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2023 Pacific hurricane season

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Through El Niño–Southern Oscillation

Forecasts at the outset of the 2023 season predicted busier-than-normal tropical cyclone activity in the eastern Pacific basin, largely due to El Niño. However, no tropical cyclones developed until June 27, when Hurricane Adrian initially formed, becoming the latest first-named Eastern Pacific tropical storm since Tropical Storm Agatha in 2016. In July, Hurricane Calvin became the season's first major hurricane, later passing just south of the Big Island of Hawaii as a tropical storm, bringing widespread rainfall to the area and neighboring Maui. In August, Category 4 Hurricane Dora passed south of the Hawaiian Islands and contributed to strong gradient winds over Hawaii, which in turn helped fan the flames of multiple devastating wildfires. Later that month, Hurricane Hilary made landfall as a tropical storm in Baja California, later bringing torrential rainfall and gusty winds to the Southwestern United States. In early September, Hurricane Jova, the first Category 5 hurricane in the basin since 2018, caused rainfall, high waves and rip currents in areas previously affected by Hilary.

October saw four tropical cyclones strike the Pacific Coast of Mexico. Tropical Storm Max struck Guerrero on October 9, resulting in intense flooding. Less than two days later, Hurricane Lidia rapidly intensified into a Category 4 hurricane and made landfall at peak intensity on Jalisco. Lidia was followed by Hurricane Norma, which made two landfalls in northwestern Mexico less than two weeks later. Hurricane Otis developed in the time period between Norma's landfalls, rapidly intensified into the second Category 5 hurricane of the season, and devastated Acapulco when it became the first Pacific hurricane to make landfall at Category 5 intensity, therefore surpassing Hurricane Patricia as the strongest landfalling Pacific hurricane on record. Tropical Storm Pilar caused severe flooding in El Salvador and Honduras while passing offshore. In November, the last storm of the season, Ramon, dissipated with no effects to land.


Seasonal forecasts

In advance of each Pacific hurricane season, forecasts of hurricane activity are issued by the United States National Oceanic and Atmospheric Administration (NOAA)'s Climate Prediction Center and Mexico's Servicio Meteorológico Nacional (SMN). These include weekly and monthly changes in significant factors that help determine the number of tropical storms, hurricanes, and major hurricanes within a particular year. According to NOAA, the average eastern Pacific hurricane season between 1991 and 2020 contained roughly 15 tropical storms, 8 hurricanes, 4 major hurricanes, with a near-normal accumulated cyclone energy (ACE) index between 80 and 115. Broadly speaking, ACE is a measure of the power of a tropical or subtropical storm multiplied by the length of time it existed. It is only calculated for full advisories on specific tropical and subtropical systems reaching or exceeding wind speeds of 39 mph (63 km/h). NOAA typically categorizes a season as above-average, average, or below-average based on the cumulative ACE index, but the number of tropical storms, hurricanes, and major hurricanes within a hurricane season is sometimes also considered.

On May 4, 2023, SMN issued its forecast for the season, forecasting a total of 16–22 named storms developing, with 7–11 hurricanes, and 3–5 major hurricanes. Factors they expected to increase activity were above-average sea surface temperatures across the eastern Pacific and the El Niño–Southern Oscillation (ENSO) remaining in the neutral phase, with the possibility of a strong El Niño developing. On May 25, 2023, NOAA issued their outlook, calling for an above-normal season with 14–20 named storms overall, 7–11 hurricanes, 4–8 major hurricanes, and an ACE index of 90% to 155% of the median.

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