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Debris Flow Risk Area Map
This debris flow map, updated March 10 with additional mapping in Carpinteria, shows the areas of greatest risk for debris flows during heavy rains. 
County of Santa Barbara
A strong winter storm poised to move over the Central Coast has led Santa Barbara County officials to issue mandatory evacuation orders effective at noon Tuesday for all people in the "risk" areas for flooding and debris flows.
The evacuation orders were issued just before 4:30 p.m. Monday. They call for residents in "extreme risk" and "high risk" areas — the red, yellow and grey zones on the Debris Flow Risk Map that can be accessed at www.readysbc.org — near the Thomas, Sherpa and Whittier burn areas to be out of the evacuation areas by noon Tuesday.
"Individuals in the Alamo burn area are in a recommended evacuation warning area," according to a county spokesman. "People with access and functional needs in the extreme and high risk areas should consider immediate evacuation. Owners of large animals and livestock should consider relocating immediately."
The evacuation orders were made in consultation with the National Weather Service, according to county officials.
"Tuesday will start off uneventfully," National Weather Service officials said, describing a mostly cloudy start to the day. "But then, there will be a startling change in the weather."
The system, known as an atmospheric river — a relatively long and narrow region of the atmosphere that transports moisture out of the tropics — could bring the highest rainfall totals for the season.
Updated meteorological models issued Monday afternoon by the National Weather Service indicate that there is potential for rainfall intensity of between 0.5 to 0.75 inches per hour, which could trigger debris flows at any time during the storm. In addition, the storm is expected to bring between 5 and 10 inches of rain in the foothills and mountains. That is significantly more total rainfall than the 1/9 Debris Flow, which brought between 3 and 6 inches to the region.
The heaviest rainfall is expected between Tuesday night and Thursday morning, with 2 to 4 inches of rain possible in coastal areas and 4 to 6 inches in the foothills. Rainfall totals of 8 inches cannot be ruled out, forecasters say, and are possible among southward-facing slopes.
Nonburn areas, according to the National Weather Service, may see significant flooding due to the long duration and intensity of the storm. Roadways may be flooded, and rockslides or mudslides are possible near canyon roadways.
Authorities advise individuals within the affected areas not to wait for notification to evacuate if they feel threatened. 
According to Rob Lewin, director of the Santa Barbara County Office of Emergency Management, the amount of rain and the intensity will likely be enough to cause flooding even without the impact of the recent fires.
“We could experience localized flooding and road closures, which are not isolated to the burn areas," Lewin said. "The threat of rock falls, mud slides and debris flow is high."

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The California Highway Patrol, the National Weather Service and public safety partners will monitor storm activity, according to the county, to ensure Highway 101 remains open to facilitate resident evacuations.
"If Highway 101 needs to be closed, CHP would do so just prior to the arrival of the intense portion of the storm," the county spokesman said. "Bands of rain, timing and intensity will guide this decision. Closure information will be communicated broadly to the public as decisions are made."
Showers are expected to diminish by Friday after a dry, northwestern flow settles over the area. Skies are expected to clear and temperatures will return to normal during the weekend.
The Red Cross will open an evacuation center in Santa Barbara at the Earl Warren Showgrounds, Warren Hall, 3400 Calle Real, at noon Tuesday. Anyone evacuated or otherwise affected by the approaching storm is welcome at the shelter.
For assistance evacuating large and small animals, contact the Santa Barbara County Animal Services hotline at 681-4332.
To stay up to date on county advisories, visit www.readysbc.org.
Staff Writer Willis Jacobson contributed to this report. 
Mathew Burciaga covers education in Santa Maria and the surrounding area for Lee Central Coast Newspapers. Follow him on Twitter @math_burciaga. Willis Jacobson also contributed to this report. He can be reached at wjacobson@leecentralcoastnews.com or on Twitter @WJacobsonLR.