The timing between rainfall events stresses plants throughout the region. The decrease in moisture leads to more intense fires and dried up vegetation needed for wildlife and agriculture alike.
The research was led by University of Arizona climate scientist Fangyue Zhang. The reduction in drought busting rainfall across the southwest is consistent with climate models forecasting decreased moisture as the overall atmosphere warms due to human-caused greenhouse gas increases.
“Human activity is driving climate change.” said Colm Sweeney of NOAA’s Global Monitoring Laboratory this Wednesday according to an article in the USA Today which continued: “…the level of carbon dioxide (CO2) in the Earth’s atmosphere is now higher than it has been in at least 3.6 million years.”
Droughts appear to be lasting longer as the active winter pattern of Pacific storms shift north more frequently. This year in California and western Nevada, only one significant storm in January upped the percentage of the meager snowpack. Ultimately, the snowpack topped out around 68% for the Tahoe-Truckee River by April 1, but runoff will be less than 40% of the average due to the extremely dry soils throughout the Sierra and Nevada.
The National Weather Service forecast model shows the flow of the Truckee River at Floriston, CA peaking by April 27. The extremely dry soils in the Truckee River watershed at both Lake Tahoe and the Truckee Basin are contributing to the lower runoff as well as the below average snowpack this year and last year.
The actual peak in river flows could be earlier if the weather remains warmer than expected or be later if cooler and stormier weather comes in. The 10 day forecast doesn’t appear to offer much in the way of precipitation through the first part of April, however. The Carson and Walker Rivers are also expected to have peak flows early.
Currently, the snowpack is melting fast and earlier than would be indicated by historical data. With an early melting of the snow, rivers and streams will likely be well below their average flow into the first part of the summer. The Truckee River, due to upstream storage in reservoirs and Lake Tahoe, will have summer flows while the Carson and Walker Rivers will likely be dry in early summer in many locations.