TL;DR

• Small, background swell to 2ft for the first two days of the waiting period
• New, inconsistent S'ly groundswell for days 3 and 4 around 3-4ft
• Reinforcing, inconsistent SW groundswell for days 5 and 6 to 3-4ft
• Better SW groundswell likely for the final days of competition

There’s a palpable sense of expectation as the Woz approaches the eighth event of the CT, the Corona Open Mexico.

For one, surfing is coming off an Olympic high and the powers that be would be hoping to deliver while interest in the sport remains heightened.

Secondly, after an almost two month break, the surfers are returning to competition, and as Mexico is the third-last event of the year it’s crunch time for anyone hoping to make the Top 5, or to maintain their position within the five. Currently, only Gabriel Medina has a Finals spot locked up.

Lastly, after a fifteen year hiatus, the Woz is returning to Barra de la Cruz. Though it was held only once, the 2006 contest was both sensational and controversial. Can the 2021 version also deliver?

Situated on the southern Pacific coast of Mexico, midway between Puerto Escondido and the town of Salina Cruz, Barra is at the western end of the Salina Cruz coast, a coastline defined by multiple sand-bottom, right hand pointbreaks. The geology and sand delivery system is not unlike that of Australia’s East Coast north from Newcastle, with protruding headlands giving way to large sandy bays fed by sediment from multiple rivers flowing down from the coastal mountains.

The other defining feature of the Salina Cruz coast is, unlike much of the Pacific coast which faces south-west, it faces south, even tending south-east. This limits the swell direction needed to turn on the numerous pointbreaks. The bread and butter swell direction for much of Mexico is south-west, however it needs to be very large from that direction to wrap into Barra, and even then it’s heavily reliant on sand quality - think Scotts Head on a big south when the sand is deep.

Coastal alignment of the Oxaca region and Barra de la Cruz

The very best direction for Barra - and all the regional pointbreaks - is south. The storms that form south of Rapa Nui and send swell sweeping up past the Galapagos, nearly parallel to the South American coastline, perform the best.

Being exposed to the whole South Pacific Ocean, and being winter you'd expect there to be a plentiful supply of long-range swells from strong Southern Ocean storms.

Alas, the main engine room where these storms develop is expected to see higher than normal pressure this week. You see, with travel times of five to seven days from the Southern Ocean, up into Mexico, we need the see swell producing storms developing from now through until Thursday week.

While the roaring forties will remain subdued over this coming week, there are still a couple of swell producers showing up on the charts.

Mean Sea Level Pressure anomaly forecast for the week Monday 2nd August to Monday 9th August. Source: ECMWF

Firstly, we’re expected to see a relatively weak polar storm forming east-southeast of Chile generating an inconsistent S'ly groundswell, followed by two separate mid-latitude lows firing up east of New Zealand, generating inconsistent SW groundswells.

The first swells from the S and SW are due through the middle of the waiting period, with the second and likely better SW groundswell, for the end of the waiting period.

As discussed above, Barra's alignment to these incoming SW groundswells isn't ideal, and with the long distance between the source, it'll be compounded by the lack of consistency.

Coming back to the first, most favourable swell generator, and that'll be a polar frontal system firing up in the south swell window, east-southeast of Chile. While not overly strong, a good, broad fetch of strong to gale-force S/SW winds will be projected northwards. This will hit the point the best, arriving through days three and four of the waiting period (that being Thursday and Friday the 12th and 13th respectively) likely offering inconsistent 3-4ft sets.

Surface wind forecast and source of the first S'ly groundswell

At the same time as this swell is being generated, a slow moving mid-latitude low will form just east of New Zealand. What this low lacks in strength, it'll make up for in longevity with a slow moving fetch of strong to gale-force W/SW winds due to be projected through Mexico's swell window for a couple of days, weakening slowly into Friday.

Surface wind forecast and the source of the secondary, reinforcing pulse of SW groundswell

The big factor with swell from this low, especially the initial stages is how much effect the French Polynesian island chain has on swell shadowing. Once the low moves further east of New Zealand the islands will become less of an issue, but it'll be interesting to see play out.

Satellite imagery identifying the swell shadowing of the French Polynesian island chain. Source: Google Earth

Timing wise this secondary SW groundswell looks to arrive through the middle of the waiting period, providing similar inconsistent 3-4ft sets on the outside of the point, though running smaller inside compared to the S'th energy.

Locally winds look to be favourable at this stage, offshore in the mornings ahead of afternoon sea breezes.

Looking longer term, and a secondary mid-latitude low is due to fire up east of New Zealand early next week, being positioned a little further south but being a little stronger, hopefully generating a slightly better SW groundswell for the end of the waiting period, but we'll continue to keep an eye on these developments and providing running commentary in the comments section below.