Hefty amounts of rain and snow expected in central San Joaquin Valley, Sierra

Up to an inch of rain or more could fall on the central San Joaquin Valley on Tuesday, the National Weather Service said, as the first in a series of El Niño-fueled storms arrives in California.

Around the Valley, workers were preparing by making sandbags available to residents and pumping water through the basin systems, but the storms are expected to drop large amounts of rain over a long period instead of brief, strong showers that frequently cause flooding.

“It will pretty much be a steady rain,” said David Spector, a meteorologist for the National Weather Service in Hanford.

Tuesday’s rains will amount to between 0.75 inches and 1.25 inches in the Valley. On Wednesday into Thursday, a second, slightly colder storm will bring about half an inch of rain. Two more weaker systems could bring additional rain Friday and Saturday, Spector said.

As of Monday, Fresno’s seasonal total was 5.20 inches, which is 1.51 inches – or 29 percent – above the normal for the date of 3.69 inches.

Preparations were underway to ensure roads won’t flood and basins will have enough capacity to store excess water.

Some of the flood-prone locations in the city of Fresno, such as Shields and Wishon avenues and Marks and Shaw avenues, likely will handle the storms without flooding provided there isn’t a sudden torrent, said Mark Standriff, city spokesman.

If there is, he said, the city has a “storm SWAT team” ready to combat any problems.

About 160 water-retention basins around the Fresno-Clovis area have capacity for a record 48-hour storm, said Alan Hofmann, general manager for the Fresno Metropolitan Flood Control District.

He said the “winter criteria” is to keep enough room in the basins for a storm that will drop 3.5 inches in the Valley, the largest 48-hour downpour on record.

“When we have trouble is when there are a continual series of storms on consecutive days and we can’t pump the basins out as fast as the water comes in,” he said.

In Clovis, streets have been cleared since most trees are bare of leaves, said Luke Serpa, the city’s public utilities director.

A storm over a few days totaling 1.5 inches to 2 inches “shouldn’t cause us too much of a problem,” he said.

Fresno County has some localized problems in the Fig Garden, Mayfair and Tarpey areas, said Alan Weaver, public works and planning director, but he doesn’t expect the series of storms to cause issues.

In rural areas, maintenance crews are always on the alert for problems near Mendota, along Belmont Avenue and the Panoche Creek, and the Highway 269 bridge north of Huron, officials said.

A $24 million Huron bridge replacement is expected to begin some time next year, which would allow passage during the worst storms. The project is expected to be finished in 2018, said Tony Boren, executive director for the Fresno Council of Governments.

A winter storm warning has been issued by the weather service for the Sierra above 6,000 feet from Yosemite National Park to the Tulare-Kern counties line. Up to 16 inches of new snow was forecast from 10 p.m. Monday to 10 p.m. Tuesday.

Under such a warning, motorists need to use caution when driving in the mountains and be prepared to put on chains if required. Roads also could be closed. To check road conditions, call Caltrans at 800-427-7623 or visit http://www.dot.ca.gov/cgi-bin/roads.cgi.

Snow already had started to fall Monday afternoon in the central Sierra.

Another storm is expected Wednesday, and it will be colder and pack less precipitation. The snow level will drop to 4,500 feet by Wednesday afternoon.

The colder storms expected Thursday afternoon through Friday morning will drop snow levels to 3,500 feet.

The precipitation is the result of the El Niño condition that exists along the West Coast.

Statewide impact

El Niño storms finally are lined up over the Pacific and rain is expected to last for most of the next two weeks, forecasters said Monday.

As much as 15 inches of rain could fall in the next 16 days in Northern California, with about 2 feet of snow expected in the highest points of the Sierra Nevada, said Johnny Powell, a forecaster with the National Weather Service.

To the south, persistent wet conditions could put some Los Angeles County communities at risk of flash-flooding along with mud and debris flows, especially in wildfire burn areas.

The brewing El Niño system – a warming in the Pacific Ocean that alters weather worldwide – is expected to affect California and the rest of the nation in the coming weeks and months.

Its effects on California’s drought are difficult to predict, but Jet Propulsion Laboratory climatologist Bill Patzert said it should bring at least some relief from the four-year drought that has left the state parched.

Doug Carlson, spokesman for the California Department of Water Resources, pointed out that the drought has left California with a water deficit that is too large for one El Niño year to totally overcome.

Come April 1 – when the snowpack typically is at its deepest – water managers will be better able to gauge the situation.

El Niños in the early 1980s and late 1990s brought about twice as much rain as normal, Patzert said. The weather also caused mudslides, flooding and high surf.

In recent weeks, a weather pattern partly linked with El Niño has turned winter upside-down across the nation, bringing spring-like warmth to the Northeast, a risk of tornadoes in the South, and so much snow across the West that even ski slopes have been overwhelmed.

Big parts of the country are basking in above-average temperatures, especially east of the Mississippi River and across the Northern Plains.

In Los Angeles County foothills beneath wildfire burn areas, residents braced Monday for possible flash flooding and debris flows. Workers in Azusa cleared storm drains and handed out sandbags, while in nearby Glendora, police announced restricted parking measures for steep roadways under barren hillsides.

Residents were urged to monitor weather reports and consider stockpiling sandbags.

Marc Benjamin: 559-441-6166, @beebenjamin. The Associated Press contributed to this report.

Do-it-yourself flood protection:

Sand and sandbags are available 24 hours a day to people living in unincorporated areas of Fresno County at the following work yards. Residents need to take their own shovels to do the filling:

▪ Biola, Area 4 Road Yard, 12855 W. G St.

▪ Fresno-Clovis area, Area 7 Road Yard, 9400 N. Matus Ave.

▪ Sanger, Area 8 Road Yard, 9525 E. Olive Ave.

Clovis residents can fill sandbags at the City Corporation Yard, 155 N. Sunnyside Ave.