LOS ANGELES (CBS) — An advisory went into effect Monday warning people who live in the burn areas of Santa Barbara County to be prepared to evacuate.
Santa Barbara County issued a mandatory evacuation order which takes effect at noon Tuesday for the Thomas, Whittier and Sherpa burn areas.
This storm system is expected to be the biggest of the season for Southern California – and here’s what you can expect.
The setup is much like what we saw with the storms last year – a strong low that originated from the Pacific tapping into a long fetch of subtropical moisture we call an atmospheric river event. These storms can deliver very impressive rainfall totals – and the models are implying they will do just that over the next several days. Flash flood watches could be issued as early as Monday afternoon and then evacuation orders accordingly.
Atmospheric River events are difficult to forecast in regards to timing because the placement of the trough axis determines who will be hit the hardest and when, but as of now the timing looks like rain arrives Tuesday afternoon and continues into late Thursday. The heaviest rain looks like it will fall late Tuesday into early Wednesday, throughout the day Wednesday and into early Thursday. There’s a good chance we see 36 hours of moderate to heavy rain.
– Coasts/Valleys: 2”-4”
– Foothills/Mountains: 4”-6”
– Some of the S/SW facing slopes could see isolated totals up to 8”
Rain rates of 0.50”-0.75” per hour are also expected – this will cause flash flooding
The cold front will approach Wednesday night into Thursday morning, which is when rainfall rates could get up to 1” per hour.
-Not limited to but including flash flooding, debris flow, mudslides, rockslides, roadway flooding, and stream overflow
The recent burn areas in the Thomas, Whittier, Creek, and La Tuna fires will be of big concern and rain rates will likely exceed the USGS thresholds causing flash flooding and debris flow.
Montecito, which has faced mud slides and flooding in recent months, could see as much as 4” of rain for Montecito, while southern L.A. County, Orange and Riverside counties could be spared the worst of the storm.