A flash flood watch has been issued for recent burn areas in Santa Barbara County including the Whittier, Sherpa and Thomas Fire burn scars from 4 a.m. Saturday into 4 a.m. Sunday.
Rain will not develop again until later Friday night but when it does it will have serious potential. The time of key concern will be in the early morning hours Saturday into early Saturday afternoon across burn areas. Recent modeling shows some potential of continuing showers into Saturday night.
There is an elevated risk of flash flooding with mud and debris flows in and around recent burn areas. In addition, roadway flooding is likely, especially in low lying areas, along with rock and mudslides on canyon roads and below steep terrain.
Peak rainfall rates of 0.50 to 1.00 inch per hour are likely. Local rates up to 1.25 inches per hour will be possible across south facing foothills and coastal slopes. Storm totals are expected to range between 2.00 and 4.00 inches across these burn areas, with 4.00 to 7.00-inch totals possible across south facing foothills and coastal slopes. Locations outside of the flash flood watch have 1.00-3.00″ rain potential.
Shallow mud and debris flows will be likely across the recent burn areas. There is the potential for more significant and damaging debris flows. There will also be an increased threat of rockslides and mudslides which could produce road closures.
On top of this threat, there are also powerful winds in the forecast from the SE of 30-45mph with some isolated gusts of 50-70mph, especially at higher elevations.
This brings the possibility of downed trees or power lines.
This storm is connected to an atmospheric river which is a sub-tropical moisture supply which enhances rainfall.
On Thursday, The Santa Barbara County Office of Emergency Management issued an evacuation warning for the Thomas, Whittier, and Sherpa fire burn areas because of the heavy rain in the forecast. Emergency officials say, if the forecast does not change, an evacuation order will be issued Friday. Residents in those areas are urged to prepare for an evacuation order, getting essential personal items and pets ready to leave at a moment’s notice.