Hurricanes generally aren’t concerns of Californians. However, there have been some rumblings about whether Hurricane Kay, which recently formed off the western coast of Mexico, could make a run at a California landfall. I have even seen some “social media-rologists” suggesting that it will.
Here’s why it probably will not (but pay attention anyhow).
The answer involves several meteorological and oceanographic factors.
First off, Hurricane Kay will get close enough to the Baja California peninsula to impact the region. By the way, a quick geography lesson is in order. Baja California is a Mexican state that borders California. NOAA’s Weather Prediction Center has issued alerts noting that rain bands from Kay could cause flash flooding in some parts of Southern California and Arizona into the weekend. Dangerous water conditions (swells, rip currents, and life-threatening surf) are also expected. At the time of writing, hurricane warnings are up for parts of the central Baja California peninsula. The current forecast from the National Hurricane Center suggests that the hurricane will strengthen some on Wednesday before a weakening trend begins on Thursday.
So while the focus for many has been on the relative novelty of Kay potentially approaching the California coastline, my focus has been on potential impacts articulated above. Let’s dig a bit deeper into two aspects of the discussion – Why the hurricane likely will NOT make landfall in California and the novelty aspect.
I spoke with University of South Carolina Geography Professor Cary Mock who is an expert on hurricane climatology. Mock wrote on his social media pages, “Model forecasts right now suggest a upper-level ridge centered over the interior Western USA, which would keep Kay from getting to California and push it westward. S California may get some rain though.”
Ironically, the area of high pressure Mock is referring to (map above) is also responsible for “off-the-chart” heat in the western U.S. Heat records are being shattered by more the 3 to 5 degrees in many cases (and its September). Relative to the hurricane, the clockwise flow (those circular contours) around the high pressure center is likely a significant player in the “hard left” that Kay is expected to take this weekend. Professor Mock also told me by direct message, “Some rare occasions of California tropical systems, need some help from a trough in the NE Pacific to steer it there. That is missing right now.”
Though very uncommon in the region, Mock noted that tropical systems creeping into the area (map above) are not unprecedented. In 1997, powerful Hurricane Linda was briefly expected to make a beeline for California but turned out to sea. The Los Angeles Times recently documented four storms that came close to Southern California area in 1939, one of which actually made landfall as a Tropical Storm. In his outstanding and thorough piece, Paul Duginski writes, “Storms such as this have been given the name el Cordonazo de San Francisco by fishermen in the villages along the Pacific Coast of Mexico….means “the Lash of St. Francis,” because they occur in the fall, close to the Oct. 4 feast of St. Francis of Assisi.”
Another reasons tropical systems do not thrive off the coast of California is that the waters are typically too cold. If you’ve ever been to the beach on the West Coast and East Coast respectively, you may have noticed that waters are colder out west. The California Current flows equator-ward flowing and transports colder water. By contrast, the Gulf Stream is a poleward flowing current off the East Coast of the U.S. that transports warmer water. These currents are a part of the process of redistribution of excess heat in the Tropics to the heat-starved Polar regions.
There is also a process called upwelling. NOAA’s Ocean Explorer website explains, “Along a coastline oriented North-South, like much of the west coast of the U.S., winds that blow from the north tend to drive ocean surface currents to the right of the wind direction, thus pushing surface waters offshore.” When the water is pushed offshore, colder, deeper water from below replaces it. While still much cooler than the 80 deg F threshold we often look for in hurricane-breeding grounds, the sea surface temperature (SST) anomalies (differences from “normal”) near Southern California (map below) are currently on the warm side of the ledger. The “triple-dip” La Nina is also apparent as cooler than normal temperatures in the central Pacific Ocean.
It is bizarre that I am writing about a hurricane approaching Baja California and 110+ deg F temperatures in the state of California in the same week. Yikes.