New Pacific storm brings flood risk to Sierra foothills

A new Pacific storm forecast to bring heavy rain to the Sierra and flash flooding to the foothills prompted a flood watch that was to remain in effect into Friday night.

Rain and possible thunderstorms were expected for Friday, mainly after 10 a.m., the National Weather Service in Hanford said. New rainfall totals of between one-tenth and a quarter of an inch were expected for Merced, with possibly higher amounts from thunderstorms.

On Saturday, the chance of showers was forecast at 20 percent, with skies expected to be mostly sunny after 10 a.m., according to the weather service. Sunshine was expected to return Sunday through mid-week.

A flood watch was in place for the foothills from Mariposa to Tulare counties, and in the Sierra Nevada through 10 p.m. Friday, the weather service said.

“The heaviest rain is expected across the Sierra Nevada with lesser amounts toward the west side of the San Joaquin Valley,” the weather service said in a statement.

Rainfall accumulations of a half-inch to more than an inch are possible in the San Joaquin Valley, with 2.5 to 4.5 inches possible in the higher terrain, it said.

“Snow levels have risen to above 9,000 feet and will result in additional runoff from melting snow, but snow levels will gradually lower to around 7,000 feet by Friday afternoon.”

The storm is the latest in a string of sodden “Pineapple Express” weather-makers saturating California this winter. Since the rain season began in October, every month so far has been wetter than average for Merced.

In addition to wet weather this week, the National Weather Service said overnight lows have been unseasonably warm. Merced’s nighttime low on Wednesday was 59, compared with the average of 38 for the date.

The storm that hit the region earlier this week triggered mudslides and rockslides, threatened to rupture an earthen dam near Oakhurst and prompted some evacuation orders and advisories.

The Madera County Sheriff’s Office issued a pre-evacuation warning late Wednesday for an area southwest of Chowchilla due to increased flows down the Brenda Slough. The affected area includes: Highway 152 (Avenue 23) south to Avenue 18 1/2 between Robertson Boulevard and Road 16.

This story was originally published February 9, 2017 at 3:45 PM with the headline "New Pacific storm brings flood risk to Sierra foothills."