Rain and snow may return to Calaveras and Tuolumne counties later this week and into the weekend, with the best chances expected Wednesday and Thursday.

Forecasters say Sonora and other Mother Lode foothill towns along Highway 49 could receive a half-inch to one inch of rain between Wednesday and Saturday.

Higher in the Central Sierra, 4 to 6 inches of snow could fall at Ebbetts Pass on Highway 4, at Sonora Pass on Highway 108, and at Tioga Pass on Highway 120. All three passes are already closed for the winter.

The approaching system is coming off the Pacific and most of the rain and snow it’s bringing is expected to fall north of the Mother Lode.

“The heavier precipitation is going to be north of I-80 for Wednesday through Saturday,” Craig Shoemaker, a National Weather Service meteorologist in Sacramento, said New Year’s Day in a phone interview. Shoemaker was talking about Interstate 80, which crosses the Sierra Nevada north of Lake Tahoe.

Forecasters say confidence in their prediction for the wet weather pattern this week is “medium.”

The possible weather change should be welcome in the Mother Lode, where residents just came through one of the driest Decembers on record. It’s been a comparatively dry water year since Oct. 1, with less than 40 percent of average precipitation in the Central Sierra for Jan. 1.

A special weather statement issued at noon Monday says precipitation from the approaching system is expected to begin over coastal and northern California mountains Wednesday afternoon, then spread farther inland to the Sierra Nevada later Wednesday and into Thursday.

“Another storm brings more widespread rain and mountain snow Thursday night into early Saturday,” the special weather statement says. “Light to moderate precipitation expected with these storms. . . . Threat of scattered showers, mainly over the mountains, may continue over the weekend.”

For San Andreas, Angels Camp and Sonora, Tuesday and Wednesday are expected to be partly cloudy to mostly cloudy with daytime highs in the 60s and overnight lows in the 40s. Rain chances are 60 to 70 percent Wednesday night and Thursday.

If the approaching storm tracks south far enough to include the Mother Lode, foothill towns could get up to one inch of rain by Saturday. Snow levels could lower to 5,500 by Saturday morning. Wind gusts with the storm could reach 45 miles per hour on the most exposed ridges and peaks.

“This system looks like it started up in the Gulf of Alaska and now it’s coming out of the Central Pacific,” Mike Kochasic, another meteorologist with the National Weather Service in Sacramento, said Friday in a phone interview. “The last few days the model forecasts have been flip flopping. Our confidence is increasing for some rain.”

The federal Climate Prediction Center put out an “experimental 3-4 week outlook” that shows a good chance of above normal precipitation for Northern California from Jan. 6 to Jan. 19. Asked if he could add anything to that experimental long-term forecast, Kochasic said he could not.

Another “experimental 3-4 week outlook” for Jan. 13 to Jan. 26 shows drier weather might come back.

“We’re expecting an active period over the next two weeks and after that possibly drying,” Shoemaker said Monday. “Right now it’s looking dry the last half of January.”

The most recent Climate Prediction Center forecast, dated Dec. 29, says that jet stream extension across the Pacific later this month places most above-normal precipitation for the second half of January in the Alaskan Panhandle and other parts of the Pacific Northwest.

“Much of California and the Southwest is favored to experience below-normal precipitation given the favored jet placement being north of the region, and the background La Niña state favoring anomalous dryness,” the Climate Prediction Center forecast says, referring to Jan. 13 through Jan. 26.

Contact Guy McCarthy at gmccarthy@uniondemocrat.com or (209) 588-4585. Follow him on Twitter @GuyMcCarthy.