1970 Pacific hurricane season

Infobox hurricane season
Basin=EPac
Year=1970
Track=1970 Pacific hurricane season map.png First storm formed=May 30, 1970
Last storm dissipated=November 8, 1970
Strongest storm name=Lorraine
Strongest storm pressure=963
Strongest storm winds=85
Average wind speed=1
Total depressions=22
Total storms=19
Total hurricanes=5
Total intense=
Fatalities=0 direct, 22 indirect
Da

Inflated=
five seasons=1968, 1969, 1970, 1971, 1972The 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 cyclones 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.

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torms

Hurricane Adele

Infobox Hurricane Small
Basin=EPac


Track=Adele 1970 track.pngFormed=May 30
Dissipated=June 7
1-min winds=75
Prepressure=≤
Pressure=993The first named storm and hurricane of the season developed on May 30 southwest of Mexico. Adele tracked westward, becoming a hurricane on June 1. It slowly died down, and 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

Infobox Hurricane Small
Basin=EPac

---

Formed=June 10
Dissipated=June 12
1-min winds=50The tropical disturbance that became Blanca was first noted on June 8th 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 the 12th.

Tropical Storm Connie

Infobox Hurricane Small
Basin=EPac


Track=Connie 1970 track.pngFormed=June 17
Dissipated=June 21
1-min winds=45Near the same location where Hurricane Adele formed two weeks earlier, a disturbance was noted on June 13th. The disturbance abruptly became a tropical storm on June 17th. The newly named Connie moved slowly to the northwest, reaching a peak intensity of 50 mph on June 18. Connie started weakening on the 19th, finally dissipating on June 21 after stalling 100 nautical miles (190 km) from Clarion Island.

Tropical Depression Dolores

Infobox Hurricane Small
Basin=EPac


Formed=June 19
Dissipated=June 20
1-min winds=25A disturbance first noted on June 19th 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

Infobox Hurricane Small
Basin=EPac

---

Formed=June 26
Dissipated=June 29
1-min winds=40A 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 mph winds, and hit western Mexico.

Hurricane Francesca

Infobox Hurricane Small
Basin=EPac


Track=Francesca 1970 track.pngFormed=July 1
Dissipated=July 10
1-min winds=85
Prepressure=≤
Pressure=971Francesca 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 mph, 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 5th. 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

Infobox Hurricane Small
Basin=EPac

---

Formed=July 14
Dissipated=July 21
1-min winds=45
Pressure=1009Gretchen was first noticed on satellite imagery on July 14th. 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

Infobox Hurricane Small
Basin=EPac

---

Formed=July 16
Dissipated=July 20
1-min winds=50The system that became Helga was first noticed on July 16th. The next day, reconnaissance found a minimal tropical storm with winds of only 40 mph. 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 100 nautical miles (190 km) south of the tip of Baja California, Helga dissipated.

Tropical Storm Ione Two

Infobox Hurricane Small
Basin=EPac


Track=Ione 2 1970 track.pngFormed=July 22
Dissipated=July 26
1-min winds=45A 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 mph winds before dissipating on July 25.

Tropical Storm Ione One

Infobox Hurricane Small
Basin=EPac


Track=Ione 1 1970 track.pngFormed=July 24
Dissipated=July 25
1-min winds=40

Tropical Storm Joyce

Infobox Hurricane Small
Basin=EPac


Track=Joyce 1970 track.pngFormed=July 29
Dissipated=August 4
1-min winds=50A broad, flat low-pressure area persisted south of Baja California after Ione dissipated. On July 29th, 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 mph 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 31st with winds of near 60 mph before weakening, becoming a depression on August 1st. Joyce dissipated on August 4th.

Tropical Storm Kristen

Infobox Hurricane Small
Basin=EPac

---

Formed=August 5
Dissipated=August 8
1-min winds=45Kristen 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 5th. Kristen was tracked by ship reports and satellite pictures. Kristen reached its peak intensity of 50 mph winds on August 6th. The storm dissipated on August 8th while over cold water.

Hurricane Lorraine

Infobox Hurricane Small
Basin=EPac


Track=Lorraine 1970 track.pngFormed=August 16
Dissipated=August 27
1-min winds=85
Pressure=963Tropical 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 Center 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

Infobox Hurricane Small
Basin=EPac


Track=Maggie 1970 track.pngFormed=August 20
Dissipated=August 27
1-min winds=50A small cloud vortex slowly organized into a tropical depression on August 20 while southeast of Hawaii. 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.

Tropical Storm Norma

Infobox Hurricane Small
Basin=EPAC


Track=Norma 1970 track.pngFormed=August 31
Dissipated=September 5
1-min winds=50
Pressure=992Norma 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 Arizona. 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.

Hurricane Dot

Infobox Hurricane Small
Basin=EPac

---

Formed=September 1
Dissipated=September 4
1-min winds=70A 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 Line 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.

Tropical Storm Orlene

Infobox Hurricane Small
Basin=EPac

---

Formed=September 7
Dissipated=September 8
1-min winds=5565 mph Tropical Storm Orlene hit Mexico in eastern Oaxaca on September 8, having maintained a northeast track for its short lifetime.

Hurricane Patricia

Infobox Hurricane Small
Basin=EPac


Track=Patricia 1970 track.pngFormed=October 4
Dissipated=October 11
1-min winds=95
Pressure=972Hurricane Patricia, the strongest storm of the season with winds of 95 knots, remained over the open waters of the Eastern Pacific. It lasted from October 4 to October 11.

Tropical Storm Rosalie

Infobox Hurricane Small
Basin=EPac

---

Formed=October 21
Dissipated=October 23
1-min winds=45
Pressure=1006Rosalie's existence was confirmed on October 21st 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

Infobox Hurricane Small
Basin=EPac


Track=Selma 1970 track.pngFormed=November 1
Dissipated=November 8
1-min winds=60
Pressure=995The 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 season. 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 first and 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.

Administrative Changes

This is the first season that the Redwood City-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.

ee also

*List of Pacific hurricanes
*List of Pacific hurricane seasons
*1970 Atlantic hurricane season
*1970 Pacific typhoon season
*1970 North Indian Ocean cyclone season
*Southern Hemisphere tropical cyclone seasons: 1969–70, 1970–71

References

* [http://www.weather.unisys.com/hurricane/e_pacific/1970/index.html Unisys Storm Tracks] accessed November 17, 2005
* [http://www.prh.noaa.gov/cphc/pages/hurrclimate.php#1970 CPHC Archive] accessed November 17, 2005
* [http://docs.lib.noaa.gov/rescue/mwr/099/mwr-099-04-0286.pdf NOAA Monthly Weather Review] accessed November 17, 2005
* [http://www.wrh.noaa.gov/psr/tropics/hurricanes.htm Arizona's tropical cyclones] accessed November 17, 2005

External links

* [http://docs.lib.noaa.gov/rescue/mwr/099/mwr-099-04-0286.pdf Eastern Pacific Hurricane Season of 1970]
* [http://www.prh.noaa.gov/cphc/summaries/1970.php CPHC Season Summary]
* [http://metocph.nmci.navy.mil/jtwc/atcr/1970atcr/pdf/annexa.pdf ATCR Eastern Pacific summary]
* [http://www.weather.unisys.com/hurricane/e_pacific/1970/index.html Unisys Storm Tracks]