12:45 PM, Thursday, April 14, 2015
The big weekend storm from Friday afternoon through Sunday morning (and some lingering effects into Monday) is looking like it will bring wet snow accumulation, possibly heavy, to the Front Range urban corridor beginning Friday night or in the predawn hours on Saturday.
Front Range mountains and foothills (above 6500 feet): this is the relatively easy part. Heavy snow (rain at first Friday afternoon in the foothills). Accumulations 1-4 feet, heaviest above 9000 feet. It appears that Nederland and the high points of the Palmer Divide may see 2-3 feet.
Below 6500 feet:
Rain and maybe a strong thunderstorm with hail Friday afternoon and evening. The changeover to snow should occur after dark and maybe after midnight. Some heavy, wet snow is probable by daybreak Saturday.
Snow intensity is likely to vary Saturday through Sunday morning, with moderate to heavy periods and some lulls. After Sunday morning precipitation will probably be more intermittent and lighter.
Accumulation below 6500 feet:
5-15 inches, highly variable, and I will update this tomorrow.
- The higher end of that range is a little more likely along the west and south sides of metro Denver (including Boulder and Broomfield), and in the Cheyenne area.
- The lower end of that range is a little more likely in places where northeast winds are a “downslope” direction, such as Lyons and many parts of Weld and northeastern Larimer counties.
- The greatest accumulation will be in grassy areas, but dense slush is likely on roads, especially in heavy snow areas.
- Broken tree limbs and power disruptions are likely.
Why the variability? At the time of year enough of the sun’s energy gets through the clouds to enhance melting. The most efficient accumulation will be at night, or during heavy daytime precipitation when cooling from evaporation is greatest. During light precipitation intervals melting is likely to take over.