Hurricane Olaf was a Category 2 Pacific hurricane that struck the Baja California Peninsula in September 2021. The fifteenth named storm and sixth hurricane of the 2021 Pacific hurricane season, the cyclone formed from an area of low pressure that developed off the southwestern coast of Mexico on September 5, 2021. The disturbance developed within a favorable environment, acquiring more convection and a closed surface circulation. The disturbance developed into Tropical Depression Fifteen-E by 18:00 UTC on September 7. The depression strengthened into a tropical storm and was named Olaf at 12:00 UTC the next day. Olaf quickly strengthened as it moved to the north-northwest, and was upgraded to a hurricane 24 hours after being named. Hurricane Olaf continued to intensify and reached peak intensity while its center was just offshore the southwestern coast of Baja California Sur, with maximum sustained winds of and a minimum barometric pressure of . Just after reaching peak intensity, the hurricane made landfall near San José del Cabo. Interaction with the mountainous terrain of the Baja California Peninsula caused Olaf to quickly weaken. It was downgraded to a tropical storm at 12:00 UTC on September 10. The system became devoid of convection later that day and degenerated to a remnant low by 06:00 UTC on September 11.
The precursor disturbance to Olaf caused flooding in the southwestern Mexican states of Jalisco and Colima. The storm triggered school, port, and COVID-19 vaccination-site closures in Baja California Sur as it approached the peninsula. Severe rainfall, flooding, mudslides, uprooted trees and damage to power lines and hotels affected the state as the hurricane made landfall and moved over the peninsula. Total damage from Olaf was estimated at US$10 million, and one person died due to a mudslide produced by the storm in Jalisco.
Meteorological history
On September 3 at 00:00 UTC, the National Hurricane Center (NHC) noted the potential for an area of low pressure to develop off of the southwest coast of Mexico. The area eventually developed as predicted around 18:00 UTC on September 5. Over the next few days, conditions progressively got more conductive as the disturbance better organized, producing a large area of gradually organizing thunderstorms while it progressively became better defined. The disturbance then moved north-northwest and acquired a low-level circulation, prompting its designation as a tropical depression at 00:00 UTC on September 8. The depression's inner-core convection was disheveled after formation, but the cyclone organized and became better defined throughout the day. At 15:00 UTC on the same day, the cyclone was upgraded to a tropical storm and was given the name Olaf. Moving northwestward at a slow pace, Olaf developed banding features and good outflow within very favorable environmental conditions for intensification, featuring warm sea-surface temperatures (SSTs) and low amounts of vertical wind shear. On September 9, the storm developed a well-defined eye and became a Category 1 hurricane around 15:00 UTC.
Olaf intensified at an even quicker rate as it neared to southwestern coast of the Baja California Peninsula, developing a symmetrical eyewall as its winds increased by 20 mph in just six hours. At 03:00 UTC on September 10, Olaf was upgraded to a Category 2 hurricane; it reached peak intensity at this time with maximum sustained winds of and a minimum barometric pressure of . Twenty minutes later, the storm made landfall very near San José del Cabo. Olaf's center briefly crossed the peninsula before re-emerging back over water, weakening back to Category 1 status in the process. Shortly after emerging back over water, the organization of Olaf collapsed, including its eye and eyewall, and it was downgraded to a tropical storm at 15:00 UTC on September 10. Gradually moving westward away from land, Olaf continued to rapidly weaken, with its low-level center becoming exposed and devoid of any deep convection by 21:00 UTC. By 09:00 UTC on September 11, Olaf had been devoid of any organized deep convection for 18 hours, and was therefore designated a remnant low as it turned back to the southwest.
Preparations
At 03:00 UTC on September 8, tropical storm watches were issued for southern portions of Baja California Sur. These were extended northward at 09:00 UTC before tropical storm warnings were issued for the same areas. These remained until 09:00 UTC on September 9, when hurricane warnings were issued and tropical storm warnings were extended northward. Hurricane and tropical storm warnings were once again extended northward twelve hours later at 21:00 UTC, six hours before landfall. A red alert was issued statewide.