Why does the Pacific storm rarely attack the United States?

News of the storm that struck the coast of Florida, Louisiana and many other southeastern states of the United States regularly appeared on the news during the summer, while the storm warning came from the Pacific as Hurricane Jimena, for example, is very rare.

In fact, there is only one storm believed to have attacked California and this happened in 1858. Does it happen again? The answer is not really 'no', but it is difficult to say when it will happen again.

The difference is the result of ocean and atmospheric conditions occurring in both bays, which makes the Atlantic storm tending to land while the Pacific storm goes away. coastal area. This is the reason why the West Coast of the United States rarely suffers from hurricanes coming from the ocean.

The storms on both of these oceans share a common mechanism in which warm ocean water is the main cause.

'They are the same in every way, from formation to shape,' says Dennis Feltgen, spokesman for the National Hurricane Center, located in Miami.

But storms in the Pacific are less frequently mentioned and less damaging than the Atlantic storm. On average, every 15 storms occurring in the Northeastern Pacific Ocean correspond to 11 storms in the Atlantic Ocean. It is worth noting that the Pacific storm almost never attacked the continent of the United States, while the Atlantic storm hit this mainland on average nearly 2 times per year. (The Atlantic hurricane season usually lasts from 1/6 to November 30.)

Conditions that affect the development and movement of these storms will determine whether storms land on the land, as well as their specific landings.

Wind and warmth

Wind in the tropical North Hemisphere, where tropical cyclones often form, blow in the direction from east to west, so it is certain that ocean storms must also move in this direction. This means that the Atlantic storm will move to the mainland, particularly in the eastern and southern United States, as well as the Caribbean Islands and sometimes Mexico.

But in the Pacific, these winds will also push the storm away from the mainland. ' Almost all storms move to the sea,' Feltgen said.

Hurricane Jimena is heading to Mexico's Baja Peninsula when these images were taken back by NASA's Aqua satellite on August 30. At that time, the storm maintained winds of up to 140 miles per hour (equivalent to 225 km / h) and was at level 4 storm. Storm clouds spread across the western Mexico region. . (Photo: Jeff Schmaltz, Goddard Space Flight Operations Center)

Sometimes, some special weather types cause the storm on the Atlantic Ocean to move to the sea and push the Pacific storm toward the mainland as in the case of Hurricane Jimena.

Another factor contributing to the protection of US west coast cities, such as California, is the ocean water temperature. Sea storms often form on warm ocean waters, lower water temperatures will reduce the 'fuel' source and weaken storms.

While the Pacific storm was often weakened before it hit California, the East Coast storm was growing under the influence of heat from the Gulf Stream (warm water from the Gulf of Mexico to the Atlantic Ocean). Europe).

Pacific storm

In 2004 it was discovered that a sea storm had devastated San Diego in 1858. Michael Chenoweth, a researcher with the National Oceanic and Climate Authority, found data about storm on the California newspaper face. Chenoweth and Chris Landsea, two members of the agency, used press material and meteorological observations to describe the forgotten storm and redraw its path.

The description of this storm refers to the extremely strong whirlwind, the roof being blown away, the tree uprooted and the fence collapsed.

That year may be a year of intense El Nino phenomenon, making the Pacific water warmer than usual, facilitating the formation of sea storms (while less favorable for Atlantic storms).

This finding is important for the hypothesis that global warming raises ocean surface temperatures. If a level 1 (Saffir-Simpson low-level) storm struck San Diego or Los Angeles today, it could cause at least a few hundred million dollars in damage.