Winter storm warnings are now in effect in Denver and Boulder, where double-digit totals are predicted and perhaps the most snow from a single storm since 2021. Rain developing Wednesday is predicted to turn to snow by nightfall and then become heavy.

The National Weather Service office serving the Denver-Boulder area expects a wet snow that could damage trees and power lines. The office also warned of “difficult to nearly impossible travel” in Boulder, Denver’s western suburbs and other Front Range communities through Thursday night.

The most significant impacts are expected in the zone from near Boulder to the west of Colorado Springs. There, the Weather Service anticipates “extreme” Level 5 out of 5 impacts, including dangerous travel, widespread closings of roads, schools and businesses, as well as a threat for power outages.

The same storm system is expected to unleash strong winds between eastern New Mexico and western Oklahoma, generating a dangerous fire threat. Farther to the east and northeast, it is forecast to fuel severe thunderstorms and possibly tornadoes, first between eastern Kansas and northern Missouri, including Kansas City on Wednesday. That threat will spread over a larger section of the Midwest on Thursday, spanning from Dallas to just south of Chicago.

The storm is organizing in the lee of the Rocky Mountains as the jet stream takes a sharp dip over the Intermountain West. As the storm strengthens, it will draw an abundance of moisture northward from the Gulf of Mexico.

This surge of moisture is a critical ingredient in the snowfall forecast. Projections suggest atmospheric moisture levels could be more than double the norm.

How much snow is predicted

The Weather Service is forecasting 8 to 15 inches for Denver itself, and up to 20 inches in its western suburbs. In the mountains, a widespread 18 to 36 inches is anticipated, with peak amounts near 4 feet. Snowfall rates of up to 2 to 3 inches per hour are likely in the Front Range, according the Weather Service. Here are some forecasts for specific locations:

• Boulder: The forecast for the city 30 miles northwest of Denver calls for 12 to 22 inches and the potential for thundersnow Wednesday night.
• Denver: The Mile High City is potentially looking at its biggest snowfall since 27.1 inches fell in March 2021. In addition to around a foot of accumulation, the forecast calls for the possibility of thundersnow and gusts of 30 mph causing blowing and drifting.
• Evergreen: Less than 40 miles west-southwest of Denver, this Front Range town could see a foot or more Wednesday night, another foot Thursday and some more thereafter. Temperatures fall into the 20s, with winds gusting to around 30 mph.

• Cheyenne: Just across the border from Colorado, and about 100 miles north of Denver, Cheyenne sits near the edge of an area of predicted heavy snow. The forecast here is for 4 to 8 inches and wind gusts around 35 to 45 mph.
• Colorado Springs: About an hour south of Denver on Interstate 25, Colorado Springs is also on the edge of more substantial snow potential. It’s predicted to receive about 6 to 12 inches.

Snow should wind down from north to south as the storm moves away between late Thursday and midday Friday.

Snowstorm predictions are typically challenging, and this storm is no different. Three factors, in particular, make this forecast difficult:

• Uncertainty as to when the rain changes to snow: If the changeover to snow is slower than forecast, this could lower amounts, especially in lower-elevation areas like Denver.
• Where heavy areas of snow start and stop: Snow amounts are forecast to vary widely from west to east, with totals that peak in the high elevations and drop off into the high plains east of Denver. Where the drop-off occurs and where particularly heavy bands of snow concentrate are difficult to predict.
• An unusual setup: The Weather Service office in Boulder said in a discussion that the track of this storm is “typically not favorable for a big snowstorm” but that other factors — such as the large amount of moisture available — should compensate for the less-than-ideal track.

Despite uncertainties, the Weather Service concluded, “confidence is high for a major winter storm in/near the Front Range mountains and foothills.”

It’s prime time for heavy snow

Unlike many places, late winter and early spring is prime time for snow in much of the Rockies and High Plains.

Brian Brettschneider, a climatologist based in Alaska, recently shared the image above on X, showing where March is the snowiest month of the year. Many of the same locations threatened by this storm are included in shades of pink where March ranks as either the snowiest or second-snowiest month.

Jason Samenow contributed to this report.