On June 2, 1973, a tropical depression formed about 250 miles (400 km) south of Salina Cruz, Oaxaca.

[3] Ava was also a hurricane with windspeeds rapidly increasing the closer to the eye they were measured.

[1] After its peak, Ava started weakening on June 7, as it continued its westward path.

This 14° error five days out was mainly due to its northward turn when it was a weakening depression.

[1] Astronauts acquired photographs of the hurricane,[4] which was big enough for Science Pilot Joseph Kerwin to describe it as "an enormous spiral" that was big enough to dominate the view outside the space station's window and prevent anything else from being seen.

[5] Astronauts also provided microwave data through Earth Resources Experiment Package sensors.

Satellite images were useful throughout the cyclone's existence, as did the wind reports of three ships when Ava was a young tropical storm.

The observations also provided confirmation that clouds that are not vertically developed very much can produce tropical rainfall.

[11] NOAA craft were laden with sensors and measured wave heights reaching 40 feet (12 metres) with a microwave radar system and a laser altimeter.

[12] Collectively, all of this measuring made Hurricane Ava the best-measured northeastern Pacific tropical cyclone at the time.

However, when it was a recently named tropical storm, Ava did cause sustained winds below gale-force to three ships called the Joseph Lykes, Hoegh Trotter, and Volnay.

[15] This span of 7,712 days, which Ava began and Emilia ended, is the longest time between successive Category 5 hurricanes in the northeastern Pacific, and anywhere worldwide, in recorded history.

[16] In addition, Ava is the strongest June tropical cyclone in the western hemisphere north of the equator.

[14] However, the official "Best track" data file and the seasonal summary in the Monthly Weather Review contradict that report and give maximum winds of 140 knots.

[20] However, the meteorological record for the eastern north Pacific are unreliable because geostationary satellite observation did not begin until 1966.