"Those numbers tell Prather that these winter clouds are cold and heavy, –30 degrees Fahrenheit and just over 100 percent relative humidity. Yet despite being 62 degrees below the freezing point of water, the cloud droplets remain stubbornly liquid. As long as they don’t form ice crystals, these clouds won’t shed more than a few flakes of snow over the Sierras’ 13,000-foot peaks. They are typical clouds, teasers that won’t drop much of anything." (Quoted from article)