Atmospheric River Flowing Toward NorCal: Timeline

SAN FRANCISCO, CA — The phrase "atmospheric river" is back in the weather forecast for Northern California — the same "conveyer belt of moisture" that drenched the area for three straight weeks from late December to mid-January, according to the National Weather Service.

While scattered showers can be expected throughout the week, the weather service reports that the potent atmospheric river will arrive Thursday and continue through Friday. In fact, the weather service has issued a flood watch.

The storm is coming from the tropics in the Pacific Ocean, with an increasing possibility of several inches of rain. The areas at highest risk of more than 2 inches of rainfall include the North Bay, elevated parts of the peninsula in San Mateo County, southern Monterey County and the Central Valley.

Since the moisture is coming from the tropics, the rain could prove to be a threat for the deep Sierra snowpack.

Related: 'Huge Gains' In CA Snowpack Free Half Of State From Drought

The National Weather Service in Reno cautions residents that snow at 5500 feet or lower is at risk of being melted by the rain.

Keep up to date on the latest forecast at AccuWeather. Put in your zip code for a hyperlocal forecast.

Bay City News contributed to this story.