A winter storm sweeping through California on Thursday prompted mandatory evacuations for 22,000 residents of coastal areas in southern Santa Barbara County that were devastated by deadly mudslides in January. 

The evacuation order went into effect at noon and affected areas in Goleta, Santa Barbara, Montecito, Summerland and Carpinteria. Residents were ordered to vacate affected areas by 6 p.m. Thursday, according to the Santa Barbara County Sheriff's Office. 

“The decision to evacuate these areas is being made out of an abundance of caution," County Sheriff Bill Brown said during Thursday morning's press conference. "We will not drag you out of your home — it's ultimately a choice everyone has to make."

Brown called the decision to evacuate the area "something that has to be part of the new normal for south Santa Barbara County."

As of Thursday evening, Highway 101 remained open to allow for individuals to evacuate. California Highway Patrol will decide whether or not to close Highway 101 based on the intensity of the storm and potential to create a debris flow. Should the need arise, CHP would close Highway 101 just prior to the arrival of the intense portion of the storm.

The bulk of the rain should pass through the area by Friday afternoon, according to Stuart Seto, weather specialist with the National Weather Service in Oxnard. Between 2 and 3 inches was expected to fall in the Santa Barbara County Mountains (including recent burn areas) from 2 to 8 a.m. Friday. 

A flash flood watch set to go into effect at 9 p.m. Thursday will run through Friday morning. No thunderstorms are expected in the system, but rainfall rates -- the primary factor contributing to mud or debris flow -- are expected to exceed the one-half inch per hour threshold.

"You can expect to see higher rainfall rates in the upper reaches of the burn areas," Seto explained. "The U.S. Geological Survey and Santa Barbara County officials have determined that it can create mud and debris flows."

Brown said the situation remains "precarious and dangerous" due to the potential for flooding, mud or debris flow.

"We still have this potential threat of coming our way," he said. "It's right on the cusp of our protocol. This is the first storm in the wake of the disaster, and we don't know how our watershed will react to this."

County officials caution that waterway flows may be rapid; blockage and overtopping are expected to occur. Individuals close to and downstream of choke points face possible danger, they warn, and community members should heed the warnings of county officials and other authorities.

"It is not our intention to cause panic," Brown said. "This is the first storm since the 1/9 Debris Flow and we can't take unnecessary chances. We want everyone to be safe and out of harm's way."

Still, some chose not to evacuate Thursday. 

"I'm not going anywhere," Montecito resident Harriet Mosson said.

The 76-year-old said the three-story condo building where she lives was not damaged in January because it's on the ocean side of Highway 101, which helped divert the mudslides that came down the mountains.

"Can it happen again? Yeah, I guess it can. Will it, now? I doubt it," she said. "And if something terrible happens, I'll be able to get out of here."

People cannot be forced to leave their homes under a mandatory evacuation order, but authorities said they should not be expected to be rescued while the storm event is occurring.

Significant preparations were being made Thursday in the event of flooding or mud flows. 

The Santa Barbara County chapter of the American Red Cross established an evacuation center at the Earl Warren Showgrounds, located at 3400 Calle Real in Santa Barbara. Showgrounds officials also were accepting large animals that needed temporary shelter. Anyone seeking assistance evacuating animals (either large or small) can contact Santa Barbara County Animal Services at 681-4332.

Earlier this week, the Montecito Union School District opted to host Thursday and Friday classes at schools in the Hope Elementary School District. Westmont College suspended classes and programs between 6 p.m. Thursday and 11:30 a.m. Friday. Santa Barbara Unified announced Thursday afternoon that all schools in the district would remain open.

"Everyone has seen the potential for disaster that can happen," Brown said. "We want people to recognize that this is just an inconvenience. We encourage everyone to cooperate with this evacuation order."

While the bulk of rain should pass through the area by Friday afternoon, the area still may see light showers through Saturday in the coastal areas and through Sunday in the mountains. A high-pressure ridge will begin to form Sunday afternoon, contributing to a warmup early next week.

The Associated Press 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