Preliminary federal readings show San Francisco’s tide gauge topping Monday’s October record on Tuesday, and forecasters expect water about 1.9 feet above normal high tide again around 12:56 p.m. today.
By midday Tuesday, the stretch of the Embarcadero near Pier 14 had taken on a routine. The city closed part of the sidewalk and the bike lane, the “Corpus” sculpture at the foot of the pier was blocked off, and passers-by stopped at the caution tape to photograph seawater where pedestrians and cyclists usually are.
It was the third straight day of it, and the water was higher each time. Preliminary six-minute readings from NOAA’s San Francisco tide gauge show the bay peaking at 1.67 feet above mean higher high water, the average daily high tide, at 11:24 a.m. Sunday; 1.87 feet at 11:36 a.m. Monday; and 2.0 feet at 12:24 p.m. Tuesday.
Monday’s 1.87 feet was, according to the National Weather Service, the highest October tide on record at the gauge, breaking a mark set on Oct. 11. Forecasters warned at the time that the record “may be short lived.” Tuesday’s preliminary reading was higher still; the weather service had not, as of late Tuesday, said whether it counts as a new record, and NOAA’s six-minute data remain subject to review.
What to expect today
The weather service’s Coastal Flood Advisory for the San Francisco Bay, San Pablo Bay and Monterey Bay shorelines and the Pacific coast remains in effect until 5 p.m. Friday. In its Tuesday afternoon update, issued at 3:11 p.m., the agency said up to 2.1 feet of inundation above ground level is possible in low-lying areas near shorelines and tidal waterways.
At the San Francisco gauge, it forecast high tide at 1.9 feet above normal (7.7 feet above mean lower low water) at 12:56 p.m. today, 1.7 feet at 1:43 p.m. Thursday and 1.6 feet at 2:39 p.m. Friday. Those figures, the agency said, include up to 1.2 feet of surge on top of the astronomical tide. High tide can arrive up to 90 minutes earlier on the Pacific coast and up to 90 minutes later deeper in the bay.
The weather service expects the most serious problems along the Marin County bayshore. In southern Marin, drivers were stranded and had to be rescued from flooded streets on Monday and Tuesday, and Mill Valley police on Tuesday urged drivers to avoid Miller Avenue between Camino Alto and Almonte Boulevard and part of the Redwood Highway Frontage Road near the Highway 101 ramps, CBS News Bay Area reported. Caltrans closed a Highway 101 on-ramp in Mill Valley on Monday, the San Francisco Chronicle reported.
The agency’s standing advice: do not drive around barricades or through water of unknown depth, and allow extra time if travel along the shoreline is required.
Why the water is a foot higher than the tide tables
The gap between what the tide tables predicted and what the gauge recorded is the story of the week. NOAA’s astronomical prediction for Tuesday’s high tide at the gauge was 0.80 feet above mean higher high water; the measured peak was about 1.2 feet higher. On Monday, the prediction was 0.65 feet and the reading 1.87.
Eric Young, a spokesperson for the Port of San Francisco, attributed the extra water to the developing El Niño. “What happens with El Niño is there’s a warming trend in the water,” he told KQED. “That leads to tides being a foot or more higher than they normally are on average at this time of year.”
What made Monday and Tuesday unusual was the weather, or the lack of it. Flooding like this along the Embarcadero usually comes with a winter storm. This week there were no major waves or wind pushing water inland; the bay simply rose over the edge and, in at least one spot, bubbled up through a storm drain in the roadway, where Port crews set out cones, the Chronicle reported.
The Port’s playbook, and the longer bill
Young said the Port is prepared to put up barriers in low-lying areas, close traffic near the waterfront and pump out water when needed, and has told waterfront businesses that their operations could be affected. “We have a playbook for when stormwater or floods come into the sidewalk, come into the bike lane, or come into the traffic lanes,” he told KQED. “And we have ways to deal with that in our playbook that’s well established.”
The city declared a local emergency last week in anticipation of heavy rain and flooding from an expected El Niño winter.
The higher-stakes dates are still ahead. The king tides of Thanksgiving and Christmas weeks will be higher than this week’s, the Chronicle reported, and a storm arriving at the same time would make the disruption far worse than a sunny-day puddle at Pier 14.
The permanent fix is measured in billions and decades. The recommended plan from the U.S. Army Corps of Engineers’ San Francisco Waterfront Flood Study, published in August, would combine seawalls, floodwalls, berms and nature-based features along the waterfront at an estimated cost of $17.8 billion in 2026 dollars. If Congress approves it, the federal government could pay up to 65 percent of construction. The study estimates that without federal action, 100 to 500 structures and assets will be vulnerable to flooding by 2050, and that cumulative flood damage and lost waterfront property could exceed $23 billion by 2140.
None of that will be built by Friday. For now, the city’s defense along the Embarcadero is cones, caution tape and a 12:56 p.m. tide.
Celia Marroquín covers San Francisco City Hall, the Board of Supervisors, city departments and the neighborhoods where their decisions land, for the Inquirer’s City Desk. More from Celia Marroquín
