possibly.

13 hours ago, LongBeachSurfFreak said:

For sure, it’s been shockingly cold in the Arctic this summer. So cold air is available to source. And anyone that claims to know exactly what is going to happen during an unprecedented event is just wishcasting. A very warm start, possibly record warm and of course wet is starting to lock in. After that the amount of uncertainty is off the charts. That’s why I think something like 83 or 16 is really on the table just as much as 73 or 98.


.

 
 I closely followed the DMI site’s 80+N Arctic temps showing 2026 being THE coldest on record (back to 1958) by a good margin late May-early August and posted many times about that here and in the Arctic Ice thread. There’s little doubt it was notably colder there than recent summers, especially N of Alaska, and it helped the Arctic ice.

 However, as@bluewave@OSUmetstudemphasized in discussions with me, they convinced me to think that comparing to DMI charts prior to 2002 per Chris (see his quote below) and possibly even to all years through 2025 per @OSUmetstud (due possibly to a cooler ECMWF bias introduced in May of 2026) MAY make the appearance of the summer of 2026 being significantly colder than all years 1958-2025 per the DMI graphs deceptive because of the DMI ECMWF data.
 

Per Chris in Arctic Ice thread:

“Even the less reliable ECWMF only starts in 2002, so an apples to apples comparison to any year earlier than 2002 can’t be made.”

——————

 However, I’m still very open-minded about just how cold it really was in 80N+ late May-early Aug relative to 1958-2025, especially 2002+, pending continued research of other knowledgeable people’s opinions. Look how cold June 2026 was N of 80N per actual ERA5 reanalysis:

1. only ~1/7 is in warmest 1/2 of years vs ~6/7 in coldest 1/2

2. a little >50% is in 4 coldest colors meaning coldest 11 of 87 while only ~6% is in warmest 11, which is <1/8 the size of coldest 11

3. ~25% is in coldest 3 of 8 while only ~1% is in warmest 3 of 87, which is a mere 1/25 of the size of coldest 3

This 80N+ close-up came from this image below: only the relatively small area (~1/7 of 80N+) of light green, beige, yellow, orange, and reds is warmer than the median while >50% (4 coldest colors or coldest 11 of 87) is 87%+ percentile cold!

 So, does this cold of an ERA5 reanalysis (in image above) actually support this cold of a DMI 80N+ June ‘26 (in image below)? Food for thought at least. Keep in mind that it says this at the DMI site, itself:

“The 'plus 80 North mean temperature' graphs can be used for comparing one year to an other.”

34 minutes ago, LakePaste25 said:

Classic CAD. In theory it should be more likely in El Niño due to less SE ridging.  

32 minutes ago, Typhoon Tip said:

Likely related ...

... for one, although the sample size is not appreciably large ( on the order of 10 or 12 spanning 200 years ), of those warm ENSO, something like 9 or 10 had these autumn hybrid like circulations.   Not meaning to say that is what's going on down there at this time, but... you know, if you're going to hybridize a gyre in that region, you wanna start with something like the theme we are in fact seeing so far ( the unusual end September coastal event that was over publicized (snark) being a fair example).  Some guidance couldn't resist and bored that thing down to almost 970 mb..  as it were ... it was just a pedestrian. But still very really and albeit asynchronous low - one which happens to fit the total idea. 

We are still in the correlation window so this weakness/tendency for another low there ... it's suggestive enough.

It's important to note however, El Ninos do not directly cause storm or no storm formation. 

 Thanks.
 So, since this pattern of this offshore low and associated cooler air in the E US is likely indirectly related to the very strong Nino, is this possibly a sign of things to come this winter?

1 hour ago, Typhoon Tip said:

I'm noticing that we are being sort of "cheated" from realizing a stunningly warm October along 80W over the continent, due to "pinch low" phenomenon and/or sneaky llv cool inserts, despite the fact that a truer polar branch of the westerlies (jet) has been situating N-W.  Technically a -PNAP baseline. It just one with limited warm benefits, because anticorrelary/anomalies are taking place within the more typical ridge region of the -PNAP...  Thus masking the former warmer signals to some degree.

The present extended out look has positive anomalies in the 500 mb non-hydrostatic heights ~ 70 % of the time over the eastern mid latitude continent.  This has been going on for awhile actually. In fact, we are like that now... yet have pervasive frost/freeze headlines throughout the OV and it's 25 to 30 F this morning throughout NE.  We've seen temperatures 80/60 with these heights in November before!   it's really interesting, this masking aspect.   

 Is the offshore E US strong low bringing down the cool air into the E US this entire week likely related to the very strong Nino?

0Z 10/12 GEFS forecast for 6Z 10/21: no offshore storm and thus no cool air pinned in E US:

0Z 10/18 GEFS forecast for 6Z 10/21: much cooler E US in reality associated with offshore strong storm working in tandem with 3 Canadian highs keeping cool dry Canadian air pinned in E US:

Cool air this week E US thanks to the above pattern consistent with Euro Weeklies’ significantly cooler change: (had been warm on runs from Oct 12-13 when no offshore storm)

^Further to the above: illustrates the E US cooling power of the offshore storm this week!

1. Temps:
Euro Weeklies 10/12 run for 10/19-25: warm E US because there was no offshore storm on model yet


10/18 run for 10/19-25 is much cooler E due to strong offshore storm: thank you storm! 

——————-

2. Precip for 10/19-25:
10/12 run: no offshore storm


10/18 run: strong offshore storm keeping it cool in E US!

The non-tropical low now forming gas gone orange:


Tropical Weather Outlook
NWS National Hurricane Center Miami FL
800 PM EDT Sun Oct 18 2026

1. Off the East Coast of the United States:
A storm-force non-tropical low pressure area is developing along a 
frontal boundary tonight off the southeast coast of the United 
States. This low is likely to move slowly and erratically over the 
next couple of days while it initially remains non-tropical. Later 
this week, if the system stays over the Gulf Stream, environmental 
conditions could become more conducive for the low to develop some 
subtropical characteristics. A subtropical cyclone could form over 
the second half of this week as the system begins moving generally 
northeastward, offshore of the eastern United States. Regardless of 
development, this system will cause high winds, coastal flooding, 
and dangerous surf along portions of the U.S. East Coast. Please 
consult statements and warnings from local National Weather Service 
offices and the Weather Prediction Center for more information, 
along with High Seas Forecasts and Storm Warnings issued by the 
National Weather Service.
* Formation chance through 48 hours...low...near 0 percent.
* Formation chance through 7 days...medium...40 percent.

4 hours ago, 40/70 Benchmark said:

This tied into what I have been arguing....there are going to continue to be other competing forces dictating the weather in the mid latitudes....in addition to some competing convection in the central ENSO zones, there is another high latitude teleconnection at play that is tied to the Kuroshio current.

 Thanks. Do you know whether or not it’s normal for +AAM to be prevalent within 30-50N at any point during a strong El Niño? Or does it tend to stick closer to the equator? Have you seen any actual data?
 
 The only other El Niño for which I can see latitude based relative AAM from this site’s data is 23-4 because it only goes back to 2022. Reviewing 23-4, the 30S to 30N region had the main +AAM only during Dec 1st-Jan 15th and it never exceeded +3 SD for any latitude. That paled in comparison to Sept 14th-Oct 3rd of ‘26, when it exceeded +4 SD in portions of 15S to 15N!

On 9/22/2026 at 9:17 AM, 40/70 Benchmark said:

I get that it's fluid, as is everything.....but it's been a consistent theme.

Here is the graphic from a month ago:

 

The graphics are tools, not substitutes for critical thinking. We have a developing record El Nino abutting a decade of cool ENSO residue throughout the N HEM....this resistance makes sense, and is not the product of some short-term perturbation. Although it is true that forcing and gradients are comparatively weak in the summer relative to the cold season, there is no disputing that summer 2026 has diverged from the intense El Niño composite, which validates the disconnect between the tropical and mid latitude AAM data. The theme of this summer has been ridging and much above normal temperatures throughout much of the CONUS.

 

This is in stark contrast to the summer pattern preceding other intense El Niño events, which featured a prevailing trough and much cooler temps across much of the CONUS.

 

 

Ray et al,

A similar theme to what Ray emphasized last month remains even nearly a month later where the really impressive +AAM emphasis is mainly 30S to 30N:

 Is it normal during El Nino for the +AAM (atmosphere rotating faster than the solid earth as I understand it), which we know is characterized as El Niñoish, to usually be strongest mainly in the 30S to 30N latitudes (with the highest near the equator) since that is nearer to the Nino regions than latitudes outside of that region? If so, do the regions outside of 30S to 30N normally get consistently positive during strong El Niños? Do they ever consistently average +AAM for long periods or is that typically relegated to 30S to 30N even during the subsequent N hem. winter?

———————— 
By the way, the relative AAM by lat. above is not surprisingly still supporting a very strong global relative mean +AAM with it back >+3 since Oct 12th:

18 minutes ago, WinstonSalemArlington said:

The end of the growing season 

 

 The many upcoming chilly nights throughout the SE that have started will accelerate the autumn leaf changes everywhere, even where it’s too warm for frost.

 Is anyone seeing significant colors yet? I expect higher elevations almost certainly are, but what about those at 1,000 feet or lower? Here, the deciduous trees are almost all still green. By the end of the week, however, I wouldn’t be surprised to see a few starting to change even this far SE near sea level.

 About as beautiful and comfortable a full late Oct week as is possible for outdoor activities is in the cards this week for a large portion of the SE away from coastal NC with lots of sunshine, high temps in the 60s-70s, mainly 15 mph or lower winds after today, and dewpoints down in the 30s-40s. We can thank persistent mainly N to NE winds resulting from three sprawling areas of Canadian high pressure centered to our NE, helped by persistent low pressure offshore the E coast especially the first half of this week. Enjoy it while you can, especially with the amount of rainfall expected Nov-March due to the very strong Nino.

4 minutes ago, snowman19 said:

 

Thanks, Adam. I’m certainly not worried about a persistent SE ridge this winter!