2:40 PM MDT, Wednesday, March 18, 2020
Spring officially begins tomorrow at 9:49 PM. A strong storm should move fairly quickly through the region in the morning to afternoon hours with rain, snow and wind. There may be a few showers scattered around this evening. Toward morning rain below 6000 is likely, and snow above 6000 feet (probably starting as rain between 6000 and 7000 feet). The heaviest precipitation is likely Thursday morning when it will transition to snow at all elevations, probably organized into some intense north-south bands. If those bands occur before the changeover in lower elevations, most precipitation will fall as rain. For low elevation areas that experience the heavier bands after the change to snow, there could be 6 inches in a few hours.
One of the better performing high-resolution models, the HRRR, forecasts little or no snow for parts of the region below 6000 feet (including Boulder and northwest Denver). Although I can’t dismiss that, I think a more likely scenario is widespread accumulation below 6000 feet, with some locally heavy areas.
Mountains, foothills, Palmer Divide above 6500 feet: 10-18 inches.
Below 6500 feet: widespread 3-6 inches mainly in grassy areas, with a subset of the area (not necessarily near the foothills) getting 6-10 inches in a short period of time and experiencing travel disruptions. Colorado Springs will probably get less than 3″.
Gusty north-northeast winds will probably cause blowing snow, especially along and east of I-25.