A late-season Pacific trough is dropping operational Winter Storm Warnings across southern Wyoming and Winter Storm Watches across the Colorado high country today, Sunday May 17, 2026, with up to 2 feet of snow forecast for the Snowy Range and gusts to 40 mph stacking against the I-80 Summit between Cheyenne and Laramie. NWS Cheyenne upgraded its Watches to Warnings at 150 AM MDT this morning, and NWS Boulder is expected to follow with operational Warning text for the Colorado high country before the storm window opens this evening.
Peak Driving Danger Window
Sunday evening through Monday morning carries the worst risk along both corridors, with the I-80 Summit between Cheyenne and Laramie facing 6 to 10 inches of heavy wet snow as the warning window opens at 6 PM MDT and Colorado’s I-70 chokepoints seeing snow levels crash through Eisenhower Tunnel, Loveland Pass, and Vail Pass overnight.
What to Expect
- Wyoming peak snow totals: 10 to 20 inches in the Snowy Range and North Laramie Range above 8,500 feet, including Centennial, Albany, and Garrett; 6 to 10 inches at the South Laramie Range including the I-80 Summit (Buford, Vedauwoo, Pumpkin Vine).
- Colorado peak snow totals: Up to 14 inches at the highest elevations of the Front Range and Western Slope above 9,000 feet, with 3 to 6 inches across mid-elevation foothills.
- Peak wind gusts: 30 to 40 mph at exposed passes per NWS Cheyenne, with potential for slightly higher at Colorado’s Continental Divide passes including Eisenhower Tunnel and Berthoud Pass.
- Worst corridors: I-80 Summit between Cheyenne and Laramie, I-70 through Eisenhower Tunnel, Loveland Pass, and Vail Pass, US 40 over Berthoud Pass, US 285 across Kenosha Pass.
The setup is a deep upper-level Pacific trough digging across the West, the same system that produced the 16-inch Wyoming Winter Storm Warning along I-80 in central Wyoming on Saturday. As the trough drops south and east, snow levels fall toward 8,500 feet across the Snowy Range and 9,000 feet across the Colorado high country. The NWS Cheyenne bulletin explicitly tells drivers along the I-80 Summit that “persons should delay all travel if possible.”
Road Conditions
The I-80 Summit between Cheyenne and Laramie at 8,640 feet is a notorious winter weather chokepoint and is now under operational Winter Storm Warning. WYDOT closures here routinely run hours during spring storms, and heavy wet snow plus 30 to 40 mph gusts is the high-profile vehicle rollover scenario. Drivers crossing I-80 between 6 PM Sunday and 6 PM Monday MDT should bookmark wyoroad.info or dial 511 for live conditions and closure status.
I-70 across the Colorado Continental Divide is the southern arm of the same event. Eisenhower Tunnel at 11,158 feet, Loveland Pass on US 6 at 11,991 feet, and Vail Pass at 10,662 feet are all inside the watch footprint and will likely fall under operational Warning text by midday Sunday. Colorado’s Traction Law typically activates ahead of these events, and AWD alone does not exempt drivers from the Passenger Vehicle Chain Law once it activates. If you are weighing whether traction will be enough for the higher passes, our guide on the best cars for snow and winter driving breaks down AWD systems and ground clearance trade-offs.
Cross-Border Travel and the Monday Mountain Commute
Drivers connecting Wyoming and Colorado via I-25 will encounter the heaviest snow stacked across the Snowy Range to the west and the Cameron Pass and Rocky Mountain National Park zone to the south. The Monday morning commute is the highest-risk window for both states, with mountain town residents from Centennial, Wyoming through Estes Park and Idaho Springs, Colorado expecting slick conditions before sunrise. Recreational traffic heading west out of Denver or Cheyenne Monday afternoon will encounter chain controls and deteriorating conditions through the storm’s peak window Monday night into early Tuesday. Arapahoe Basin remains in late-season operations on the Colorado side and may extend its closing window into Memorial Day on the back of this snowfall.
Winter Driving Tips
- Tire tread: 4/32 of an inch is the minimum acceptable depth for snow traction; below 6/32, stopping distances on packed snow lengthen significantly. Colorado’s Passenger Vehicle Traction Law requires at least 3/16 of an inch (roughly 6/32) when active. Our roundup of the best snow tires covers Three Peak Mountain Snowflake (3PMSF) options.
- Tire pressure: Pressure drops about 1 PSI for every 10°F of temperature drop. A tire set at 35 PSI in Denver at 70°F can sit 4 to 6 PSI low at Eisenhower Tunnel.
- Stopping distance: Triple your normal following distance on snow, slush, or ice. Never use cruise control in winter conditions; cruise can accelerate into a skid before you have time to respond.
- Chain readiness: Carry chains regardless of drive type when crossing the I-80 Summit or any Colorado Continental Divide pass during the warning window. AWD does not exempt you from the Colorado Passenger Vehicle Chain Law once activated.
- What to drive: Our roundup of the best cars and SUVs for snow and winter driving ranks options by AWD system, ground clearance, and snow-mode tuning.
For live Wyoming road conditions, use wyoroad.info; for Colorado conditions and chain control status, use COtrip.org.
Timing
The Wyoming Winter Storm Warning window opens 6 PM Sunday May 17 and runs through 6 PM Monday May 18, 2026 MDT. NWS Boulder is expected to upgrade its Colorado Watches to Winter Storm Warnings later today, with peak snow Monday night into Tuesday morning across the I-70 corridor. The storm clears the West by Wednesday May 20, 2026, leaving the long Memorial Day weekend (May 23-25) mostly clear for high-country travel. We’ll update this article as conditions evolve.
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