Dr. Wallace E. Howell, meteorologist at the Blue Hill Observatory, will conduct a $50,000 rain-making experiment that may end New York City's year-long water shortage, Mayor William O'Dwyer announced yesterday.

It will be the first practical rain-making test in the East. Howell plans to run it whenever conditions are favorable next week. He will shoot fine particles of silver iodide at cold-water clouds to cause condensation and precipitation.

If the scheme works it would end New Yorkers' dry Tuesdays and waterless weekends; city dwellers could shave two or three times a day and shower whenever they pleased.

O'Dwyer hopes the city's reservoirs can be refilled before heavy Summer consumption begins. In a statement emphasizing the importance of the test the mayor said, "If we succeed in making rain it might well be the experiment that will set a standard in solving water problems in many parts of the world."

The $50,000 will finance the first six months of what may be a year-long experiment. Howell will spot the clouds he wants to bombard by radar. Then he will either shoot rockets or drop pellets into the clouds from airplanes, causing ice formation, which precipitates rain.

This is a new technique believed far superior to the old clumsy method of dropping dry ice on the clouds from an aeroplane.