Forecasters warn of up to 4 feet of snow and hazardous travel conditions across major highways
Category: Climate & Environment
A powerful late-season winter storm is set to impact the Sierra Nevada region, bringing with it the potential for up to 4 feet of snow and hazardous travel conditions. The storm, which is characterized by unusually high moisture levels for this time of year, is expected to develop from Sunday night through Tuesday morning, significantly disrupting travel along key highways in California.
The National Weather Service (NWS) has issued Winter Storm Warnings as a Pacific low-pressure system drives moisture levels approximately 90% above seasonal norms into the high country. Snow is already falling at elevations above 7,000 feet, but the most disruptive phase of the storm is anticipated to arrive Sunday night into Monday, when snow levels are predicted to drop dramatically to as low as 4,500 feet. This descent will bring heavy accumulations to areas that typically remain snow-free by early May.
As the storm approaches, forecasters predict that Interstate 80 over Donner Pass and Highway 50 over Echo Summit will face the most severe disruptions, with both routes at risk of simultaneous closure. The possibility of both highways shutting down at once poses a serious challenge, as there are no realistic alternative routes for drivers needing to travel between California’s Central Valley and points east. The California Department of Transportation (Caltrans) is closely monitoring conditions and is prepared to enforce chain controls and road closures as necessary.
Expectations for snowfall range from 1 to 2 feet at elevations above 6,000 feet, with the highest peaks potentially receiving 3 to 4 feet of snow. Wind gusts along the Sierra crest are forecasted to reach between 50 and 70 mph, with localized gusts possibly hitting 80 mph in the most exposed areas. These strong winds, combined with heavy snowfall, will create near-blizzard conditions and significantly reduce visibility during the storm's peak periods.
This late-season storm is particularly alarming because such weather events are rare in May. The NWS has raised Colorado’s mountains to a “moderate” heavy snow risk for Wednesday, May 6, marking the third late-season storm in just two weeks. The cumulative effect of these storms is expected to layer fresh heavy snow on a cold, saturated base, increasing the avalanche risk for backcountry travelers.
For California, where the Sierra snowpack was recorded at just 18% of normal on April 1, the arrival of this storm carries outsized significance for summer water supply. With a forecasted storm window from May 4 to May 6, the implications for water resources and travel safety are considerable.
Travelers are strongly advised to delay any non-essential trips over Sierra passes until conditions improve, which is expected to be by Tuesday as the storm system moves eastward into Nevada and Colorado. For those who must travel, authorities recommend carrying an emergency kit that includes extra food, water, a flashlight, and a full tank of fuel before entering the mountain zones. It is also advised to check real-time road conditions and chain requirements before departing, as conditions can change rapidly.
Chain controls are expected to begin for most vehicles at elevations above 5,000 feet, and drivers with all-wheel drive or four-wheel drive vehicles equipped with snow tires should be aware that chain installation may still be required depending on the severity of conditions at the time of travel. If drivers become stranded, they should stay with their vehicles, run the engine periodically for warmth, and keep the exhaust pipe clear of snow to avoid carbon monoxide buildup.
As the storm progresses, it will continue to spread eastward into Colorado, affecting major mountain corridors such as I-70 over Loveland Pass and Eisenhower Tunnel, US-50 over Monarch Pass, and US-160 over Wolf Creek. The National Weather Service has already flagged Tuesday and Wednesday as the focus window for heavy snow in Colorado, with avalanche risks expected to spike.
In light of these conditions, travelers planning mountain travel anywhere between California and Colorado through Tuesday should check forecasts and road conditions for their specific routes before heading out. The weather patterns associated with this storm are reminiscent of mid-winter conditions rather than typical spring weather, making preparedness key to ensuring safety during this unusual event.
As the storm approaches, authorities continue to stress the importance of being prepared for rapidly changing conditions. With the potential for heavy snowfall, strong winds, and dangerous travel conditions, those in affected areas are urged to take precautions and remain informed. This late-season storm poses challenges for travelers and carries implications for the region's water supply as the snowpack is critically low.
As the NWS notes, this late-season storm is shaping up to be one of the most impactful weather events in recent years for the Sierra Nevada region. With heavy snow and strong winds expected, officials are urging caution and preparedness among travelers. If you don’t absolutely need to travel during the peak of this winter storm, it may be safest to delay your plans until conditions improve.