Q: Hurricanes Hitting Los Angeles Area & Points North

[Saul Trabal]

How rare is it for hurricanes to hit areas like Los Angeles, California and further north? What are some of the factors that keep hurricanes from going up into that part of the U.S?

:?

 

[Aaron Kennedy]

On the east coast, there is a warm current of water called the gulf stream. On the west coast, however, there is the direct opposite. A cold current of water that flows from the NW pacific down along the CA coast. Since hurricanes require ocean temps of 28C or so, this pretty much kills the chance for hurricanes along LA.

Aaron

 

[Jeff Wear]

Cold water is the main thing that keeps hurricanes from hitting CA. Sea surface temperatures rarely get much above 70F off the coast of southern CA - while sea surface temperatures off the coast of central and northern CA often stay in the 50s all summer.

To date, no tropical cyclone has made landfall in CA at hurricane intensity. The last tropical cyclone to make landfall as a tropical storm in CA did so between Los Angeles and San Diego in 1939.

 

[B Ozanne]

Cold, cold, cold...did I mention the water in California is really cold? Only during the dead of summer is the water tolerable in San Diego and LA. Actually the warmest season for coastal CA tends to be in the fall when downsloping winds bring in warm/dry continental air. Which is also what feeds CA wildfires. The west coast of the US is under the influence of cold ocean currents coming from the north. Great for kelp and cute sea otters, bad for tropical cyclones.

Not to mention the mid-level stearing currents only occaisionally push the remnants of a tropical system into that area.

 

[Thomas Loades]

On the east coast, there is a warm current of water called the gulf stream. On the west coast, however, there is the direct opposite. A cold current of water that flows from the NW pacific down along the CA coast. Since hurricanes require ocean temps of 28C or so, this pretty much kills the chance for hurricanes along LA.

Aaron

Oddly, this doesn't seem to reverse in El Niño years, when cold water wouldn't be a problem — unless of course 1939 was an El Niño year.

 

[Jeff Wear]

Oddly, this doesn't seem to reverse in El Niño years, when cold water wouldn't be a problem — unless of course 1939 was an El Niño year.

El Niño has little to no effect on the water temperatures off the coast of California - the warm water anomalies tend to stay within 20 degrees of the equator. Storms do tend to recurve northward towards the west coast of Mexico and California more often during El Niño years, although I believe that has more to do with the steering currents being different....the easterly trades are not present during an El Niño and more troughs tend to form off the west coast of the United States during the late summer and early fall. The tropical cyclones almost always totally dissipate before reaching southern CA however as waters north of Punta Eugenia in Baja California are always in the mid 70s or lower. The few that do hit California as a tropical depression usually are the ones that are major hurricanes as far north as Cabo San Lucas as well as the ones that accelerate northward in advance of a trough and therefore spend lesser time over the colder waters.

1939 I do believe was an El Niño year - there were about 4 or 5 tropical cyclones that hit either California or Baja California that September.