Rainfall:
Experts say there’s still time — and hope — for lots of rain
Despite the dry conditions, experts say it’s too early to call El Niño a bust.
February wasn’t supposed to be like this. Winter held promise of biblical rains, driven by a strong El Niño that would relieve California of its crushing drought. Instead, it has barely rained a drop this month, record heat has descended on the Bay Area, and there’s no sign of a storm anytime soon.
“It’s half of February that’s on track to be dry. This is not what you want to see if you’re trying to have a wetter- than- average winter and spring and reinvigorate the hydrology,” said Mike Anderson, state climatologist with California’s Department of Water Resources. “This is much different than what we’ve seen in past El Niño events.”
Anderson and other climate experts caution that it’s too soon to call this year’s El Niño a bust. Even California’s wettest winters have had prolonged dry periods, and the nearly two months that remain in the rainy season could still deliver.
The current dry spell — with its record high temperatures for Tuesday’s date of 70 degrees at Oakland International Airport, 76 degrees in San Jose and 85 degrees in Santa Cruz — is the result of high pressure off the California coast that is diverting Pacific storms well to the north.
This high- pressure pattern has been common during the drought. However, El Niño had its characteristic effect of pushing the storm track southward and ensuring California a healthy dose of rain — at least
until this month.
The storm track is now pushing storms toward Canada.
“It definitely brings us back to what we saw during the past four years, and it’s not what you want to see during one of your three wettest months,” Anderson said.
The past seven days have been bone dry in the Bay Area. National Weather Service models don’t show any rain in the forecast for at least another week.
For comparison, the longest dry spell in February 1998, during an El Niño winter that wreaked havoc on California, was just three days, according to the National Weather Service. The longest rainless period in February during the monster 1982- 83 El Niño was four days.
High pressure won’t last
Neither year saw more than 10 days without rain during the month.
Daniel Swain, a climate researcher at Stanford University, said the success of the wet season doesn’t hinge on February.
“It’s not to say the dry spell is great news from a drought perspective, but the fact that’s it’s dry for a week or two amid a wet winter is neither surprising or concerning,” Swain said.
The high- pressure system that’s preventing rain, Swain said, is not likely to stick around. Swain, who has studied the pattern as much as anyone over the past four years and famously coined it the Ridiculously Resilient Ridge, said the atmospheric mass, while widespread, probably won’t out- compete El Niño.
“Historically, these strong El Niños have had strong finishes,” he said. “That’s often what ends up happening in the end.”
February’s balmy weather has turned a wetter- than- average rain year for much of Northern California into a slightly drier- than- normal one. Through Monday, San Francisco had received 13.9 inches of rain since July 1, or 93 percent of average, and Sacramento had seen 9.4 inches, or 77 percent of average.
Maybe next week
Snowpack in the Sierra was at 102 percent of average as of Tuesday, though most of the big reservoirs fed by the snow remain emptier than normal for this time of year.
National Weather Service forecaster Steve Anderson said there’s hope that a wet system brewing in the northern Pacific will provide some relief by the middle of next week.
“It’s abnormally dry for February, but the rainy season isn’t over,” he said. “The pattern coming down from the Gulf of Alaska may beat down the ridge of high pressure that’s over us now. That will allow the jet stream to dive farther south and bring the storm track to where it normally is in the winter.”