A late-season snowstorm is set to bury Colorado’s mountain passes under more than a foot of snow this week, threatening travel on some of the state’s most heavily used corridors just as many drivers assume winter is behind them. The National Weather Service issued a Winter Storm Warning for the Sangre de Cristo and Wet Mountains on Tuesday, April 29, 2026, projecting 12 to 16 inches of snow in the highest terrain. Farther north along Interstate 70, a Winter Weather Advisory calls for 5 to 13 inches above 9,000 feet between Thursday, April 30, morning and Friday, May 1, morning, putting Berthoud Pass, Eisenhower Tunnel, Breckenridge, Winter Park, and Rocky Mountain National Park directly in the storm’s path.
For anyone planning a Thursday, April 30, drive over the Continental Divide or a late-April ski trip, the message from forecasters and state transportation officials is blunt: winter driving rules are still in full effect, and conditions could deteriorate fast.
Where the heaviest snow is expected
Two distinct NWS alerts frame the forecast. The Winter Storm Warning from NWS Pueblo covers southern Colorado’s highest terrain, including the Pikes Peak area, where one forecast segment projects 12 to 16 inches and another calls for 6 to 16 inches. The warning window runs through Friday, May 1, morning, and travel conditions on those passes could deteriorate quickly once accumulation begins.
Along the I-70 high country, the Winter Weather Advisory from NWS Denver/Boulder is in effect from 6 AM Thursday, April 30, to 6 AM Friday, May 1. It names specific recreation and commuter nodes: Berthoud Pass, Eisenhower Tunnel, Breckenridge, Winter Park, and Rocky Mountain National Park. At the high end of the forecast range, 13 inches is enough to create whiteout conditions on exposed stretches and slow traffic to a crawl through the tunnel approaches.
The NWS Denver/Boulder Area Forecast Discussion, issued at 6:27 PM MDT on Tuesday, April 29, adds important detail. Forecasters expect the heaviest snow south of I-70, with lighter totals in western and leeward valleys. Snow levels are projected to hover between roughly 6,500 and 7,000 feet, meaning Front Range cities at lower elevations are unlikely to see significant accumulation. But mountain communities and highway corridors above 7,000 feet sit squarely in the bull’s-eye.
What CDOT wants drivers to know
The Colorado Department of Transportation has been preparing for exactly this scenario. In an April 16 travel advisory, CDOT warned that “winter isn’t over yet” and used a National Weather Service storm-total snowfall graphic to illustrate the threat. That advisory remains posted and carries a critical reminder: Colorado’s traction law and chain requirements stay in effect through May 31 on designated mountain routes, including stretches of I-70.
Under the traction law, vehicles on affected highways must carry chains or be equipped with tires rated mud-and-snow (M+S) with at least 3/16-inch tread depth, or have four-wheel or all-wheel drive. Fines apply for motorists caught without adequate equipment during adverse conditions. When conditions worsen further, CDOT can escalate to a full chain law, requiring chains or an approved alternative on all vehicles regardless of drivetrain.
Drivers heading to ski areas still operating in late April and early May, including Arapahoe Basin and Winter Park, should plan for the possibility of temporary road closures, especially on Berthoud Pass (US 40) and Loveland Pass (US 6), where steep grades and exposure make those routes among the first to close during heavy snow.
Potential ripple effects at Denver International Airport
Heavy mountain snow does not always disrupt operations at Denver International Airport, which sits on the plains at about 5,430 feet. But when storm systems are strong enough to push snow and low visibility onto the Front Range, the FAA’s Air Traffic Control System Command Center has historically responded with reduced arrival rates, temporary runway closures, and deicing-related delays.
A March 2026 operational advisory from the FAA illustrates how those constraints can cascade, with reduced capacity contributing to missed connections and longer gate holds. No storm-specific FAA notice for this late-April system has been issued yet, but the ATCSCC advisory system publishes constraints in near-real time. Travelers flying through Denver on Thursday, April 30, should monitor airline apps and FAA updates closely, particularly if the snow line drops below forecast levels.
What forecasters are still watching
Several elements of this storm remain unresolved, and the gap between the low-end and high-end forecasts is wide enough to matter. The NWS Denver/Boulder forecast discussion flags uncertainty in quantitative precipitation amounts. The difference between 5 inches along I-70 and 13 inches or more will determine whether road crews can keep passes open or whether closures become necessary.
The snow-level forecast of 6,500 to 7,000 feet also carries a margin of error. If the snow line drops a few hundred feet, foothill communities and lower canyon routes could see accumulation that current guidance does not anticipate.
Timing is the other wild card. A slower-developing system would spread lighter snow over a longer window, giving plows more time to keep up. A faster, more organized band of heavy snow could produce intense bursts that rapidly cover lanes and reduce visibility to near zero on exposed passes. That distinction will not be fully resolved until radar and surface observations capture the storm’s evolution Thursday, April 30, morning.
Post-storm snowfall verification, drawn from automated gauges, cooperative observers, and trained spotters, typically follows within a day or two after an event. Any comparison between forecast and actual accumulation will have to wait until Friday, May 1, or later.
What drivers and travelers should do before Thursday
The combination of federal forecast alerts and active state traction law enforcement offers a clear signal: treat this storm seriously, even if the calendar says spring. Drivers crossing mountain passes on Thursday, April 30, should carry chains or verify their tires meet traction law requirements, check CDOT’s COtrip road conditions page before departing, and build extra time into travel plans. Delaying a mountain trip by 24 hours, until Friday, May 1, afternoon or Saturday, May 2, could mean the difference between a routine drive and a white-knuckle crawl through near-zero visibility.
Air travelers should set up flight alerts and monitor the FAA’s real-time advisory system as the storm window opens. And hikers or backcountry users heading into Rocky Mountain National Park or the high country should be aware that Trail Ridge Road, which RMNP crews typically work to open in late spring, could see additional delays from this storm’s accumulation.
Updated NWS forecasts will be issued throughout Wednesday, April 29, evening and Thursday, April 30, morning. Those products, not 48-hour-old projections, will carry the most reliable snowfall totals and timing as the storm moves in.
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*This article was researched with the help of AI, with human editors creating the final content.
