Atmospheric River Targets L.A.; Evacuation Warnings Issued For Residents Near Palisades, Eaton, Hurst & Sunset Fire Burn Scars

Los Angeles has a love-hate relationship with rain.

On the plus side, it helps with drought conditions, greens up the hills and keeps us from being 90 degrees in November.

On the minus side, it often means more worry and potential disaster for those who’ve suffered through recent wildfires.

The latter was in play when, due to the impending rainstorm, the City of Los Angeles today issued an evacuation warning that will last from from 6 p.m. Thursday to 11 a.m. Sunday for residents near the Palisades, Hurst and Sunset Fire burn zones. Los Angeles Police Department officers were expected to go door-to-door in particularly high-risk neighborhoods to contact residents.

County officials, meanwhile, issued an evacuation warning for residents near the Eaton Fire area in Altadena. County officials warned that any other recent burn area could also be at increased risk of flooding or debris flows.

The National Weather Service warned that the region could be in for a “significant” soaking of rain over the next few days, beginning Thursday night, prompting warnings for residents be prepared to evacuate.

“Based on the model projections today (Wednesday), the upper low is expected to move into a position that will generate widespread 2-4 inches of rain, starting Thursday afternoon along the Central Coast, then Friday and Saturday elsewhere, highest south of Point Conception and especially in upslope areas. Could even see some amounts in the 5-6 inch range in the foothills and mountains,” according to NWS projections. There is also a slight chance of rain on Monday.

Of course, the Palisades, Eaton, Hurst and Sunset fire zones are all located on — or adjacent to — hilly terrain where the combination of slope and maybe even some orographic enhancement could increase rainfall and debris flow amounts.

“Hourly rates of a half-inch would be common in this scenario with isolated rates up to an inch. Thunderstorms are possible as well, best chances from Santa Barbara north but can’t rule out a storm or two down south as well.”

“With this in mind, residents, especially those in vulnerable areas, should start taking precautions immediately to prepare for the storm and protect their interests. This scenario would potentially create many significant impacts area-wide, including possible debris flows in the burn areas, significant ponding of roads and highways, mudslides through the canyons, fallen trees, etc.”

The NWS offered a detailed explanation for the mid-range cloudiness of their forecast.

“We have good confidence in Thur/Thur night w a front passage, but low confidence Fri-Sun,” reads a just-posted statement from the National Weather Service. “This is because a closed low brings rain chcs Fri-Sun & models struggle greatly with this pattern. Stay tuned, as things may change.”

The wet pattern is indicative of an atmospheric river which often brings a string of storms to Southern California. Per the NWS, “Atmospheric rivers are relatively long, narrow regions in the atmosphere – like rivers in the sky – that transport most of the water vapor outside of the tropics.”

This time, however, it is unclear exactly how long the river will flow.

“There remains a lot of uncertainty with how this will play out because the low is expected to cut off and once that happens the predictability of the storm decreases dramatically,” according to the National Weather Service.

“If the upper low moves as models are indicating the storm door will be open for another upper low to come through on Monday, creating another chance of rain, though all indications now are that this next system would be quite weak with any rain totals under a half inch. Then dry weather the rest of the week with no indications of any Santa Ana wind events or additional storms.”

City News Service contributed to this report.