Snow Briefing · Mountain pass
Parleys Summit, UT
Mountain pass • I-80 • 7,077 ft • NBM 18Z 15 Nov 2026 • issued 19:39Z
The blend has 3.0″ of snow for Parleys Summit over the next three days, and 20.3″ 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 | 0.0″ | 0.0–0.0″ | 0.00″ | 0% | 0% |
| Next 72 h | 3.0″ | — | 0.00″ | — | — |
| 5 days | 11.4″ | — | — | — | — |
| 7 days | 16.0″ | — | — | — | — |
| 10 days | 20.3″ | — | — | — | — |
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 | 0.0″ | 0.0″ | 0% | 0% |
| Wed 18 Nov | 3.0″ | — | — | — |
| Thu 19 Nov | 0.3″ | — | — | — |
| Fri 20 Nov | 5.9″ | — | — | — |
| Sat 21 Nov | 6.2″ | — | — | — |
| Sun 22 Nov | 0.4″ | — | — | — |
| Mon 23 Nov | 1.4″ | — | — | — |
| Tue 24 Nov | 0.6″ | — | — | — |
| Wed 25 Nov | 1.3″ | — | — | — |
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 | 1.1″ | 3.1″ | 5.8″ | 92% | 8% |
| Day 5 | 3.3″ | 8.2″ | 14.0″ | 100% | 76% |
| Day 7 | 9.3″ | 13.6″ | 20.5″ | 100% | 96% |
| Day 10 | 9.7″ | 14.3″ | 22.2″ | 100% | 98% |
| Day 15 | 13.8″ | 21.0″ | 28.1″ | 100% | 100% |
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 | — |
| Load at 48 h | — |
| Snow-to-liquid ratio at 48 h | — |
| Snow level at 24 h / 48 h | — / 8,366 ft |
| Freezing rain chance, 48 h | 0% |
| Trend | down 0.3″ 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.
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forecastflakes.com/products/parleys-summit-ut-pass · NWS National Blend of Models · ECMWF open data · © 2026 Forecast Flakes · not an official warning source