Above 165 inches

- [2026-10-26] The official Mammoth snowfall-history page shows 3" for 2026-27, all in October, and 0 before October. The page says the totals are reported from Main Lodge. https://www.mammothmountain.com/on-the-mountain/snowfall-history - [2026-10-26] The Main Lodge season total counted toward the Dec 24 resolution is therefore about 3". Reaching more than 165" needs roughly 162" more in about 8.5 weeks. This is my arithmetic from the page above. I did not directly open the live Mountain Report field named in the rules. https://www.mammothmountain.com/on-the-mountain/snowfall-history - [2026-10-22/23] A storm on Oct 22 left 3" and 0.71–0.74" of precipitation at the 9,000 ft snow study site, a ratio of about 4:1. It was heavy wet snow. https://www.mammothsnowman.com/mammoth-mountain-snow-report/ - [2026-10-20] The Snowman reported a season total of 1" and base depth of 0" at the study site. That was before the Oct 22 storm. https://www.mammothsnowman.com/mammoth-mountain-snow-report/ - [2026-10-26] The Snowman's 8 AM report says skies are clear and the summit has a SW wind at 38 mph. The forecast is clear and breezy into Friday, and the weekend outlook is possible snow showers and colder air. Snowmaking ran Friday and Saturday nights. https://www.mammothsnowman.com/ - [2026-10-21] The NWS forecaster quoted by Yahoo saw hints of a wetter, more active pattern around the end of October, with near-average temperatures. https://www.yahoo.com/news/weather-news/articles/storm-bring-snow-high-peaks-213716107.html - [2026-10-26] The resort's scheduled opening day is Nov 13, weather permitting. Last year opening slipped to Nov 20. Third-party aggregators list Nov 21, which conflicts with the resort's date. https://www.mammothsnowman.com/ and https://www.aol.com/articles/mammoth-mountain-teases-opening-day-193057000.html - [2026-09-10] NOAA gave a more than 90% chance of a very strong El Niño for winter 2026-27. https://unofficialnetworks.com/2026/09/10/ski-season-opening-dates-2026-27/ - [2026-10-23] SnowBrains' outlook favors above-normal Sierra snowfall at higher elevations. It cautions that storm timing and temperatures are uncertain. https://snowbrains.com/mammoth-mountain-ca-picks-up-3-5-inches-of-snow-in-october-storm/ (read via search snippet only). - [Historical, official] Main Lodge Oct 1–Dec 24 totals can be approximated by Oct+Nov plus most of Dec. Season totals and monthly figures from the official table (Oct/Nov/Dec): 2025-26 was 16/24/73, and 2024-25 was 3/62/39. 2022-23 was 0/61/116 (Oct/Nov/Dec). 2021-22 was 32/9/161. 2012-13 was 18/60.7/147.1. 2010-11 was 10/88/209. 2015-16 was 0/56/71. https://www.mammothmountain.com/on-the-mountain/snowfall-history - [Historical arithmetic] Oct+Nov+full-Dec sums above 165" in 2010-11 (307"), 2012-13 (226"), 2021-22 (202") and 2022-23 (177"). They fall below 165" in the other years listed. The Dec 24 cutoff trims the December figures, so these sums overstate the full-December comparison. Source table: https://www.mammothmountain.com/on-the-mountain/snowfall-history BOTTOM LINE: As of Oct 26 the official Main Lodge total is about 3", so the question needs about 162" more by Dec 24. That has happened in only a few past seasons, and none of them is a close analogue to this one. A strong El Niño is forecast for this winter, but no major storm is forecast through at least Oct 30. NOT FOUND: The live Mountain Report "Main Lodge Season Total" field itself (JS-rendered, not opened). Any long-range forecast for November–December snowfall from a primary source (NWS/CPC). Any confirmation that the Oct 22 storm total is already in the official 3" figure beyond the snowfall-history page.

**Method.** The Main Lodge monthly table gives Oct+Nov+Dec totals, which are an upper bound on the Oct 1–Dec 24 figure. Pre-October snow is excluded because the contract counts from Oct 1. I computed the sums myself from the official table. - [2026-10-26] Over 57 seasons (1969-70 to 2025-26), Oct+Nov+Dec Main Lodge snowfall exceeded 165" in only 6 seasons, about 10%. The 6 are 2010-11 (307"), 2012-13 (226"), 2004-05 (223"), 2021-22 (202"), 1996-97 (189") and 2022-23 (177"). Full-December totals overstate the Dec 24 figure, so the true count through Dec 24 could be lower. The Dec 24 cutoff matters most for 2021-22 and 2022-23, where much of December's snow came mid-to-late month. https://www.mammothmountain.com/on-the-mountain/snowfall-history - [2026-10-26] Near misses through Dec 31, all below 165": 1983-84 (162"), 2002-03 (159"), 2009-10 (158") and 2008-09 (157"). Another 4 or so seasons fell in the 120–150" range. The threshold therefore sits around the 90th percentile of the historical distribution. https://www.mammothmountain.com/on-the-mountain/snowfall-history - [2026-10-26] The last 10 seasons' Oct–Dec totals were 113" (2025-26), 104" (2024-25), 26" (2023-24), 177" (2022-23), 202" (2021-22), 54", 125", 81", 38" and 104". Only 2 of the 10 exceeded 165". The median is about 93". https://www.mammothmountain.com/on-the-mountain/snowfall-history - [2026-10-26] The official 2026-27 season total on the resort page was 3" (all in October). The Snowman's site reported a 1" season total as of Oct 20. A storm on Oct 22 gave 3" at the snow study site, with 0.71" of precipitation. https://www.mammothmountain.com/on-the-mountain/snowfall-history ; https://www.mammothsnowman.com/ - [2026-10-26] The 2026-27 season has a very strong El Niño, possibly the strongest on record. Reports say the opening is scheduled for Nov 13. The Snowman's forecast for Oct 26 shows dry, breezy weather into Friday, with possible snow showers over the weekend. https://www.mammothsnowman.com/ ; https://www.onthesnow.com/news/winter-long-range-weather-forecast/ - [2026-10-15] OpenSnow's preview says all California ski regions are favored for above-average snowfall, with the strongest signal in the Central Sierra including Mammoth. NOAA's Oct 15 outlook favors above-normal California precipitation. https://opensnow.com/news/post/2026-2027-winter-forecast-preview ; https://opensnow.com/news/post/noaa-2026-2027-winter-forecast - [2026-10-15] Severe-weather.eu's October seasonal-model ensemble (six models) shows Mammoth leading U.S. ski areas, with about 31" more snow than normal for Dec–Feb. All six models agree on a good snow season. That is a seasonal anomaly for Dec–Feb, not an Oct–Dec forecast. https://www.severe-weather.eu/long-range-2/winter-2026-2027-snow-forecast-october-update-snowfall-explorer-super-el-nino-ski-season-united-states-canada-europe-fa/ - [2026-10-19] A local forecaster (Natalie's substack) notes a wetter-than-average signal for Nov–Apr. The main early-season risk is warmth, since Nov/Dec show a slightly warmer-than-average signal. That means snow lines above Canyon Lodge, which is not a Main Lodge issue at about 9,000 ft. Medium-range models show a possible trough around Halloween, but with low confidence. https://mammothnatalie.substack.com/p/2026-2027-winter-outlook - [2026-10-26] Climatology: the Mammoth Snowman says Nov averages about 29" and Dec about 50–70". That puts the mean Oct–Dec total near 90–100", well below 165". https://www.mammothsnowman.com/mammoth-mountain-snow-report/ - [2026-10-26] ENSO is a weak predictor of early-season snow at Mammoth. Unofficial Alpine says El Niño correlates with snow mainly at Mammoth. The table's strong-El Niño-type years are mixed, and a Dec-heavy blowout needs a specific storm sequence. OnTheSnow warns that last year's La Niña-based snow forecasts missed across the West. https://unofficialalpine.com/?p=25133 ; https://www.onthesnow.com/news/winter-long-range-weather-forecast/ - [2026-10-26] Early-season snow at Mammoth is lumpy and driven by a few storms. Examples are December 2021 (161" in the month, with storms of 40"+) and 2012-13 (147" in December). https://asomammoth.com/mammoth-mountains-historic-december-2021-snowfall/ ; https://www.mammothmountain.com/on-the-mountain/snowfall-history BOTTOM LINE: The historical base rate for more than 165" by late December is roughly 10% (6 of 57 seasons, and 2 of the last 10). The very strong El Niño and wet seasonal outlooks justify some upward adjustment, but these are probabilistic and low-skill for a Dec 24 cutoff. The season starts near 3". NOT FOUND: a Dec 24-specific cumulative history (only monthly totals exist), any published Oct–Dec expert snowfall forecast for Mammoth, and a historical record of how El Niño years specifically performed through Dec 24.

YES means: Mammoth's official Main Lodge Season Total (counting from Oct 1) is above 165" at 4 PM ET on Dec 24, 2026. - [2026-10-25] The CPC week-2 hazards outlook (Oct 25, fetched) forecasts an active West Coast pattern. It cites a Gulf of Alaska trough shifting southwest, rising moisture transport (IVT) into the West Coast from mid-week-2 into week-3, and a "slight risk" of heavy snow for the Sierra Nevada on Nov 4-8. The CPC specifically names the northern Sierra, not Mammoth. This is a primary-source signal of a pattern change after the dry week ahead. https://www.cpc.ncep.noaa.gov/products/predictions/threats/threats.php - [2026-10-26] Eastside Weather (fetched; NWS-derived) calls a Halloween storm "a coin toss", at most weak to moderate but colder than the Oct 22 storm. The site's 10-day Mammoth Mountain (9,100 ft) total is about 6.1" (range 1.2–8.5") on about 0.69" liquid. Its outlook says the storm door may stay open into the first week of November. The near-term amounts are small relative to the roughly 162" gap. The point is the pattern, not the totals. https://eastsideweather.com/ - [2026-10-19] Eastside Weather's earlier outlook (search snippet) said long-range modeling shows a Gulf of Alaska trough sticking around "more often than not the entirety of November". It framed this as the canonical response to an emerging El Niño, which would then be favored through winter. This is the best-sourced mechanism for a wet November. https://eastsideweather.com/ - [2026-10-22] OpenSnow's Chris Tomer expects colder air and a "more permanent shift" in the pattern later in November. OpenSnow's snowfall forecast through Nov 4 is about 10" at Mammoth. Powder.com carried the report. https://www.powder.com/news/west-storm-snow-forecast-ski-resorts - [2026-10-?? (about 2026-09)] The Oregon Dept. of Agriculture's Nov 2026 seasonal brief (search snippet, not fetched) says analog years show a split-flow pattern with "anomalous troughing over California". It says that pattern delivers potent systems into California. Its blended analog precipitation for November is only near average, so this supports intensity per storm rather than a wet month. https://www.oregon.gov/oda/natural-resources/Documents/Weather/forecast.pdf - [2026-09-30] ONI for Jul–Sep 2026 reached +2.2°C, the "Very Strong El Niño" range. CPC expects further strengthening through year-end. This is a number behind the El Niño headline. The CPC's Sept 17 outlook favors above-normal precipitation for coastal California, with 50–60% probabilities in Dec–Feb. https://www.oregon.gov/oda/natural-resources/Documents/Weather/forecast.pdf ; https://stormbag.co/blogs/stormbag-flood-protection-blog/super-el-nino-2026-27-what-noaas-off-the-charts-forecast-means-for-the-year-ahead - [2026-10-17] SF Chronicle meteorologist Greg Porter says seasonal models favor about 40% more Jan–Mar snow than normal near the Central Sierra. Mammoth sits by a low gap in the crest, and its high base gives it more cushion against rain than other California resorts. Those two features mean warm El Niño storms still produce snow at 9,000 ft Main Lodge. https://www.sfchronicle.com/weather/article/snow-el-nino-sierra-tahoe-california-22475780.php - [2026-10-12] OpenSnow's Bryan Allegretto (via SFGATE, relayed by Patch) says Mammoth sits better than Tahoe for El Niño storm tracks. Tahoe is nearer the northern edge, where storms can miss. https://patch.com/california/across-ca/california-ski-season-2026-27-mammoth-tahoe-resorts-opening-dates-snow-arrives - [2026-10-08] Powderchasers: strong El Niño Main Lodge seasonal totals were 557.9" (2009-10), 546.3" (1982-83), 362" (2015-16), 367" (2023-24) and 226" (1991-92). Two of the four very strong events (1997-98 and 1982-83) are known for big early-winter dumps. The 1997-98 storm of 3–5 ft on Nov 27, 1997 is an example of the early-season lumpiness a YES needs. https://powderchasers.com/blogs/powderchasers-forecasts/2026-27-north-american-ski-season-forecast-a-very-strong-el-nino-favors-a-late-southern-weighted-winter ; https://www.yahoo.com/news/weather-news/articles/were-weather-farmers-tahoe-see-120000250.html - [2026-10-14] The California Avocado Growers' CFSv2-based outlook says heavier rains in California begin late November and December. It sees the most reliable heavy-rain support in mid-December through January. A heavy mid-to-late December would fit the pattern behind past crossings of 165" (the Oct–Dec totals in the colleagues' table, e.g. 2021-22 and 2022-23). The date cutoff, Dec 24, falls before the January peak. https://www.californiaavocadogrowers.com/articles/weather-outlook-october-november-2026 Most likely path to YES: a Nov 4–8 storm series gives roughly 20–40" at Main Lodge, which is the only near-term signal. A Gulf of Alaska trough then keeps the storm door open through November, for about 60–80" in November. One or more atmospheric-river or cold-trough December events then deliver 80–100" or more by Dec 24. Prerequisites: snow levels stay below about 8,500 ft, so these arrive as snow rather than rain. At least one 40"+ storm lands between mid-November and Dec 24, as in Dec 2021. No extended ridge or dry spell occurs, as in Dec 2022's mid-month or 2015's warm Decembers. BOTTOM LINE: The strongest YES case is a very strong El Niño (ONI +2.2°C) with a trough over California, a favorable seasonal signal for Mammoth specifically, and a CPC-flagged pattern change from about Nov 4. That reaches 165" only through an exceptional November–December, which needs roughly 160" in about 8 weeks, and no source forecasts that. NOT FOUND: A Mammoth-specific Oct–Dec snowfall forecast, a CPC monthly or seasonal outlook for November (the next one is due Nov 19), the live Mountain Report "Main Lodge Season Total" field, and any historical Dec 24 cumulative series for El Niño years.

YES means: the official Main Lodge Season Total (Oct 1 – 4 PM ET Dec 24, 2026) is above 165". - [2026-10-25] The Snowman's Oct 25 post says the Oct 22 storm gave 3" and 0.71" of precipitation at the 9,000 ft study site. It forecasts sunny, weak ridging for the next week, with a weak Monday system that "only kicks up some winds." The next snow chance is about a week out, around Nov 1. So the Oct 22 storm adds to the starting total and nothing more is forecast for about 7 days. https://www.mammothsnowman.com/ - [2026-10-26] The official table was re-read directly (it lists 2026-27 at 3", all October). Strong El Niño analogs, Oct+Nov+full Dec: 1982-83 = 147.5", 2009-10 = 158", 2015-16 = 127", 1997-98 = 78.2", 1991-92 = 69.3", 2023-24 = 26". None of these six exceeded 165" even counting all of December, which overstates the Dec 24 figure. The roughly 10% base rate is not improved by this analog set. https://www.mammothmountain.com/on-the-mountain/snowfall-history - [2026-10-26] The seasons that did top 165" were not El Niño years, apart from 2004-05, 1996-97 and 2012-13 (weak or neutral ENSO, from my own recollection, not verified in a source). 2021-22 had 161" in December alone, and 2022-23 had a 116" December. These years were driven by one or two exceptional storm sequences. Even 2021-22 and 2012-13 reached 165" only with a huge December. https://www.mammothmountain.com/on-the-mountain/snowfall-history - [2026-10-08] Powderchasers states the strongest southern influence is expected in the core and later winter, "rather than necessarily at opening day." It says a slow start is plausible. It also notes that seasonal guidance cannot pick out specific powder weeks. https://powderchasers.com/blogs/powderchasers-forecasts/2026-27-north-american-ski-season-forecast-a-very-strong-el-nino-favors-a-late-southern-weighted-winter - [2026-10-08] The same piece shows El Niño outcomes at Mammoth are wide-ranging: 1991-92 gave 226" (60% of average), and 2015-16 and 2023-24 finished near average. Early-season totals in those years were low. It also warns that warm storms can rain at low elevations. https://powderchasers.com/blogs/powderchasers-forecasts/2026-27-north-american-ski-season-forecast-a-very-strong-el-nino-favors-a-late-southern-weighted-winter - [2026-10] ZRankings, using 40 winters of data, finds El Niño winters averaged 4% less snow at Mammoth than normal, and 1% less in the strongest ones. That is no clear signal. It also ranks December only fifth-best for snow. https://www.zrankings.com/mammoth-december - [2026-10-26] The mean Oct–Dec total is about 90–100". Reaching 165" needs roughly 162" more in 8.5 weeks. That is about 1.7x the normal November plus December. Historical Nov averages are about 29–32" and Dec about 50–67" (OnTheSnow, with the Snowman's figures cited in the earlier report). https://www.onthesnow.com/california/mammoth-mountain-ski-area/historical-snowfall - [2026-10-26] The cutoff is Dec 24 at 4 PM ET, which is 1 PM Pacific. About a week of December is lost. Late-December storms, as in 2021-22 (when much of December's 161" fell mid-to-late month), would not count if they arrive after the cutoff. The measure is also the Main Lodge field only, not the summit, where totals run higher. https://www.mammothmountain.com/on-the-mountain/snowfall-history - [2026-10-27 snapshot] Snow-forecast and J2Ski GFS data around Oct 20–22 show only about 1 inch for the Oct 22 storm at mid-mountain. They show no accumulating storm through Oct 28. This is consistent with the official 3". The total will probably stay near 3" through at least the first days of November. https://us.j2ski.com/snow_forecast/United_States/Mammoth_Mountain_snow_forecast_long_range.html - [2026-10-22] KTLA reported only 4–6" in the Eastern Sierra from the Oct 22 storm, with drier, sunnier weather returning from Friday through the weekend. Scale check: this "great start" storm is about 2% of the 165" needed. https://ktla.com/weather/mammoth-mountain-snow-storm/ - [2026-09-27] The Snowman uses ECMWF weeklies only for trends, not snowfall forecasts. He wrote that past strong El Niño falls "brought some early base snow" but outcomes vary, and that cool, wet Octobers often turn warm and dry for weeks. There is no published Mammoth snowfall forecast for November–December. https://www.mammothsnowman.com/2026/09/27/mammoth-mountain-weather-discussion-6/ - [2026-10-26] Status-quo logic: with about 3" on the board and a dry week ahead, the season total needs a top-decile outcome in a short window. If Nov brings an average 29" and Dec 1–24 a normal 40–55", the total lands near 75–90". Resolving YES requires about double that. BOTTOM LINE: The No case rests on a roughly 10% base rate, 0 of 6 strong El Niño analogs exceeding 165" through December even counting the full month, and a start of about 3" with a dry week ahead. The Dec 24 cutoff trims the December figures that the YES years depend on, so YES needs a rare, record-class Nov–Dec storm sequence. NOT FOUND: The live Mountain Report "Main Lodge Season Total" field. A Dec 24-specific cumulative history. Any primary NWS/CPC Nov–Dec snowfall forecast for Mammoth. Any source stating how the Dec 24 4 PM ET cutoff will be read operationally.