A cold storm sliding in from the Pacific Northwest will impact San Diego County later in the week and going into the weekend, but forecasters were uncertain Monday whether the precipitation would produce significant rain and snow.

According to the National Weather Service, a trough of low pressure will push down from the Gulf of Alaska and reach Southern California Thursday.

The system will generate “unsettled” conditions, with rain at the lower elevations and snow in the mountains, though how much was “highly uncertain at this time,” according to the NWS.

Prognostication charts published by the Weather Service showed rain developing midday Thursday and continuing sporadically into Saturday night throughout the region.

“The highest chances for rain currently are Thursday night into Friday, but this could potentially change as we get closer to the event,” the NWS said.

The mercury will tend to the low side all week, with many lower elevations reaching the low 60s and higher mountain elevations staying in the 40s.

Forecasters said another trough will edge toward Southern California over the weekend, on the heels of the first one, potentially producing rain showers on Sunday or Monday.

City News Service contributed to this article.