Ураган Нора: Траектория и последствия тихоокеанского шторма 1997 года.

Category 4 Pacific hurricane in 1997

Hurricane Nora was the first tropical cyclone to enter the Continental United States from the Pacific Ocean since Hurricane Lester in 1992. Nora was the fourteenth named tropical cyclone and the seventh hurricane of the 1997 Pacific hurricane season. The September storm formed off the Pacific coast of Mexico, and aided by waters warmed by the 1997–98 El Niño event, eventually peaked at Category 4 intensity on the Saffir–Simpson hurricane scale. Nora took an unusual path, making landfall twice as a hurricane in the Baja California Peninsula. Weakening quickly after landfall, it lashed the Southwestern United States with tropical storm force winds, torrential rain, and flooding before becoming a remnant low. The storm was blamed for two direct casualties in Mexico, as well as substantial beach erosion on the Mexican coast, flash flooding in Baja California, and record precipitation in Arizona. It persisted far inland and eventually dissipated near the Arizona–Nevada border. The system that was to become Hurricane Nora was likely related to a tropical wave, that had moved off the coast of Africa at the end of August 1997 and entered the Pacific Ocean during September 12. After entering the Pacific Ocean, the wave encountered a favourable environment for tropical cyclogenesis, which caused the system to become better organised and develop into Tropical Storm Nora on September 16. Over the next couple of days, the system continued to become better organised as it slowly moved north westwards over the Pacific Ocean away from southwestern Mexico and intensified into a Category 2 hurricane on the Saffir Simpson hurricane wind scale during September 18. The steering currents subsequently became weak or balanced over the hurricane which caused the system to become near stationary and weaken into a Category 1 hurricane. Nora impacted the majority of Mexico's Pacific facing coasts including the states of Baja California, Colima, Guerrero, Jalisco, Michoacán, Nayarit, Oaxaca, Sinaloa and Sonora.

The system that was to become Hurricane Nora was likely related to a tropical wave, that had moved off the coast of Africa at the end of August 1997. The wave subsequently moved across the Atlantic Ocean and spawned Hurricane Erika in early September, before it continued to move westwards through the Caribbean Sea and entered the Pacific Ocean during September 12. After entering the Pacific Ocean, the wave encountered a favourable environment for tropical cyclogenesis, with very warm waters of around and relatively light vertical wind shear. As a result, the system became better organised and developed a closed circulation, before the United States National Hurricane Center (NHC) initiated advisories and designated the disturbance as Tropical Depression Sixteen E during September 16. At this time the system was located about 310 mile (499 km) to the south of Acapulco, Mexico and had started to be steered towards the west northwest, as a result of a ridge of high pressure over northern Mexico. At this time, the NHC noted that they had limited guidance on Nora as a result of various computer problems and that there was considerable uncertainty in the forecast track. During September 18, after a Dvorak classification that correlated to 1 minute sustained winds of was received from the Tropical Forecast and Analysis Branch, the NHC reported that Nora had become a Category 1 hurricane on the Saffir–Simpson hurricane wind scale. During that day, a large and ragged banding type eye appeared on satellite imagery, which shrank as the system intensified into a Category 2 hurricane with 1 minute sustained wind speeds of At around this time, steering currents over the system became weak or balanced which caused the hurricane to become near stationary, while it was located about 320 mile (515 km) to the southwest of Acapulco. Over the next couple of days, Nora started to weaken over waters that had been upwelled by its circulation, with atmospheric convection becoming almost non existent over Nora's eye and north western semicircle, before it weakened into a Category 1 hurricane. During September 20, Nora started to drift north northwestwards along a ridge of high pressure, into an area of very warm sea surface temperatures parallel to Mexico's western coast. Over the next day, atmospheric convection surrounding the eye increased and quickly cooled, as the hurricane quickly intensified and ultimately peaked as a Category 4 hurricane with 1 minute sustained windspeeds of At this time the system was located about 245 mile (394 km) to the southeast of Socorro in the Revillagigedo Islands and was starting to move over waters that Hurricane Linda had cooled a few weeks earlier, while it was a Category 5 hurricane. As a result, Nora weakened into a Category 3 hurricane, before it passed within of Socorro in the Revillagigedo Islands during September 22. Over the next day, the hurricane continued to move over Linda's wake and gradually weaken with the eye becoming ragged, cloud tops warming and its eyewall becoming broken. As a result, the system was classified as a Category 1 hurricane at around 04:00 Pacific Standard Time (12:00 UTC) on September 23, while it was located about to the southwest of Cabo San Lucas on the Baja California peninsula. Warm waters off the west coast of Baja California allowed the system to reintensify slightly and weaken slower than most tropical cyclones in the region, before it made landfall near Punta Eugenia in Baja California Sur at about 22:30 PST on September 24 (06:30 UTC, September 25). The system subsequently moved over water in the vincinty of the Sebastián Vizcaíno Bay, before it made landfall at about 03:00 PST (11:00 UTC) to the south southeast of San Fernando in Baja California as a Category 1 hurricane. Later that day, Nora emerged into the northern Gulf of California and skirted the western coast as it moved northwards, before it made its final landfall near the mouth of the Colorado river to the west of Puerto Penasco, Sonora. After moving into the Continental United States, the system rapidly weakened and broke up over the mountainous terrain of the southwestern United States, before it degenerated into a tropical depression while it was located in between Blythe and Needles. The system subsequently started to move towards the north=northeast and started to look like a mid latitude system on radar, before it was last noted at 22:00 PST (06:00 UTC, September 26), while it was located 55 mile (89 km) to the east of Las Vegas, Nevada. Nora's upper level circulation did not have enough time to wind down and persisted for another couple of days before it dissipated on September 28, after it had moved through portions of Utah, Colorado, Idaho and Wyoming.

Hurricane Nora was the first of four tropical cyclones to impact Mexico during the latter part of the 1997 Pacific hurricane season, with Tropical Storm Olaf, Hurricanes Pauline and Rick impacting southern Mexico later in the season. The system impacted the majority of Mexico's Pacific coast with effects reported in Baja California, Colima, Guerrero, Jalisco, Michoacán, Nayarit, Oaxaca, Sinaloa and Sonora.

After Nora had become a tropical storm on September 16, the Servicio Meteorológico Nacional (SMN) issued a hurricane watch for the coast between Lázaro Cárdenas, Michoacán and Cabo Corrientes, Jalisco, as it was feared that the system could make landfall on Mexico's Pacific coast. Later that day, the SMN issued a tropical storm warning for the area between Lázaro Cárdenas, Michoacán and Puntá Maldonado, Guerrero, in addition to the hurricane watch, because of the close proximity of the system to the coast. As a result, authorities set up evacuation centres on higher ground in case evacuations were ordered, while several major ports including Acapulco, Huatulco, Lazaro Cardenas and Zihuatanejo were closed to shipping or restricted to bigger vessels. Over the next couple of days, the tropical storm warning and hurricane watch was cancelled and replaced with a flood warnings by the Mexican Government. Despite the system remaining over open waters, parts of Guerrero reported experiencing gusty winds and heavy rain from Nora's outer bands. During September 18, radar imagery from Acapulco showed that Nora's outer rain bands had started to impact Mexico's Pacific facing coast. Offshore, the strong swells generated by the hurricane caused widespread loss of growing sea lettuce (Ulva lactuca), exacerbating the negative biological effects of the 1997–98 El Niño event.

The port of Huatulco was closed to small craft for at least four days as Nora caused high seas.

The ports of Acapulco and Zihuatanejo were closed to shipping for at least three days. High surf caused the beach at Pie de la Cuesta to virtually disappear.

The port at Lazaro Cardenas was closed to shipping. 80% of the arbours at the El Paraiso Balneario in Armería were destroyed. Researchers investigating the maximum potential intensity of tropical cyclones near the island, later found that no useful atmospheric soundings were available to assess Nora's intensity while near the island. They also issued a tropical storm warning from 24N northwards to Bahia Balleno and Santa Rosalía as well as a tropical storm watch between Puerto Santo Tomás northwards to Tijuana. There, heavy damage and flooding were reported, as well as extensive beach erosion. 500 people were evacuated from their homes near Cabo San Lucas, Baja California Sur, and placed in shelters to prepare for the storm's impact. 9 feet (3 m) waves were reported in Cabo San Lucas. A person was electrocuted by a downed power line in Mexicali. The death of a diver who had been harvesting sea urchins of the San Quintin Valley and had died of Nitrogen narcosis, was partially attributed by Mexican authorities to strong underwater currents created by Nora.

During September 24, the SMN issued a hurricane watch and a tropical storm warning for the eastern Gulf of California coast from Bahía Kino northwards. After Nora had moved into the Gulf of California during the next day, the watch and warning were discontinued, however, a tropical storm warning was briefly issued during September 25 for the coastline above 30N. Authorities in the towns of Puerto Peñasco, San Luis Río Colorado and Plutarco Elías Calles cancelled schools and advised residents to stay home and avoid driving. In the town of Puerto Peñasco, it was suggested that most people were calm about the threat posed by Nora, with only a few people taking any precautions against the threat posed by flooding and strong winds. During September 25, tropical storm force winds of up to were reported in the town, which caused trees to fall on power lines and prompted local officials to turn off the electric supplies. Waves of up to 10 feet (3 m) impacted a seawall located offshore but did not topple the wall or cause any damage in the town. At the height of the storm, approximately 300 people were staying in shelters at local schools. Nora's threat to the United States was considered unusual and required an unprecedented coordination effort, between the National Hurricane Center (NHC) and various National Weather Service Weather Forecast Offices in the Western United States. As Nora impacted Arizona and California, bird watchers observed and studied various rare seabirds, that were found along the Colorado River and the Salton Sea.

Nora was the fourth named storm to impact California during the 1997 Pacific hurricane season, after Guillermo, Ignacio and Linda had impacted the state earlier in the season. Ahead of the Nora impacting California, residents were warned that there was a chance that tropical storm force winds, would be experienced in Southern California despite Nora being expected to significantly weaken over land. They also warned that tropical moisture associated with the storm would bring showers and thunderstorms, which could produce locally heavy rainfall and increase the potential for flash flooding. During September 24, the system started to impact California with high clouds, moisture and isolated thunderstorms reported over the state, which had the effect of causing hot temperatures, high humidity and enhancing wildfires over the state. As a result of the rain, minor flooding was reported in the counties of Imperial, Inyo, Los Angeles, Orange, Riverside, San Bernardino, San Diego and Ventura. On the highways of Los Angeles and San Diego, the rain was responsible for over three times the usual amount of traffic accidents, while the California Highway Patrol attributed three traffic fatalities to Nora's rain. Five people were hospitalized with injuries in a separate traffic collision. In the 1–2 p. m. PST period, the California Highway Patrol logged 51 traffic incidents. Extensive damage valued at $4.5 million was inflicted on crops such as carrots and cotton in Imperial County as a result of the heavy rainfall and flooding. Winds associated with Hurricane Nora did not significantly impact California. However, cool moist winds associated with the system stifled a wildfire occurring on the Del Dios highway. Gusty winds also toppled telephone poles in Seeley. Rainfall from Nora also reduced large fire activity throughout southern California.

Hurricane Nora was the eighth tropical depression, fifth tropical storm and one of the overall strongest tropical cyclones on record to move into Arizona, since the start of the satellite era in 1965. Ahead of Nora impacting Arizona, it was predicted that the system could produce strong winds of between over the state, which was thought to be enough to cause patio furniture to go flying. The main threat though was thought to be from the rain, with rainfall totals of and isolated totals of expected in areas, where the average annual rainfall was about However, the Salt River Project refused to increase its flood storage capacities through emergency reservoir releases, as the reservoirs were nowhere near full and could cope with the expected flooding. Nora moved into the state on September 25 as a weakening tropical storm and deviated from its forecast track, which meant that eastern and central parts of the state including Tucson received only minimal rainfall and breezy conditions. The system was also responsible for a significant rainfall event over parts of western and northern Arizona, with rainfall totals of widely reported, while a rainfall total of was reported on the Harquahala Mountains broke the states 24 hour rainfall record set during Tropical Storm Norma in September 1970. As a result of the rain, significant flooding and runoff events were reported on several washes in Wickenburg, as well as on the Centennial Wash, Hassayampa River, Jackrabbit Wash and Tiger Wash. The counties of La Paz, Maricopa and Mohave subsequently declared that an emergency existed in Aguila, which allowed them to receive state funds. The combination of torrential rainfall and preexisting groundwater related subsidence led to the opening of a fissure in the Harquahala Plain west of Phoenix. The fissure was 1341.12 m long, 3.05 m wide, and 1.52 m deep. It was later estimated that Nora had caused around $3 million in damages to both local government and state property as well as $150 to $200 million of damage to crops.<! Three mobile homes were flooded in Vicksburg, one of which had a family inside, however, there were no casualties reported as all were rescued and put into an emergency shelter. Within the counties of Coconino, Maricopa and Yavapai counties, heavy rain associated with Nora caused flooding, flash flooding and urban flooding which in turn caused rock and mudslides, as well as the closure of several state, county and city roads. Within the state, it was feared that heavy rain would cause flash flooding and that streams and rivers, would suddenly and unexpectedly rise if tropical moisture associated with Nora impacted the area. As a result, flash flood watches and warnings were issued for Southern Utah during September 25, while emergency services in Kane and Washington Counties provided sandbags to fire departments which were subsequently handed out for free to residents. Nora's remnant upper level circulation moved into Utah during September 25, where it produced a period of near hurricane force winds that were observed at the Blowhard Mountain radar site, near Cedar City. The winds were also thought to be responsible for producing straight line winds, which downed or sheared the tops of approximately 400 trees off in the Dixie National Forest, Brian Head Ski Resort and the Cedar Breaks National Monument. It was later estimated that Nora had caused a total of $108 thousand in damages to crops and property in Utah. As the system moved into Nevada, the Las Vegas Radar showed that the system had a small area of winds over the Spring Mountains, however, surface observations showed that these winds were not experienced at the lower levels of Nevada.

On September 23, the American Red Cross chapter in New Mexico issued a media release, which stated that Nora would produce of rain over the state and suggested that the central part of the state near Belen was most at risk as heavy rain had previously fallen there. As a result, they suggested that people prepare by elevating their furniture and other valuables to areas where they wouldn't be impacted by flood waters and announced that they were prepared to open shelters for residents and emergency workers. Forecasters from the National Weather Service stated that the Red Cross rainfall estimates were overestimates and predicted that the remnants might produce up to of rain in the northwest of the state, while other parts of the state might see some showers or no rain at all from Nora. There were no impacts reported in New Mexico from Nora after the system had moved more west than forecast, however, it left twice the normal amount of moisture in the air over the four corners area which eventually condensed into rain producing clouds.