Perfect Macaronis Barrel (Courtesy: Rip Curl)

Rip Curl hardly have chosen a better location for the inaugural Mentawai Pro. With the Southern Indian Ocean as your swell source and uninterrupted fetch from a wide range of angles you could pretty much pick the heat times now and be all but guaranteed the right conditions. The world’s ‘funnest’ wave, a pro surfers playground of choice, is also a surf forecasters dream. Working on almost any swell direction (but preferring just a touch of west) and any tide the wave even eats up onshore winds, turning into exactly the kind of fun park aerialists dream of. In fact the only scenario likely to cause concern is too much swell, beyond about double over head the wave becomes a different sort of challenge. With the historical record showing this time of year all but certain to deliver consistently in the 4-8ft@13 seconds swell range the outlook this early in the window is for a continued run of exactly this sort of conditions, giving most likely head to head and a half conditions on the reef. However we’ve already seen a couple of really solid early season swells hit Indo so we’ll be keeping our eyes open for repeats of this scenario too.

A decades data for the opening day of the Rip Curl Pro. Spot the bad day???

Rip Curl Mentwai Pro Website
MSW Official Mentawai Pro Forecast
Typical conditions for the start of the event

Macaronis broad swell window exposed it to the Indian Ocean full fury.

The Atlantic storm responsible for a late weekend pulse for western facing coasts runs through earlier this week.

The blocking high that’s delivered such warm, calm early spring weather moves west bringing stronger winds and unsettled weather. However a series of small storm systems off the US Eastern seaboard culminating in a deep low earlier on Tuesday are sending a steady stream of mid sized long period swell to exposed coasts over the long weekend. Monday sees a change in tempo frustrating the efforts of most Atlantic facing coasts but delivering cheer for wave starved channel coast surfers. That same northerly airflow means the North East might be pick of the bunch for the long weekend with steady swell and much more favourable winds.

Friday 6th

The first pulse of small swell arrives for more northerly facing coasts (North cornwall and North Devon) with potential for waist to chest high waves by the evening for the most exposed spots but all but obliterated by the freshening north westerly devil wind. Hard to find shelter in these conditions.

The South Cornwall and Devon coasts and South Wales might see a tiny wave at the very best spots with that same wind running offshore but nothing to drive for.

Further up the channel forget about surfing unless you fancy a drive.

Saturday 7th

The first pulse of swell fades replaced by the stronger pulse set to dominate the rest of the weekend. Although modest in size the long period power of this second swell will mean potential for head high waves by evening and these smaller long period swells love to find shape on the better banks and barrel at beaches that allow for it, however all this is just hypothetical unless there’s a change to the forecast onshore NW wind that again looks to set the theme. There simply isn’t decent shelter from this on most of the exposed North Cornwall coast, best bet might be the North Devon beaches that will show less size but potentially see those same winds run cross-shore through the middle of the day.

South facing coasts fare better with the wind, but the latest model runs look unlikely to deliver too much in the way of size. We’re looking at waist high waves by the end of the day, perhaps a little better at the standout spots. South Wales fares a little better for size than South Devon and Cornwall and those winds are blowing offshore so worth a check of the cams if you’re in the area.

Perhaps just the tiniest hint of a wave on the very best reefs further up the channel by the end of the day.

While the South and West of the country waits for tomorrows swell the real pick will be the North East coast, with that same northerly air flow delivering a solid wind sea with variable winds but looking really light through the middle of the day.

Sunday 8th

This is pick of the weekend for pretty much everywhere. The North Coast of Cornwall and Devon maintains that annoying north west wind, onshore at all spots, but at least latest advice moderates it in strength to annoying but not complete game over. In fact if onshore’s the new offshore for you there might even be reasons for cheer. The swell peaks at a size that could shape waves in the head high plus range at the better spots on the incoming tide. Check the winds before you travel though – that swells 100% guaranteed (the storms run through already) but the winds can change.

South facing coasts (Wales, Cornwall and Devon) also see the peak of the swell with continued offshore winds although a tendency for more westerly airflow further north could cause conditions to deteriorate at many Welsh spots. The swell size is relatively modest and at an angle that takes a good deal of the power out but the odd more southerly set should show waves in the chest plus range at better exposures. We’d expect this swell to sneak up the channel to the best exposed spots and reefs further up the coast although we’d not expect a great deal of size.

Again the North East facing coasts see good conditions with a mid sized, mid period swell and offshore winds all day.

Monday 9th

The game changes considerably on Monday on the latest models. The high pressure that’s been responsible for that NW air flow moves further west allowing a large developing low pressure to start sending us a familiar pattern of strong south westerly winds and associated wind waves. For North Cornwall it’s touch and go that this swell will be big enough for the spots normally used as shelter from a strong SW wind. For North Devon likewise the real wrap around SW sheltered spots are definitely not going to see much action from this swell, best bet is the limited shelter of Putsborough and an acceptance of short period swell and brisk cross/onshore wind.

South facing coasts take a direct hit from that wind, with larger wind swell and strong onshore conditions frustrating anyone hoping to catch the last of the ground swell. Further up the channel from Dorset and Bournemouth all the way through to the recently wave starved beaches of the Witterings and Brighton have reason for cheer – with strong onshore never dampening the spirit of those reliant on it for the bulk of their wind swell diet.

North east sees dying swell with strong offshores kicking the last of the life out of it.

Bit of back to basics for many but we know a lot of keen surfers still feel less than confident with understanding swell direction*. We’ve written a little example of reading swell direction on your surf forecast that talks about the importance of this for understanding the surf  (there’s plenty more to add – it’s a critical part of the forecast) but before you can even do that you need to get to grips with the terminology. This diagram is a nice illustration to understand the relationship between degrees and the compass points. On MSW we always talk about swell and wind directions as the direction they come FROM. So a South West swell is coming from the South West (and heading to the North East) and you can see from the diagram that the angle would be 225 degrees (numbers on the outside edge). Bear in mind there’s no hard and fast convention on this, most surf forecasters do the same but you will find information using different systems elsewhere on the web.

North Swell (0 Degrees) = Heading South

East Swell (90 Degrees)  = Heading West

South Swell (180 Degrees) = Heading North

West Swell (270 Degrees) = Heading East

So back to a MSW forecast – you can see the swell direction arrows (ringed red in this example). These arrows point in the direction the swell is heading TO, in this case TO the South East – so the swell is coming FROM the North West or 315 degrees so we call it a North West swell. To get the precise swell direction from your MSW forecast just hold your mouse over the swell direction arrow and we’ll give you the reading in degrees.

*Same direction convention applies to wind as well as swell.

The back story to this swell is almost as interesting. Early in March the US experienced severe weather conditions as warm air from the Gulf of Mexico hit a cold front over the mainland. The storm system created wreaked havoc across the tornado belt. Forecasters are already talking about this storm as one of the worst in history for this time of year, with 45 comfirmed tornadoes and a further 77 reported. This same system continued to roll north bringing a late season spell of winter weather to the northern US.  Moving over Eastern Canada the storm system split briefly before gathering strength over the ocean and heading north towards Greenland. At the same time a second, weaker, storm developed over Florida and moved up the coast and into the Atlantic.

What happened next was a combination of (for Irish surfers) extremely favourable conditions. The jetstream, the path of strong upper atmosphere wind responsible for the strength and development of sea level storm systems, itself decided to cooperate and a powerful, sustained SW flow deepened the second system and sling shot it at such an angle to join forces with the first storm extending it’s power and, most importantly, size.

At this stage on wednesday 7th March the storm created had westerly gale force winds extending for over a 1000 miles of ocean pointing at Ireland and Scotland. Crucially a phenomena known as the Greenland Jet Tip exaggerated the inital storms power. The topography at the tip of Southern Greenland creating a funnel of extremely strong westerly winds. This effect has created this stretch of oceans deserved reputation as the windiest on the planet. No bad thing for Northern European surfers.

This next image shows the development of the swell. You can clearly see the influence of the Greenland Jet Tip in creating the largest waves. The other interesting facet of this chart is the location of the swell. The circle lines define the typical window for big waves swells hitting Mullaghmore. You can see from the charts that this swell came in right in the northern edge of this window. Mully is a typical point break in many ways, as swell wraps around the headland it loses size and power and the further south a swell originates the more this is an issue. However there’s a cut off for the benefits of north in the swell with too much of a Northerly direction causing waves to section and closeout. At 297 degrees at it’s peak on arrival this swell flirted with the northerly edge of the optimum window and in doing so allowed the maximum possible ridable wave size to be realised from this huge swell.

We’ve been working hard to improve our swell charts recently. One of the major developments we’ll put live shortly is a new colour scheme to give greater clarity to exceptional swells. This extends the range from dark red, through on into purple and ultimately grey to black for the very most exceptional swells. This swell is one of the occasions where this change came into it’s own:

The same Jetstream track that worked so well for that second system encouraged this storm to continue to the North of Ireland. The result might have been slightly smaller waves (the coast of Scotland scored the full brunt) but did mean the local winds were nothing like as strong as have been seen on previous storms and from a favourable SW direction. The results? Waves like this:

So just how exceptional was this swell? Combine the size of the swell, with those contestable local winds and a swell direction giving maximum impact on the reef and there’s nothing quite like it in our archive. Checking the records we’re looking at storms in the size range about 5 times in a decade (most recently the tow comp near miss of the 13th December 2011). Ignoring the ones that arrive with storm force winds (the issue with Decembers swell) and you’re talking about 3 times a decade historically.

The other exciting aspect of this swell, from our perspective, is that it actually cropped up in the MSW forecast models over a fortnight ago. As we headed towards the end of the Billabong Tow Comp window we had a catch up with contest organiser Paul O’Kane, we discussed the poor outlook towards the end of the window but did mention a hint (and it was just a hint at this stage with a large swell showing as a modest probability on our 16 day forecasts) of this storm in the outlook*. Quite sensibly Paul had to take a view to the logistical and safety aspects of extending the window for such a possibility which made it impossible in this case.

* Operational 16 day forecasts will be available publicly on MSW shortly.