(CNN) People living near the Russian River in Northern California's Sonoma County were ordered to evacuate Tuesday ahead of possible flooding.

The Russian River is expected to rise about 14 feet over the next day, according to an alert sent by Sonoma County Emergency Services.

The river is expected to reach flood stage Tuesday evening and crest Wednesday night near record-level, Sonoma County Sheriff Sgt. Spencer Crum said. The sheriff's office said the river is projected to crest at 46.1 feet on Wednesday night.

Russian River keeps rising. Photos from Guerneville. See interactive flood map and more info at https://t.co/3E8qX9nNBl. Be prepared to evacuate if you live near the river. pic.twitter.com/ARtWup3EeG — Sonoma Sheriff (@sonomasheriff) February 26, 2019

Potentially thousands of people will be affected, not necessarily because of direct flooding, but stranded because of flooded roads, according to Crum.

Tues. 10:40am: Russian River expected to hit flood stage (32') at 6pm tonight in Guerneville. River expected to crest at 45.9 feet Wed. at 11pm In Guerneville. Lower Russian River residents, be prepared to move to higher ground. Photo from Monte Rio Bridge. pic.twitter.com/zxgAQr46nF — Sonoma Sheriff (@sonomasheriff) February 26, 2019

Areas are already being affected, and the National Weather Service expects heavy rainfall over the next couple of days.

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