Frequency of Bay Area beach hazards, high tides explained: Zoomin' with Zoe

The coast has been very active this summer, and I'm not just talking about people going to the beach. 

Since the start of May, there have been 10 beach hazard statements issued in the Bay Area, the most on record for this time of year. At the same time, there's been record high tides for summertime. There are three main reasons for this: increased southerly swells, the moon, and thermal expansion.

Right now, there are beach hazard statements and coastal flood alerts in effect all along the California coast. The beach hazard statements have been in effect mainly due to the strong southerly swells brought by storms that have been ongoing in the south Pacific, sending waves of energy that slam into the West Coast.

And did you know the moon actually has a significant impact on our coastal flooding? The moon's gravitational pull on earth is what creates our tides; high tide twice a day when the pull is stronger, and low tide twice a day when it's weaker. When the earth, moon, and sun are all lined up, during new and full moons, the moon has an even stronger influence to create higher high tides and lower low tides, which is what we're dealing with right now. A new moon and high tide flooding, which is why the coastal flood advisory is in effect.

But there has been South Pacific storms before, and there have always been new and full moons creating high tide flooding. So why is this year breaking records? It all revolves around El Niño and thermal expansion.

We are currently in an El Niño, a rather strong one at that, and it's bringing warmer than normal sea surface temperatures to the equatorial pacific. As the ocean gets warmed up from El Niño, the water molecules bounce more rapidly off each other and cause the water to expand. The volume of water in the ocean literally increases because it's warmer, known as thermal expansion. This leads to rising sea levels. 

Because of the warm sea surface temperatures, we've seen record flooding this summer and more is likely into the winter as El Niño continues to keep temperatures warm.

The National Weather Service estimates roughly 3 to 6 inches of additional high tide flooding since the tidal data was established between 1983 and 2001. These higher tidal levels will become the new normal and high tide flooding will become increasingly common. 

So it's the southerly swells, the moon, and thermal expansion that all contributed to some record rough conditions along the Bay Area shoreline. And we are going to have to make our infrastructure more resilient in order to keep us safe from rising sea levels and the threats that come with it.