Weather Watch

A ladybug swarm showing up on weather radar? This SLO meteorologist doesn’t buy it

I’ve heard plenty of rumors and stories over the decades of thought-provoking, rarely seen natural phenomena.

By my nature, I tend to be a skeptic. For example, grunion runs along the Central Coast; if I didn’t see it occur one late night at Port San Luis, I would probably remain unconvinced to this day. Over the last few weeks, two captivating natural events occurred, one that I questioned, and the other I did not, and here’s why.

The weather radar at San Diego, which is part of a vast network of 159 National Weather Service (NWS) high-resolution Doppler weather radars that cover most of the United States, showed a 160-square-mile green blob of precipitation moving in a southwesterly direction Tuesday from Riverside toward San Clemente.

Typically, this wouldn’t be all that unusual, but it occurred on a clear and dry day. National Weather Service meteorologists at the San Diego office asked their local network of weather spotters to verify if it was raining. All reported dry conditions, but a few of the NWS spotters saw ladybugs.

Perhaps it was a massive swarm of orange polka dotted beetles on the wing trying to find their way home.

You see, the weather radars send out a beam of radio waves from their antenna as they rotate 360 degrees. If the radio waves strike rain, hail, snow or even insects or birds, a small portion of the reflective beam is directed back toward the radar antenna. Computers analyze the strength and frequency shift of the returned radar waves and produce a display of the location and intensity of precipitation that we see.

Rainfall is shown as blue and green; heavier rain is indicated by yellow, with orange and red representing the heaviest precipitation. Doppler radar uses the principle called Doppler shift, which is a change of frequency caused by movement and is named for Austrian physicist Christian Doppler, who proposed the theory in 1842.

A classic example is a fast-moving truck passing your location. The sound from the truck is shifted to a higher pitch — a higher frequency — as it moves toward you. As the semi passes and travels away from you, its sound is changed to a lower pitch or frequency.

Ladybugs can’t fly in cold

Why do I remain skeptical of the ladybug swarm hypothesis?

The weather radar indicated that they were flying at around 7,500 feet. Ladybugs are not cold weather fliers; they are unable to fly when the temperature drops below 55 degrees. Weather balloon radiosonde data from Marine Corps Air Station Miramar near San Diego indicated the afternoon air temperature at that altitude was below 55 degrees.

The green blob of ladybird beetles on the radar was spotted later in the evening, so the air temperatures may have increased. To be clear, these beetles do hibernate in the Sierra Nevada and other California mountain ranges where they gather in groups of millions under the snow cover, before migrating in the spring.

However, no one knows for sure what caused this mysterious anomaly.

Other rare phenomena has me wondering

The other rare event occurred during the early morning hours on May 20. Since 1976, PG&E and Tenera Environmental Services scientists have conducted marine biological and physical oceanographic surveys along the rugged cliffs, coastal terraces and open ocean along the Pecho Coast near the Diablo Canyon Power Plant.

The Pecho Coast stretches from Montaña de Oro State Park south to the Point San Luis Lighthouse and remains one of the most pristine and unspoiled coastlines found anywhere in California. Various marine biologists have journeyed to the tide pools at minus low tides along the Pecho Coast and performed these studies, often at night.

If the conditions are right at night, bioluminescence from plankton blooms and/or the deep scattering layer can mark their track across the cool, wet and slippery rocks of the littoral. During one of these low tide morning surveys, Tenera Environmental scientist Andrew Harmer saw something you don’t see every day, a sea anemone eating a snake!

“I have read that aquatic garters will go into the intertidal zone hunting fishes, but this is the only evidence I have ever seen personally,” Harmer said.

This reminds me of the Sarlacc, a fictional creature in Star Wars movie saga that resembles a giant sea anemone, except for its beaked tongue. This creature inhabits the Great Pit of Carkoon where it slowly digests its prey over thousands of years, a bit like that anemone and the unlucky garter snake.

John Lindsey’s column is special to The Tribune. He is PG&E’s Diablo Canyon marine meteorologist and a media relations representative. Email him at or follow him on Twitter: @PGE_John.
Related stories from San Luis Obispo Tribune