Thursday, March 11, 2010

Southern California Long-range Surf Forecast – 3/11/2010

Forecast Overview

Cleaner conditions and fading swell will hold into Friday. New round of NW windswell and some increasing WNW-NW/S-SW background swell helps to increase wave heights on Saturday and eventually peaks on Sunday. More WNW-NW swell and more Southern Hemi swell on tap for the middle of next week.

Short Range (next 4 days)

The NW/SW swell mix will back off slightly on Friday…but conditions should hold together to keep us in small but playful surf at the exposed breaks. Look for knee-waist high waves for most of the average breaks with some chest high sets still sneaking into the best combo breaks. The standout NW facing spots will be more in the waist-chest high range with a few chest-shoulder high sets if the beach has some SW exposure to mix things up. Winds/Weather: Winds will be light and variable in the morning with some areas of light offshore flow. Look for variable onshore winds in the afternoon…mostly below the 10-12 knot range.

Another weird, early spring cold front is supposed to push through Central California and in the process drive up another pulse of steeply angled NW windswell (290-300) that will start moving in on Saturday. This NW windswell will mix with some smaller WNW-NW leftovers and some smaller less consistent S-SW swell (190-220). Most spots can expect surf in the knee-waist high+ range with some chest high+ sets sneaking in on the lower tides. The standout NW facing breaks and excellent combo spots, mostly in Ventura, the South Bay, and Southern SD, can expect more chest-shoulder high surf with some inconsistent head high sets. Shape should be ok for the morning but increasing NW winds may hamper things through midday and on into the afternoon. Winds/Weather: Right now it looks like Saturday morning should be fairly clean…sort of light/variable to light N winds on tap for most areas…maybe a couple of pockets of texture but surfable for the most part. NW winds 10-15 knots build in through lunchtime and we can expect NW winds 10-20 knots hitting by late in the afternoon.

We get some new WNW-NW swell (285-300) moving in…this will be a mix of local NW windswell and some medium-period (12-15 second periods) that will peak Sunday morning while a smaller, less consistent S-SW swell (190-220) mix holds in the background. Look for the average WNW-NW facing spots to build into the waist-shoulder high range. Standout NW facing breaks and the excellent combo spots will be in the chest-head high range and it looks like a few of the best San Diego NW breaks will see some overhead sets. Winds/Weather: The cold front is supposed to be on the way out on Saturday night and high-pressure is forecast to build back in on Sunday. If reality lives up to forecasts…we should have some N-NE winds setting up for Sunday morning…mostly below 10-knots and semi-variable in a few areas. So basically we can expect clean conditions, even slightly offshore flow for the morning and then moderate N-NW winds around 10-15+ knots for the afternoon.

The surf drops off on Monday as the WNW-NW energy and the small SW swell fade out. Still some rideable waves sneaking around at the best exposed spots but we can expect it to be pretty small for the most part. Look for the average spots to back down into the knee-waist high range while the standout spots see some chest high sets. Winds/Weather: Conditions look really good for Monday…light offshore in the morning and then just variable/semi-onshore in the afternoon…with winds staying below 10-12 knots for most of the day. The beach temps are going to go way up…probably hitting the mid- to upper-70’s in some areas. Hell yeah summer is just around the corner!


North Pacific
The NPAC is still holding onto some leftover winter energy, but you can definitely tell that it is flagging compared to even a few weeks ago. Right now we have a tightly wound low just off the coast of British Columbia that, back in the backside of the low, is setting up some WNW-NW swell (285-300) for the weekend…it will also drop a cold front down the California Coast on Saturday that will help spin up some local NW windswell (290-300) that will peak on Saturday night and hold into Sunday. Both of these swells will set up some waist-shoulder high surf for the average NW facing spots this weekend…and probably some head high+ sets at the standout NW breaks, mostly in Ventura, the South Bay, and Southern San Diego.

Further out there is still at least one more decent looking storm left in the NPAC arsenal…it is forecast to form in about 2-3 days…setting up just on the western edge of the Gulf of Alaska by Sunday morning. While the core of the storm is a little high in latitude it does set up some fetch down inside of Socal’s swell windswell. Check out the FNMOC charts that I usually use for some of my forecasting…this is a little weather nerdy so feel free to skip ahead to the surf stuff…WEATHER NERD ALERT.

All of these charts are showing the same time-period…Sunday Morning around 4-5am. I like to look at the Sea-Level-pressure charts (generated by the GFS weather model) to establish the wind direction and the core elements of the fetch. The isobar lines between the high/low pressures indicate a pressure gradient…and the more lines, packed tighter together, mean stronger winds. Generally winds follow almost directly along these lines…so if they line up, pointed your direction inside your swell window, it is a good thing. I use a chart like this to determine the position of the storm, the size of the fetch, the intensity of the winds, and the swell-direction spread (that you don’t really get just looking at a wave model).

The second chart is the 10-meter wind forecast…basically this means that it is using the GFS model to show the forecast winds occurring along the surface (10-meters and below). Since we need wind actually blowing along the surface of the water this is pretty much the only “storm winds” that matter. The

This chart isn’t all that useful to me, mostly because the resolution is pretty poor (I usually look at the 10-meter winds in a much tighter view…like the COAMPS charts that I show you guys for local Socal winds), but it is a great tool for you guys that want to do a little forecasting yourselves…if you look at the Sea-level-pressure chart and the 10-meter wind chart for the same time periods you will start to get a feel for how the lows behave, what you can expect with particular pressure gradients, and how they change at the different latitudes.

The final chart is one that most of you are pretty familiar with…it is the WavewatchIII significant sea-height chart…it is generated using the same sort of atmospheric models (the GFS/Ensemble model in this case) that are used to generate the other charts. While this is a good chart to look at by itself you can learn a lot more by looking at it in tandem with the SLP and 10-meter wind charts. One of the biggest things you can see is how the sea-state is reflective of the wind…normally, when seas are big, it is because the wind/storm is right on top of that stretch of water, occasionally though you can see a large lump of swell that has left the “storm area” and is en-route to somewhere else (hopefully Socal or your various vacation destination of choice). I use this chart and the variation where I can see the dominant swell-period (rather than the sea-height) to track the large-scale behavior of storms and swell while they are in deep water.

Anyway…I thought you guys might like to see a few of the forecasting elements that I am currently using to generate these bad boys. You can find those charts here…just click through the “certificate warning” to get to the charts…


Ok back on track…those charts are cool…but I was overlooking the most important part, which is that they are going to set up some waves for next week. At this point it looks like the combo of winds/position of this storm is going push a new WNW-NW swell (285-300 but with most of the energy up around 290-300) our way for early next week. We can expect the initial portion of the swell, the long-period stuff, to start arriving through the second half of the day on Tuesday (Mar 16) and then the peak of the swell hitting Wednesday/Thursday (Mar 17-18). This swell mix looks good for waist-shoulder high+ surf for most WNW-NW facing breaks…with some overhead+ sets hitting the standout NW areas (Ventura, South Bay, and South SD)…it also looks like there might be some ok S-SW swell in the water and good weather…so it could end up being pretty fun by the middle of next week.

Even further out the storm track sort of sputters out after this last system…nothing significant showing on the long-range charts at this point.


South Pacific
Right now we can expect a mix of SSW-SW swells (190-220) that will filter through over the next few days with some inconsistent surf in the knee-waist high range for most SW exposed spots and some chest high sets at the standouts. By Thursday the shot of SW energy will pulse up a little more pushing average spots more into the waist-chest high range with some shoulder high waves at the standouts. These sizes with stick around into the weekend but then trail off a bit by early next week.

Further out there is a better storm that pulled together over the last couple of days that is sending swell for next week…this one looks a little better than the last few storms…with a more defined fetch that makes the south-to-north movement that we need to get a bit more energy from the storm. This new round of S-SSW swell (180-210) begins moving in on Tuesday (march 16) but looks like it will peak more Wednesday/Thursday (March 17-18). This one won’t be huge but I do expect some waist-chest high+ sets at the average spots and some shoulder high+ sets at the standout S facing breaks.

Next Long-range forecast will be posted on Monday, March 15th, 2010.

Adam Wright
Surf Forecaster

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