.gif)
Tropical Storm Norma (1970)
Encyclopedia
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 Baja California
.
While the storm never made landfall, the remnants from the storm fueled the Labor Day Storm of 1970, which caused floods in Arizona
that resulted in heavy damage and loss of life. The rainfall from this storm broke records, mostly for 24 hour rainfall totals. Despite not being tropical when the damages were done, Norma is considered to be the deadliest system in Arizona
history.
picture taken on August 30. Soon after, a weak low pressure center associated with the system formed 100 nautical miles (185.2 km) southwest of Acapulco
, Mexico
. The system later went through rapid intensification, becoming a tropical depression on August 31 and Tropical Storm Norma later that day. Initially with a loose organization, Norma continued to organize and strengthen, reaching its peak of 60 mi/h on September 2. Satellite pictures showed cirrus
outflow was greater in the tops of the feeder bands than in the eyewall chimney. On September 3, Navy reconnaissance reported a 992 mbar pressure, Norma's lowest.
Shortly after the 992 mbar report, however, Norma began to weaken. The same recon that reported the 60 mi/h and 992 mbar reading reported back with a mere 40 mi/h some time after. Despite the sudden drop in winds, the minimum pressure remained around 994 mbar. The weakening became obvious on satellite presentation, which showed cool inflow and a sheet of stratocumulus clouds around the west semicircle extending under the storm clouds. Norma continued to weaken, degrading into a depression by September 4. At this point, the circulation
forced moist and unstable
maritime air into Arizona which resulted in disastrous floods during Labor Day
along with a slow moving cold front
. This system would become known as the Labor Day Storm of 1970. On September 5, a cloud spiral was still visible west of Baja California
, but the storm's circulation dissipated, with the remnants of the storm finally dissipating on September 6, just before making landfall on Baja California.
while tropical (even though it came close to making landfall on Baja California
before dissipating), the circulation introduced unstable air into Arizona
and Utah
which, along with a cold front, resulted in record amounts of rainfall.
drivers. Total rainfall exceeded 7 inches in certain locations, with Workman's Creek receiving 11.92 inches (302.8 mm) of rain. Other amounts were recorded in Upper Parker Creek (9.09 inches), Mount Lemmon
(8.74 inches), Sunflower (8.44 inches), Kitt Peak
(8.08 inches), Tonto Creek Fish Hatchery (7.12 inches), and Crown King (7.02 inches). There were also reports of injuries by campers in Mogollon Rim
and Scottsdale
reported significant property damage
. The major flooding in the state prompted a presidential disaster declaration.
were also experiencing heavy rainfall. The most noteworthy rainfall total was recorded in Bug Creek, which experienced an estimated 6 inches (152.4 mm) of rain in a 24 hour period. No deaths or damage was reported in connection to the storm.
in a 24 hour period. The record stood until 1997, when the remnants of Hurricane Nora
produced 11.97 inches (304 mm) of rain on the top of Harquahala Mountain
.
A similar record was recorded in Utah when 6 inches (152.4 mm) of rain fell in Bug Creek in a 24 hour period. Unlike the Arizona rainfall record, this record still stands today.
When the rains of Norma caused the San Juan River to flood its banks, a size of 1,090 m3 was obtained, making this the largest flood of the San Juan since 1962, when the Navajo Dam
was completed. The most runoff from the storm was downstream from the reservoir.
With 23 associated deaths in Arizona
, Norma was the deadliest storm in the state's history.
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...
of the 1970 Pacific hurricane season
1970 Pacific hurricane season
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 cyclones form in the eastern Pacific Ocean.This season had an above average...
. 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 Baja California
Baja California
Baja California officially Estado Libre y Soberano de Baja California is one of the 31 states which, with the Federal District, comprise the 32 Federal Entities of Mexico. It is both the northernmost and westernmost state of Mexico. Before becoming a state in 1953, the area was known as the North...
.
While the storm never made landfall, the remnants from the storm fueled the Labor Day Storm of 1970, which caused floods in Arizona
Arizona
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...
that resulted in heavy damage and loss of life. The rainfall from this storm broke records, mostly for 24 hour rainfall totals. Despite not being tropical when the damages were done, Norma is considered to be the deadliest system in Arizona
Arizona
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...
history.
Meteorological history
A tropical disturbance was first noted in a satelliteSatellite
In the context of spaceflight, a satellite is an object which has been placed into orbit by human endeavour. Such objects are sometimes called artificial satellites to distinguish them from natural satellites such as the Moon....
picture taken on August 30. Soon after, a weak low pressure center associated with the system formed 100 nautical miles (185.2 km) southwest of Acapulco
Acapulco
Acapulco is a city, municipality and major sea port in the state of Guerrero on the Pacific coast of Mexico, southwest from Mexico City. Acapulco is located on a deep, semi-circular bay and has been a port since the early colonial period of Mexico’s history...
, Mexico
Mexico
The United Mexican States , commonly known as Mexico , is a federal constitutional republic in North America. It is bordered on the north by the United States; on the south and west by the Pacific Ocean; on the southeast by Guatemala, Belize, and the Caribbean Sea; and on the east by the Gulf of...
. The system later went through rapid intensification, becoming a tropical depression on August 31 and Tropical Storm Norma later that day. Initially with a loose organization, Norma continued to organize and strengthen, reaching its peak of 60 mi/h on September 2. Satellite pictures showed cirrus
Cirrus cloud
Cirrus clouds are atmospheric clouds generally characterized by thin, wispy strands, giving them their name from the Latin word cirrus meaning a ringlet or curling lock of hair...
outflow was greater in the tops of the feeder bands than in the eyewall chimney. On September 3, Navy reconnaissance reported a 992 mbar pressure, Norma's lowest.
Shortly after the 992 mbar report, however, Norma began to weaken. The same recon that reported the 60 mi/h and 992 mbar reading reported back with a mere 40 mi/h some time after. Despite the sudden drop in winds, the minimum pressure remained around 994 mbar. The weakening became obvious on satellite presentation, which showed cool inflow and a sheet of stratocumulus clouds around the west semicircle extending under the storm clouds. Norma continued to weaken, degrading into a depression by September 4. At this point, the circulation
Atmospheric circulation
Atmospheric circulation is the large-scale movement of air, and the means by which thermal energy is distributed on the surface of the Earth....
forced moist and unstable
maritime air into Arizona which resulted in disastrous floods during Labor Day
Labor Day
Labor Day is a United States federal holiday observed on the first Monday in September that celebrates the economic and social contributions of workers.-History:...
along with a slow moving cold front
Cold front
A cold front is defined as the leading edge of a cooler mass of air, replacing a warmer mass of air.-Development of cold front:The cooler and denser air wedges under the less-dense warmer air, lifting it...
. This system would become known as the Labor Day Storm of 1970. On September 5, a cloud spiral was still visible west of Baja California
Baja California
Baja California officially Estado Libre y Soberano de Baja California is one of the 31 states which, with the Federal District, comprise the 32 Federal Entities of Mexico. It is both the northernmost and westernmost state of Mexico. Before becoming a state in 1953, the area was known as the North...
, but the storm's circulation dissipated, with the remnants of the storm finally dissipating on September 6, just before making landfall on Baja California.
Impact
While Norma did not make landfallLandfall (meteorology)
Landfall is the event of a tropical cyclone or a waterspout coming onto land after being over water. When a waterspout makes landfall it is reclassified as a tornado, which can then cause damage inland...
while tropical (even though it came close to making landfall on Baja California
Baja California
Baja California officially Estado Libre y Soberano de Baja California is one of the 31 states which, with the Federal District, comprise the 32 Federal Entities of Mexico. It is both the northernmost and westernmost state of Mexico. Before becoming a state in 1953, the area was known as the North...
before dissipating), the circulation introduced unstable air into Arizona
Arizona
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...
and Utah
Utah
Utah is a state in the Western United States. It was the 45th state to join the Union, on January 4, 1896. Approximately 80% of Utah's 2,763,885 people live along the Wasatch Front, centering on Salt Lake City. This leaves vast expanses of the state nearly uninhabited, making the population the...
which, along with a cold front, resulted in record amounts of rainfall.
Baja California
For an 800 mi (1,287.5 km) stretch of the coat, 12 ft (3.7 m) waves were measured. Winds of 60 mph (96.6 km/h) were recorded at Bahia Tortugas, a village on Punta Eugenia.Arizona
The rainfall in Arizona produced deadly flash floods which caused over $1 million in damages and killed 23 people, 14 of which died when Tonto Creek, which was in the vicinity of Kohl's Ranch, became flooded. Other deaths were reported among automobileAutomobile
An automobile, autocar, motor car or car is a wheeled motor vehicle used for transporting passengers, which also carries its own engine or motor...
drivers. Total rainfall exceeded 7 inches in certain locations, with Workman's Creek receiving 11.92 inches (302.8 mm) of rain. Other amounts were recorded in Upper Parker Creek (9.09 inches), Mount Lemmon
Mount Lemmon
Mount Lemmon is in the Santa Catalina Mountains located in the Coronado National Forest north of Tucson, Arizona, United States. It is above sea-level, and receives approximately 180 inches of snow annually. Mount Lemmon was named in honor of botanist Sarah Lemmon, who trekked to the top of...
(8.74 inches), Sunflower (8.44 inches), Kitt Peak
Kitt Peak
Kitt Peak is a mountain in the U.S. state of Arizona. It is the location of the Kitt Peak National Observatory. The radio telescope at the Observatory is one of ten dishes comprising the Very Long Baseline Array ....
(8.08 inches), Tonto Creek Fish Hatchery (7.12 inches), and Crown King (7.02 inches). There were also reports of injuries by campers in Mogollon Rim
Mogollon Rim
The Mogollon Rim is a topographical and geological feature running across the U.S. state of Arizona. It extends approximately from northern Yavapai County eastward to near the border with New Mexico.-Description:...
and Scottsdale
Scottsdale, Arizona
Scottsdale is a city in the eastern part of Maricopa County, Arizona, United States, adjacent to Phoenix. According to the U.S. Census Bureau, as of 2010 the population of the city was 217,385...
reported significant property damage
Property damage
Property damage is damage to or the destruction of public or private property, caused either by a person who is not its owner or by natural phenomena. Property damage caused by persons is generally categorized by its cause: neglect , and intentional damage...
. The major flooding in the state prompted a presidential disaster declaration.
Utah
While the storm was causing floods in Arizona, the lower cities of UtahUtah
Utah is a state in the Western United States. It was the 45th state to join the Union, on January 4, 1896. Approximately 80% of Utah's 2,763,885 people live along the Wasatch Front, centering on Salt Lake City. This leaves vast expanses of the state nearly uninhabited, making the population the...
were also experiencing heavy rainfall. The most noteworthy rainfall total was recorded in Bug Creek, which experienced an estimated 6 inches (152.4 mm) of rain in a 24 hour period. No deaths or damage was reported in connection to the storm.
Records
When 11.4 inches (289.6 mm) of rain fell at Workman's Creek in a 24-hour period, it became the highest amount of rain to fall in 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...
in a 24 hour period. The record stood until 1997, when the remnants of Hurricane Nora
Hurricane Nora (1997)
Hurricane Nora was only the third tropical cyclone on record to reach Arizona as a tropical storm. Nora was the fourteenth named tropical cyclone and seventh hurricane of the 1997 Pacific hurricane season...
produced 11.97 inches (304 mm) of rain on the top of Harquahala Mountain
Harquahala Mountains
The Harquahala Mountains are the highest mountain range in southwestern Arizona, USA and are located southwest of the towns of Aguila and Wenden. The name originated from a local Native American people "Aha qua hala" which meant "water there is high up". The range is oriented from northeast to...
.
A similar record was recorded in Utah when 6 inches (152.4 mm) of rain fell in Bug Creek in a 24 hour period. Unlike the Arizona rainfall record, this record still stands today.
When the rains of Norma caused the San Juan River to flood its banks, a size of 1,090 m3 was obtained, making this the largest flood of the San Juan since 1962, when the Navajo Dam
Navajo Dam
Navajo Dam is an earthen dam on the San Juan River, a tributary of the Colorado River, in northwestern New Mexico in the United States. The dam and its reservoir, Navajo Lake, lie in the arid western foothills of the Rocky Mountains about east of Farmington....
was completed. The most runoff from the storm was downstream from the reservoir.
With 23 associated deaths in Arizona
Arizona
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...
, Norma was the deadliest storm in the state's history.
See also
- List of tropical cyclones
- List of Pacific hurricanes
- List of wettest tropical cyclones in Arizona
- Hurricane Nora (1997)Hurricane Nora (1997)Hurricane Nora was only the third tropical cyclone on record to reach Arizona as a tropical storm. Nora was the fourteenth named tropical cyclone and seventh hurricane of the 1997 Pacific hurricane season...
- 1997 hurricane in the East Pacific that produced gale-force winds and heavy rainfall in the Southwestern United StatesSouthwestern United StatesThe Southwestern United States is a region defined in different ways by different sources. Broad definitions include nearly a quarter of the United States, including Arizona, California, Colorado, Nevada, New Mexico, Oklahoma, Texas and Utah...
. - Other storms with the same name