Hurricane Rachel's swell will combine with 7-foot high tides to hit Carlsbad's eroded Tamarack State Beach starting Wednesday, Oct. 7. Forecasters warn the surf could strip more sand from a shoreline already scoured to cobblestones this summer.

The National Weather Service issued beach hazard warnings and coastal flood advisories for San Diego County, forecasting surf in the 3- to 5-foot range Wednesday morning with sets reaching 6 feet, the San Diego Union-Tribune reported. The conditions are expected to last several days.

NWS meteorologist Rose Schoenfeld told the Desert Sun that southerly swells from tropical systems like Rachel "can be more impactful" than typical surf. Southern California beaches usually receive swells from the west or northwest, so southwest-facing stretches near Carlsbad are especially exposed.

Tamarack lost most of its sand between August and September after storm swells from Hurricane Genevieve, KPBS reported. Much of the beach between Tamarack and Pine avenues has eroded down to cobblestones at the base of the seawall. The Tamarack Avenue parking lot has been closed to vehicles since late August.

Rachel is the latest in a busy eastern Pacific hurricane season fueled by El Niño. Seven hurricanes have formed so far, two more than normal. El Niño has also pushed ocean temperatures to 73 to 75 degrees, well above the typical 65 to 70.

Eric Snortum, an oceanography and geology professor at MiraCosta College, told KPBS that Kelvin waves tied to El Niño can raise sea level about 6 inches. That higher baseline increases the potential for larger waves and more erosion, he said.

As of Wednesday afternoon, Oct. 7, Rachel remained a Category 1 storm hundreds of miles south of Baja California, with sustained winds near 80 mph and gusts to 100 mph, KTLA reported. The National Hurricane Center extended its forecast cone into Southern California, with remnants projected to arrive early Sunday roughly 100 miles south of San Diego.

Forecasters warned that incoming waves could also push water onto railroad tracks in southern San Diego County, potentially disrupting passenger rail service. This summer, high waves in San Clemente eroded beach-side tracks and shorted out underground communications equipment, at times suspending trains between Oceanside and San Clemente.

The city declared a local emergency on Wednesday, Sept. 9, to fast-track a 192-foot extension of the rock revetment along south Carlsbad Boulevard, where erosion threatens to undermine the roadway. California State Parks, which owns about six of Carlsbad's seven miles of coastline, controls Tamarack State Beach. The city does not have authority to lead repairs there, according to a city manager's update posted Sept. 10.

A coastal engineer has been contracted to plan repairs to the damaged Tamarack parking lot, state Parks Lt. Sean Homer told the Carlsbad Environmental Sustainability Commission on Friday, Oct. 2, the Union-Tribune reported. Bids are expected within the next month, with work targeted for completion by the end of December.

Carlsbad resident Amber Martinez told the same commission meeting that the damage is visible and alarming. Jason Haber, Carlsbad's intergovernmental affairs director, told the commission at its Friday, Oct. 2, meeting: "We've already seen significant erosion, and we anticipate more."

No public statement from the city specifically addressing Hurricane Rachel's coastal threat had been posted as of Wednesday, Oct. 7.

The NWS warnings remain in effect, and beachgoers should expect life-threatening rip currents through the week.