GaWx

Today’s Euro Weeklies for Dec 1-21 are still showing consistent strong cold largely avoiding the E and especially SE due to a neutral PNA to -PNA not driving the coldest anomalies far into the SE. The Midwest to N Rockies are where the coldest anomalies remain concentrated.

AAM is still looking to go back to a solid negative next week and last for 2 weeks. However, afterward, this is showing a move back up closer to neutral for early Dec fwiw:

Natgas is up a whopping 5% due to increased late Nov-Dec cold potential.

The Earth’s average CO2 level was 333 during the very cold winter of 1976-7. That’s pretty impressive considering that it had risen from 285 in 1850. I’m assuming that the increase in sulfates was probably a big reason. To compare, it is now all of the way up to ~431!

This map gives a good perspective that shows the record cold was widespread from the mid-south to the SE US and with a few in the lower Midwest and also in TX although, indeed, none in the NE US:

Followup to the above based on lowest hourlies through 7AM (I’ll update this if any official lows turn out to be lower):These appear to be the lows along with the model that was closest out of the 11/7 6Z GFS/ICON/Euro runs and 11/7 0Z UKMET/CMC runs:SAV: 28/ICONNE ATL: 28/EuroGSP: 23/ICONCAE: 29/ICONCLT: 29/CMCRDU: 30/ICON, Euro, GFS tied-Avg of these: 27.8, which is significantly colder than my guess of 30.5 and lead me to be dead wrong with my prediction of ICON to be the furthest away!-So, although the CMC was closest to only 1 of the 6, it’s average of 28.5 followed by ICON’s 26.3 were closest to the 27.8 actual-UKMET’s 32.6 was easily the furthest-So, ICON, alone, was closest to 3 of the 6So, ICON and CMC did the best overall due to being the coldest while UKMET was the worst due to being the warmest

@donsutherland1put together and posted this excellent table in the SE thread that says a lot about how historic this cold is in the Deep South:

Thanks, Don! To add to this, today’s 28 F at KSAV (SAV airport) was colder than 78% of the coldest official Savannah lows for the ENTIRE November (records back to 1874)! The last time it was colder during the entire November was 2014. Even Hunter AAF base, which is ~6 miles to the SE (closer to the ocean), was able to have a low of 29! So, the ability of this windy freeze (as opposed to it being a radiational freeze) getting the cold all of the way to the coast was quite evident! Also, the official Jacksonville, FL, station (more inland airport) got down to 28! Closer to town lows were 30-32. It looks like various stations in Gainesville, FL, got down to 30-34. The official Gainesville (airport) got down at least to 32. I’m guessing its official low will end up at 31.

My city’s official low (KSAV) as of 7AM EST was way down to 28 F, which beats the 31 record low for the day (records back to 1874). Not only that but also: -last time it was this cold or colder this early in season was 1976 -colder than 78% of coldest for ENTIRE November -last time it was colder in entire November was 2014

This Euro Weeklies run verbatim looks to me like it may be closer to a neutral PNA than a -PNA for the avg of the 3 weeks and especially weeks 1-2 as 3 does look like it may be more -PNA (along with a -EPO, -NAO, and -AO): (not favoring the SE for intense cold and favoring the Midwest over the NE) Dec 1-7: Dec 8-14: Dec 15-21:

You can add Wilmington, NC to that record earliest snow. Their previous record earliest was also 11/12/2013.

The wind here has been crazy high. It was enough to blow over my trash bin on its side, which I don’t recall ever happening before!

WCS accidentally left out the SSWE of 11/30/1958 unless they don’t think 1958 counts as modern: https://www.researchgate.net/figure/The-SSW-and-SFW-event-onset-date-year-and-type-identified-in-the-NCEP-NCAR-dataset-The_tbl1_267063738

That -1.2 is the RONI daily equivalent value, not trimonth, and that seems legit. OTOH, the last released trimonth RONI was -0.78.

My niece in Emory area (NE Atlanta) reported snow flurries just before 5:15PM. She was so excited! Edit: Also two friends in different parts of Cobb County (NW of Atlantic) saw snow flurries/showers this afternoon…one said they lasted a couple of hours with it coming down “pretty good” for a few minutes

Euro Weeklies: coldest run yet for 1st 3 weeks in Dec for US overall. The maps don’t even have a speck of warmer than normal in the entire Conus except for S TX and S/C FL. Dec 1-7: Dec 8-14: Dec 15-21:

What has been the approximate range of total snowfall for Chicago, itself, so far? I know there’s a last gasp now near the shoreline.

ONI: -0.45 NDJ 2024 26.09 -0.53 DJF 2025 26.05 -0.59 JFM 2025 26.49 -0.38 FMA 2025 27.11 -0.18 MAM 2025 27.60 -0.09 AMJ 2025 27.72 -0.11 MJJ 2025 27.54 -0.11 JJA 2025 27.11 -0.19 JAS 2025 26.63 -0.32 ASO 2025 26.31 -0.45 ———— RONI: -0.78 NDJ 2024 -1.07 DJF 2025 -1.12 JFM 2025 -0.90 FMA 2025 -0.67 MAM 2025 -0.52 AMJ 2025 -0.49 MJJ 2025 -0.43 JJA 2025 -0.47 JAS 2025 -0.63 ASO 2025 -0.78 ———— So, RONI less ONI -0.33 RONI less ONI: NDJ -0.54 DJF -0.53 JFM -0.52 FMA -0.49 MAM -0.43 AMJ -0.38 MJJ -0.32 JJA -0.28 JAS -0.31 ASO -0.33 So, after slowly falling NDJ through JJA, RONI less ONI has bounced back some. ONI link: https://www.cpc.ncep.noaa.gov/data/indices/oni.ascii.txt

Just out from LOT (11:37 PM): THE INITIAL PUSH OF SNOW THAT DROPPED VIS DOWN TO 3/4SM AT CHICAGO TERMINALS IS PUSHING SOUTHWESTWARD TOWARD KPIA. HOWEVER, THE NEXT BAND OF SNOW IS RIGHT ALONG THE LAKE SHORELINE AT THE TIME THIS DISCUSSION WAS PUBLISHED. CURRENTLY CONDITIONS AT CHICAGO TERMINALS ARE VFR, BUT WITH THE NEXT BAND ABOUT TO MOVE ONSHORE, THE TAFS WERE SENT WITH WORSE CONDITIONS DUE TO THE EXPECTATIONS THAT THINGS WILL DETERIORATE QUICKLY AFTER 06Z. THIS BAND WILL BE HAVE MORE VIGOROUS SNOW RATES AND STRONG GUSTY WINDS. LOW VIS IS EXPECTED, BUT MAY EXCEED EXPECTATIONS AND BECOME SUB-1/4SM. ADDITIONALLY, BUOYS HAVE ALREADY REPORTED GUSTS TO 31 KNOTS, AND WHILE 35 KNOTS IS IN THE TAF, IT IS ENTIRELY POSSIBLE THAT GUSTS TOUCH 40 KNOTS AT TIMES. IT IS POSSIBLE THE THE TEMPO FROM 06Z TO 09Z IS A HAIR LONG, BUT HAVE MODERATE CONFIDENCE THAT THERE COULD BE 3 HOURS OF REALLY INTENSE SNOW RATES. LOOKING AT REGIONAL RADAR, THERE IS A LONG LAKE ORIENTED BAND OFF THE WISCONSIN SHORELINE MOVING SOUTHWARD. THIS BAND WILL BE "ROUND 2" AS IT MOVES INTO ILLINOIS. THERE WILL THE EXPECTATION IS THAT THERE WILL PROBABLY SOME TIME OF "BREAK" IN THE INTENSE SNOW BEFORE IT MOVES SOUTHWARD (LONGER AT KMDW AND KGYY). CAN'T RULE OUT SOME QUICK VFR CONDITIONS, BUT FELT MORE PRUDENT TO LEAVE IFR/MVFR CONDITIONS FOR ONGOING SNOWFALL. NEVERTHELESS, A SECOND ROUND OF INTENSE LAKE EFFECT SNOW IS EXPECTED BEFORE DAYBREAK.

Fascinating very detailed update just a few minutes ago from Chi NWSFO explaining how difficult this forecast is:UPDATE ISSUED AT 944 PM CST SUN NOV 9 2025 HAVE EXPANDED THE WINTER WEATHER ADVISORY TO INCLUDE FORD AND BENTON COUNTIES, OTHERWISE NO CHANGES TO THE MANY, MANY HEADLINES IN EFFECT. ALSO, NO BIG CHANGES TO THE FORECAST GRIDS THIS EVENING. CONVECTIVE ALLOWING MODELS (CAMS) OFTEN STRUGGLE WITH THE EXACT DETAILS OF LAKE EFFECT SNOW, MUCH LIKE THEY DO WITH SPECIFICS OF SUMMERTIME CONVECTION. THIS WAS THE CASE THIS EVENING WITH THE MOVEMENT AND TIMING OF THE LAKE INDUCED/ENHANCED MESO-LOW, WHICH MOVED INLAND INTO NORTHERN IN HOURS EARLIER THAN MOST CAM GUIDANCE HAD BEEN INDICATING. THE FASTER AND FARTHER EAST TRACK OF THIS MESOLOW HAS RESULTED IN CAMS BEING WRONG IN THEIR DEPICTION OF A LARGE INITIAL WESTWARD SURGING LAKE EFFECT SNOW PLUME WELL INLAND INTO NORTHEASTERN IL LATE THIS EVENING. RATHER, THIS MESOLOW HAS BECOME NEARLY STATIONARY OVER NORTH CENTRAL INDIANA WITH A COHERENT, INTENSE SINGLE BAND OF LAKE EFFECT SNOW EXTENDING NORTHWEST THEN NORTH UP THE SPINE OF THE LAKE FROM THIS MESOLOW. SURFACE OBSERVATIONS DEPICT A SHARP SURFACE TROUGH EXTENDING NORTHWEST FROM THE MESOLOW ACROSS SOUTHERN LAKE MICHIGAN. THIS TROUGH AXIS HAS BEEN STEADILY MOVING SOUTHWARD DOWN THE LAKE, WITH THE STRONG LOW LEVEL NORTHEASTERLY FLOW IN THE WAKE OF THIS TROUGH HELPING PUSH THE LAKE EFFECT PLUME STEADILY WESTWARD. AS THIS TROUGH CONTINUES TO PUSH SOUTH OF THE LAKE, ANTICIPATE THAT WESTWARD PROGRESSION OF THE LAKE PLUME SHOULD PUSH IT INTO NORTHEAST IL BETWEEN 11 PM AND MIDNIGHT. CONFIDENCE IS LOW IN HOW FAR WEST THIS PLUME WILL GET INTO NE IL BEFORE BECOMING QUASI-STATIONARY FOR A TIME, THEN LIKELY SHIFTING BACK EASTWARD TOWARD AND ACROSS NORTHWEST IN MONDAY. REALLY NOT PUTTING A TON OF STOCK IN CAM GUIDANCE AT THIS POINT, SO ONCOMING MIDNIGHT SHIFT WILL BE NOWCASTING THIS BAND THROUGH THE NIGHT BASED ON OBSERVATIONAL TRENDS. NO CHANGE TO THE MAGNITUDE OF INSTABILITY, WHICH IS CONFIRMED BY A SPECIAL 0030Z VALPARAISO UNIVERSITY SOUNDING FROM THIS EVENING. STILL ANTICIPATE SNOWFALL RATES OF AT LEAST 2-3 INCHES PER HOUR WITHIN THE HEAVIEST ELEMENTS OF THIS BAND. DEPENDING ON HOW LONG THE BAND BECOMES QUASI-STATIONARY, IT IS CERTAINLY POSSIBLE THAT WE COULD SEE ISOLATED TOTALS PUSHING OR EVEN EXCEEDING A FOOT BEFORE THE BAND BEGINS SHIFTING EASTWARD. CURRENT TRENDS WOULD SEEM TO SUGGEST THAT LAKE OR COOK COUNTY IL COULD BE THAT WESTWARD TERMINUS THAT SEES SOME OF THE HEAVIER TOTALS. WHERE EVER THE BAND IS DURING RUSH HOUR TOMORROW MORNING, TRAVEL CONDITIONS WILL BE VERY DIFFICULT TO NEARLY IMPOSSIBLE. - IZZI

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!