National Weather Service employees filed suit Thursday in federal court challenging the constitutionality of President Reagan's order requiring random drug testing.

The suit by the National Weather Service Employees Organization and 16 Northern California employees challenges Reagan's executive order, issued Sept. 15, 1986, as a violation of their constitutional rights against unreasonable search and seizure.The employee organization represents more than 5,000 weather service employees, including 3,500 meteorologists and meteorological technicians, under the jurisdiction of the Department of Commerce at 300 facilities around the nation.

The executive order mandates various executive agencies to establish drug testing programs for random testing of employees in "sensitive" positions.

The instructions were to give agency heads discretion to determine what jobs should be subject to random tests as "sensitive" jobs, but generally defined them as involving protection of "life, property, public health and safety."

The testing plan was called "unreasonable" by the employees, in part because it "does not measure workplace impairment." The employees contend there must be an individualized suspicion of drug use to require a tast.

Named at the top of the lawsuit was plaintiff John D. Quadros, a meteorologist at the Redwood City, Calif., Weather Service office and president of the National Weather Service Employees Organization.

Quadros and the others ask, among other things, that U.S. District Judge Robert Schnacke declare the order unconstitutional.