GaWx

Speaking of Conus troughs: After having a few chilly runs in late Oct in the E US for the period around Veteran’s Day and then backing off to mild, the model consensus since Nov 1st has gotten much colder for then with the last few runs being the coldest yet! Check out this EPS progression for 0Z on Nov 9th from the 0Z 10/30 run through the 0Z 11/3 run: check out the big rise in Greenland heights along with the increased +PNA intensity: this shows that models out 10 days were clueless!

After having a few chilly runs in late Oct for the period around Veteran’s Day and then backing off to mild, the model consensus since Nov 1st has gotten much colder for then with the last few runs being the coldest yet!

Yes. So, even if there’s no more ACE, 2025 will end above the 1991-2020 average of 122.

Sep 17th through Nov 3rd highest ACE back to 1851 based on tracks on record and my ACE calculations/estimates: 1878: ~105-110 1894: ~100-110 2025: 94 1893: ~89 2017: 88 2024: 86 2016: 85 2005: 85 So, 2025 had the highest Sept 17th-Nov 3rd ACE since 1895 and the 3rd highest on record! Sept 17th-Nov 3rd ACE 2025-2010: 2025: 94 2024: 86 2023: 42 2022: 58 2021: 64 2020: 70 2019: 58 2018: 45 2017: 88 2016: 85 2015: 32 2014: 36 2013: 7 2012: 44 2011: 45 2010: 51 ————— Edit: As we move forward through the rest of the season and look at Sept. 17th+ ACE, these seasons would overtake 2025 if it has no more ACE: 1932, 2005, 2020, and 2024 with 1893, 1896, and 1961 coming very close.

New BoM RONI prog (I love that they prog RONI these days!) is slightly cooler than last week’s prog with NDJ low at -0.9 vs last week’s -0.8, possibly being aided by current very strong -IOD. Last week’s RONI progged low: -0.8 (NDJ)

Oct 30 mb QBO came in at -24.65 vs Sept’s -24.26: https://psl.noaa.gov/data/correlation/qbo.data

My lowest so far is ~lower 40s.

This has the ens 10 mb mean zonal wind as low as only +14 to +15 in late Nov (prior runs’ lowest were +18) and is at least tied for the highest % of members of any run so far this season with a very early season major SSW (reversal) at 25%+.

This is just one place that flooded from extreme rains coming off the nearby ridges, the well inland Mandeville to the E of Santa Cruz (which also flooded) and 20 miles E of the worst devastation from surge and winds:

Unfortunately you were right about Jamaica as it’s now up to 28 and probably still climbing as they find more bodies:

New CFS forecast for Indian Ocean Nov: still -IOD (W IO less E IO) Dec: rising quickly toward neutral, which would be consistent with climo since -IOD typically is already peaking or has already peaked @snowman19

Hey Mitch, I’d love to see it! But a huge grain of salt is advised. One year ago the CANSIPS was forecasting a Modoki Nino for now, about which I posted last year and got excited. Obviously, that failed miserably and I’ve learned from it. One year ago, CANSIPS forecasted this for Oct of 2025: Compare that to the new CANSIPS for Oct of 2026: the entire globe looks so similar that it almost looks like a copy and paste although it’s slightly warmer in Nino regions. Hopefully this new CANSIPS for next Oct won’t also verify way off! @Carvers Gap@donsutherland1@Daniel Boone

Here’s a WxBell CFS control Jan map (originally posted today by an unknown person, who added his own comments) that was reposted today at another BB by someone who got this in his FB feed (i.e., this is NOT a WxBell post..it is someone else posting a WxBell map with his own commentary): Here was my response: This is a control run (18Z of yesterday) of the WxBell CFS being forecasted out 2 months. Even calling this map less than worthless is being kind. Keep in mind that these are in C, not F. So, it gives the majority of the middle 1/3 of the US a record obliterating cold Jan. To show how silly this run is, it has Chicago at an obliterating alltime record breaking cold Jan of 14C/25F BN, which is -1F! The coldest Jan (and any month for that matter) on record back to 1873 is +10.1F (1977). So, this CFS control run is forecasting Chicago to have a Jan that is 11F colder than any month they’ve had during the last 153 years! Now here’s the very next CFS control run, the 0Z 11/2 run: Instead of mid-America having a record obliterating cold Jan, it has much warmer than normal in much of the same area! It has Chicago only 3 F AN because the WxBell CFS maps always show a funky cold spot centered on Lake Michigan (funky WxBell CFS algos is another issue for another time that I’ve posted about before). So, it has Chicago at an AN +27F vs -1F on the prior run or 28F warmer lmao! @donsutherland1

Thanks, Chris. I forgot that your analysis of Dec NYC area snow is just for La Niña winters.

Since this 10/28/25 post, I got another 0.05” to give me a total of 2.80” of rainfall in October. That’s only modestly below normal. This area ended up 2F BN, coolest Oct since 2022 and second coolest Oct since 2011.

We’ll see. Latest MJO forecasts: 1. GEFS, which has been doing much better than EPS as is often the case in this part of the diagram (10/20-3 GEFS runs had today in moderate 5/6 while EPS was a fail with inside circle): slowly headed to strong 6 in direction of strong 7 2. EPS: headed to moderate 7:

One year ago today the daily WCS PDO was ~-2.25. On 10/31/25, it was -1.29:

Credit to Chris and Don for bringing this strong correlation to the board’s attention: Whether Dec snow at NYC is 3”+ has been a good indicator of how Jan+ has done since 1980-1: -a whopping 23 of 28 (82%) Dec’s with <3” had <22” Jan+ -but only 4 of 17 (24%) Dec’s with 3”+ had <22” Jan+ So, watch Dec NYC snow closely! Correlation didn’t work before 1980. Anyone know why? @donsutherland1@bluewave

Thanks. I had just seen that at https://cyclonicwx.com/climatology/ But that looks suspiciously too high as NHC has only 34.7: https://www.nhc.noaa.gov/data/tcr/index.php?season=2025&basin=atl

Followup: This was the 11/30/24 CANSIPS fcast for last winter, similar in much of the N Hem including even colder/coldest 1981-2010 anomalies in N Hem again centered over W Lakes: What verified? It did well in most of the Conus but winter verified to be NN vs 81-00 in W Lakes/upper MW. The coldest was to the W in W Dakotas/SE MT, where Cansips was much too warm. So, is it possible that the CANSIPS has a cold bias in the W Great Lakes? @donsutherland1@mitchnick@SnowGoose69 *Edit: corrected for 2 typos

The new CANSIPS for DJF is the 9th in a row with the coldest winter anomalies (vs colder 1981-2010 than 1991-2020) in the N Hem centered over the W. Great Lakes: Any thoughts?

Here are before and after SSTs to see how much Melissa cooled the ocean on and near its track: 10/24/25: 10/30/25: So, it cooled only ~1C/2F around Jamaica/E Cuba (from slightly over 30C to near or slightly over 29C). Unfortunately, that wasn’t nearly enough to keep Melissa from exploding. Much of the area around the Bahamas also cooled some (perhaps ~0.5C/1F) but the full cooling may have to wait til the 10/31 SST map. Also, Melissa wasn’t as strong and was moving much more quickly through the Bahamas thus likely meaning less cooling influence. In contrast, note that most of the Gulf and far W Caribbean cooled hardly at all, if any, as they were too far west to be cooled by Melissa.

Thank you, snowman. Y’all may find this interesting. Eric Webb just posted this at another BB after I asked him the same Q: There's lots of co-variability between ENSO and the IOD, and there's a positive correlation between ENSO & IOD intensity. Oth, when you try to isolate the influence of the IOD alone here in the context of weak to moderate La Ninas, this is what happens: The Nov-Dec 500mb & SLP difference composite of +IOD & -IOD years with weak to moderate La Niña captures some of the things we're currently seeing like the very extended Pacific Jet/+EPO, +PNA, and even perhaps the -SAM/-AAO. The NAO is completely different this year though. Then he posted this: This is what happens if you take that difference composite through the winter. The big takeaway I glean from this is the transition from an early winter +PNA type pattern to a canonical Nina look w/ a +NAM/AO is much sharper in these winters with a bigger -IOD in the preceding fall. Also, the classic Seasonal Footprinting Mechanism (SFM) pattern is more prominent in Feb-Mar in the -IOD years, which would hasten the development of +PMM in the spring and be more favorable for El Niño development later next year. ———— So, Webb and you may be in agreement at least to an extent.

Very strange! When you go to https://www.americanwx.com/bb/ do you see what the first screenshot I posted shows with “General Forecasting and Discussion” showing and not “Weather Forecasting and Discussion”?

What are you saying this very strong Oct -IOD is going to cause in December in the E US? What’s your prediction?