Sonoma County could be next to evacuate ahead of storm

SANTA ROSA, Calif. - Sonoma County is poised to issue an evacuation warning for burn areas in the path of predicted rainstorms.

Between 4 to 6 inches of rain is forecast for the North Bay from Tuesday night into Wednesday, enough to set off mudslides, debris flows and flooding.

"This is going to be our first true test of what the conditions are like, " said Paul Lowenthal, Santa Rosa's Assistant Fire Marshal.

Santa Rosa and Sonoma County collaborated on new "Rain Ready Maps" showing areas in jeopardy from the Glass, Myers, and Walbridge Fires of five months ago.

"Basically the darker the color on the map, the more at risk that area is," explained Lowenthal.

Officials hope people will find their location on the maps and realize the risk.

"Block after block after block of neighborhoods have homes that are still standing but their backyards have been destroyed and stripped of vegetation and that's where our outreach efforts are focused," said Lowenthal.

On Tuesday, fire personnel will walk the east Santa Rosa neighborhoods affected along the Highway 12 corridor.

They will warn residents that the charred hills above their properties could send a torrent of mud, sediment, and debris crashing down.

"I'm just hoping it doesn't happen but it could," said Skyhawk resident Cathy Kunkle.

"We're used to being evacuated at this point so we can act pretty quickly if we have to."

Santa Barbara County saw how devastating it can be.

In January 2018, torrential rain hit the fresh scar of the huge Thomas Fire and the resulting mudflow killed two dozen people, most of them as they slept. 

Nothing that bad is expected in the Bay Area; the geography and geology are different from Northern California to South, but emergency planners are concerned nonetheless.

"We anticipate if an incident is going to happen, it's will happen overnight," said Lowenthal. "The scale of it obviously we don't know but we have to be prepared for the worst."

Analysis of the burn areas shows soils subjected to the most intense heat have lost all absorbency and are susceptible to slippage.

As little as one inch of rain in an hour would be sufficient to trigger a slide.

"Because we've been through the fires we know exactly what to do, what to take, and where everything is, so we are prepared that way," said Skyhawk resident Joel Fine.

The extra discharge of water from the hills could also overwhelm creeks, culverts and storm drains, adding to localized flooding.

If it comes to that we'll get out of here," said Skyhawk resident Jim KInkela. 

"But everybody seems well prepared, they're giving us warnings so I feel pretty comfortable they're on top of it."

Debora Villalon is a reporter for KTVU.  Email Debora at debora.villalon@foxtv.com and follow her on Twitter@DeboraKTVU