Snow Briefing · Mountain pass
Marias Pass, MT
Mountain pass • US-2 • 5,245 ft • NBM 18Z 15 Nov 2026 • issued 19:39Z
The blend has 3.6″ of snow for Marias Pass over the next three days, and 5.4″ over its ten days. Verdict: plow it.
The next ten days
Plow verdict on the 72-hour total: Plow it
| Horizon | Snow | Range 10–90% | Ice | Chance ≥1″ | Chance ≥6″ |
|---|---|---|---|---|---|
| Next 24 h | 0.0″ | 0.0–0.0″ | 0.00″ | 0% | 0% |
| Next 48 h | 1.8″ | 0.0–4.6″ | 0.00″ | 56% | 0% |
| Next 72 h | 3.6″ | — | 0.00″ | — | — |
| 5 days | 4.0″ | — | — | — | — |
| 7 days | 4.6″ | — | — | — | — |
| 10 days | 5.4″ | — | — | — | — |
Snow is the blend's deterministic forecast; the range is its 10th to 90th percentile and the chances are its own exceedance probabilities. Ice is freezing-rain accretion.
Day by day
| Climate day (12Z–12Z) | Snow | 90th pct | Chance ≥1″ | Chance ≥6″ |
|---|---|---|---|---|
| Tue 17 Nov | 0.6″ | 1.7″ | 22% | 0% |
| Wed 18 Nov | 2.9″ | — | — | — |
| Thu 19 Nov | 0.1″ | — | — | — |
| Fri 20 Nov | 0.3″ | — | — | — |
| Sat 21 Nov | 0.4″ | — | — | — |
| Sun 22 Nov | 0.1″ | — | — | — |
| Mon 23 Nov | 0.5″ | — | — | — |
| Tue 24 Nov | 0.1″ | — | — | — |
| Wed 25 Nov | 0.2″ | — | — | — |
Climate days run 12Z to 12Z, the window the NWS national snowfall analysis scores. Percentiles and chances are available for the first two days.
Two weeks out · ECMWF ensemble
| By | p10 | Median | p90 | Members ≥1″ | Members ≥6″ |
|---|---|---|---|---|---|
| Day 3 | 0.6″ | 2.3″ | 5.4″ | 80% | 8% |
| Day 5 | 0.9″ | 3.0″ | 6.9″ | 86% | 16% |
| Day 7 | 1.1″ | 3.6″ | 7.4″ | 94% | 24% |
| Day 10 | 1.5″ | 4.2″ | 8.4″ | 96% | 24% |
| Day 15 | 3.3″ | 7.6″ | 13.0″ | 100% | 66% |
ECMWF open data, 50 perturbed members at 0.25°, snow at a fixed 10:1 ratio, run 00Z 15 Nov. Cumulative from the run.
Density, level and trend
| Density at 48 h | 5.2 lb/ft³ |
| Load at 48 h | 0.8 lb/ft² |
| Snow-to-liquid ratio at 48 h | 12:1 |
| Snow level at 24 h / 48 h | — / 3,957 ft |
| Freezing rain chance, 48 h | 0% |
| Trend | steady vs the previous run (48 h) |
How good is this forecast?
The blend's day-1 snowfall this season, scored against the NWS national snowfall analysis: mean absolute error 1.12″, bias −0.21″, critical success index at 6″ 0.06 over 71 scored days. Last scored day: 14 Nov 2026.
Nearby briefings
forecastflakes.com/products/marias-pass-mt-pass · NWS National Blend of Models · ECMWF open data · © 2026 Forecast Flakes · not an official warning source