Central Idea

Hurricane Hilary’s unexpected trajectory towards Southern California and Mexico has caught meteorologists and residents off guard.
The only recorded instance of a tropical storm with hurricane-force winds hitting Southern California dates back to 1858, impacting San Diego.

What is a Hurricane?

A hurricane, also known as a tropical cyclone or typhoon in different regions, is a powerful and intense tropical storm characterized by strong winds, heavy rainfall, and low atmospheric pressure.
Here are the key features and characteristics of a hurricane:

Formation: Hurricanes typically form over warm ocean waters, where the sea surface temperature is at least 26.5 degrees Celsius (about 80 degrees Fahrenheit) or higher. Warm ocean water provides the energy needed to fuel the storm’s growth.
Energy Source: Hurricanes derive their energy from the heat released when moist air rises and condenses into clouds and rain. This process, known as latent heat release, powers the storm and leads to the development of strong winds.
Eye: At the center of a hurricane is a relatively calm and clear area known as the “eye.” The eye is surrounded by a circular band of intense thunderstorms called the “eyewall,” where the strongest winds and heaviest rainfall occur.
Wind Speeds: Hurricanes are characterized by extremely strong winds that can reach speeds of over 74 miles per hour (119 kilometres per hour) for a storm to be classified as a hurricane. Major hurricanes can have wind speeds exceeding 111 miles per hour (179 kilometers per hour).
Categories: Hurricanes are categorized based on the Saffir-Simpson Hurricane Wind Scale, which ranges from Category 1 (weakest) to Category 5 (strongest). Category 1 hurricanes have sustained winds of 74-95 mph, while Category 5 hurricanes have winds greater than 157 mph.

Unlike hurricane-prone states on the Gulf of Mexico, California and Mexico’s west coast lack experience in dealing with such events.
Hurricane Hilary’s expected landfall in the Baja peninsula of Mexico poses risks of landslides, flooding, and extensive damage due to the region’s geographical features and population density.

Factors behind its intensification

Ocean Temperature Factor: Hurricanes require ocean waters above 26 degrees Celsius to form. The west coast’s colder waters are less conducive to hurricane formation.
Vertical Wind Shear: Strong upper-level winds can disrupt hurricanes’ structure and prevent their formation. West coast’s stronger wind shear reduces the likelihood of hurricanes.
Trade Wind Influence: Trade winds, which steer hurricanes, play a pivotal role in directing them toward the east coast while diverting them away from the west coast.
Westward Trajectory: Hurricanes originating in the eastern Pacific tend to move west-northwest, taking them away from the west coast and out to sea.

Climate Change Impact: Climate change leads to more frequent and intense hurricanes. Rising ocean temperatures due to greenhouse gas emissions contribute to increased hurricane intensity.
Ocean Heat Absorption: Oceans have absorbed 90% of excess heat from greenhouse gas emissions, leading to higher sea surface temperatures and stronger hurricanes.
Marine Heat Waves: Elevated sea surface temperatures result in marine heat waves, intensifying storm systems and amplifying their impact on land.
El Nino’s Role: El Niño, an abnormal warming of equatorial Pacific Ocean waters, can weaken wind shear in the eastern Pacific, creating conditions conducive to hurricane formation.