1:00 PM MDT, Tuesday, March 12, 2019
A very strong cyclonic storm will move through eastern Colorado and into Kansas Wednesday and Wednesday evening. Rain and then snow & blowing snow are likely with a range of possible accumulations. Even within the Denver metro accumulations below 6500 feet might vary from less than 3 inches in some northwestern suburbs to a foot with considerable drifting on the east side. Very strong north winds will cause some blowing snow, especially along and east of I-25.
Scattered rain and maybe a thundershower are possible this evening or overnight. Rain will change to snow early morning Wednesday around Cheyenne and the Front Range foothills above 6500 feet. Rain should change to snow in other areas below 6500 feet during the late morning and early afternoon. Changeover is likely first where the heavier rain is. The snow should taper off before Thursday morning along the Front Range.
Accumulation below 6500 feet:
- 6-12″ with blowing snow: Heaviest accumulation and blizzard conditions are most likely around Aurora and DIA extending northeast onto the plains (especially between I-76 and I-70). Other areas with the good potential for heavy snow and blowing snow are the north facing slopes of the Palmer Divide and Cheyenne Ridge (this includes Cheyenne, and the area south of Denver but north of Colorado Springs). Expect travel disruptions along I-76 and I-70 east of Denver, parts of I-25, and at DIA.
- 4-8″ central Denver, and Denver’s south suburbs.
- 1-5″ closer to the foothills. This type of storm often has a relative minimum (due to lack of upslope flow) in a corridor in and along the lower foothills from Fort Collins to Golden, including Boulder, Broomfield, and Longmont. There is always a chance that the storm can surprise us with a wobble that shifts the heavy snow farther west into Boulder, but I’d say that is only about a 20% chance.
- <3″ in Colorado Springs, but watch out for strong north winds
Accumulation above 6500 feet:
4-14 inches: here the variability is mainly elevation dependent (probably 5-8 around Nederland and Estes)
What is a blizzard?
This is a good time to remind everyone that a blizzard is not just a big snowstorm. We can have blizzards with relatively small accumulations. A blizzard is when the combination of snow and wind cause dangerous blowing snow conditions that could be life threatening if caught out in the open. Blizzard warnings are issued when visibility in snow and blowing snow is expected to drop below 1/4 mile for several hours.