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Over the weekend the atmospheric river slammed into Northern California and settled over us for a few days. Our weather station at home, roughly at sea level, measured 4.5 inches of rain. On Sunday afternoon it was extremely windy, and I think the rain wasn't falling vertically enough to be captured by the rain gauge, and my guess is that another half-inch or so fell but wasn't measured. A total of about 5 inches of rain feels right.

This storm was a very big deal for us, for a couple of reasons. The most obvious is that California is in the midst of another severe drought. There wasn't much rain or snowfall at all in the 2020-2021 rain season, reservoirs are drier than I remember seeing them, and the governor has asked residents to reduce water consumption statewide by 15%. We are woefully short of that conservation mark. So yeah, the amount of water available to all consumers is (or should be) of concern to all of us.

A second reason why we all paid so much attention to this storm was the fact that much of the rain was forecast to fall on areas that had burnt recently, including the 2020 CZU Lightning Complex fire burn scar. Both the 2020 and 2021 fire seasons were horrendous, leaving many acres of previously forested land bare and prone to mudslides, or "debris flows" in modern parlance. Residents in the Santa Cruz Mountains were warned to prepare for evacuation, just in case. And everyone was prepared to deal with power outages, which, oddly enough, didn't happen.

On Friday the 22nd, before the major storm blew in, I went to Younger Lagoon to record some video clips for my Marine Biology class. One smaller storm had already blown through and it was very windy. I encountered two birders who were looking for pelagic birds that had been swept into the lagoon or were seeking shelter from the elements.

This is what the lagoon looked like on Friday:

North end of Younger Lagoon
Younger Lagoon
2021-10-22
© Allison J. Gong

In fact, here's the video I put together for the students:

So that was Friday. On Saturday we went hiking at Moore Creek Preserve with our god-daughter and family. We all wanted some quality outdoors time before the major storm event on Sunday/Monday.

Yesterday (Monday) I went back to Younger Lagoon to see how much it had changed with all the rainfall. I could tell from the smell that the sand berm hadn't been breached yet. We can always tell when the lagoon breaks through, because all of the hydrogen sulfide buried in the sediment gets into the air. It's a smell that, once known, is difficult to forget. Anyway, I took a photo of the top of the lagoon from the same spot as on Friday. And see how much difference one big rain event can make:

Younger Lagoon
2021-10-25
© Allison J. Gong

To make the comparison easier, let's look at those photos side-by-side:

We had a high surf advisory yesterday, so I wandered down into Younger Lagoon to check out the ocean conditions. I could hear that the surf was really big. It was still windy, too.

Just to make sure my intuition was correct, I stopped to check out the sand berm. And yes, it was still there.

Sand berm between the Pacific Ocean and Younger Lagoon
2021-10-25
© Allison J. Gong

The waves were big and the sets were coming in fast. I shot this video at about low tide yesterday morning. We're in neap tides right now so the low wasn't very low.

High surf advisory at Younger Lagoon
2021-10-25
© Allison J. Gong

Storms and tidal surge, when combined, can wreak havoc on nearshore coastal habitats. One of the obvious victims of the recent violence is the kelp bed. The kelps have been on their seasonal decline for weeks now, and the storm-strengthened swell tore up a lot of kelp and deposited it on the beach. Thousands of detached pneumatocysts (floats) of Macrocystis pyrifera had been blown into windrows. The lighter colored pneumatocysts are the ones that were washed up earlier, probably in the second-most-recent high tide; the darker ones were deposited during the most recent high tide, about six hours earlier.

Kelp debris, mostly Macrocystis pyrifera, on the beach at Younger Lagoon
2021-10-25
© Allison J. Gong

I expected to see dead animals on the beach, too, and was surprised that there weren't any carcasses in sight. Then I looked across the beach with binoculars and saw a couple of turkey vultures (Cathartes aura) on the sand, and a third on the fence above. Vultures eat carrion, so there must be a corpse over there after all. Sure enough, there was a dead bird. As I approached I saw a black body with a smaller reddish part, and my first thought was, "Are turkey vultures cannibals? Will they eat their own dead?" because turkey vultures have unfeathered red heads. But when I got closer I could see that this corpse had webbed feet. It was, in fact, a cormorant.

Dead cormorant at Younger Lagoon
2021-10-25
© Allison J. Gong

The scavenging turkey vultures flew away as I approached. I didn't want to interrupt their brunch any longer than necessary, so stuck around just long enough to snap a few photos. By the time I had crossed back to the near side of the beach, they had returned to their feeding.

All told, this storm was a good start to the rain season. It put an end to the fire season, which is a huge relief to all of us living in California. We have a long way to go to return to normal rain levels, whatever they are in this era of anthropogenic climate change, and it irks me to hear people saying that we've had a lot of rain now, so the drought must be over. Too bad it doesn't work that way, or we would all be rejoicing big time.

Climate change models predict, among other things, oscillation between extreme rain events and extreme drought in California. Just in the past handful of years we've had drought plus the Blob (2015), a wet winter in 2016-2017, and a return to dry conditions from 2018-2020. And we all remember the extreme fire seasons of 2020 and 2021. So what is "normal" these days? I think it's impossible to know. We are experiencing climate change as it happens, and we don't know how or when things will begin to stabilize. I suspect it won't be within the lifetime of anyone reading this blog.

Still, after having about zilch in the way of rain last year, it's good to see that Mother Nature can still throw an atmospheric river at us. Fingers crossed for more rain as the season continues.

In terms of weather, this has been the first real week of winter we've had so far this season. But finally we're getting some action from an atmospheric river, and it is bringing both much-needed rain and the threat of mudslides in mountain regions that were badly burnt just a few months ago.

Graphic showing what atmospheric rivers are and how they affect precipitation

During an El Niño event, the probability of higher-than-average rainfall in California is usually due to what are called Pineapple Express storms. These warm, wet storms occur when the atmospheric river is to the south and picks up and transports water from the tropics. La Niña, which is the counterpart to El Niño, typically results in drier-than-average conditions in California, but when the atmospheric river does come into play it comes from the north and is cold.

We are currently at the mercy of La Niña, and weather forecasters predict these conditions will continue through February and then begin to wane through the early spring. This means that the storms we've had over the past several days have been cold. According to our weather station, on Monday 18 January the high temperature was 24ºC (75ºF), and a week later on Monday 25 January the high was 12ºC (53ºF). It has continued to be chilly throughout the week. Today, Friday 29 January, we're getting a break between storm systems and it's beautifully sunny. Because of the sun it feels warmer, but the actual air temperature probably won't get much higher than it has been already this week.

Yesterday we were hit by what was probably the strongest of the storms in this particular atmospheric river. At the marine lab the waves were routinely splashing up and over the cliffs. When that much water crashes into solid land, the pounding is felt as much as it is heard. After doing my chores I wandered over to Younger Lagoon to see what was going on. I wanted to see if the lagoon had broken through the sand bar.

I spent some time watching the ocean, and this is what I saw:

Storm waves at Younger Lagoon
2021-01-28

That sand bar forms as sand accumulates on the beach during the summer, following the typical sand cycle along the California coast. Younger Lagoon does not drain a river, so there is not a constant flow of fresh water down to the ocean. There is some run-off from the surrounding agriculture fields, but the vast majority of water flowing through the lagoon is run-off from rain. It's that heavy flow of fresh water that sometimes breaches the sand bar and allows water from the ocean to mix with water in the lagoon.

Given how much rain we'd had, I thought it likely that the lagoon would have breached. But as you can see from the video above, it had not. Clearly, there hasn't yet been enough fresh water flow through the lagoon to break through the sandbar.

So we're still waiting for that event. I suspect that once it does, we'll know because of the smell.

In the meantime, the ocean continued to pound the coast. I was wearing my foul weather gear so I went to Natural Bridges to watch the waves slam against the rock formations. That was a fun excursion! The big swells were coming in so fast that the deep BOOM-BOOM-BOOM was almost continuous. Close to shore the water was a constant froth of movement.

Storm waves at Natural Bridges
2021-01-28

You can see how high the waves were hitting against the cliff. The mist blew quite far across the parking lot, and I went home with saltwater drying in my hair. Fortunately I got to spend the rest of the day indoors, drinking tea and keeping dry. Winter storms are great fun, as long as you don't have to be out in them!

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