风切变
Rick maintained its peak intensity for roughly two hours between 7:00 pm and 9:00 pm PDT (0200 and 0400 UTC) on October 17, before it began to weaken in response to an eyewall replacement cycle and increasing wind shear. Throughout the day, deep convection around the eye warmed slightly and a combination of dry air and wind shear restrained the extent of the storms' outflow to the west. The combination of these factors imparted steady weakening. Later that day, Rick began to turn towards the northwest as the subtropical ridge north of the system began to weaken. Early on October 19, Rick degraded to a Category 3 hurricane as it began its approach to the southern end of the Baja California peninsula. Wind shear and dry air quickly entered the core of the system, with the eye disappearing from satellite imagery later that morning.