Probabilistic forecast guidance from NBM for one aspect of the weather: percentile ranges (p10-p90), exceedance probabilities, and ensemble spread. Use this for any question about odds, ranges, potential or confidence ("how much could we get", "worst case for the wind", "how sure is this") -- a deterministic forecast value cannot answer one. Reading the percentiles: p50 is the most likely outcome, p90 is the reasonable worst case when the risk is the high end (snow totals, wind, rainfall), and p10 is the reasonable worst case when the risk is the low end (cold, minimum visibility, ceiling). A single percentile is not the forecast -- report the likely value with the tail that matters, and label which is which. Aspects: precip (PoP, QPF + percentiles), snow (accumulation percentiles, >1/2/4in probabilities, snow level), ice (freezing rain, accretion), temperature (temp/dewpoint + stddev), wind (speed/gust percentiles), severe (hail/tornado/damaging-wind probabilities), aviation (LIFR/IFR/MVFR visibility + ceiling probabilities), confidence (ensemble stddev; low spread = settled forecast, high spread = details still in play). Examples: {"location": "Denver", "aspect": "snow", "hours": 72} or {"lat": 32.9, "lon": -97.0, "aspect": "severe"}.