Surfline Pacific Forecaster Schaler Perry stacks up August 2013 in SoCal against the waves of August past

Any chance you have a way of showing cycles over, say, the last ten years in terms of wave heights over a given part of the year? It would be interesting to see a chart of August averages over ten years (would this year be the lowest?)--and temperatures as well (same?).



-Dan

Good question. And if you follow social media, don't live under a rock, or are the significant other of someone who hasn't surfed in several weeks - surfing is extinct/it's been flat for everrr/what's up with Lake Pacific? (eastcoasters kindly ask everyone crying over marginally rideable waves for three weeks to keep it coming). Dan here isn't our first user to question the SPAC's, and to a lesser extent the Tropical EPAC's, deal this August. There have been a slew of "what gives?" "are there ever going to be waves again?" "is this the worst August ever?" rumblings.So, we've dug a little deeper to see what exactly gives this August, and how it stacks up against the climatological norms. To give this August some credit where credit is due, it did start off on a fairly decent note with head high+ waves at focal points like Lowers ( Here's proof ), and looks to offer a few modest to locally fun-zone waves through the end of the month and a potential fun-zone pulse of tropical swell to boot ( North OC Forecast ). But that said, what happened to those three weeks in the middle?Well, to be frank, statistical averages happened to those three weeks in the middle of August. For us jaded Socalians, it's easy to forget that from May through July the surf barely dropped below the chest/shoulder high threshold on account of the SPAC being an absolute workhorse. During that time a virtual conveyer belt of strong lows were sliding out from under New Zealand and into the Central South Pacific pushing up fun-zone to slightly better Southerly swells one after another. Waves for days and the jaded were cheery. But what tipped the scales back towards average?NCEP/NCAR Reanalysis depicting the Sea Level Pressure Anomaly back when we had waves (from mid March through July). Those dark blues and purples across the SPAC equate to lower than normal pressure, which equates to more storm activity, which equates to more waves (most of the time).By the end of July, a shift was beginning to take hold. Strong, blocking high pressure became the dominant feature in the Southwest Pacific, anchoring in to the E/SE of New Zealand. The outlier isn't that there was high pressure to the E/SE of New Zealand, as often times areas of high pressure in this region will develop adjacent to strong lows (storms) and help drive more consistent fetches/swells for SoCal.What really stands out this August was the prevalence/dominance of the high pressure that developed and its effectiveness in shutting down storm activity in the Southwest Pacific. If you look at image three below, which displays the composite mean sea level pressure chart from late July through August 19th, 2013, you can clearly see a void in low pressure (storm activity) in the Southwest Pacific and much more prevalent high pressure when compared to the climatological average from 1981-2010 (Image 2). Slow goings for the west coast.NCEP/NCAR Reanalysis showing Mean Sea Level Pressure for the month of August from 1981-2010. This is what "normal" looks like with swaths of deep purple (storm activity) encompassing the "roaring 40s" "furious 50s" and "screaming 60s" of the Southern Hemisphere, as high pressure dominates around 30 degrees S.NCEP/NCAR Reanalysis depicting the Sea Level Pressure Anomaly for August 2013. Colors from green to deeper orange denote higher than normal pressure (notice the large area of higher than normal pressure over the Southwest Pacific). The persistence of much higher than normal pressure there shut down storm activity and in turn swell generation.What does a typical August look like? Based on the rumblings in and around our office and throughout the surfing public, there's usually waves. Right? Right. Throughout August the dominating feature in the SPAC is low pressure, more specifically large winter storms (as easily noted in the 1981-2010 mean sea level pressure chart for August). And those storms typically send us inconsistent, lully, but often times pretty fun and occasionally large Southern Hemi swells.We did some digging in our Surfline Climatology Model, filtering for swells from 155-225 degrees with a height greater than 2.5' and period greater than 9s. That will allow us to see any tropical or Southern Hemi swells that would keep Southern California's exposures in better than dismal 1-2' surf. To no major surprise, there typically are waves and they meet that criteria 81% of the time. That ranks August 4th overall, right behind July in 2nd, and a tie for 1st between May and June. So how does that look on a day-to-day basis? Better than your odds in Vegas. Based on the 30 years we've evaluated, August 2013 has been very slow in comparison to the norm.Top graph shows the consistency at which swells will be greater than 2.5' @ 9s or more by month (think at least knee-waist high+ surf). The bottom breaks down that consistency on a day-to-day basis through the month of August.Leave your questions in the comments section below and we'll do our best to answer them.~ Schaler Perry and the Surfline Forecast TeamFollow us on on twitter @SLforecast