A record-warm March has melted already heavy snowfall across the western United States, the effects of which can be clearly seen in satellite images. It prepares for a particularly worrying summer season for regions that rely heavily on mountain snow.
Snowpack in the western United States, which typically reaches its highest levels by late March and early April, is instead at record lows, meaning a range of potential impacts heading into summer, including increased wildfire risk and reduced water availability to river basins. That includes the Colorado River Basin, which has been suffering from water scarcity issues for years.
A major snowmelt began two weeks ago, sparking an unprecedented heat wave that peaked at the highest March temperatures on record in the country. Ten days later, we are still experiencing record temperatures.
The West’s winter was one of the driest and warmest on record, and snowfall was already at record lows even before the heating dome of climate change arrived.
Temperatures then rose 30 degrees above normal and snowpack plummeted in the Colorado Rockies.
Snowfall typically peaks in early April in the Colorado Rockies, but due to continued heat, this peak may have occurred in the first week of March, a month earlier than usual.
The forecast calls for some snow next week, but with the already low snowpack and the lingering heat, it will be very difficult to see any real improvement in the snowpack in the Rocky Mountains.
In California, the snow water equivalent, a measurement that monitors the health of the snowpack, dropped to 22% of last month’s average as record heat significantly reduced snowpack across the state.
Snowfall in California may have reached its peak about a month earlier than usual. Snow cover, the percentage of land area covered by snow in the Sierra Nevada, has decreased dramatically from 52% on March 1st to 21% on March 24th.
Snow water equivalents are at their lowest on record in both the lower and upper Colorado River basins. These watersheds feed the Colorado River, which provides water to more than 35 million people, industries, and crops in seven states.
As summer begins, rivers and people alike may begin to feel the effects of low snowpack, as the mountains are cleared of snow and water supplies are cut off earlier than usual.
The loss could deepen the West’s long-standing drought and worsen already contentious water negotiations along the Colorado River. Continued hot and dry conditions could strain water supplies for households, agriculture and power generation across the region.
As pollution from global warming increases the likelihood, duration, and intensity of heat waves, the Colorado River Basin’s low snowpack may become an issue more frequently. Climate scientists at World Weather Attribution published an analysis showing that without human-induced global warming, the ongoing heatwave would be “virtually impossible at this time of year.”
Climate change is also changing the timing of the seasons, which could further worsen future snowpack trends. Winter is the warmest season in much of the United States, which will likely reduce overall snowpack, peak earlier, and worsen the outlook for the Colorado River in the coming years.
