Storm of 1862 made an inland sea

My mother’s ancestors came to California by covered wagon over the Sierra Nevada in the summer of 1847, a few months after the Donner Party tragedy. They settled in the vast Sacramento Valley in what is now Colusa County and tried to build a future along the fertile banks of the Sacramento River.

About 13 years later, they took refuge on the nearby Sutter Buttes because of one of the worst floods ever to hit California.

Many years ago, my grandmother, Frances Graham, passed along this bit of family folklore to me from her mother about a deluge of biblical proportions that occurred in 1862.

The flood devastated their farm. She said it was like nature taking revenge for the hydraulic mining that took place during the California Gold Rush. Many called this flood the “Noachian deluge of California Floods.”

Toward the end of 1861, a series of storms produced nearly continuous rain that lasted through February over most of California.

Los Angeles recorded nearly 36 inches of rain while Sonora in the Sierra Nevada foothills measured more than 100 inches!

By February 1862, the Sacramento and San Joaquin valleys became almost an inland sea stretching nearly 300 miles in length, forcing the state capital in Sacramento to move to San Francisco.

In addition, the normally salty waters in San Francisco and San Pablo Bay became nearly fresh with a continuous and nearly unimaginably heavy flow of silted water through the Golden Gate.

The Santa Ana River in Southern California became a raging torrent, laying waste to farms along its banks. River settlements throughout California were inundated.

Of course no one alive today witnessed this terrible series of storms, and weather data from so long ago is sparse.

However, a few weather experts believe that atmospheric rivers stretching across the Pacific Ocean channel vast amounts of water vapor from near the equator into large storms coming out of the Gulf of Alaska.

Atmospheric river-transported moisture from a weakening typhoon in the Western Pacific significantly enhanced the storm that struck San Luis Obispo County with record amounts of rainfall Oct. 13-14, 2009. This condition is also sometimes called the Pineapple Express.

After Hurricane Katrina, concern about widespread flooding in parts of the nation became heightened, especially with climate change.

In January, the U.S. Geological Survey, the Federal Emergency Management Agency and the California Emergency Management Agency convened the ARkStorm Summit.

A team of federal, state, academic and business experts attended the event to consider emergency planning if another storm of this magnitude was to hit.

This week’s forecast

A very cold upper-level, low-pressure system moved over San Luis Obispo County on Saturday and produced snow flurries down to about 1,000 feet along with scattered rain showers and hail.

Mostly clear skies and a very cold air mass has allowed air temperatures to plummet into the mid-20s in the North County and low 30s in the coastal valleys and even along beaches this morning with widespread frost throughout the county.

Fair and warmer weather will occur later today with highs in the 50s. Another cold morning is expected Monday, but the minimums will be a little warmer than this morning’s.

Warmer and mostly clear weather will develop Monday afternoon into Tuesday with temperatures reaching the 60s.

The weather pattern will take a turn toward mild temperatures and wet and windy weather Wednesday as a somewhat subtropical weather system crosses the Central Coast.

This front is forecast to pass over the Central Coast later Wednesday with strong to gale-force (25 to 38 mph) southeasterly winds and moderate to heavy rain.

Showers will continue into Thursday morning with dry weather returning Thursday afternoon and Friday. Rain amounts with this system could range between 1 and 2 inches. Another potentially very wet weather system will approach the Central Coast with another round of heavy rain and gusty winds next weekend.

Surf and sea report

Today’s 6- to 8-foot northwesterly (300-degree deep-water) sea and swell (with a 7- to 13-second period) will decrease to 4 to 6 feet (with an 8- to 11-second period) by tonight.

A 3- to 5-foot northwesterly (300-degree deep-water) swell with a 9- to 15-second period is forecast along our coastline Monday and Tuesday.

Increasing southerly winds will generate 7- to 9-foot southerly (195-degree shallow water) seas Wednesday, followed by a 6- to 8-foot (270-degree deep- water) swell with a 10- to 12-second period Thursday.

This swell will lower to 3 to 5 feet (with an 8- to 11-second period) Friday.

Today’s longer-range models are not indicating any high-energy swells in the next two weeks.

Seawater temperatures will range between 54 and 56 degrees through Friday.

Be a weather spotter

The National Weather Service will conduct Weather Spotter Training at the PG&E Energy Education Center on Monday at 6:30 p.m.

The National Weather Service Storm Spotter Program is a volunteer organization of people with an interest in the weather. Whenever significant weather is occurring, weather spotters call in a report to the National Weather Service. These reports provide important ground truth for forecasters.

This training session is free and open to the public. Anyone interested in volunteering to be a storm spotter for the National Weather Service is welcome.

John Lindsey is a media relations representative for PG&E. He is also a local weather expert and has lived along the Central Coast for nearly 25 years. To subscribe to his daily weather forecast or ask him a question, e-mail pge weather@pge.com.