Rain arriving in Monterey County on Tuesday, Oct. 20, is raising debris-flow concerns near the Timber and Plaskett fire burn scars south of Big Sur.

A low-pressure system moving in from the Pacific should bring light rain to the Central Coast starting Tuesday evening before spreading across the broader region, KSBW meteorologist Kyle Bergerson reported. Showers could linger through Thursday, Oct. 22, with the Central Coast likely receiving the highest rainfall totals.

The system could bring upwards of half an inch of rain to Monterey County, Bergerson said. SFGate reported the Central Coast could see up to 0.75 inch, citing the National Weather Service.

The weather service also estimated an up to 20% chance of thunderstorms in the area. That risk is highest Wednesday, Oct. 21, over the Santa Lucia Range and Sierra de Salinas, according to KSBW. Any storms that develop could produce heavier downpours and gusty, erratic winds.

The biggest concern is for residents near the burn scars left by the Timber and Plaskett fires. The two blazes burned more than 55,000 acres combined this summer, according to Monterey County Now. Stripped of vegetation, those hillsides shed water fast, increasing the chance of debris flows and flash flooding.

The National Weather Service warned in its forecast discussion, as quoted by SFGate, that if rainfall rates exceed certain thresholds near the scars, water will run off the surface and potentially trigger debris flows leading to flash floods. KSBW recommended that residents downslope of the burn scars prepare for rapidly changing conditions and avoid unnecessary travel along Highway 1.

The danger is something Big Sur leaders have been preparing for. At a Big Sur Multi-Agency Advisory Committee meeting on Sept. 28, Kirk Gafill, owner of the Nepenthe restaurant and president of the Big Sur Chamber of Commerce, put it bluntly.

"You cannot stop a debris flow with your vehicle, a tractor, or sandbags, so people need to look at those in a very different way," Gafill said at the meeting, as reported by Monterey County Now.

Big Sur Fire Chief Matt Harris has urged residents to prepare their properties. One million sandbags were available at the Big Sur fire station as of early October, Monterey County Now reported.

Beyond the rain, large surf will persist throughout the week. Waves arriving from both the southwest and northwest will create hazardous conditions at all Central Coast beaches, including sneaker waves and rip currents, according to KSBW.

The National Weather Service forecast for Monterey shows showers likely Wednesday night, with a low of 54 degrees. A chance of showers continues into Thursday before diminishing Thursday night.

Monterey County residents can sign up for emergency alerts at AlertMontereyCounty.org. Sandbag locations are listed at readymontereycounty.org.