A powerful winter storm is set to slam the Sierra Nevada starting Tuesday evening, bringing heavy snowfall, strong winds and hazardous travel through Thursday, according to the National Weather Service.
A winter storm watch has been issued for the greater Lake Tahoe area and Mono, Lassen, eastern Plumas and eastern Sierra counties, with 2 to 3 feet of snow possible along the Sierra crest and 12 to 18 inches expected in lower-elevation areas. Winds gusting up to 70 mph could create “near whiteout conditions,” Monday’s forecast discussion said.
The storm system is predicted to bring some of the heaviest snowfall rates seen this season. Although it will likely contain less moisture than previous atmospheric river storms this winter, powdery snow should lead to higher accumulations.
“We are tracking more snow within this system,” said Gigi Giralte, a meteorologist with the weather service’s Reno office, noting February storms had area-wide impacts. “The last significant storm we had had multiple waves. This storm is bringing heavier snowfall rates, and we’ve got some larger snowfall totals we’re expecting right now.”
Because of the fluffier nature of the snow, there may be more volume. “We can get more accumulation just because the snowfall-liquid ratio is such that there’ll be more snow produced from one inch of liquid,” she added.
The weather service recommended drivers brace for widespread chain controls and nearly impossible travel along Interstate 80 at Donner Pass, Highway 50 at Echo Summit and other major Sierra passes.
The best travel window is through Tuesday, as conditions will likely deteriorate rapidly by Wednesday. Another weaker system is expected Thursday night into Friday, followed by a stronger storm Sunday into Monday.
Residents and travelers should take precautions ahead of the incoming storm. The National Weather Service’s Reno office recommends carrying an emergency kit with blankets, water, snacks and a flashlight in case of delays or road closures. Ensuring tires are properly inflated and carrying chains is crucial for those driving into the Sierra, as chain controls are expected to be widespread. Additionally, having a shovel, ice scraper and snow brush can help clear vehicles, if needed.
Travelers should check road conditions before departing using Caltrans QuickMap. For more information and updates, check weather.gov.
Electric fields in thunderclouds are often too weak to ignite a powerful discharge.
A new study just published in the Journal of Geophysical Research may have solved the mystery.
"We believe that that most lightning flashes in thunderstorms are ignited by cosmic ray showers," says the study's lead author Xuan-Min Shao, a senior scientist at the Los Alamos National Laboratory in New Mexico.
To investigate the earliest moments of lightning formation, Shao and colleagues built a radio interferometer named "BIMAP-3D." Consisting of an array of 8 antennas in Los Alamos, BIMAP-3D can make three dimensional images of lightning and pinpoint the bolts inside thunderclouds. Here's an example:
Caption: Colors in the image represent time. Blue traces the earliest moments of the bolt, while red denotes the end.
This is a lightning bolt from a massive thunderstorm that passed by Los Alamos on July 30, 2022. BIMAP-3D imaged more than 300 bolts during the 90-minute storm. It was a treasure trove of data.
The experimenters realized that some of the bolts they observed happened in parts of the storm where electric fields were too weak to cause the "Initial Breakdown Event" (IBE)--the initial spark that sets the lightning in motion. Modern theories of relativistic electron avalanche couldn't explain what they saw. Their suspicions soon focused on cosmic rays.
Cosmic rays are high energy particles that come from distant supernova explosions and other violent events across the cosmos. They strike Earth's atmosphere all the time, creating a secondary spray of particles called "cosmic ray showers." Regular readers are familiar with these showers because we routinely monitor them using Earth to Sky cosmic ray balloons over California.
One of the important things about cosmic ray showers is that they contain antimatter--positrons as well as ordinary electrons. The Los Alamos 3D lightning maps contained strong evidence for positrons. Electrons and positrons are bent in opposite directions by Earth's magnetic field, so they leave opposite imprints on the lightning's polarization, which BIMAP-3D also measured.
"It took me a while to figure this out," admits Shao. "I started with electrons only at the beginning, but could not explain the observations. With both electrons and positrons involved, all the observations can be consistently explained."
Positrons clinched the case for cosmic rays. "The fact that a cosmic ray shower provides an ionized path in the cloud that otherwise lacks free electrons strongly favor the inference that most lightning flashes are ignited by cosmic rays," the authors wrote.
In fact, it's still unclear how much of Earth's lightning is sparked by cosmic rays. Many more storms need to be studied with this method to improve the statistics. "This will require a lot of long-term and good quality lightning data," Shao says.
Funny... my husband and I were talking about ball lightning yesterday morning, out of the blue. (I can't remember that we ever mentioned or discussed ball lightning before)Ball lightning spotted after lightning strike during Alberta storm.
Ball was seen in Rich Valley, Alberta...
That sure looks like, lasted as long and popped at the end just like an American transformer popping on a distribution feeder.Here's the video of that big glowing sphere.
Edit: Oh, never mind. Already posted.