Two major Washington state east-west routes, White Pass and Stevens Pass, remain closed Monday evening after dayslong closures due to safety concerns, according to the Washington State Department of Transportation.

Officials briefly reopened Highway 12 over White Pass shortly after 3 p.m. Monday but closed it again shortly after 5:30 p.m. due to a rockslide and unstable slopes west of the summit, the agency said.

Geotechs will evaluate conditions Tuesday morning to determine next measures to safely reopen the pass, WSDOT said.

Additionally, the agency said Highway 2 Stevens Pass would not reopen before Wednesday, as crews continue to clear the area from dangerous road conditions.

Officials closed the state’s four main highway passes for nearly four days last week due to heavy snow, rain and avalanche dangers. Interstate 90 over Snoqualmie Pass and Blewett Pass on Highway 97 reopened Sunday evening, according to WSDOT.

WSDOT spokesperson Lauren Loebsack said the agency may need to perform additional avalanche control work, if an atmospheric river heading to the region Monday evening brings freezing rain and adds a heavy top layer over softer snowbanks.

Seattle Times staff reporter Mike Lindblom contributed to this report.