GaWx

Any opinions about this, which suggests Greenland blocking throughout this winter? @bluewave@snowman19

The official Chicago records have been at O’Hare since 1980 and were at Midway 1942-79. Prior to that they were even closer to the lake. Keeping this in mind: the official Chicago record heaviest Nov snowfall for a single storm is 12.0” (11/25-6 of 1895). That was from a strong low (rather than pure Lake Effect) that moved from N Miss to E of MI per old wx maps. Like @donsutherland1said, it’s highly unlikely this will even be close to 12” officially. (I saw that he mentioned that 4”+ is reachable though).THE FOLLOWING IS THE UPDATED LIST OF THE LARGEST SNOW EVENTSDURING THE MONTH OF NOVEMBER FOR CHICAGO DURING THE PERIOD OFRECORD...WHICH IS SINCE 1884:RANK DATES EVENT SNOWFALL /IN/-----------------------------------------1. NOV 25-26 1895 12.02. NOV 20-21 2015 11.23. NOV 6-7 1951 9.34. NOV 26-27 1975 8.6 5. NOV 27-28 1891 6.0RANK MONTH MONTHLY SNOWFALL /IN/-----------------------------------------1. NOV 1940 14.82. NOV 1895 14.53. NOV 1951 14.34. NOV 2015* 11.25. NOV 1975 10.8 https://www.weather.gov/lot/earliestnovsnows

Thanks, Chris. It still was a 6 day long phase 8 last January (Jan 7-12) that peaked at a decent amplitude of 2.1. I consider that near an average length phase 8 in January rather than brief. Phase 8’s 6 days was as long or longer than any other phase last January as it went around to phase 4. Granted, the average amplitude of the 6 days in phase 8 wasn’t nearly as high as that of phases 1-4, which were closer to 2 and thus not as pronounced an amplitude as those as you said, but it still averaged ~1.3, a moderate phase 8. I consider weak to be <1, moderate 1-2, and strong 2+. So, I have it as an avg length near avg amplitude phase 8 during last Jan. I have phases 1-3 of last Jan at higher than average amp and fairly close to an avg length overall. Phase 4’s amp was closer to avg. *Edited last 2 sentences

It wasn’t Dec. of ‘24. Yeah, you must be thinking of another year, perhaps ‘23 as you suggested though ‘23 actually had a pretty strong 1 and 2 Dec 23-31 (maybe models were too strong in 8 though). Here’s ‘23: For Dec of ‘24, they correctly predicted 4-5-6-7 (they didn’t predict 8-1-2), but they tended to not be strong enough in 4-5:

The current and recent KCHS NWS forecasts for KSAV have been for 30 on 11/11 in a windy freeze. If that were to verify, it would be the earliest 30 or colder since way back in 1976! However, latest and recent model consensus is suggesting that 30 is on the low end (Icon). ICON actually warmed some from 27s on Sat runs. Latest ICON/GFS/CMC/Euro/UKMET (through 6Z/0Z 11/9 runs) have 30/32/33/33/34. If this were a radiational cooling night, I’d likely favor the low end per slight warm bias of consensus. But with it being windy, I’m currently thinking near the model avg of 32. However, if the model consensus were to cool, I’d adjust colder. Even just getting to 32 would mean the earliest freeze since 2010!

Snowman, Please clarify when you say models were showing an amplified 8-1-2 MJO last Dec: -What were the approximate dates of model runs you are referring to? And which models? -For around what dates are you saying these runs projected an amplified 8-1-2? (Aside: I generally concentrate on following only the GEFS/EPS and even they aren’t reliable. I describe them as the least unreliable with GEFS being better than EPS, especially Maritime/W Pac. Lately they’ve been too fast in their progs through phase 6 into 7 and with EPS not having enough amplitude, a common problem of it in those regions.)

Indeed, Don! The current and recent KCHS NWS forecasts for KSAV have been for 30 on 11/11 in a windy freeze. If that were to verify, it would be the earliest 30 or colder since way back in 1976! However, latest and recent model consensus is suggesting that 30 is on the low end (Icon). ICON actually warmed some from 27s on Sat runs. Latest ICON/GFS/CMC/Euro/UKMET (as of 6Z/0Z 11/9 runs) have 30/32/33/33/34. If this were a radiational cooling night, I’d likely favor the low end per slight warm bias of consensus. But with it being windy, I’m currently thinking near the model avg of 32. However, if the model consensus were to cool, I’d adjust colder.

And also the real “Rain Cold” as he is also known. Based on ensemble 2 week progs, the -NAO for Nov overall is quite possibly (or even probably) going to end up the strongest in Nov since 2010. 2000 is a Nov strong -NAO, late Nov weak SPV, and active sunspots analog. If the MJO were to keep going and get into 7/8/1/2/3 in Dec, that would also be like 2000.

Also on 2000’s side is that it had a very weak SPV in late Nov (though not a reversal) and active sunspots. If the MJO were to keep going and get into 7/8/1/2/3 in Dec, that would also be like 2000.

Today’s Euro 10 mb got slightly weaker and I’d call it 2nd best only barely behind 3 days ago (depends on criteria): once again it’s showing a real threat of earliest SSWE since 1968! 3 days ago 1 year ago: near avg/much stronger than ‘25:

Per model consensus progs: -Nov ‘25 is likely headed toward a strong -NAO Niña Nov like that of 2010, 2000, 1995, 1983, 1973, 1955, and 1950. -Of those: all but 1973 had BN temp. in Dec at NYC with 4 of 7 having a MB Dec including the 1st 3 on the list. Though on avg for all winters Feb has been 3 F colder than Dec, the Febs for these 7 averaged 2.4 F warmer than the Decs. -Of these: 2010, 1973, and 1955 also had a -NAO Oct like 2025. -Of those, 1995 had a similar Nov MJO. -Of those: 2010, 1995, and 1955 had a sub -0.25 NAO winter. All 3 of those had a very cold Dec. But of those 3, only 1955 had active sunspots fwiw. https://www.cpc.ncep.noaa.gov/products/precip/CWlink/pna/norm.nao.monthly.b5001.current.ascii.table

Here’s today’s GEFS MJO forecast: EPS: ——————- Here are the 4 closest Niña Nov MJO analogs: 2007: 1998: 1995: 1985: —————— Now here are the 4 honorable mentions: 2022: 2008: 1989: 1983: @snowman19

Similar to yesterday meaning Wednesday’s run (mean dipped to only +7) remains the weakest: Wed. run:

I don’t think this is true. Now if they had a cold bias, that would be true.

I of course don’t post every day’s runs. But because I posted yesterday’s significantly colder week 4, I felt obligated to post today’s significantly warmer week 4 so as to not appear one-sided. Chuck’s guess that that was a top 15 percentile jump is as reasonable an educated guess as any. So, it was a “pretty big jump” as he said though nothing at all extreme, especially considering that’s still out at week 4. Consider how much colder it got for early next week on all models since that was during only week 2! So, considering all of this and the inherent unpredictability out a month, sig. jumps that far out on any long range ensemble are pretty common and shouldn’t ever be surprising.