Thanks to a series of atmospheric rivers that coursed through San Diego over the winter season, Anza-Borrego Desert is expected to see a desert flower bloom.
KPBS Roundtable Host Mark Sauer met with meteorologist Alex Tardy of the National Weather Service to talk about the cause and effect of the so-called super bloom. Here are some of the highlights of that interview.
Q: Define what is an atmospheric river and how long can we expect it to last?
A: It’s not really [a new term] but what it is is an abundance of moisture that comes out of the Pacific Ocean. Sometimes out of the tropics. But anywhere in the Pacific and storm systems, we get that moisture. And we don’t hear about it during the drought years much, because we don’t have any storms to draw that moisture up. So it’s kinda a combination of the two. But really, it’s like a regular river or stream. It’s a flow of moisture high up in the atmosphere, 10,000 to 20,000 feet, and when that’s pointed on you, you get a lot of rain and sometimes snow, too, in the high terrain.
Q: And how do weeks of solid rain trigger an event like a super bloom we’re seeing out in the desert? And do we need a drought to precede the rain?
A: So the rain, obviously, is very important to for any germination of seeds, whether it be out in the desert or your own garden. So this rain is the biggest component. We don’t need a drought before, because the seeds are typically laying around and ready to go, if you will. But we need that right combination of rain, early or middle of the winter, and then we need warmth conditions on top of that. So that when the seeds germinate, they don’t rot, and they turn into flowers and start growing. But ultimately, yeah, the rain is the most important.
Q: Is there anything unique about the Anza-Borrego area that makes it a prime location for a super bloom?
A: A lot of the deserts have it. Back in 2017, it wasn’t just Anza-Borrego. We saw it through the Coachella Valley, Mojave Valley, it was widespread, even some of the Imperial Valley. But you still need the soil conditions that support the seeds. Some of the sand dune areas in the desert, you’re not gonna see the flowers. Anza-Borrego is unique in that is has a lot of the cacti. It has a lot of native vegetation. It used to be a lake bed. It’s very fertile to allow growth of these flowers.
