A storm heading southward from the Gulf of Alaska could dump as much as 3 inches of rain on Fresno and 3 feet of snow in the Sierra by the end of next week, the National Weather Service is forecasting.

But the amount of rain and snow could be lessened if a nearby high-pressure ridge causes the winter storm to waver offshore and drop some of its precipitation in the Pacific, meteorologist Andy Bollenbacher said Friday morning.

“So it’s a meandering disturbance, basically. So you think of the meandering disturbance, quote unquote, as an upper-level low that actually generates the potential for precipitation,” he said.

Forecasters will have a better idea by Monday whether the storm will hit Wednesday with more or less intensity, he said. The heaviest rains and snowfall would be Thursday and Friday, Bollenbacher said.

Rain and snow are forecast to begin Wednesday and continue for at least a few days, and possibly into the weekend. It has the potential to be Central California’s first major winter storm of the season.

Big Spread on Forecast Amounts

As of Friday morning, the storm forecast for Fresno ranged from sprinkles to 1.8 inches of rain, depending on the storm’s intensity, Bollenbacher said. The foothills at about 5,000 feet could get anywhere from a half-inch to 3 inches of rain, and snow will fall above 6,500 to 7,000 feet, with snow amounts ranging from 3 to 5 inches up to 3 feet, he said.

“There’s quite a bit of spread in the model uncertainty, just because of the timing, which potentially has a dramatic change in how much rain and snow we can see,” Bollenbacher said.