|Category 4 major hurricane (SSHWS/NWS)|
|Formed||September 25, 2018|
|Dissipated||October 3, 2018|
|(Remnant low after October 2)|
|Highest winds|| 1-minute sustained: 150 mph (240 km/h)|
|Lowest pressure||936 mbar (hPa); 27.64 inHg|
|Fatalities||1 direct, 2 indirect|
|Damage||$50.5 million (2018 USD)|
|Areas affected||Baja California Peninsula, Northwestern Mexico, Southwestern United States|
|Part of the 2018 Pacific hurricane season|
Hurricane Rosa brought widespread flooding to northwestern Mexico and the Southwestern United States in late September 2018, and was the first tropical cyclone to make landfall in Baja California since Nora in 1997. The seventeenth named storm, tenth hurricane, and seventh major hurricane of the 2018 Pacific hurricane season; Rosa originated from an Atlantic tropical wave that crossed the West African coast on September 6. The wave proceeded westward across the Atlantic, traversing Central America before entering the Gulf of Tehuantepec on September 22. There, the weather system acquired cyclonic features and became a tropical storm on September 25. Within a favorable atmosphere, Rosa entered a period of rapid intensification on September 27, peaking as a Category 4 hurricane with maximum sustained winds of 150 mph (240 km/h) a day later. Over the next few days, Rosa turned north and then northeast while steadily weakening, making landfall in Baja California as a tropical depression on October 2. After crossing over into the Gulf of California, the remnant system split apart and merged with an upper-level low off the coast of California by October 3.
Rosa prompted the issuance of tropical storm watches and warnings along the coast of Baja California, as well as various flood watches and warnings throughout the Southwestern United States. The impact of Rosa was relatively minor, as a combination of wind shear and cooler seas had weakened the storm significantly by the time it made landfall. Widespread flooding throughout northwestern Mexico, mainly in Sonora and Baja California, led to one drowning and minor damage. In Arizona, rainfall peaked at 6.89 in (175 mm) and caused flash floods that killed two people. Flood damage from Rosa and its remnants totaled $50 million (2018 USD) in the Southwestern United States and $530,000 in Baja California.
Hurricane Rosa originated from a vigorous tropical wave that departed from the west coast of Africa on September 6. The wave traveled across the tropical Atlantic with minimal associated weather and became difficult to track after interacting with a mid-level trough in the Caribbean Sea. 350 mi (560 km) south-southwest of Manzanillo, Mexico.The National Hurricane Center (NHC) issued a Tropical Weather Outlook on September 19, anticipating that an area of low pressure would form in the Gulf of Tehuantepec over the weekend. The wave crossed Central America and entered the gulf on September 22, where it produced a surface circulation with convective activity aloft. Though broad in structure, the system consolidated as it proceeded slightly north of west. It was officially classified as Tropical Depression Twenty-E on September 25, at 06:00 UTC, located
At the time of its formation, the depression was located within a favorable tropospheric environment of warm sea surface temperatures and minimal vertical wind shear, featuring a well-defined center of circulation under an expanding area of strong convection. 150 mph (240 km/h) and a minimum central pressure of 936 mbar (27.6 inHg). This made Rosa the seventh Category 4 hurricane of the year's season.The depression maintained a trend of steady strengthening over the 24 hours: it was upgraded to Tropical Storm Rosa six hours after being classified, and became the tenth hurricane of the season a day later, at 12:00 UTC on September 26. The NHC remarked that Rosa's structure was well developed at the middle levels of the troposphere, with distinct rainbands wrapped around the southern semicircle of the cyclone. The hurricane leveled in intensity for eighteen hours before proceeding into another phase of rapid intensification; it reached major hurricane status at 18:00 UTC on September 27, peaking in intensity with maximum sustained winds of
After Rosa reached its peak, the hurricane's eyewall – an inner ring of clouds around the eye, marked by high winds – began to warm considerably, signaling the start of an eyewall replacement cycle. by 00:00 UTC, September 29, while undergoing its eyewall replacement. Once the replacement cycle was completed, the storm briefly restrengthened because of its much-improved structure, with expanding outflow to the northeast of the eye. However, Rosa began to experience impinging wind shear from the developing trough, causing a misalignment between the upper and lower levels of the hurricane, as well as coinciding with a final weakening phase.Rosa turned to the northwest on the afternoon of September 28 in response to an approaching mid- to upper-level trough, which would continue to influence the remainder of the hurricane's development. Now tracking over cooler seas, Rosa steadily weakened down to Category 2
Rosa turned to the north on September 29, ahead of the trough. 1 while being steered towards the northeast between the trough and a subtropical ridge. Rosa lost its hurricane status twelve hours later, proceeding towards the Baja California Peninsula as a tropical storm. It further weakened to a tropical depression on October 2, after the convection became displaced from the elongating center. At 11:00 UTC on October 2, Rosa made landfall about 70 mi (110 km) southeast of Punta San Antonio in Baja California, becoming the first tropical cyclone to move over the state since Nora of 1997. During its approach towards the Gulf of California, Rosa exhibited an increasingly unwound and diffuse structure, prompting the NHC to declassify it as a tropical cyclone at 15:00 UTC. Shortly after, forecasters at the Weather Prediction Center (WPC) noted that the low- and mid-level circulations of Rosa's remnant had decoupled; the mid-level remnants proceeded into northeast Arizona, while the lower segment traced behind it over the Gulf of California. On October 3, in their final advisory on the system, the WPC reported that the remnants had been absorbed into a deepening non-tropical low off the coast of California.The unrelenting wind shear – combined with progressively cooler seas and drier air – quickly eroded Rosa's core, disrupting the eye and convection over the southern half of the hurricane. At 12:00 UTC on September 30, the diminishing hurricane dropped to Category
The Government of Mexico issued a tropical storm watch on September 29 for the Pacific Coast of the Baja California Peninsula from Punta Abreojos to Cabo San Quintín. The watches on the west coast of Baja California were changed to tropical storm warnings, and watches were issued for the east coast of Baja California from Bahía de los Angeles to San Felipe on the next day. All the watches and warnings were discontinued after Rosa weakened to a tropical depression. 1 as Rosa approached Baja California. On the same day, schools were closed in several communities throughout Baja California as well as in the neighboring state of Sonora. The Marine Plan, an evacuation and rescue plan, was activated in the states of Baja California, Baja California Sur, Sonora, and Sinaloa.The State Unit of Civil Protection of Sonora issued a yellow alert (imminent severe weather) for 11 municipalities and a green alert (possible severe weather) for 19 municipalities on September 30. A red alert was issued for San Felipe on October
Because of its significant weakening before landfall, Rosa had a relatively minor impact in Mexico. 6.54 in (166 mm) in Percebu and at 5.39 in (137 mm) in San Felipe. Floods in San Felipe collapsed part of a highway and opened up a sinkhole in the city's port. The port suffered MX$10 million (US$530,000) in losses following a five-day shutdown of its operations. In Los Cabos, Baja California Sur, rainstorms triggered power outages and floods swept away vehicles. In Puerto Peñasco, Sonora, dozens of homes and businesses suffered from flooding after an estimated 4 in (100 mm) of rain fell. Many of the town's roads were closed, and four bridges became impassable. A woman drowned in Caborca, Sonora, after being swept away by floodwaters.Rainfall was heaviest in Baja California, peaking at
Farther south, in the state of Colima, floodwaters swept through the city of Manzanillo, causing sinkholes, rupturing underground pipes, and inundating buildings. Landslides in and around the city blocked roads and buried three vehicles in mud. 86,000 acres (35,000 ha) of crops. After Rosa's passage, states of emergency were issued for the cities of Ensenada, Mexicali, and Puerto Peñasco.Throughout the state of Michoacán, the combined effects from Rosa and nearby Tropical Storm Sergio destroyed
Exiting the Gulf of California, the remnants of Rosa tracked northward, spawning showers and thunderstorms in the Four Corners region.Damage from flooding in the Southwestern United States totaled about $50 million (USD). Flood watches and warnings were issued on September 30 for Southern California, Arizona, southwest Colorado, Utah, central Nevada, and a small portion of southeast Idaho. On October 1, an interaction between Rosa's remnants and a Pacific low produced severe thunderstorms in San Bernardino County. Surging floodwaters carried rocks onto portions of U.S. Route 95 and coated parts of state routes 62 and 127 in mud and debris. Effects from the severe weather extended into Nevada, where flash floods inundated buildings and deposited rubble along Pioche's Main Street.
By the time of Rosa's absorption on October 3, a total of 6.89 in (175 mm) of rain was recorded at Towers Mountain, Arizona, located about 85 mi (137 km) north of Phoenix; other areas throughout the state reported up to 5.5 in (140 mm) of rain. The remnants of Rosa caused flash floods throughout the communities of Guadalupe, Glendale, Scottsdale, Fountain Hills, Deer Valley, and Sun City and knocked out power in Yuma. As rainfall exceeded 2 in (50 mm), the National Weather Service issued a flash flood warning for the Phoenix area. Though over two dozen roads, as well as schools and businesses, had been closed, 80 car accidents occurred during the torrential rains. Outside the Phoenix area, weather-related traffic accidents resulted in the deaths of a 26-year-old woman just north of Cameron and a 34-year-old man in Kingman.
At Menagers Dam near Sells, Arizona, rainfall from Rosa brought the water level within 1 foot (0.30 m) of maximum capacity on October 2, raising concerns about the dam's structural integrity. Saying dam failure was imminent, the National Weather Service in Tucson urged residents of Ali Chuk to evacuate immediately. Later that day, 162 people were evacuated from Ali Chuk, as well as 32 from Kohatk and 23 from the Menagers Dam community. Engineers were recruited to carry out assessments of the dam, and authorities continued to monitor the water level for two weeks before allowing residents to return to their homes on October 17.
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Hurricane Nora was only the third tropical cyclone on record to reach Arizona as a tropical storm, and one of the rare cyclones to make landfall in Baja California. Nora was the fourteenth named tropical cyclone and 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.
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Hurricane Jimena was the second-strongest hurricane of the 2009 Pacific hurricane season, and tied with Hurricane Norbert as the strongest tropical cyclone to make landfall on western portion of the Baja California Peninsula. Forming from a tropical wave late on August 28, 2009, off of Mexico's Pacific coast, the system rapidly intensified into a Category 2 hurricane on the next day. Two days after developing, Jimena strengthened into a Category 4 hurricane. After peaking close to Category 5 intensity on September 1, it encountered cold water and began to weaken. When the hurricane made landfall on the Baja California Peninsula on September 3, it was only a Category 2 hurricane. On the next day, the tropical cyclone entered the Gulf of California, though the storm weakened into a remnant low after looping back eastward towards Baja California. The storm's remnants drifted westward into the Pacific afterward, before dissipating on September 8.
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Hurricane Odile is tied for the most intense landfalling tropical cyclone in the Baja California Peninsula during the satellite era. Sweeping across the peninsula in September 2014, Odile inflicted widespread damage, particularly in the state of Baja California Sur, in addition to causing lesser impacts on the Mexican mainland and Southwestern United States. The precursor to Odile developed into a tropical depression south of Mexico on September 10 and quickly reached tropical storm strength. After meandering for several days, Odile began to track northwestward, intensifying to hurricane status before rapidly reaching its Category 4 hurricane peak intensity on September 14. The cyclone slightly weakened before making landfall near Cabo San Lucas with winds of 125 mph (205 km/h). Odile gradually weakened as it tracked across the length of the Baja California Peninsula, briefly crossing into the Gulf of California before degenerating into a remnant system on September 17. These remnants tracked northeastward across the Southwestern United States before they were no longer identifiable on September 19.
Hurricane Blanca in 2015 was the earliest recorded tropical cyclone to make landfall on the Baja California Peninsula. Forming as a tropical depression on May 31, Blanca initially struggled to organize due to strong wind shear. However, once this abated, the system took advantage of high sea surface temperatures and ample moisture. After becoming a tropical storm on June 1, Blanca rapidly intensified on June 2–3, becoming a powerful Category 4 hurricane on the Saffir–Simpson hurricane wind scale; maximum sustained winds reached 145 mph (230 km/h) at this time. The hurricane's slow motion resulted in tremendous upwelling of cooler water, resulting in a period of weakening. Blanca gradually recovered from this and briefly regained Category 4 status on June 6 as it moved generally northwest toward the Baja California peninsula. Cooler waters and increased shear again prompted weakening on June 7 and the system struck Baja California Sur on June 8 as a weak tropical storm. It quickly degraded to a depression and dissipated early the next day.
Hurricane Linda was a strong tropical cyclone in September 2015 that resulted in heavy rains across portions of Mexico and the Southwestern United States. The seventeenth named storm, eleventh hurricane, and eighth major hurricane of the season, Linda developed southwest of Mexico from a low-pressure area on September 5. Under warm sea surface temperatures and low to moderate wind shear, the system intensified into Tropical Storm Linda by September 6 and a hurricane by the next day. A well-defined eye soon formed within the storm's central dense overcast and Linda reached its peak intensity as a 125 mph (205 km/h) Category 3 major hurricane on the Saffir–Simpson hurricane wind scale on September 8. Thereafter, the storm moved into a stable environment and an area of lower sea surface temperatures, causing rapid weakening. Convective activity dissipated and Linda degenerated into a remnant low on September 10. The lingering system persisted southwest of Baja California, ultimately opening up into a trough on September 14.
Tropical Storm Lidia was a large tropical cyclone that caused flooding in Baja California Peninsula and parts of western Mexico. The fourteenth tropical cyclone and twelfth named storm of the 2017 Pacific hurricane season, Lidia developed from a large area of disturbed weather west of the Pacific Coast of Mexico on August 31. The storm intensified while moving generally northward or northwestward, peaking with maximum sustained winds of 65 mph (100 km/h) later that day. On September 1, Lidia made landfall in Mexico near Puerto Chale, Baja California Sur, at peak intensity. The storm weakened while traversing the peninsula, ultimately emerging over the Pacific Ocean on September 3, where the storm degenerated into a remnant low. The system brought thunderstorms and wind gusts to Southern California, before dissipating on September 4.
The 2018 Pacific hurricane season was one of the most active Pacific hurricane seasons on record, producing the highest accumulated cyclone energy value on record in the basin. The season had the fourth-highest number of named storms – 23, tied with 1982. The season also featured eight landfalls, six of which occurred in Mexico. The season officially began on May 15 in the Eastern Pacific, and on June 1 in the Central Pacific; they both ended on November 30. These dates conventionally delimit the period of each year when most tropical cyclones form in the Pacific basin. However, tropical cyclone formation is possible at any time of the year, as illustrated when the first tropical depression formed on May 10, five days prior to the official start of the season.
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Hurricane Sergio was a powerful and long-lived tropical cyclone that affected the Baja California Peninsula as a tropical storm which caused significant flooding throughout southern Texas. Forming in late September 2018, Sergio became the eighth Category 4 hurricane in the 2018 Pacific Hurricane Season, breaking the old record of seven set by Hurricane Olaf from the 2015 Pacific Hurricane Season, which formed in mid-October. As the twentieth named storm, eleventh hurricane, and ninth major hurricane of the season, Sergio originated from a disturbance that was located over northwestern South America on September 24. The National Hurricane Center monitored the disturbance for several days as the system organized into a tropical storm on September 29. Sergio gradually strengthened for the next couple of days as it traveled west-southwestward, becoming a hurricane on October 2. The storm then turned towards the northwest as it underwent rapid intensification and an eyewall replacement cycle, before peaking as a Category 4 hurricane on October 4, with maximum sustained winds of 140 mph (220 km/h). The hurricane maintained peak intensity for 12 hours before undergoing a second eyewall replacement and turning towards the southwest. The system then began another period of intensification, achieving a secondary peak with winds of 125 mph (205 km/h) on October 6. The next day, Sergio began a third eyewall replacement cycle, falling below major hurricane strength. At the same time, the system unexpectedly assumed some annular characteristics. Over the next few days, the cyclone curved from the southwest to the northeast, weakening into a tropical storm on October 9. Sergio made landfall as a tropical storm on October 12 on the Baja California Peninsula, and later in northwestern Mexico as a tropical depression before dissipating early on October 13.
Hurricane Lorena was a strong Pacific hurricane in September 2019 that brought heavy rainfall, flooding, and mudslides to Southwestern Mexico and the Baja California Peninsula and also brought severe weather to the U.S. state of Arizona. Lorena was the thirteenth named storm and seventh and final hurricane of the 2019 Pacific hurricane season. A tropical wave, originally from the North Atlantic, entered the East Pacific basin on September 16. With increasing thunderstorm development, Lorena formed as a tropical storm on September 17 alongside Tropical Storm Mario. Lorena made its passage northwestward and quickly gained strength before it made landfall as a Category 1 hurricane in Jalisco on September 19. Due to interaction with the mountainous terrain, Lorena weakened back to a tropical storm. After moving into the warm ocean temperatures of the Gulf of California, however, Lorena re-strengthened into a hurricane, and reached its peak intensity with 1-minute sustained winds of 85 mph and a minimum barometric pressure of 985 millibars Lorena made a second landfall in the Mexican state of Baja California Sur, and quickly weakened thereafter. Lorena weakened to a tropical storm over the Gulf of California, and became a remnant low on September 22, shortly after making landfall in Sonora as a tropical depression. The remnant low moved inland over Mexico, and eventually dissipated inland over Arizona on September 24.
Hurricane Dolores was a powerful and moderately damaging tropical cyclone whose remnants brought record-breaking heavy rains and strong winds to California. The seventh named storm, fourth hurricane, and third major hurricane of the record-breaking 2015 Pacific hurricane season, Dolores formed from a tropical wave on July 11. The system gradually strengthened, attaining hurricane status on July 13. Dolores rapidly intensified as it neared the Baja California peninsula, finally peaking as a Category 4 hurricane on the Saffir–Simpson scale with winds of 130 mph (215 km/h) on July 15. An eyewall replacement cycle began and cooler sea-surface temperatures rapidly weakened the hurricane, and Dolores weakened to a tropical storm two days later. On July 18, Dolores degenerated into a remnant low west of the Baja California peninsula.
person reportedly drowned in Mexico after being swept away by floodwaters.
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This article incorporates public domain material from websites or documents ofthe National Weather Service .