A vast, stagnant hot air mass stretching from Louisiana to New York has stalled over much of the East Coast, making ovens of city streets and threatening to keep things miserable through the weekend.

The high pressure area, centered in West Virginia, has been more or less stalled for the last five days, according to meteorologist Dave Caldwell of the U.S. Weather Service.

No help is in sight, and temperatures are expected to remain in the 90s at least until early next week.

A spokesman for the Center for Environmental Physiology said yesterday his research group was issuing an "alert" because of the hot weather.

Calling heat a "major epidemiological problem in this country," Moulton Avery said most people, "particularly the elderly" don't realize that when it's hot they should try to stay cool.

Caldwell called yesterday's steamy atmosphere "fairly typical summer weather for Washington," well short of the 98-degree record for July 15 set for this area back in 1879. Yesterday never got above 95.

"Whenever it gets hot people start calling up all excited," Caldwell said. "They forget it was like this just a couple of weeks ago."

Meanwhile, approximately 200 employes at the Naval Intelligence Command headquarters in Suitland were sent home yesterday when an air conditioning failure sent temperatures in the building above 100 degrees.

William F. Madison, regional administrator for the General Services Administration, said a builder damaged a chilled-water feeder pipe, but said the system would be "back on line by Monday--or it's my head."

No other federal agencies reported sending employes home, but the GSA said one wing of the Interstate Commerce Commission-Customs Service building on Constitution Avenue lost air conditioning Thursday and Friday, affecting about 30 offices.

If the weather was hot yesterday it was at least clear enough for the National Aeronautics and Space Administration, which fired off a series of barium cloud experiments from the Wallops Island, Va., research facility.

A NASA spokesman said the two-stage Taurus-Orion rocket launched at 4:49 a.m. released two brightly colored clouds while ascending and one while descending to measure wind patterns in the upper atmosphere.

The drifting clouds, illuminated brightly by the predawn sunlight in the upper atmosphere, were visible from Portland, Me., to Fort Macon, N.C., the spokesman said.

A similar rocket experiment will be launched at 4:50 a.m. Saturday, weather permitting.