Drought conditions continue to spread across California, with nearly half the state now affected, federal scientists reported Thursday, as recent rains weren’t enough to significantly slow a drying trend that has been growing more serious all winter.
Overall, 48% of California is classified as being in moderate drought — up from 34% a week ago, according to the U.S. Drought Monitor, a weekly report issued by the National Oceanic and Atmospheric Administration, the U.S. Department of Agriculture and the University of Nebraska-Lincoln.
That’s the highest percentage in California since January, 2019.
Most of the Bay Area, Los Angeles and the Central Valley has now slipped into moderate drought conditions, and an additional 30% of California is classified as abnormally dry. The only parts of the state that have experienced anything close to normal rainfall this winter are in San Diego and parts of the Mojave Desert.
Other areas of the United States, particularly South Carolina, Alabama and Georgia, received five inches of rain last week — more San Jose, Fresno and other cities have received combined over the past five months.
“The Pacific Northwest and California also saw some precipitation over the past week, but amounts were not enough to reduce any deficits,” wrote Adam Hartman, a NOAA meteorologist who wrote this week’s report.
There is some hope in the forecast. Cooler, wetter conditions are expected this weekend.
“While moisture will not be all that impressive, there will be enough to produce scattered rain showers over the region,” the National Weather Service office in Monterey reported early Thursday morning.
Rain is forecast to hit the Bay Area on Saturday, Sunday and Monday, forecasters say. Totals are expected to range from a quarter inch to three-quarters of an inch for the storm system in most Bay Area cities, with up to 1.5 inches in the hills, ridges and peaks across the region. Colder temperatures also could bring some snow to the Bay Area’s highest peaks.
Luckily for California’s water supply, because of a wet winter last year and the year before, reservoirs across the state continue to hold a significant amount of water, which will help reduce the risk of shortages this year.
On Wednesday, Shasta Lake, the state’s largest reservoir, was 77% full — 102% of its historic average for late February. Lake Oroville was 64% full, or 88% of its historic average. And San Luis Reservoir near Los Banos was 69% full, or 79% of average for this time of year.
The unusually dry conditions, however, are generating concern that if dry conditions continue next winter, California may be heading toward another drought crisis, not unlike the five-year drought it experienced recently. And the dry winter this year likely means a summer with high fire danger.
The Sierra Nevada snowpack, the source of one-third of California’s water, on Wednesday was just 38% of its historical average — down from 92% on New Year’s Day.
Cities across California are 5 to 10 inches under seasonal rainfall averages, a deficit that would require 15-20 more storms like the one expected this weekend to get back to normal.
Since Oct. 1, San Jose had received just 4.1 inches of rain through Wednesday night, or 34% of its historical average for that date. Oakland was at 36%, with 5.8 inches. And San Francisco was at 47% of normal, with 9 inches.
Light rain last Friday and Saturday snapped a 37-day winter dry spell in San Francisco, the fourth longest consecutive streak without winter rain in that city since the Gold Rush in 1850 when modern records first began.
What about a “Miracle March” with late, drenching Pineapple Express storms that could bring rain totals back near normal? Not likely, if history is any guide.
San Francisco has had 18 years since 1850 when February rain totals were below half an inch — unusually dry. And in those years, only six times did March end up with above-normal rainfall, according to a recent analysis by Golden Gate Weather Services.
In other words, two-thirds of the time when the Bay Area has a dry February, March ends up dry also.
