West broiling, burning despite drought relief
SACRAMENTO, Calif. (CN) — While California and Nevada remain virtually drought-free, climate experts say extreme heat and wildfire risk may continue plaguing the West for months.
Scientists with the National Oceanic and Atmospheric Administration said during a webinar Monday that ongoing heat events across the West present a major risk to vulnerable communities, despite a good water supply outlook for the region.
Joseph Casola, the regional climate services director at the National Centers for Environmental Information, called the drought outlook "relatively rosy for California and Nevada.” Data shows few pockets of drought in both states, aside from several areas along the California-Oregon border.
Many reservoirs across California sit above their average holding capacity thanks to the water year’s extended periods of late-spring rain and snow storms.
However, in Arizona the Colorado River’s main reservoirs continue to struggle, with Lake Powell at 42% and Lake Mead at 32% of their total capacity.
While Casola said the levels at Powell and Mead were substantially better than previous years, it's concerning to see the reservoirs remaining at less than half full.
Scientists also worry that the string of extreme heat waves will hasten dry conditions typically seen in the fall.
“We’ve broken a lot of records, particularly in the period over the Fourth of July and this last weekend in Las Vegas,” Casola said of this summer's heat. For example, Redding in the north valley broke an all-time record in early July with 119 degrees, which demolished the previous daily record of 111 degrees set in 1984. Stockton set a daily temperature record over the Fourth of July weekend with a high of 111 degrees, compared to 106 degrees in 1905.
More than 270,000 acres have already burned in California, per Cal Fire’s latest report. There are elevated chances of fire during August and September, and relief from high risk is not expected until October.
Casola added that the chances of a coming La Niña pattern — which consists of cooler climate trends that worsen drought in the western U.S. and exacerbate the Atlantic hurricane season — are elevated in September and October. Still, there's a one in three chance a La Niña may not materialize at all, he said.
Jiabao Wang — a researcher with the Scripps Institution of Oceanography’s Center for Western Weather and Water Extremes — said meteorologists are closely monitoring weather systems in the tropics to determine how likely that outcome is.
She presented animations of current weather systems underway, saying models seem to show a La Niña shift could arrive within four to seven weeks, with some wiggle room for uncertainty. Much depends on the convection patterns being seen in the tropics and the conditions underway over the oceans, Wang added.
Going forward, temperatures across the West appear to sit around normal for the next two weeks, Casola said. But California will continue to grapple with the danger of extreme heat.
The National Weather Service’s Sacramento office reported Monday that much of the north state and Central Valley can expect the return of widespread triple digit heat with well above normal high temperatures through Wednesday.
“Areas of major heat risk become more abundant Tuesday as overnight lows expected mainly in the 70s throughout the Central Valley, with 80s in thermal belts of the foothills,” the service’s meteorologists said in a Monday discussion.
Monsoonal moisture could spread Tuesday night, creating chances of rain showers with thunder in the mountains including the Sierra Nevada range until early Thursday.
The northern Sacramento Valley remains at the highest risk for extreme heat with possible highs up to 112 degrees for much of the week, in part due to a weakening delta breeze and limited overnight cooling.