1973 Pacific hurricane season

Twelve storms, all from the east

The site and the current best track both count 12 tropical storms, 7 hurricanes and 3 major hurricanes. Every one formed in the eastern Pacific, often off Mexico, and none formed in the central Pacific. Six more tropical depressions left no surviving data. The season ran from 2 June to 9 October, and accumulated cyclone energy came to 114.6.

The Eastern Pacific Hurricane Center in Redwood City, California, issued advisories east of 140°W, and the Central Pacific Hurricane Center in Honolulu covered the waters to the west. Both worked alongside the National Weather Service forecast offices in those cities.

Hurricane Ava, watched from the air and from Skylab

Hurricane Ava formed south of Mexico on 2 June, moved slowly west and became a hurricane on 4 June. It reached major strength two days later and peaked at 140 kt, Category 5, on 7 June, the earliest date an eastern Pacific hurricane had reached that level. Ava weakened as it slowed and dissipated on 12 June without striking land or causing reported damage.

Ava was the first Pacific hurricane that NOAA aircraft flew into. Crews tested radar and other instruments and measured wind, pressure and wave heights, which is why Ava's 915 mb pressure comes from a measurement and not an estimate. Skylab passed directly overhead during one of its missions and photographed the storm. Ava stands as the strongest June storm and the only June Category 5 in the basin until 2010.

Doreen and Emily in July

Hurricane Doreen formed from the Intertropical Convergence Zone on 18 July and briefly reached Category 4 on 21 July. It weakened to a tropical storm as it crossed into the central Pacific on a path toward the Big Island. Two high-pressure areas then merged and turned Doreen southwest on 27 July. The storm swung back northwest, regained hurricane and then major hurricane strength, and dissipated on 3 August.

Doreen lasted 16.25 days and covered about 4,200 miles, tying Celeste's record for the longest-lasting Pacific hurricane; the archive gives it 384 recorded hours. The Greek ship Cornelia lost its rudder in 35-foot waves but reached Panama, and swells of 9 feet reached Kapoho on 29 July.

Hurricane Emily formed in the Gulf of Tehuantepec on 21 July and peaked at 120 kt, the same one-minute wind as Doreen, with a pressure of 972 mb, unusually high for a Category 4. Its broad wind field spread gales 300 miles east of the center. Hurricane Florence and Tropical Storm Glenda followed similar west-northwest paths without reported impact.

Landfalls along the Mexican coast

Tropical Storm Bernice struck about 50 miles southwest of Zihuatanejo on 23 June, and Tropical Storm Claudia came ashore about 30 miles east of Acapulco on 28 June. Tropical Storm Heather, the only storm to form in August, headed north toward the Gulf of Tehuantepec and dissipated just before landfall. None caused reported deaths.

Hurricane Irah reached 95 kt, Category 2, on 25 September and dropped back to Category 1 as it recurved toward the southern Baja California Peninsula. Its landfall there was the strongest of the season. It knocked down power and communication lines, destroyed at least ten houses in Cabo San Lucas and injured one person. Rain reached 10.24 inches at Sierra de la Laguna. Irah crossed the Gulf of California as a tropical storm and made a second landfall about 30 miles northwest of Los Mochis; forecasters had worried it might disrupt the Skylab 3 splashdown, which went ahead without serious trouble.

Tropical Storm Jennifer circled the southern side of Irah in a Fujiwhara interaction, brushed the Islas Marías and came ashore southeast of Mazatlán as a depression, with 7.48 inches of rain at San Blas. Hurricanes Katherine and Lillian stayed at sea to close the season.