1970 Pacific hurricane season
Encyclopedia
The 1970 Pacific hurricane season began on May 15, 1970 in the east Pacific
, and on June 1, 1970 in the central Pacific. It ended on November 30, 1970. These dates conventionally delimit the period of time when tropical cyclone
s form in the eastern Pacific Ocean.
This season had an above average number of storms. There were twenty-one tropical cyclones, of which eighteen reached tropical storm strength. Four storms became hurricanes, of which none reached major hurricane strength. In the central Pacific, one hurricane and one tropical depression formed. One of the depressions crossed the dateline to become a typhoon.
, and it dissipated on June 7. Despite that it remained away from any land masses, Adele was retired after this season for unknown reasons.
estimated it had winds of 115 mph (185 km/h). Without a chance to strengthen further, Lorraine weakened, finally dissipating on August 27 due to dry air.
. It headed west-northwestward, becoming a tropical storm that night and reaching a peak of 60 mph (97 km/h) winds on August 23. A westward turn saved Hawaii from a direct hit, but Maggie still brought strong surf and heavy yet beneficial rain to the island of Hawaii
.
. As Norma dissipated, record rains fell over the state from September 4 to September 6.
The rains were deadly. There were a total of 22 deaths, including 14 from a flash flood
on a creek. The damage amounted to over 1 million dollars.
and Midway Island
but remaining in the Central Pacific. Dot turned to the northeast, reaching tropical storm strength on September 2 and hurricane strength September 3 before being absorbed by a cold core system the next day. When Dot became a hurricane at 35° north, it became the second highest latitude for a storm to reach hurricane strength, only behind Hurricane 12 of the 1975 season
.
on September 8, having maintained a northeast track for its short lifetime.
. Names not retired from this list were used again in the 1974 season
. Storms were named Norma, Orlene, Patricia, Rosalie, and Selma for the first time this season. Names not used this year are marked in gray.
One storm, Ione, was treated as one storm operationally but was found to have been two storms in post-analysis. Another storm, Dolores, was found to have been a tropical depression in post-season analysis and shouldn't have been named.
The central Pacific used names and numbers from the west Pacific's typhoon list. One name— Dot— was required.
The name Adele was retired from this list for no particular reason. It was replaced in the 1974 season
with Aletta.
This is the only time that the name Kristen was used. In the 1966 season
the name Kirsten was used. It was changed to Kristen this year, perhaps due to a clerical error. In the 1974 season
, it reverted back to Kirsten.
-based Eastern Pacific Hurricane Center
started issuing advisories on tropical cyclones in the eastern north Pacific. It replaced the previous forecaster, Fleet Weather Central.
The Central Pacific Hurricane Center
started to issue advisories on tropical cyclones in its area of responsibility this season. It replaced the Joint Hurricane Warning Center.
Pacific Ocean
The Pacific Ocean is the largest of the Earth's oceanic divisions. It extends from the Arctic in the north to the Southern Ocean in the south, bounded by Asia and Australia in the west, and the Americas in the east.At 165.2 million square kilometres in area, this largest division of the World...
, and on June 1, 1970 in the central Pacific. It ended on November 30, 1970. These dates conventionally delimit the period of time when tropical cyclone
Tropical cyclone
A tropical cyclone is a storm system characterized by a large low-pressure center and numerous thunderstorms that produce strong winds and heavy rain. Tropical cyclones strengthen when water evaporated from the ocean is released as the saturated air rises, resulting in condensation of water vapor...
s form in the eastern Pacific Ocean.
This season had an above average number of storms. There were twenty-one tropical cyclones, of which eighteen reached tropical storm strength. Four storms became hurricanes, of which none reached major hurricane strength. In the central Pacific, one hurricane and one tropical depression formed. One of the depressions crossed the dateline to become a typhoon.
Hurricane Adele
An area of low pressure lacked strong convection until May 30, when it strengthened into Tropical Depression One-E. On May 31, the storm further intensified into Tropical Storm Adele, the first named storm and Hurricane of the season. Adele tracked westward, as it strengthened into a hurricane on June 1. It reached its peak intensity later that day. As Adele moved west, A hostile environment caused it to weaken into a Tropical Storm. Adele further weakened, and it was downgraded into a depression on June 7. It was degenerated into an open troughTrough (meteorology)
A trough is an elongated region of relatively low atmospheric pressure, often associated with fronts.Unlike fronts, there is not a universal symbol for a trough on a weather chart. The weather charts in some countries or regions mark troughs by a line. In the United States, a trough may be marked...
, and it dissipated on June 7. Despite that it remained away from any land masses, Adele was retired after this season for unknown reasons.
Tropical Storm Blanca
The tropical disturbance that became Blanca was first noted on June 8 from satellite pictures. The new disturbance would reach tropical storm strength 24 hours later. Blanca moved in a northwest direction throughout its short life, dissipating on June 12.Tropical Storm Connie
Near the same location where Hurricane Adele formed two weeks earlier, a disturbance was noted on June 13. The disturbance abruptly became a tropical storm on June 17. The newly named Connie moved slowly to the northwest, reaching a peak intensity of 50 mi/h on June 18. Connie started weakening on June 19, finally dissipating on June 21 after stalling 118 mi (189.9 km) from Clarion Island.Tropical Depression Dolores
A disturbance first noted on June 19 had efficient outflow to be called a tropical depression. Satellite photos taken the same day revealed cloud structure that resembled a tropical storm forming, resulting in the system being called Dolores. The day after, no traces of a storm or of "Dolores" were found by reconnaissance. Post season analysis revealed Dolores to have only been a tropical depression.Tropical Storm Eileen
A tropical depression formed just off the southern coast of Mexico on June 26. It headed northwestward, reaching storm strength on June 28. The next day, Eileen turned to the northeast, reached a peak of 45 mi/h winds, and hit western Mexico.Hurricane Francesca
Francesca was a Category 2 hurricane which was, for a period of time, obscured by a cap of clouds above the hurricane's eye, distorting the appearance of the hurricane. The precursor disturbance to Hurricane Francesca was first noticed on July 1. The system became a tropical depression later that day and reached tropical storm strength the next day. On July 3, data from a ship indicated winds of near 100 mi/h, which indicate a storm of Category 2 strength, near the center of Francesca. The cloud cap, which remained over the hurricane since it first became a hurricane, started to move off the lower clouds around the center of the system around July 5. A center fix was obtained, but the maximum sustained winds were unobtainable from the sea surface because of cloud cover in and around the center. Francesca started weakening on July 6, a fact made clear by reconnaissance which indicated that the system had weakened to a tropical storm. The further weakening was obscured by the cloud cover. The final reconnaissance on the weakening system was reported on July 8, two days before Francesca dissipated.Tropical Storm Gretchen
Gretchen was first noticed on satellite imagery on July 14. From then on out, Gretchen was a hard storm to predict, leading to large errors in forecasting. The storm dissipated on July 21.Tropical Storm Helga
The system that became Helga was first noticed on July 16. The next day, reconnaissance found a minimal tropical storm with winds of only 40 mi/h. Based on satellite imagery, Helga was believed to be gaining strength as it approached Baja California. At one point during intensification, the storm abruptly started weakening, and on July 19, after stalling less than 118 miles (190 km) south of the tip of Baja California, Helga dissipated.Tropical Storm Ione Two
A tropical depression developed off the southern coast of Mexico on July 22. It tracked westward, reaching tropical storm strength on the two days later before dissipating on July 26. What was unusual about the system was that another tropical storm developed just to its northeast on July 24. That storm, also named Ione, tracked northward, reaching a peak of 60 mi/h winds before dissipating on July 25.Tropical Storm Joyce
A broad, flat low-pressure area persisted south of Baja California after Ione dissipated. On July 29, a small low circulation developed with a center about 120 nautical miles (220 km) south of Manzanillo. The system was given the name Joyce after winds of 40 mi/h were reported by a ship. In a similar way to Hurricane Francesca, Tropical Storm Joyce's low level center was unclear due to a cap of cirrus clouds. Joyce reached its peak intensity on July 31 with winds of near 60 mi/h before weakening, becoming a depression on August 1. Joyce dissipated on August 4.Tropical Storm Kristen
Kristen was a loosely organized storm that formed from a disturbance that was causing squalls near the Mexican coast. Tropical storm-force winds were found on August 5. Kristen was tracked by ship reports and satellite pictures. Kristen reached its peak intensity of 50 mi/h winds on August 6. The storm dissipated on August 8 while over cold water.Hurricane Lorraine
Tropical Storm Lorraine, which formed on August 16 south of Mexico, intensified to a hurricane on the 20th. Two days later over open waters, it reached a peak of 95 mph (153 km/h) winds, but estimates from the Central Pacific Hurricane CenterCentral Pacific Hurricane Center
The Central Pacific Hurricane Center 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 North Pacific Basin...
estimated it had winds of 115 mph (185 km/h). Without a chance to strengthen further, Lorraine weakened, finally dissipating on August 27 due to dry air.
Tropical Storm Maggie
A small cloud vortex slowly organized into a tropical depression on August 20 while southeast of HawaiiHawaii
Hawaii is the newest of the 50 U.S. states , and is the only U.S. state made up entirely of islands. It is the northernmost island group in Polynesia, occupying most of an archipelago in the central Pacific Ocean, southwest of the continental United States, southeast of Japan, and northeast of...
. It headed west-northwestward, becoming a tropical storm that night and reaching a peak of 60 mph (97 km/h) winds on August 23. A westward turn saved Hawaii from a direct hit, but Maggie still brought strong surf and heavy yet beneficial rain to the island of Hawaii
Hawaii (island)
The Island of Hawaii, also called the Big Island or Hawaii Island , is a volcanic island in the North Pacific Ocean...
.
Tropical Storm Norma
Norma was an indirect but essential cause of a flood disaster in Arizona that became known as the "Labor Day Storm of 1970". A depression formed August 31 and rapidly intensified into a tropical storm. Moving rapidly, it headed out to sea before slowing down and weakening. Norma's circulation fed humid unstable air into a large extratropical cyclone over ArizonaArizona
Arizona ; is a state located in the southwestern region of the United States. It is also part of the western United States and the mountain west. The capital and largest city is Phoenix...
. As Norma dissipated, record rains fell over the state from September 4 to September 6.
The rains were deadly. There were a total of 22 deaths, including 14 from a flash flood
Flash flood
A flash flood is a rapid flooding of geomorphic low-lying areas—washes, rivers, dry lakes and basins. It may be caused by heavy rain associated with a storm, hurricane, or tropical storm or meltwater from ice or snow flowing over ice sheets or snowfields...
on a creek. The damage amounted to over 1 million dollars.
Hurricane Dot
A tropical disturbance, possibly the remnants of Tropical Storm Maggie, became a tropical depression on September 1 to the northwest of Hawaii. It moved to the northwest, coming within miles of the International Date LineInternational Date Line
The International Date Line is a generally north-south imaginary line on the surface of the Earth, passing through the middle of the Pacific Ocean, that designates the place where each calendar day begins...
and Midway Island
Midway Atoll
Midway Atoll is a atoll in the North Pacific Ocean, near the northwestern end of the Hawaiian archipelago, about one-third of the way between Honolulu, Hawaii, and Tokyo, Japan. Unique among the Hawaiian islands, Midway observes UTC-11 , eleven hours behind Coordinated Universal Time and one hour...
but remaining in the Central Pacific. Dot turned to the northeast, reaching tropical storm strength on September 2 and hurricane strength September 3 before being absorbed by a cold core system the next day. When Dot became a hurricane at 35° north, it became the second highest latitude for a storm to reach hurricane strength, only behind Hurricane 12 of the 1975 season
1975 Pacific hurricane season
The 1975 Pacific hurricane season officially started May 15, 1975 in the eastern Pacific, and June 1, 1975 in the central Pacific, and lasted until November 30, 1975. These dates conventionally delimit the period of each year when most tropical cyclones form in the northeast Pacific Ocean.The 1975...
.
Tropical Storm Orlene
65 mi/h Tropical Storm Orlene hit Mexico in eastern OaxacaOaxaca
Oaxaca , , officially Estado Libre y Soberano de Oaxaca is one of the 31 states which, along with the Federal District, comprise the 32 federative entities of Mexico. It is divided into 571 municipalities; of which 418 are governed by the system of customs and traditions...
on September 8, having maintained a northeast track for its short lifetime.
Hurricane Patricia
Hurricane Patricia, the strongest storm of the season with winds of 95 knots (186.2 km/h), remained over the open waters of the Eastern Pacific. It lasted from October 4 to October 11.Tropical Storm Rosalie
Rosalie's existence was confirmed on October 21 by observation from a ship. Reconnaissance on the 22nd reported a central pressure of 1006 mb. After a slight regeneration on the 23rd, Rosalie began rapid dissipation, finally dissipating on the 23rd.Tropical Storm Selma
The final storm of the season, Tropical Storm Selma, developed on November 1 to the southwest of Mexico. It meandered to the north, turning to the northeast and northwest before heading southeastward and dissipating on November 8.1970 Storm Names
These names were used for storms that formed in the east Pacific Ocean this season. It is the same list used in the 1966 season1950-1969 Pacific hurricane seasons
The 1950–1963 Pacific hurricane seasons all began on May 15, 1950-65 in the northeast Pacific Ocean and on June 1, 1950-65 in the central Pacific. They ended on November 30, 1950-65...
. Names not retired from this list were used again in the 1974 season
1974 Pacific hurricane season
The 1974 Pacific hurricane season officially started May 15, 1974 in the eastern Pacific, and June 1, 1974 in the central Pacific, and lasted until November 30, 1974. These dates conventionally delimit the period of each year when most tropical cyclones form in the northeast Pacific Ocean.With...
. Storms were named Norma, Orlene, Patricia, Rosalie, and Selma for the first time this season. Names not used this year are marked in gray.
One storm, Ione, was treated as one storm operationally but was found to have been two storms in post-analysis. Another storm, Dolores, was found to have been a tropical depression in post-season analysis and shouldn't have been named.
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Tropical Storm Norma (1970) Tropical Storm Norma was the fourteenth named tropical cyclone of the 1970 Pacific hurricane season. The storm formed off the coast of Mexico and intensified rapidly, peaking as a strong tropical storm on September 3 before starting a weakening trend which saw it dissipate before making landfall on... |
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The central Pacific used names and numbers from the west Pacific's typhoon list. One name— Dot— was required.
The name Adele was retired from this list for no particular reason. It was replaced in the 1974 season
1974 Pacific hurricane season
The 1974 Pacific hurricane season officially started May 15, 1974 in the eastern Pacific, and June 1, 1974 in the central Pacific, and lasted until November 30, 1974. These dates conventionally delimit the period of each year when most tropical cyclones form in the northeast Pacific Ocean.With...
with Aletta.
This is the only time that the name Kristen was used. In the 1966 season
1950-1969 Pacific hurricane seasons
The 1950–1963 Pacific hurricane seasons all began on May 15, 1950-65 in the northeast Pacific Ocean and on June 1, 1950-65 in the central Pacific. They ended on November 30, 1950-65...
the name Kirsten was used. It was changed to Kristen this year, perhaps due to a clerical error. In the 1974 season
1974 Pacific hurricane season
The 1974 Pacific hurricane season officially started May 15, 1974 in the eastern Pacific, and June 1, 1974 in the central Pacific, and lasted until November 30, 1974. These dates conventionally delimit the period of each year when most tropical cyclones form in the northeast Pacific Ocean.With...
, it reverted back to Kirsten.
Administrative Changes
This is the first season that the Redwood CityRedwood City, California
Redwood City is a California charter city located on the San Francisco Peninsula in Northern California, approximately 27 miles south of San Francisco, and 24 miles north of San Jose. Redwood City's history spans from its earliest inhabitation by the Ohlone people, to its tradition as a port for...
-based Eastern Pacific Hurricane Center
Eastern Pacific Hurricane Center
The Eastern Pacific Hurricane Center was formerly the Regional Specialized Meteorological Center responsible for forecasting Pacific hurricanes in the eastern north Pacific east of 140°W...
started issuing advisories on tropical cyclones in the eastern north Pacific. It replaced the previous forecaster, Fleet Weather Central.
The Central Pacific Hurricane Center
Central Pacific Hurricane Center
The Central Pacific Hurricane Center 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 North Pacific Basin...
started to issue advisories on tropical cyclones in its area of responsibility this season. It replaced the Joint Hurricane Warning Center.
See also
- List of Pacific hurricanes
- List of Pacific hurricane seasons
- 1970 Atlantic hurricane season1970 Atlantic hurricane seasonThe 1970 Atlantic hurricane season officially began on June 1, 1970, and lasted until November 30, 1970. These dates conventionally delimit the period of each year when most tropical cyclones form in the Atlantic basin...
- 1970 Pacific typhoon season1970 Pacific typhoon seasonThe 1970 Pacific typhoon season has no official bounds; it ran year-round in 1970, but most tropical cyclones tend to form in the northwestern Pacific Ocean between June and December...
- 1970 North Indian Ocean cyclone season1970 North Indian Ocean cyclone seasonThe 1970 North Indian Ocean cyclone season had no bounds, but tropical cyclones in the North Indian Ocean tend to form between April and December, with peaks in May and November. The 1970 season saw a total of seven cyclonic storms, of which three developed into severe cyclonic storms...
- Southern Hemisphere tropical cyclone seasons: 1969–70, 1970–71