2012 Pacific hurricane season

Season overview

By storm counts the season ran a little above the long-term norm, while its accumulated cyclone energy of 98.5 units was below the 1971 to 2006 average of about 113 that NOAA uses as a baseline. Activity was concentrated in the eastern part of the basin: every storm formed east of 140°W, none developed in the central Pacific, and only Hurricane Daniel crossed into that region, as a weakening tropical storm. The dominant pattern was westward and northwestward motion away from Mexico, and an unusually large number of systems passed west of the Baja California peninsula rather than striking the mainland.

The Climate Prediction Center's outlook in late May leaned toward a near-normal or quieter year, calling for 12 to 18 named storms, 5 to 9 hurricanes and 2 to 5 major hurricanes. Forecasters pointed to lingering La Niña conditions early on, an expected shift to ENSO-neutral conditions for the peak months and increased wind shear. The final totals landed at or just above the top of that range.

The site's counts use US-agency one-minute winds during the tropical stage in the IBTrACS archive. For 2012 they match the National Hurricane Center best-track totals of 17 named storms, 10 hurricanes and 5 major hurricanes, so no storm is counted differently between the two definitions.

How the season unfolded

The first tropical depression formed on 14 May, a day before the official start of the eastern Pacific season, and became Tropical Storm Aletta after an eastward-moving Kelvin wave helped a broad low organize in the Intertropical Convergence Zone well south of Mexico. Hurricane Bud followed within a week, reaching hurricane strength on 23 May and a peak of 100 kt two days later, so the season had a major hurricane before June. Bud then turned northeast toward southwestern Mexico under increasing shear and fell apart just offshore.

June brought only Hurricane Carlotta, a short-lived but intense storm that developed south of Guatemala on 14 June and hit the Oaxaca coast less than two days later. Early July was the season's busiest stretch at sea. Hurricane Daniel formed on 4 July, Hurricane Emilia on 7 July and Hurricane Fabio on 12 July, and all three were active at once on 12 July, marching west-northwest across warm water well away from land. Fabio became the season's fifth hurricane on 13 July.

August was quieter. Hurricane Gilma peaked at 70 kt over open water, and Tropical Storm Hector grew from the mid-level remains of Atlantic Hurricane Ernesto after it crossed Mexico from the Bay of Campeche. Hurricane Ileana formed late in the month and, counting its remnant low, left the longest recorded track of the year at about 276 hours as it drifted southwest toward the central Pacific.

September was the busiest month by formations, with five named storms: John, Kristy, Lane, Miriam and Norman. John and Kristy stayed weak in marginal conditions near the Baja California peninsula, Lane briefly became a hurricane farther west, and Miriam intensified rapidly to major hurricane strength. Norman formed on 28 September close to Cabo San Lucas and moved up the Gulf of California. October added Tropical Storm Olivia and Hurricane Paul, and the season closed with Tropical Storm Rosa, which formed on 30 October after a passage of the Madden-Julian oscillation and weakened in strong shear on 3 November without affecting land.

Strongest storms

Hurricane Emilia was the season's strongest cyclone. It strengthened rapidly in a favorable environment and peaked at 120 kt, Category 4, with a minimum pressure of 945 hPa on 10 July, about 590 nautical miles south-southwest of the southern tip of Baja California. An eyewall replacement cycle then knocked it down to 90 kt, but it recovered to a secondary peak of 105 kt early on 12 July before cooler water and drier air wore it down. Its remnant low opened into a trough south of Hawaii's Big Island on 18 July.

The other four major hurricanes were spread from May to October. Hurricane Bud and Hurricane Daniel each peaked at 100 kt with a pressure of 961 hPa, Bud in late May and Daniel on 8 July. Hurricane Miriam and Hurricane Paul both reached 105 kt and 959 hPa, Miriam on 24 September and Paul on 15 October. Paul's rise was abrupt: it became a hurricane only twelve hours before reaching its peak just east of Clarion Island. Hurricanes Carlotta and Fabio topped out at 95 kt, one step short of major strength.

Landfalls and impacts

Hurricane Carlotta was the season's most damaging landfall. After peaking at 95 kt, it came ashore about 10 nautical miles east-southeast of Puerto Escondido, Oaxaca, around 01:00 UTC on 16 June with estimated winds of 90 kt, then weakened rapidly over the mountains of Oaxaca and Guerrero. The season article describes it as the easternmost landfalling hurricane on record in the eastern Pacific.

The National Hurricane Center counted three direct deaths from Carlotta in Oaxaca: two young sisters killed when a mud-brick house collapsed in Pluma Hidalgo, and a woman whose vehicle was flipped by the wind. Other reports put the toll in Mexico at seven or more, though the NHC could not confirm whether the additional deaths were direct. At least 29,000 homes and 2,500 businesses were affected by flooding and wind, and Oaxaca requested 1.444 billion pesos, about US$113 million in 2012, for repairs to public infrastructure.

Hurricane Paul weakened quickly under strong shear as it neared Baja California Sur and dropped to a tropical storm on 17 October before its center paralleled the coast. It became post-tropical six hours later and grazed the shore at Bahía Asunción with 35 kt winds. Media reports cited by the NHC said almost 16,000 people were affected and about a thousand homes damaged, with Loreto cut off by flooded roads and about 30 percent of electricity customers in Baja California Sur losing power. La Paz estimated road damage at 200 million pesos, about US$15.5 million in 2012. No casualties were reported.

Tropical Storm Norman weakened to a tropical depression just before making landfall near Topolobampo, Sinaloa, on 29 September, and flooding was reported across several western Mexican states and in La Paz, with no damage estimate and no reported casualties. Hurricane Bud washed out a few roads near Manzanillo without casualties. The NHC reports for Daniel, Emilia, Fabio, Hector, John, Kristy and Miriam record no damage or casualties.

Names and context

Names came from the same list used in 2006, running from Aletta to Rosa, with Sergio next in line when the season ended. No names were retired afterward, so the list returned in 2018. Two of the season's storms also had Atlantic connections: Hector grew from the remains of Hurricane Ernesto, and Paul came from the same tropical wave that earlier spawned Atlantic Tropical Storm Oscar.