UPDATE: Here's a great article from CNN that confirms my suspicion that these were not rogue waves. A meteorologist from the NWS in San Francisco describes them as "sneaky / sneaker waves" caused indirectly by the generally high waves and directly by the peculiar shoreline and ocean floor in the area.
UPDATE: Charles McCreery from NOAA emailed me with this comment: "It could be surf beat -- when there is not enough time for water to drain back between waves during a large set of waves so it temporarily piles up causing minor flooding at the coast. There was big surf running and a high tide as well. This phenomenon sometimes occurs when Hawaii has big surf." I could buy that.
Also check out blog reader Mishell's comment below about a landslide -- another potential solution that I like. I also heard from Wolfgang Rosenthal from MaxWave via email who said "Concerning your remark that the NDBC buoy did not sense the rogue wave. the answer is the buoy does not measure the single waves. It just determine the statistics of the sea state over 20 minutes (sometimes somewhat longer or shorter). I believe it was not a Tsunami. This has a much longer wavelength and the flooding lasts for several minutes at least." We have issued a video on this topic, shown below (this video may expire later today), it has some unrelated large wave video at the beginning but some good slo-mo footage from the actual event near the end.
By now I'm sure you've seen the video of a "Rogue Wave" sweeping away onlookers at the Maverick's surf contest south of San Francisco Saturday. Wave interactions are very complex, can be caused by wind or earthquakes, and I'm simply not qualified to investigate this event myself, though I have hammered off some emails to people I think could help, and I'll let you know if they reply. Here are some things to consider:
2. Graphs are available for three buoys offshore from the point in question (see above) via NDBC, but none seem to show any rogue waves. What they do show is a general wave buildup from about 4 feet to about 20 feet over the 24 hours preceding this event (see below), something that is not at all unusual on the California coast this time of year (I just blogged about 40 foot waves offshore last month). They also show an increase in wave period from 5 to 14 seconds. Why did they miss it? Several possible reasons: 1. They only measure waves once per hour due to power limitations. 2. They are offshore and if this wasn't a rogue wave (see tsunami comment below) it wouldn't have been evident until it reached the shore.
3. This probably didn't meet the official qualifications for a "Rogue Wave" even though that is the media-favored term this morning (the same was true during a tragic Hurricane wave last August. Wikipedia (not that it's the most scientific journal, admittedly) defines a Rouge Wave as "Waves whose height is more than twice the significant wave height (SWH), which is itself defined as the mean of the largest third of waves in a wave record... Rogue waves seem to occur in deep water... most frequently occurs far out at sea." Essentially, it says that they are opposite from tsunamis which are benign over open, deep water but become dangerous as they approach shore, which doesn't sound like what happened on Saturday, and the article quotes the waves as "5-6 foot high" which is about a third of the waves reported offshore (see below). I would think a Rogue Wave in this context would have been 60 feet high at sea, but I have no idea what that might translate to onshore.
4. I'm not sure that we can say for sure that this wave was caused by wind. Quite frankly, it looks in the video like a surge of water rather than a high wave (again the article quoted wave heights at 5-6 feet). Could it have been a tsunami? Probably not, given the localized effects and no reports of near-shore earthquakes over the weekend; neither California Tsunami sensor recorded anything strange (see zip file above) and the fact that the Pacific Tsunami Warning Center hasn't issued any alerts since February 6. With improvements to the Tsunami warning infrastructure after the 2004 Indian Ocean Tsunami it's virtually impossible that a California tsunami went undetected.
5. I reported in 2006 that there is one agency studying rogue waves, MaxWave, but their website says that data is currently offline. (They say in a New York Times article that at any time there are 10 of these monsters roaming the seas). In that blog entry I talk about other famous rogue waves, and the wave height record.
I live 20 miles due west of Boston Mass. We used to summer at Hull, MA (Nantasket Beach is just at the beginning of Hull and is part of the Boston beaches) and I have always been fascinated by the ocean and weather.
When I found out about the Mavericks, I checked out the coastline under the ocean. The Mavericks have a very distinct coastline and this can cause the waves to become quite huge. So I agree that the waves were not rogue but were caused by the contour of the total beach. and astronomical high tides. It's also winter
From what I have read on The Mavericks, the huge waves at the shore line can be quite common in the winter. That's why the surfing contest in the winter as they do in Hawaii. The mistake made was allowing people to be too close to the shore line.
Living on the East Coast in Massachusetts, we don't have those type of waves as our continental shelf it quite different from the West Coast. It fascinates me to look at the daily wave difference just between Nantasket Beach and Coast Guard Beach on Cape Cod, both Atlantic facing beaches. Nantasket's Beach is cove shaped, is quite flat at low tide and the beach changes every day. One day sand bars and the next day they are gone and the weather and wind remains the same. Coast Guard Beach is a straight beach with a huge sand bar that can cause a rip tide. It's all how the sand moves.
The coastline for high tide at Nantasket Beach can't be seen due to the sea wall. I have to rely on Coast Guard Beach to see how high the water line is and it has been quite high. Also at some other beaches I look at I noticed the same-very high and very low tides. a February occurrence. Blizzard of 1978 here, the tides were so high that at Nantasket Beach/Hull MA, the ocean water came up and over the beach and went all the way down the streets to the bayside. So every February and August, I expect the tides to be higher than normal.
I don't really believe in 'Rogue" waves. it all has to do with the wind.
I know off South Africa waves can get to 100' high but since the shipping lanes were moved, the ships don' t encounter them anymore.
Here's a question I have--if the wave off South Africa can reach 100", what happens when that wave breaks at the shore line?
Posted by Janice | February 16, 2010 1:13 PM
I agree with Bob like seriously if I saw water rising I'd be running for the hills...lol
Posted by andrew | February 15, 2010 7:37 PM
Definitely looks like a storm surge that you would see in a Cat 1 or Cat 2 hurricane 6-12 feet high or like a low-level tsunami. It would be helpful to see the barometric pressure recorded at this buoy for the 12 hours prior to the wave and for a few hours afterwards. If it was dropping significantly until the wave passed and then started rising quickly again, it would be characteristic of a storm surge, even if no storm was within a few hundred miles.
A series of a few small earthquakes/underwater disturbances ocurring within a few hours could certainly dislocate enough water to create this phenomenon. If large swings in barometric pressure were not responsible, then this would be my second choice.
What I don't understand, is why people didn't start immediately running away from the shoreline mmediately after spotting the rising water? Anyone who saw the video (and who hasn't?) of the Thailand Tsunami in December 2004 would know to IMMEDIATELY run away from the shoreline as fast as they could!
Posted by Bob | February 15, 2010 3:13 PM
I'm not an expert; but the wave action does not appear to have typical wave behaviour, but as you mentioned more like that of a tsunami wave. If there were no offshore earthquakes reported, perhaps there was an underwater landslide? Seems as though the bouys would have recorded a rogue wave. But what if an underwater landslide happened between the bouy and the shore? There is a chance the height increase would not have been measured. Just food for thought.
FROM JESSE: Thanks, I hadn't thought of that. That would make sense.
Posted by Mishell | February 15, 2010 1:12 PM
Diana nortthern california:
re #4 above: There were 4 small earthquakes in that location before 10am. The rogue wave happened at the exact time as one of the earthquakes m2.2. I dont know that it's a significant maganitude, but according to USGS, there have been many small earthquakes in the greater San Fransisco area over the past several weeks. Just something to maybe look into :-)
Posted by Diana nortthern california | February 15, 2010 12:45 PM
The damage from the Moore, Okla., tornado of May 20, 2013, is incredible. These radar loops show the immensity of the tragic storm.
When I saw that Google had created a 30-year satellite time-lapse of Earth, I knew where the most impressive weather-related animations would be.
Whatever you call them -- "Ice Needling," "Ice Surges," or "Ice Shoves," or "Ice Heaves" -- a phenomenon that I first blogged about in 2009 is back -- with a vengeance!
17 years ago on this date, while I was taking my freshman exams at UNCA, a "cut-off" low was rumored to dump 57" of snow at nearby Mount Pisgah... but is that reading reliable?
Tornado reports and warnings are down for 2013 so far, and the last 12 months, but what about severe-thunderstorm-warned areas and lightning strikes?
The last two weeks have featured no less than four storm days, one with four storms, here in Central Pennsylvania and I've taken some neat pictures.