Roger Smith

Don, where does 2025-26 sit now in your winter severity index?

Temperatures briefly moderated in southwestern Manitoba, s SK and North Dakota, generally a little above freezing today, back into the deep freeze up there tonight. The milder air is making limited inroads into nw Ontario and Winnipeg region has warmed only into the mid-20s (F).

(version 2, Dec 2025 scores _ max 60 scoring adjustments) <<< Max 60 applied to IAH, DEN, PHX scores only >>> For contest integrity, eleven regular forecasters are scored 0 to 60 with 11 intervals ... levels can be boosted by as much as 4 to reduce steps to closest approximation to raw score differentials. Mercurial, Normal, Consensus and Persistence scores are then calculated from comparison to the regular-contestant-generated scores. Scores altered by max-60 calculations have this symbol ^ ... scores without the symbol were either higher raw scores or zero scores unchanged. Most IAH scores are not boosted as raw scores were higher than the progression. This could change if IAH anomaly is higher than my projected +4.0F. FORECASTER _____________ DCA_NYC_BOS _ east _ ORD_ATL_IAH _ cent _ c/e_ DEN_PHX_SEA_west_TOT Mercurial ______________________ 00 _ 00 _ 00 _000 _ 30 _ 80_ 66^_ 176 _176_ 05^_ 00 _ 00 _005__ 181 hudsonvalley21 ________________ 00 _ 00 _ 00 _000 _ 52 _ 96_ 50 _ 198 _198_ 16^_ 46^_ 24 _086__ 284 Scotty Lightning _______________ 00 _ 00 _ 00 _000 _ 40 _ 80_ 40_ 160 _160_ 34^_ 22^_ 40 _096__ 256 ____ Normal ____________________00 _ 00 _ 00 _000 _ 20 _ 70_ 20 _ 110 _110__ 16^_ 06^_ 30 _052__ 162 wxallannj ______________________ 20 _ 22 _ 26 _068 _ 34 _ 86_ 60^_180 _248 _ 60^_ 60^_ 80 _200__448 DonSutherland1 ________________20 _ 40 _ 40 _100 _ 86 _ 80_ 54^_220 _320 _ 54^_ 28^_ 32 _114 __ 434 BKViking _______________________24 _ 26 _ 34 _084 _ 54 _ 88_ 44 _186 _270 _ 52^_ 60^_ 60 _172 __ 442 ___ Consensus ________________26 _ 34 _ 36 _ 096 _76 _ 86_ 42 _204 _300_ 34^_ 40^_ 40 _114__414 so_whats_happening __________ 28 _ 26 _ 32 _084 _ 72 _ 86_ 44 _202 _286 _40^_ 52^_ 42 _134__ 420 Tom ____________________________38 _ 54 _ 56 _148 _ 98 _ 52 _ 30 _180 _ 328 _ 22^_ 40^_ 52 _114__ 442 RJay ___________________________ 40 _ 40 _ 40 _120 _ 80 _ 94_ 30 _204_ 324_ 34^_ 40^_ 40 _114__ 438 RodneyS _______________________ 72 _ 60 _ 46 _178 _ 86 _ 20_ 38 _126 _ 304 _ 52^_ 10^_ 40 _102__ 406 Roger Smith ____________________ 80 _ 76 _ 90_ 246_ 62_ 04_ 00 _066 _312 _ 00 _ 00 _ 00 _000__ 312 wxdude64 ______________________88 _ 62 _ 66 _ 216 _ 86 _ 20 _06 _112 _328_ 06^_ 16^_ 76 _098__ 426 ----------------- (highest and lowest forecasts above are color coded; all forecasts are below normal for ORD) __ Persistence ___(Nov 2025)___ 00 _ 16 _ 10 _026 _ 00 _ 60 _78^_ 138 _164_ 80^_ 80^_ 72 _232 __396

Another record that fell was Toronto (city) daily rainfall and precip record for December 28th. The daily precip record (28.7 mm) from the 1968 snowfall record of 11.3" was broken in 2025 by the 37.3 mm rainfall (1.47") that also broke the (relatively weak) 1863 rainfall record 0.52" (13.2 mm). Many other daily rainfall records are closer to the 2025 mark and it was not an all-time monthly record, that being 1.95" (5th 1870). The only other higher daily records were 1.81" (3rd, 1841) and 1.75" (9th also 1841), so it can be said that yesterday's rainfall was the fourth greatest daily amount in December, and largest in 155 years. It barely exceeded a fall of 1.46" on the previous date in 1942. (The 1841 events may have been over longer intervals than the calendar day, some 1841-42 data are listed as cumulative totals). Unlike U.S. climate records as available, Canadian daily climate records separate out rain and snow when various amounts fall as part of a daily precip total. Unfortunately since 2017 Toronto city has only reported daily precip and snow on ground so I now need to apply conversions myself to the data, but Toronto airport still has the full breakdown and I believe all or nearly all of the precip on the 28th was rain, some probably freezing rain at first. There had been a snowfall of about 5-6 inches on Boxing Day. The 1968 daily record snowfall added several more inches on the previous day and was around 14" in total. I recall the event from my own observing near Toronto and it was a sleety kind of snowstorm with some ice pellets in the mix. Today's record daily snowfall of 15.0" is from Dec 1855! The airport daily record is probably a lot lower because its data only begin in 1938. Today's daily record rainfall was 1.34" from 1940.

A century ago the phrase "silver thaw" was used to describe the conditions being reported in n NE today. I am not sure when that went out of the vocabulary but it was even inserted into official documents of weather data in the 1920s and earlier.

Lake effect blizzard conditions will develop rapidly across lower MI tonight and SW Ontario by morning. Heavy snow squalls with winds gusting to 55-60 mph will quickly make many highways impassable, unprepared drivers are going to be stranded in dangerous situations. I am not sure how much awareness has been created by public forecasts of these rapidly oncoming changes. Given the way the low is deepening and severe cold phasing into the circulation, and still fairly warm temps Lakes Michigan and Huron, potential for emergency situations is high. This will spread to parts of central ON, nwPA and wNY by late morning and upstate NY by afternoon-evening. Goderich to London ON needs a max alert as NW winds funnel mega-squall conditions directly across the London region. My guess is 401 will be closed or at least impassable from Chatham to Woodstock by 0900h.

Preliminary scoring for December 2025 (version 1, raw scores only) _ note for raw scores in anomalies greater than +5 or -5, error deductions are 1 pt per 0.1 error in range 5.0 to actual, and raw scores are no lower than 0.1 per correct-sign predicted 0.1 deg. When an anomaly exceeds 10.0, scores are then based on a proportional basis, for example, a +5.5 forecast against an +11.0 outcome scores 50 (raw). As another example, a forecast of +0.7 scores 07 if that is higher than the raw score would otherwise be. ... then a max-60 rule is invoked if no raw score is above 60. These max 60 scores are generally in equal increments from zero to 60, adjusted by fairness considerations when compared to the spread of raw scores. I have some objective rules that I try to apply to that adjustment but with contest results perhaps depending on exactly what the details will be (you can see DEN, PHX scores and possibly IAH will need adjustments), I will just give you the raw scores now and will be working out how adjustments affect the overall annual outcome. No idea in advance what that's going to look like (although I can't see potential for outcome to be changed by the max-60 adjustments) ... <<< Raw scores only >>> FORECASTER _____________ DCA_NYC_BOS _ east _ ORD_ATL_IAH _ cent _ c/e_ DEN_PHX_SEA_west_TOT Mercurial ______________________ 00 _ 00 _ 00 _000 _ 30 _ 80 _ 60_ 170 _170_ 00 _ 00 _ 00 _000__ 180 hudsonvalley21 ________________ 00 _ 00 _ 00 _000 _ 52 _ 96 _ 50_ 198 _198_ 04 _ 26 _ 24 _054__ 252 Scotty Lightning _______________ 00 _ 00 _ 00 _000 _ 40 _ 80 _ 40_ 160 _160_ 10 _ 10 _ 40 _060__ 220 ____ Normal ____________________00 _ 00 _ 00 _000 _ 20 _ 70 _ 20 _ 110 _110__ 00 _ 00 _ 30 _030__ 140 wxallannj ______________________ 20 _ 22 _ 26 _068 _ 34 _ 86 _ 54 _174 _242 _ 20 _ 34 _ 80 _134__ 376 DonSutherland1 ________________20 _ 40 _ 40 _100 _ 86 _ 80 _ 52 _218 _318 _ 14 _ 12 _ 32 _058 __ 376 BKViking _______________________24 _ 26 _ 34 _084 _ 54 _ 88 _ 44 _186 _270 _ 13 _ 34 _ 60 _107 __ 377 ___ Consensus ________________26 _ 34 _ 36 _ 096 _76 _ 86 _ 42 _204 _300_ 10 _ 20 _ 40 _070__370 so_whats_happening __________ 28 _ 26 _ 32 _084 _ 72 _ 86 _ 44 _202 _286 _ 11 _ 32 _ 42 _085__ 371 Tom ____________________________38 _ 54 _ 56 _148 _ 98 _ 52 _ 30 _180 _ 328 _ 06 _ 20 _ 52 _078__ 406 RJay ___________________________ 40 _ 40 _ 40 _120 _ 80 _ 94 _ 30 _204_ 324_ 10 _ 20 _ 40 _070__ 394 RodneyS _______________________ 72 _ 60 _ 46 _178 _ 86 _ 20 _ 38 _126 _ 304 _ 13 _ 05 _ 40 _058__ 362 Roger Smith ____________________ 80 _ 76 _ 90_ 246_ 62 _ 04 _ 00 _066 _312_ 00 _ 00 _ 00 _000__ 312 wxdude64 ______________________88 _ 62 _ 66 _ 216 _ 86 _ 20 _ 06 _112 _328_ 00 _ 08 _ 76 _084__ 412 ----------------- (highest and lowest forecasts above are color coded; all forecasts are below normal for ORD) __ Persistence ___(Nov 2025)___ 00 _ 16 _ 10 _026 _ 00 _ 60 _ 72_ 132 _158_ 57 _ 59 _ 72 _188 __346 EXTREME FORECASTS as of preliminary scoring ... DCA _ wxdude would win with lowest forecast NYC, BOS _ Roger Smith would win with lowest forecasts ORD _ currently just outside a win-loss outcome (4th lowest forecast high score) ... outcomes below -4.1 would make it a win-loss (RodneyS, wxdude64 win; Roger Smith loss) IAH, DEN, PHX, SEA _ definitely four wins for wxallannj with high forecasts, Mercurial also (as non-regular entrant for IAH). BKViking ties for PHX. ===================== <<< RAW SCORES for DEN and PHX will need converting to max-60, IAH possibly also but adjustments there would be very small anyway >>> Will adjust around end of month and merge with annual scoring ... given the lead Tom had before this month I cannot see how the raw-score to max-60 adjustments can remove enough of his differential to make much difference to what currently looks like Tom maintaining a 150-200 point advantage over nearest rivals. (actual forecasts) FORECASTER __________________ DCA _NYC _BOS __ORD _ATL _IAH ___ DEN _PHX _SEA Mercurial ______________________ +4.0 _+2.0 _+1.0 __-0.5 _+0.5 _+2.0___ -1.0 _ -3.0 _ -1.5 hudsonvalley21 ________________ +1.3 _+1.4 _+1.0 __ -1.6 _+1.7 _ +1.5 ___ +0.4 _+1.8 _-0.3 Scotty Lightning _______________ +1.0 _+1.0 _+0.5 __ -1.0 _+0.5 _+1.0 ___+1.0 _+1.0 _+0.5 ____ Normal ____________________ 0.0 __0.0 __0.0 ____ 0.0 __0.0 __0.0 ____ 0.0 __0.0 __0.0 wxallannj ______________________ -1.0 _ -1.1 __-1.3 ___ -0.7 _+0.8 _+1.7 ___+2.0 _+2.2 _+2.5 DonSutherland1 ________________-1.0 _ -2.0 _-2.0 ___ -3.3 _+2.5 _+1.6 ___+1.4 _+1.1 _ +0.1 BKViking _______________________-1.2 _ -1.3 _ -1.7 ___ -1.7 _+0.9 _+1.2 ___ +1.3 _+2.2 _+1.5 ___ Consensus ________________ -1.3 _ -1.7 _-1.8 ___ -2.8 _+0.7 _ +1.1 ___ +1.0 _+1.5 _+0.5 so_whats_happening __________ -1.4 _ -1.3 _ -1.6 ___ -2.6 _+0.8 _+1.2 ___+1.1 _ +2.1 _ +0.6 Tom ____________________________-1.9 _ -2.7 _-2.8 ___ -3.9 _-0.9 _+0.5 ___+0.6 _+1.5 _+1.1 RJay ___________________________ -2.0 _-2.0 _-2.0 ___ -3.0 _+1.2 _+0.5 ___+1.0 _+1.5 _+0.5 RodneyS _______________________ -3.6 _-3.0 _-2.3 ___ -4.7 _-2.5 _+0.9 ___+1.3 _+0.5 _+0.5 Roger Smith ____________________-4.0 _-3.8 _-4.5 __ -5.9 _ -3.3 _ -1.5 ___-3.6 _ -2.9 _ -2.4 wxdude64 ______________________-4.4 _-3.1 _-3.3 __ -4.7 _ -2.5 _ -0.7 ___-0.9 _+0.8 _+2.3 ----------------- (highest and lowest forecasts above are color coded; all forecasts are below normal for ORD) __ Persistence ___(Nov 2025)___ +0.4 _-0.8 _-0.5 __+1.1 _+3.5 _+5.4 ___+5.7 _+3.9 _+2.1 =====================

As I was told, ORD did not stay that close to -6 F above normal but they didn't get into the real core of that crazy warmth that is now about to get the boot east ... it has played havoc with my ATL and IAH estimates and DEN has stayed well above +10 just turning cold yesterday. Think the final values now look like being around -5.0 _ -5.0 _ -5.0 __ -4.0 _ +1.5 _ +4.0 ___ +10.0 _ +6.0 _ +3.5 will present some preliminary scoring on that basis, going to need to figure out max-60 mercy rule scoring for the western locations.

There was no storm 14 and barring the unforeseen the above scoring table (ignore the potential scores in brackets) will be FINAL CONTEST SCORING. Congrats to Retrobuc with the highest score 97.5 closely followed by StormchaserChuck (97) and Cardinalland (96.5). Will do it all again in 2026, deus volente.

The way this is rushing in with a spike of warming to follow, I would cut most of those ice accretion forecasts in half and the real problem is likely to be ponding followed by a rapid freeze by late afternoon. It's going to be a nasty mess in many areas by late Monday.

69F at CHW and 73F at HTS in approaching warm sector. Seems likely to peak in low and possibly mid 60s around 0900 EST in MA with squall line potential around 0900-1100h. Could be a brief TRW during fropa.

Correlating 12z GFS to current obs, will estimate peak in temps at 58 F around 10 or 11 a.m., then a steady fall into 30s to 4 p.m., with occasional gusts to 40 mph. Heaviest rain will fall around 11 a.m. and noon. There is a slight chance of a thunderstorm with the cold front. Temps in warm sector currently near 70 F (SDF is 74F) but I think the interaction of air mass with snow cover will fog up the mild air and the warmest portion will be experienced in s NJ where it may reach 65 F. That temperature of 74F at Louisville is a daily record, 70F in 2021 was their previous record. But they had 74F on the 27th in 2021 for yesterday's record. As I posted in storm thread, combined effects of snowmelt and 0.25" rainfall could be localized urban ponding by early Monday afternoon, and eventually any slush left on the ground will freeze Monday night, so Tuesday could be an icy mess in some places. Locations with 6" or more snow on ground will not lose all snow in the melt and what's left will become a frozen ground cover. (I am looking out on that kind of scene after past four days here brought this same sequence, our freeze-up began Friday night). Happy new year, hope the promising January pattern brings some meaningful winter weather.

Nuisance to moderately severe urban ponding is very likely to develop by mid-day Monday as temperatures rapidly rise into low 50s with this expected rain, in particular s CT could see near total melt of existing snow pack but any large snowbanks created by plow operations will survive (partially) and acr as dams for rapidly accumulating meltwater. Some drains will be blocked which will prolong the nuisance. This will be followed by a rapid freeze Monday night and any slushy cover will become solid icy glop. Despite differences in lat-long we have had this same cycle here about three days ahead, first the 4-8 inch snow cover, then the rain and the flash freeze. We lost most of our snow pack even with a peak temp of 40 F in the rainfall. It then fell to 15 F and everything has frozen solid, our partial snow cover looks like snow but is frozen solid, any slush not removed from parking lots or driveways is now a solid frozen mess. Obviously further north into n CT and w/c MA there will be less total snowmelt but there will probably be some urban ponding anyway and a similar cycle will develop without full removal of snow on ground.

Perhaps worthy of a thread, urban ponding type flood situations will develop rather quickly on Monday morning as temperatures of 55-60 F briefly spread in with 0.25" or more rain. An interval of freezing rain is likely to precede this in the late overnight and may be persistent in parts of the LHV where the warmup will be less prolific (to 48 F). All of this will rapidly be replaced by much colder temperatures, remaining slush will freeze hard on Monday night. I am not guessing at this, by a freak of nature we have been going through similar events here about three days ahead and that's what we had here on Friday into Saturday; everything now frozen solid at 15 F (as it was yesterday morning and all day). Wherever plows have made large snowbanks (this is probably more so in LI and CT, LHV) they will act as dams for accumulating meltwater. Clear all drains where possible.

Forecasts for BOS in this thread range from 47" (44" lower end of a range) to 71" which is not a very large spread for a poll with seven responses. Some gave ranges and others gave a single prediction. In order of the mid-range value where a range was used, the forecasts for BOS are in this order from top to bottom ... Torch Tiger _ 71" ... GeorgeBM _ 60" ... dmillz25 _ 53" ... Ginx and Hoth _ 52.5" ... 40/70 BM _ 49" ... Roger Smith _ 47" Don Sutherland made a prediction of 35-45" for BOS in a different thread (his winter forecast in general interest forum). Twelve people including Don and me had a range from 20" to 50.7" in the annual snowfall forecast contest. In general, that group went lower and several were below 40". I can't extrapolate BOS forecasts from two other one-location predictions but they seem consistent with BOS being in this range. Any one of these could turn out best of the bunch, I am not seeing anything to nudge 47" in either direction at this point. (BOS is only at 4.3" to date)