Alemany Boulevard completely flooded in San Francisco, no estimated time of reopening

Jack Lam, a Caltrans equipment operator, works at a freeway onramp along Alemany Boulevard to unclog a drain in a flooded area closed to traffic on Wednesday, February 13, 2019 in San Francisco, Calif. Jack Lam, a Caltrans equipment operator, works at a freeway onramp along Alemany Boulevard to unclog a drain in a flooded area closed to traffic on Wednesday, February 13, 2019 in San Francisco, Calif. Photo: Lea Suzuki, The Chronicle Buy photo Photo: Lea Suzuki, The Chronicle Image 1 of / 75 Caption Close Alemany Boulevard completely flooded in San Francisco, no estimated time of reopening 1 / 75 Back to Gallery

Flood-prone Alemany Boulevard has done it again.

After more than 12 hours of nonstop rain, the roadway completely flooded near the Highway 101 and Interstate 280 interchange in San Francisco. The onramps to 101 and were closed due to high water levels.

Drivers who tried to circumvent the flooding with a little off-roading found themselves stuck in the mud, reported KGO's Lyanne Melendez.

ALSO: New satellite captures enormity of Bay Area atmospheric river

Photos and video showed Caltrans crews trying to clear clogged storm drains and slowly reduce the flooded mess. Multiple local outlets reported there was no estimated time of reopening Alemany Boulevard.

Check out more tweets from the flooded scene below:

HAPPENING NOW: Bottom of Alemany right at 101 & 280 entrance, major flooding. These cars wanted to take a short cut through the grass and are now stuck. pic.twitter.com/y7kV7PBZOF — Lyanne Melendez (@LyanneMelendez) February 13, 2019

101 S on ramp is a no go here. Flooded by Alemany. Public Works crews on scene. Caltrans trucks in the area too. @nbcbayarea pic.twitter.com/RmvjdPmZjX — Christie Smith (@christies_nbc) February 13, 2019

Alemany on-ramp to NB and SB 101 closed due to flooding no estimate for reopening pic.twitter.com/YF33NrDJFa — Christien Kafton (@CKaftonKTVU) February 13, 2019

Localized flooding was a problem around the Bay Area as heavy rain pounded the region Wednesday. The greatest concern for flooding in the coming days is the North Bay, according to forecasters. The Russian River is expected to swell 6 feet above flood stage by Friday.

The Napa River in Napa and St. Helena, and the Navarro River near Highway 1 are also expected to reach flood stage or higher.

Read Alix Martichoux's latest stories and send her news tips at amartichoux@sfchronicle.com.

Start receiving breaking news emails on wildfires, civil emergencies, riots, national breaking news, Amber Alerts, weather emergencies, and other critical events with the SFGATE breaking news email. Click here to make sure you get the news.