Name: SnowSure MCP Server
Author: SnowSure

Tier E — Deep timing play — aim late winter

Asia

Likely closed for the season (no closing date on record)

Best months to book: January, February, March · 30-yr snow record

Scroll for happiness

Likely closed for the season (no closing date on record)

Weather data is still collected for informational purposes.

Last Snowfall

Oct 28

3d ago

Past 24 Hours

0cm

Past 48 Hours

0cm

Past 10 Days

5cm

7-Day Forecast

0cm

Snow Depth

Updated: Oct 31, 12:09 AM•Weather at base: 1,235m

SnowSure™ ScoreWhen to book

Likely closed for the season (no closing date on record)

Gassan is closed for the season. Here is when it is usually best to book.

Best months to book

#1January179cm avg
#2February117cm avg
#3March84cm avg

Ranked on 30-year snowfall and base-depth record. The live score returns when the lifts turn.

Snow Summary

Updated Oct 31 at 12:09 AM

Snow qualityLightAverageHeavy

Freezing line

5cm

Season

5cm

Past 10 days48H 0cm · 24H 0cm

0cm

Today

0cm

Next 6 days

Days 8–14 · Pro

Seasontotal

Thu29

Fri30

14 daystotal

—

WedOct 21

Thu22

Fri23

Sat24

Sun25

Mon26

Tue27

Wed28

TODAY31

SunNov 1

Mon2

Tue3

Wed4

Thu5

Fri6

Sat7

Sun8

Mon9

Tue10

Wed11

Thu12

Fri13

Freezing line

Snow qualityLight· bestAverage· okayHeavy· wet, skis heavy

Days 8–14 and every model are in SnowSure Pro.Unlock with Pro

No measurement at mid height (1,453m) reached us: past snow shown is the model's estimate at the summit.

Hourly Forecast

	31 Sat 4° / -2°			1 Sun 1° / -3°			2 Mon 4° / 0°			3 Tue 3° / -3°			4 Wed 3° / -3°			5 Thu 4° / -3°			6 Fri 7° / -3°			Days 8–14 and every model are in SnowSure Pro.Unlock with Pro
	AM	PM	Night	AM	PM	Night	AM	PM	Night	AM	PM	Night	AM	PM	Night	AM	PM	Night	AM	PM	Night	7 Sat	8 Sun	9 Mon	10 Tue	11 Wed	12 Thu	13 Fri
Conditions	🌧️	🌧️	🌧️	☁️	🌧️	🌤️	🌧️	🌧️	🌧️	🌧️	🌤️	🌧️	🌧️	🌤️	☁️	🌧️	🌧️	☁️	🌧️	🌧️	🌧️	❄️	❄️	☁️	❄️	☁️	☁️	🌧️
	drizzle	heavy drizzle	light drizzle	cloudy	light drizzle	mostly clear	light drizzle	light drizzle	light drizzle	light drizzle	mostly clear	light drizzle	light drizzle	mostly clear	cloudy	light drizzle	light drizzle	cloudy	light drizzle	drizzle	heavy drizzle	heavy snow	snow	cloudy	snow	cloudy	cloudy	rain
Mid-mountain1,453 mModeled
Temp°C	6°	5°	4°	1°	2°	1°	5°	5°	4°	2°	2°	1°	2°	3°	0°	3°	5°	3°	7°	5°	4°	-3°	-4°	-1°	-1°	0°	4°	4°
Feels like°C	2°	-1°	-1°	-6°	-4°	-5°	1°	3°	0°	-3°	-2°	-3°	-2°	-2°	-4°	-2°	0°	-2°	4°	3°	1°	-9°	-9°	-4°	-9°	-5°	0°	1°
Snowcm	·	·	·	·	·	·	·	·	·	·	·	0.1	0.3	·	0.4	·	·	0.1	·	·	1.8	16.9	10.8	8.3	4.3	0.2	·	·
Precipmm	2.8	5.2	1.8	·	0.1	0.5	6.8	4.8	11.8	1.1	0.2	3.2	1.1	·	0.6	3.4	6.1	5.3	4.0	4.3	8.0	24.7	15.5	12.4	6.3	0.4	0.2	18.9
Windkm/h	11	20	13	22	14	12	11	9	9	14	16	10	13	12	6	11	9	10	12	18	12	20	19	7	24	18	4	8
Summit1,670 mModeled
Temp°C	4°	4°	2°	0°	1°	-1°	4°	4°	3°	0°	1°	-1°	1°	2°	-2°	2°	4°	2°	5°	3°	2°	-4°	-5°	-2°	-2°	-2°	2°	3°
Feels like°C	0°	-2°	-3°	-7°	-5°	-6°	0°	1°	-2°	-4°	-3°	-5°	-3°	-3°	-6°	-4°	-1°	-4°	3°	1°	-1°	-10°	-10°	-6°	-11°	-7°	-1°	0°
Snowcm	·	·	0.4	·	·	0.2	·	·	·	0.7	·	1.1	0.5	·	0.4	0.2	·	0.6	·	·	3.1	18.8	12.2	8.3	4.3	0.2	0.1	0.1
Precipmm	2.8	5.2	1.8	·	0.1	0.5	6.8	4.8	11.8	1.1	0.2	3.2	1.1	·	0.6	3.4	6.1	5.3	4.0	4.3	8.0	24.7	15.5	12.4	6.3	0.4	0.2	18.9
Windkm/h	11	20	13	22	14	12	11	9	9	14	16	10	13	12	6	11	9	10	12	18	12	20	19	7	24	18	4	8
Base1,235 mModeled
Temp°C	7°	7°	5°	2°	4°	2°	7°	7°	6°	3°	4°	2°	3°	5°	1°	5°	6°	5°	8°	6°	5°	-2°	-2°	1°	1°	1°	5°	6°
Feels like°C	4°	1°	1°	-4°	-2°	-3°	3°	4°	2°	-1°	0°	-2°	0°	0°	-3°	-1°	2°	0°	6°	5°	3°	-7°	-7°	-3°	-8°	-4°	2°	3°
Snowcm	·	·	·	·	·	·	·	·	·	·	·	0.1	·	·	0.1	·	·	·	·	·	·	16.7	10.7	4.5	4	0.2	·	·
Precipmm	2.8	5.2	1.8	·	0.1	0.5	6.8	4.8	11.8	1.1	0.2	3.2	1.1	·	0.6	3.4	6.1	5.3	4.0	4.3	8.0	24.7	15.5	12.4	6.3	0.4	0.2	18.9
Windkm/h	11	20	13	22	14	12	11	9	9	14	16	10	13	12	6	11	9	10	12	18	12	20	19	7	24	18	4	8
Humidity%	97	98	93	74	77	89	98	96	93	91	63	96	92	68	89	88	96	85	98	100	97	96	89	83	94	79	63	93
0°C linem	—	—	—	—	—	—	—	—	—	—	—	—	—	—	—	—	—	—	—	—	—	1,100	950	1,300	1,400	1,400	1,750	2,100
Sunhours																						0.8	4.9	1.4	4.8	4.3	8.6	0

Freeze line is the height where rain turns to snow. Plain: straight from the models. Marked ○: estimated from temperature. Sun is hours of actual sunshine, not day length; blank means we have no reading.

Forecast Range · SnowSure Pro

Every model for Gassan, side by side for 14 days

Where the models agree, where they split, and which one has been most accurate here.

Unlock with Pro

SnowSure™ blend — verified model weighting

The black line is not a simple average. For Gassan (japan), we combine seven global weather models using weights learned from daily forecast verification — comparing each model's prediction to measured snowfall (SNOTEL, resort reports, ERA5).

1.Horizon buckets: days 1–3, 4–7, and 8–14 each get separate weights — short-range skill differs from long-range.
2.Regional calibration: weights come from verified error in this geography (Rockies, Alps, Japan, etc.), recalculated weekly.
3.Ground truth only: we never grade a forecast against another model — only against measured snow.

Building verification history for this resort.

How we verify forecasts →

Snowfall Forecast Maps

Japan (Tohoku & Niigata) region

14 Day map is in SnowSure ProUnlock with Pro

El Niño Outlook · Winter 2026-27

Gassan El Niño rank & forecast

Gassan ranks #402 of 488 SnowSure resorts — Tier E, −14% in strong El Niño winters.

Tier E — Deep timing play — aim late winter: Strong El Niño winters ran clearly below this resort’s own baseline (≤ −8%). Still skiable — schedule late season; one storm cycle can beat the climatology.

#402 of 488Tier E — Deep timing play — aim late winter

Strong-event signal: −14% vs this resort's 30-yr avg

In the three strongest El Niño winters on record ('97-98, '15-16, '23-24), Gassan averaged -14% versus its own 30-year snowfall baseline. Historically this is a timing play rather than a reason to stay home: aim for late winter (February–March) in winter 2026-27. Analog winters: '97-98 -35%, '15-16 -34%, '23-24 +26%. A pattern, not a promise.

'97-98 −35%'15-16 −34%'23-24 +26%

Signal = average snowfall in the three strongest El Niño winters since 1996 ('97-98, '15-16, '23-24) vs this resort's own 30-year ERA5 baseline. n=3 — a lean, not a law. Updated monthly against measured snowfall Dec–Mar.

Full El Niño report →

Key

What the tiers mean

% vs each resort's own 30-year average in strong El Niño winters.

Tier	Signal	Means
A — Prime terrain	≥ +8%	Historically much snowier than normal.
B — Favored	+3% to +8%	Modest upside vs normal.
C — ENSO-proof	about −3% to +3%	Near-normal snowfall — a hedge, not a jackpot or bust.
D — Late bloomer	−3% to −8%	Often lighter early — aim Feb–Mar.
E — Timing play	≤ −8%	Often lighter overall — aim late winter.

ENSO seasonal analog

History · not a forecast

In 10 past El Niño winters at Gassan, ERA5 season snowfall median was 508 cm (200 in), about 5% below this resort’s long-term median. This is a historical analog from reanalysis — not a prediction of this winter’s storm track.

Prevailing ONI

El Niño

JAS 2026 · ANOM +2.16°C

Analog season median

508cm

10 El Niño winters · 5% below median

All-season median

537cm

Across 30 ERA5 seasons (2026-27)

Phase	Seasons	Median	p25–p75	Recent analogs
El Niñocurrent	10	508cm	419cm – 665cm	2023, 2019, 2018, 2015, 2014, 2009
La Niña	12	561cm	510cm – 706cm	2022, 2021, 2020, 2017, 2011, 2010
ENSO-neutral	8	550cm	486cm – 771cm	2025, 2024, 2016, 2013, 2012, 2003

Season snowfall from Open-Meteo ERA5 reanalysis (~9 km). ENSO phase from NOAA CPC Oceanic Niño Index. Relative phase differences are more trustworthy than absolute cm totals. Source: NOAA CPC Oceanic Niño Index + Open-Meteo ERA5 via SnowSure season archive.

Local Reports

0 reports

How accurate is this forecast?

We verify every forecast against what actually fell — see the model-by-model results.

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