SANTA CRUZ — Rain showers on Friday simmered wildland fires that broke out across Santa Cruz and San Mateo counties, but according to the National Weather Service rains could linger well into next week, and even strengthen, which may present debris flow risk.
“We’ve been in a moderate La Niña type pattern, where California is kept dry, while most rainfall shunted northward, in Washington, Oregon, Pacific Northwest,” said Drew Peterson, a meteorologist with the National Weather Service. “That’s played out perfectly so far this winter, but we’re seeing a shift in weather pattern that will persist through the next seven or 10 days.”
That shift includes a predicted three separate storms — the first of which rolled through the Bay Area and Central Coast on Friday.
NWS Technicians working on the radar on top of Mt Umunhum in the Santa Cruz Mts just reported snow. Big fat snow flakes. Melting on the ground though. #cawx #Snow
— NWS Bay Area 🌉 (@NWSBayArea) January 22, 2021
A second storm is predicted to arrive in Santa Cruz County on Sunday, according to Peterson, and persist into Monday. That storm could result in snow on Highway 17, Peterson said. People living outside, or those that keep animals outside are urged to seek shelter Sunday and Monday.
But it’s the third storm that’s a part of this weather system — forecast to hit Tuesday and go into Wednesday — that could be heavy enough to trigger debris flows in fire-scarred areas.
“We are expecting the bullseye of the atmospheric river to be focused on Santa Cruz Mountains and southward down the Central Coast,” Peterson said.
That particular type of storm — an atmospheric river — can bring a lot of rainfall down at once.
“Think about groceries coming down that scanner belt, at first, you only have a few bags, but eventually they start piling up,” Brayden Murdock, meteorologist with the National Weather Service told the Sentinel.
Even though at this point, Murdock and fellow meteorologist, Peterson, say the storm is not predicted to be particularly torrential, it still presents hazards for residents living near burn scars.
“It’s going to come all out once for us midweek next week,” Peterson said, “These are untested burn scars and Santa Cruz County is prone to sliding already.”
The meteorologist said residents need to be on guard, and that the atmospheric river could unleash rainfall levels that hit debris flow risk-thresholds.
“This is something we’re really concerned about … people should pay attention to this and see how it evolves,” Peterson said.
Those thresholds, that could trigger evacuations, are as follows:
• More than 0.3 inches of rainfall in a 15-minute period.
• A half-inch of rainfall occurring over a 30-minute period.
• 0.7 inches of rainfall occurring over an hour period.
How to prepare
Santa Cruz County officials, who have partnered with the National Weather Service, are watching the storm system closely, and meeting every day to reassess risk levels, Santa Cruz County Communications Manager Jason Hoppin said.
“It doesn’t hurt to get your go bag ready now if you are in debris flow notice area,” Hoppin said. “As much as you can do beforehand to get ready to leave, versus doing it at last second, is going to help you and your family, and it’s going to help the people trying to help you.”
Residents living in the Santa Cruz Mountains should take time to prepare this weekend, ahead of the predicted Tuesday storm.
Residents who may live near burn scar areas are urged to take the following steps:
• KNOW YOUR ZONE: Visit the debris flow evacuation zone maps at community.zonehaven.com and memorize your zone ID.
• Make sure you are enrolled in the county’s reverse 911 call system, Code Red, by visiting https://www.scr911.org/.
• Stay alert leading up to and during the storm — monitor news online, on your phone, by listening to a radio, and through the county’s social media channels.
• Pack a go-bag with your essentials before the storm, should evacuations be ordered.
• Track local rainfall levels using One Rain santacruz.onerain.com.
• Track road closures using sccroadclosure.org.
• Stock up on batteries, should power go out, and radio communication be necessary.
Hoppin said, if the forecast for Tuesday’s storm hits levels at which present risk for debris flows, people should be ready to be noticed on Monday.
“People should be ready to get a readiness notice on Monday,” Hoppin said. That’s a step below an evacuation notice, aimed to alert at-risk households.
“Our goal is 48 hours before the event begins noticing, and 24 hours before the event our goal is to actually issue evacuations,” Hoppin said.
Still, the county communications manager warned, the weather can shift, quickly.
“There’s a chance, as we’ve kind of learned with the winds this week that resulted in a dozen fires, that weather can change quite rapidly,” Hoppin said. “We will try to give people as much notice as possible…there is a chance they won’t get the full 48 hours.”
