tropical cyclone
A tropical cyclone is a rapidly rotating storm system characterized by a low-pressure center, a closed low-level atmospheric circulation, strong winds, and a spiral arrangement of thunderstorms that produce heavy rain and squalls. Depen ...
meteorology
Meteorology is a branch of the atmospheric sciences (which include atmospheric chemistry and physics) with a major focus on weather forecasting. The study of meteorology dates back millennia, though significant progress in meteorology did no ...
. The most important system this year was
Hurricane Ava
Hurricane Ava was the earliest forming Category 5 hurricane on record in the East Pacific basin. The storm is also tied with 2006's Hurricane Ioke as the fifth-strongest Pacific hurricane on record. It was the first named storm of the 1973 Pacif ...
, which was the most intense
Pacific hurricane
A Pacific hurricane is a mature tropical cyclone that develops within the northeastern and central Pacific Ocean to the east of 180°W, north of the equator. For tropical cyclone warning purposes, the northern Pacific is divided into three regio ...
known at the time. Several other much weaker tropical cyclones came close to, or made landfall on, the Pacific coast of Mexico. The most serious of these was Hurricane Irah, which downed power and communication lines in parts of the Baja California Peninsula; the other landfalling storms caused rain and some flooding. No tropical cyclone this season caused any deaths.
This season had a quick start but a slow end. Overall activity was below average, with twelve named systems in total. Seven storms became hurricanes, of which three were major (Category 3 or higher on the Saffir-Simpson hurricane scale). Just one storm formed in August, one of the least active Augusts ever in the east Pacific. The season officially started May 15, 1973, in the eastern Pacific, and June 1, 1973, in the central Pacific, and lasted until November 30, 1973. These dates conventionally delimit the period of each year when most tropical cyclones form in the northeastern
Pacific Ocean
The Pacific Ocean is the largest and deepest of Earth's five oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean (or, depending on definition, to Antarctica) in the south, and is bounded by the contin ...
. All tropical cyclones this season formed in the eastern north
Pacific Ocean
The Pacific Ocean is the largest and deepest of Earth's five oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean (or, depending on definition, to Antarctica) in the south, and is bounded by the contin ...
, often off the coast of
Mexico
Mexico (Spanish: México), officially the United Mexican States, is a country in the southern portion of North America. It is bordered to the north by the United States; to the south and west by the Pacific Ocean; to the southeast by Guatema ...
. As is usual in the northern hemisphere, most traveled generally westward or northwestward, and two reached as far as the waters south of the Hawaiian Islands.
__TOC__
The season began with the formation of the pre-Ava tropical depression on June 2 and ended with the dissipation of Tropical Lillian on October 9. The season lasted a total of 129 days. No named storms formed in May, three in June, four in July, one in August, three in September, one in October, and none in November. Another six tropical depressions formed during the year, but data on them is unavailable. All of these tropical cyclones formed in the eastern north Pacific
tropical cyclone basin
Traditionally, areas of tropical cyclone formation are divided into seven basins. These include the north Atlantic Ocean, the eastern and western parts of the northern Pacific Ocean, the southwestern Pacific, the southwestern and southeastern Ind ...
, which encompasses the
Pacific Ocean
The Pacific Ocean is the largest and deepest of Earth's five oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean (or, depending on definition, to Antarctica) in the south, and is bounded by the contin ...
north of the equator east of 140°W. None formed in the central north Pacific, which is the remainder of the Pacific Ocean east of the international dateline.
Of the tropical cyclones that formed this year, were twelve tropical storms and seven were hurricanes. Of those hurricanes, three of them were major hurricanes because they reached Category 3 or higher on the Saffir-Simpson Scale. These totals are all below the long-term averages of thirteen tropical storms, nine hurricanes, and four major hurricanes. At the time, this season's total of twelve named tropical cyclones was exactly average, although at the time the climatology in this basin was weak because
satellite
A satellite or artificial satellite is an object intentionally placed into orbit in outer space. Except for passive satellites, most satellites have an electricity generation system for equipment on board, such as solar panels or radioi ...
coverage was spotty before 1966.
This season, all advisories and tropical cyclone data were released and collected by two agencies, the
Eastern Pacific Hurricane Center The Eastern Pacific Hurricane Center was formerly the center responsible for forecasting Pacific hurricanes in the eastern north Pacific east of 140°W. It was part of the Weather Bureau Forecast Office San Francisco and was based in Redwood City. ...
in
Redwood City, California
Redwood City is a city on the San Francisco Peninsula in Northern California's Bay Area, approximately south of San Francisco, and northwest of San Jose. Redwood City's history spans its earliest inhabitation by the Ohlone people to being a ...
, and the
Central Pacific Hurricane Center
The Central Pacific Hurricane Center (CPHC) of the United States National Weather Service is the official body responsible for tracking and issuing tropical cyclone warnings, watches, advisories, discussions, and statements for the Central Pacifi ...
in
Honolulu, Hawaii
Honolulu (; ) is the capital and largest city of the U.S. state of Hawaii, which is in the Pacific Ocean. It is an unincorporated county seat of the consolidated City and County of Honolulu, situated along the southeast coast of the island o ...
,. Retrieved 2009-05-20. both of which were coextensive with the
National Weather Service
The National Weather Service (NWS) is an agency of the United States federal government that is tasked with providing weather forecasts, warnings of hazardous weather, and other weather-related products to organizations and the public for the ...
Forecast Offices in their respective cities. The EPHC covered the area between the coast of North America and 140°W, and the CPHC the remainder of the area.
Systems
Hurricane Ava
A tropical depression formed on June 2. It steadily strengthened and headed in a generally westerly direction. It moved slowly and became Hurricane Ava on June 4. Two days later, it became a major hurricane and it sped up. On June 7, it became a Category 5 hurricane. It then started weakening and slowed down until it dissipated on June 12. No deaths or damages were attributed to Hurricane Ava.
Ava's minimum central pressure was 915
millibar
The bar is a metric unit of pressure, but not part of the International System of Units (SI). It is defined as exactly equal to 100,000 Pa (100 kPa), or slightly less than the current average atmospheric pressure on Earth at sea leve ...
s, and its
maximum sustained wind
The maximum sustained wind associated with a tropical cyclone is a common
indicator of the intensity of the storm. Within a mature tropical cyclone, it is found within the eyewall at a distance defined as the radius of maximum wind, or RMW. Unl ...
s reached . This made Ava the most intense recorded east Pacific hurricane at the time. Ava reached Category 5 intensity on June 7, the earliest date in an east Pacific season that a hurricane has done so. It was also the second known Category 5 storm in the east Pacific; (behind Patsy in 1959). Ava is the strongest June storm, the fifth most intense east Pacific hurricane, and was the only June Category 5 on record until 2010.
Ava was also flown into by hurricane hunter aircraft in what was the first penetration of a Pacific hurricane by NOAA aircraft. During these flights, radars and other devices were tested, and wind speed, pressure, and wave heights were measured. This is the reason why Hurricane Ava's pressure is measured instead of estimated. Ava was also photographed from
Skylab
Skylab was the first United States space station, launched by NASA, occupied for about 24 weeks between May 1973 and February 1974. It was operated by three separate three-astronaut crews: Skylab 2, Skylab 3, and Skylab 4. Major operations ...
because it was visible during one of the missions. At that time, it was coincidentally on the surface of the Earth directly underneath the space station. All in all, these made Hurricane Ava one of the best-observed
Pacific hurricane
A Pacific hurricane is a mature tropical cyclone that develops within the northeastern and central Pacific Ocean to the east of 180°W, north of the equator. For tropical cyclone warning purposes, the northern Pacific is divided into three regio ...
s at the time.
Tropical Storm Bernice
A nearly stationary disturbance in the Intertropical Convergence Zone spent three days organizing and finally developed into a tropical depression on June 22. The cyclone started heading northwest. After intensifying into a tropical storm, Bernice made landfall on June 23 at a location roughly southwest of
Zihuatanejo
Zihuatanejo (), or Ixtapa-Zihuatanejo, is the fourth-largest city in the Mexican state of Guerrero. It was known by 18th century English mariners as Chequetan or Seguataneo. Politically the city belongs to the municipality of Zihuatanejo de Azue ...
. It dissipated later that day. Bernice exposed two ships to
gale
A gale is a strong wind; the word is typically used as a descriptor in nautical contexts. The U.S. National Weather Service defines a gale as sustained surface winds moving at a speed of between 34 and 47 knots (, or ).Acapulco. It dissipated inland the next day. No deaths or casualties were reported due to this tropical cyclone.
Hurricane Doreen
On July 18, a tropical storm formed from a disturbance in the Intertropical Convergence Zone and was named Doreen. It steadily intensified, and became a hurricane on July 19. Doreen briefly reached Category 4 strength on July 21 with a relatively high central pressure of . It then weakened steadily as its path carried it on a direct path to the Big Island of Hawaii. Doreen weakened to a tropical storm as it entered the
Central Pacific Hurricane Center
The Central Pacific Hurricane Center (CPHC) of the United States National Weather Service is the official body responsible for tracking and issuing tropical cyclone warnings, watches, advisories, discussions, and statements for the Central Pacifi ...
's area of responsibility on July 25. A frontal system stuck between two
high-pressure area
A high-pressure area, high, or anticyclone, is an area near the surface of a planet where the atmospheric pressure is greater than the pressure in the surrounding regions. Highs are middle-scale meteorological features that result from interpl ...
s weakened as the two areas merged, creating a larger high pressure area that turned Doreen to the southwest on July 27. The hurricane then turned back to the northwest and strengthened back into a hurricane. It became a major hurricane again before weakening. Doreen dissipated August 3. Its remnant vortex continued westward until it dissipated under a trough near the dateline. Doreen's sudden change of track and restrengthening was unusual.
From formation to dissipation, Doreen lasted 16.25 days and traveled a distance of . This tied Hurricane Celeste's record for longest-lasting Pacific hurricane. Doreen was also the longest-lasting July tropical cyclone.
Hurricane Fico
Hurricane Fico was the longest-lived hurricane of the 1978 Pacific hurricane season and became the longest-lasting Pacific hurricane on record, a record broken by Hurricane Tina fourteen years later. The sixth tropical storm, fourth hurricane, ...
broke both of these records in the 1978 season. Doreen remains the eighth-longest lasting Pacific tropical cyclone, tied with two other storms. Several ships encountered Doreen. The most serious incident involved a Greek ship called ''Cornelia'' which lost its rudder in waves, but managed to escape and continue on its way to Panama. On the afternoon of July 29, swells and waves were seen from Kapoho. Otherwise, no damages or deaths were blamed on this tropical cyclone.
Hurricane Emily
A depression formed July 21 from squalls in the
Gulf of Tehuantepec
Gulf of Tehuantepec () is a large body of water on the Pacific coast of the Isthmus of Tehuantepec, southeastern Mexico, at . Many (but not all) Pacific hurricanes form in or near this body of water. A strong, gale-force wind called the Tehu ...
and headed west-northwest and strengthened into a tropical storm. Emily continued moving nearly parallel to the coast before turning to the west while steadily intensifying. Emily eventually reached Category 4 intensity on July 22. Emily then weakened as it turned to the northwest. It dissipated on July 28. Emily's wind field was large enough to bring gales areas east of the hurricane from July 22 to 24. This tropical cyclone caused no deaths or damage. Emily had a pressure of 972 mbar, which is unusually high for a hurricane of Category 4 strength.
Hurricane Florence
On July 25, a depression formed off the coast of Guatemala. The storm made a close approach to the Mexican coast as a depression, but did not make landfall. Just after that, it strengthened into a tropical storm. Florence headed west and then west-northwest. It became a hurricane on July 29. It began weakening thereafter. Florence dissipated on July 30. No damages or deaths were reported.
Tropical Storm Glenda
A depression that had formed on July 30 from a tropical disturbance quickly strengthened into a tropical storm and was named Glenda. It took a path similar to both Florence and Emily, but further from the shore. Glenda dissipated August 5. At the time it still had winds of , down from its peak of . No deaths, damage, or other impact was reported.
Tropical Storm Heather
The only storm to form in August this year formed on August 31 from an area of circulation in the ITCZ over the
Gulf of Tehuantepec
Gulf of Tehuantepec () is a large body of water on the Pacific coast of the Isthmus of Tehuantepec, southeastern Mexico, at . Many (but not all) Pacific hurricanes form in or near this body of water. A strong, gale-force wind called the Tehu ...
. It became a tropical depression on August 30. After moving northwest for a bit, it became a tropical storm and headed almost due north towards Mexico. Heather dissipated September 1, just before making landfall. Tropical Storm Heather caused no deaths or damage to any location in the coastal area of the Gulf of Tehuantepec.
Hurricane Irah
A depression formed September 22. It became a tropical storm on September 23 and a hurricane on September 24. Irah took a northwesterly path and reached Category 2 strength on the Saffir-Simpson Hurricane Scale, and then dropped back down to a 1 as it recurved. It made landfall on
Baja California
Baja California (; 'Lower California'), officially the Free and Sovereign State of Baja California ( es, Estado Libre y Soberano de Baja California), is a state in Mexico. It is the northernmost and westernmost of the 32 federal entities of Mex ...
and entered the
Gulf of California
The Gulf of California ( es, Golfo de California), also known as the Sea of Cortés (''Mar de Cortés'') or Sea of Cortez, or less commonly as the Vermilion Sea (''Mar Bermejo''), is a marginal sea of the Pacific Ocean that separates the Baja C ...
as a tropical storm, making landfall again in northwestern Mexico approximately northwest of
Los Mochis
Los Mochis () is a coastal city in northern Sinaloa, Mexico. It serves as the municipal seat of the municipality of Ahome. As of the 2010 census, the population was 362,613, which was 61 percent of the municipality's population.
Los Mochis is th ...
. Irah's first landfall was the strongest of the season. The hurricane dissipated on September 27 while heading east-northeast over mainland Mexico.
Irah blew over some
power
Power most often refers to:
* Power (physics), meaning "rate of doing work"
** Engine power, the power put out by an engine
** Electric power
* Power (social and political), the ability to influence people or events
** Abusive power
Power may a ...
Sierra de la Laguna
The Sierra de la Laguna is a mountain range at the southern end of the Baja California Peninsula in Mexico, and is the southernmost range of the Peninsular Ranges System.
It is located in La Paz Municipality and Los Cabos Municipality of sout ...
. One person was injured and at least ten houses were destroyed in Cabo San Lucas. No one was killed. There was some concern that the hurricane could disrupt
splashdown
Splashdown is the method of landing a spacecraft by parachute in a body of water. It was used by crewed American space capsules prior to the Space Shuttle program, by SpaceX Dragon and Dragon 2 capsules and by NASA's Orion Multipurpose Crew ...
procedures for astronauts at the end of
Skylab 3
Skylab 3 (also SL-3 and SLM-2) was the second crewed mission to the first American space station, Skylab. The mission began on July 28, 1973, with the launch of NASA astronauts Alan Bean, Owen Garriott, and Jack Lousma in the Apollo command ...
; however, the return to Earth was not seriously affected.
Tropical Storm Jennifer
On September 23, another depression formed. It took a northeasterly path, rotating around the southern periphery of Hurricane Irah as part of a Fujiwhara interaction. It strengthened into a tropical storm late on September 24. The peak windspeed of this tropical cyclone was . Jennifer then weakened to a depression and turned to the north-northeast. Jennifer brushed the
Islas Marías
The Islas Marías ("Mary Islands") are an archipelago of four islands that belong to Mexico. They are located in the Pacific Ocean, some off the coast of the state of Nayarit and about southeast of the tip of Baja California. They are part of t ...
. The cyclone made landfall near just southeast of
Mazatlán
Mazatlán () is a city in the Mexican state of Sinaloa. The city serves as the municipal seat for the surrounding '' municipio'', known as the Mazatlán Municipality. It is located at on the Pacific coast, across from the southernmost tip ...
and dissipated September 27. Tropical Depression Jennifer caused rain over several parts of Mexico. The highest total was at Navarette/ San Blas. No one was killed and no damage was reported.
Hurricane Katherine
Katherine became a tropical storm on September 29, just six hours after forming. It headed out to sea. On October 1, it became a Category 2 hurricane. It peaked in windspeed the next day. After weakening to storm strength, it crossed 140°W and entered the central Pacific. Katherine continued its slightly south of westward track. It dropped to a depression on October 9, and dissipated shortly after that due to the influence of a cold trough
Hurricane Lillian
A depression that formed October 5 reached storm strength the same day. It generally paralleled the coast of Mexico far offshore. Lillian reached minimal hurricane strength on October 7 and peaked the next day. The hurricane began to weaken immediately thereafter and dissipated on October 9. Through its life, Lillian at first traveled generally west-northwestward, and then westward. Lillian never threatened land, causing no known impact.
Storm names
These names were used for storms that formed in the eastern Pacific during this season. It is the same list used in the 1969 season. Storms were named Katherine and Lillian for the first time this year. No names were retired, so this list was used again in the 1977 season. Names that weren't assigned are colored gray.
The Central Pacific used names and numbers from the Western Pacific's typhoon list. No systems formed in the area, and thus no names were required.
Season effects
This is a table of all of the storms in the 1973 Pacific hurricane season. It includes their durations, peak intensities, names, landfall(s), damages, and death totals. Deaths in parentheses are additional and indirect (an example of an indirect death would be a traffic accident), but are still storm-related. Damage and deaths include totals while the storm was extratropical or a wave or a low.
See also
*
List of Pacific hurricanes
This is a list of notable Pacific hurricanes, subdivided by reason for notability. Notability means that it has met some criterion or achieved some statistic, or is part of a top ten for some superlative. It includes lists and rankings of Pacific ...
*
Pacific hurricane season
A Pacific hurricane is a mature tropical cyclone that develops within the northeastern and central Pacific Ocean to the east of 180°W, north of the equator. For tropical cyclone warning purposes, the northern Pacific is divided into three regio ...
*
1973 Atlantic hurricane season
The 1973 Atlantic hurricane season was the first season to use the Saffir–Simpson hurricane scale, a scale developed in 1971 by Herbert Saffir and Robert Simpson to rate the intensity of tropical cyclones. The season produced 24 tropical an ...
*
1973 Pacific typhoon season
The 1973 Pacific typhoon season has no official bounds; it ran year-round in 1973, but most tropical cyclones tend to form in the northwestern Pacific Ocean between June and December. These dates conventionally delimit the period of each year when ...