Storms Dump Billions of Gallons of Water Into Lake Tahoe

Blake Everett via Wikimedia Commons
Blake Everett via Wikimedia Commons

Violent storms in Northern California have deposited 33.6 billion gallons of water into Lake Tahoe, where the water level has risen by an entire foot since January 1.

The appearance of a 12-inch-high sheet of water would be dramatic in any body of water, but Lake Tahoe is massive, with a surface area of 191 square miles. And over the past six years, it’s been very, very dry.

The downpour has filled lakes and reservoirs across the region. In the last two weeks alone, storms have dumped a combined 1.3 million acre-feet of water into the 154 largest reservoirs in the state. State hydrologists say those reservoirs are currently filled to about 97 percent of their capacity. That's an impressive change from the same date last year, when the ongoing drought left them at or below 50 percent of normal levels.

In some ways the storms were right on time, as experts had begun to worry about regional water supplies. But all extreme weather events—even welcome ones—have their downside. Flooding from surging rivers has forced thousands of residents to evacuate their homes.

Jana Frazier is a tour guide for the Department of Water Resources at Lake Oroville. She says that lake has risen more than 90 feet since December, swelling above the boat ramp and edging into the parking area.

“It’s really weird,” she told the Los Angeles Times. “We’ve been in low water for so long, it seems strange to drive across the dam and see it almost full.”

Officials say it’s still too soon to declare an official end to the drought, but more storms are expected over the coming week.

What Is a Bomb Cyclone?

Maddie Meyer/Getty Images
Maddie Meyer/Getty Images

The phrase bomb cyclone has re-entered the news this week as parts of the central U.S. face severe weather. Mountain and Midwestern states, including Colorado, Nebraska, Wyoming, and South Dakota, all fall in the path of a winter storm expected to deliver tornadoes, hail, heavy snow, flooding, and hurricane-force winds on Wednesday, March 13 into Thursday. It seems appropriate for a storm that strong to have bomb in its name, but the word actually refers to a meteorological phenomenon and not the cyclone's explosive intensity.

According to The Denver Post, the bomb in bomb cyclone stands for bombogenesis. Bombogenesis occurs when a non-tropical storm experiences at least a 24 millibar (the unit used to measure barometric pressure) drop within 24 hours. Low pressure makes for intense storms, so a bomb cyclone is a system that's built up a significant amount strength in a short length of time.

This type of storm usually depends on the ocean or another large body of water for its power. During the winter, the relatively warm air coming off the ocean and the cold air above land can collide to create a sharp drop in atmospheric pressure. Also known as a winter hurricane, this effect has produced some of the worst snowstorms to ever hit the U.S.

The fact that this latest bomb cyclone has formed nowhere near the coast makes it even more remarkable. Rather, a warm, subtropical air mass and a cold, Arctic air mass crossed paths, creating the perfect conditions for a rare bombogenesis over the Rockies and Great Plains states.

Central U.S. residents in the bomb cyclone's path have taken great precautions ahead of the storm. Over 1000 flights have been canceled for Wednesday and schools throughout Colorado have closed.

[h/t The Denver Post]

Watch a Rare ‘Ice Tsunami’ Slam Lake Erie

Clean Lakes Alliance, Flickr // CC BY 2.0
Clean Lakes Alliance, Flickr // CC BY 2.0

A combination of freezing cold temperatures and high winds is creating an unusual phenomenon along Lake Erie. As KDKA reports, ice tsunamis are toppling onto lake shores, and many locals have been asked to stay inside and even evacuate their homes.

On February 24, 2019, the National Weather Service in Buffalo, New York issued a warning about dangerous wind gusts in the Lake Erie area. The service urged citizens to seek shelter indoors and avoid traveling if possible. Winds peaked at 74 mph earlier this week, the level of a Category 1 hurricane, and tore down trees and power lines throughout the region.

People who got close to Lake Erie during the windstorm witnessed a rare event known as an ice tsunami. When wind pushed ice on the lake's surface toward the retaining wall, the sheet broke apart and dumped massive ice chunks on the shore. The video below captures the phenomenon.

In some areas, the ice piles grew so large that roadways had to be closed. Residents of Hamburg, New York's Hoover Beach area were asked to voluntarily evacuate due to the encroaching ice.

Ice tsunamis, or ice shoves, are rare, but in some cases they can be life-threatening. In 2013, waves of ice shards from a Minnesota lake destroyed people's homes.

[h/t KDKA]

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