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WHAT'S UP WITH UPWELLING? Sean Collins explains SoCal's recent cold water -- and what it means for summer

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By: Sean Collins May 16, 2007 I've been wondering about the strong onshore winds we've been having lately. Is it likely that these seasonal winds will cause a lot of upwelling and keep ocean temperatures in the upper 50s and low 60s well into late May? **** Surfline's Sean Collins replies: Spring is typically windy because the eastern Pacific high pressure system strengthens off the coast, and with the air temperatures over land increasing and rising, which creates lower pressure over land, we end up with more onshore winds as the high pressure attempts to fill in the lower pressure over land.

We always get a lot of upwelling and colder water rising to the surface from these winds, especially off Point Conception, Point Mugu, Point Dume, Palos Verdes Cabrillo, Newport Pier (Newport Canyon), Laguna, and La Jolla. The colder water then drifts south along the coast through other areas. We had a pretty cool winter this year with water and air temperatures averaging about 58-60 degrees in OC. With the spring winds continuing through May, water temps will probably stay down in the high 50's through most of the month. We may have periods of south-wind eddies (strong northwest winds in the outer waters swirling around the offshore islands to approach OC from the south) that will help to counterbalance the water temps by blowing up some locally warmer water from the southwest. At this point, the way things are going I would expect OC water temperatures to average in the very low 60's in June, in the low to mid 60's in July, and then to the mid to upper 60's by late August and September. That means a few more things as everything is more or less tied into the water temperatures one way or the other. With the cooler water temperatures OC is likely to see more June gloom and marine layer well into June and July. For beachgoers and surfers that will mean more full-length wetsuits and less boardshorts throughout the beginning of summer, which will also affect surf shop sales and the general beach economy for a likely slow start of summer. At this point, the way things are going I would expect OC water temperatures to average in the very low 60's in June, in the low to mid 60's in July, and then to the mid to upper 60's by late August and September. --Sean Collins On the other side, I think there is another variable that isn't very well known or documented, and that is the thermocline or the temperatures throughout the depth of the water column. Even though surface water temperatures were on the cooler side this year, the water temperatures have usually bounced back fairly quickly to the low 60's once all the wind settled down. That suggests a warmer thermocline that may help the water temperatures to warm up faster than expected if these winds can settle down and we can get warm sunny weather for an extended period of time. What could trigger this warming trend is a strong storm over Nevada-Utah that would entice the high pressure system offshore to move over California resulting in a pseudo Santa Ana condition that would block the northwest winds. I also suspect that there are warmer subsurface currents like the Davidson Current, that runs counter to the cold California Current on the surface, that could bring warmer water further north without us being able to easily monitor it. One of the signs of this are the giant squid that have arrived in our local waters over the past couple of months. I suspect they follow these warmer subsurface currents northward. After this latest series of wind events they have all but disappeared due to the cold water but I suspect they will be back. And when we see them again it could be a good early sign that the water column is warming up. I think it's all related. We'll see... SURFLINE HOME PAGE SURFNEWS ARCHIVE

Why is the water so cold this year? (asked in May, 2003)