Tuesday, September 8, 2009

Waves for Wednesday – Still on the small side

Wednesday won’t be much of a surf day mostly due to lack of swell.

We are going to have a mix of NW windswell and inconsistent SW energy (200-220). Neither swell, even when combo’d up, will amount to much…add in a high tide through most of midday and you have a good recipe for near-flatness.



Wave heights are going to hold around knee high for most of the average exposed areas. The standout NW facing breaks and the really good SW/NW combo spots will be in the knee-waist high range with some rare (but still soft) chest high sets.

Winds look ok…sort of variable/eddy in the morning…lets just say light and variable but with a southerly tint to winds in the OC/SD areas. Generally it should be clean but there may be a pocket or two of texture. WNW winds 10-14 knots will move in through the afternoon.



Not much to ride tomorrow…but if you have to surf I would bring the micro-wave gear, and a really positive outlook on life...even the top spots are going to be a bit bogged down by the lack of waves and the building tide. If you are committed to surfing tomorrow no matter what…try and get on it early before the winds and the tide start to shut it down.

Here are the tides…

12:20AM LDT 3.5 H
05:35AM LDT 1.9 L
12:04PM LDT 5.3 H
07:33PM LDT 1.0 L

10 comments:

Anonymous said...

any outside chance of an evening glass off?



anyone know what the conditions are that cause an evening glass off? seems like we have had only a handful of them in the last year.



cheers

Anonymous said...

Adam - thanks for all the great work you do here. Read your blog religiously every morning.

Can you - or anyone else - explain why the high tide down here 'flattens' things out? Still learning the basics but logically I would just expect the break to move in further towards shore rather than flatten out.

Any insight appreciated!

- shane

Anonymous said...

take me back to Oz! yuck!

Anonymous said...

i'm not Adam but my theory on your tide question is that the extra water at your break when the tide is high will cause the waves to hit the sand bars closer to shore causing the waves to get fatter and not peak up like they do on a lower tide. When the tide is low and the waves hit the sand bar it doesnt have as much water on top of it before it gets to peak up.

Anyone else know what i'm talkin about? a little garage science i guess.

Anonymous said...

basically waves are able to peak up out of the water easier when there is less distance (water) between the sandbar/reef and the wave hitting it. the extra water at high tide boggs down the breaking waves

Adam Wright said...

Anon #1 - Evening Glass-offs are pretty rare for SoCal, at least in the majority of our areas/spots. Spring and Summer are notoriously bad for afternoon winds...though conditions for afternoon/evening sessions do improve as we head into late summer/early fall.

Glass-offs are also pretty difficult to foreacst because a lot of what drives the winds to lay-down in the evening are set up by how the weather/winds have been interacting throughout the day. Temperature variations between the ocean and the land are what drive the glass-off more than anything but there are a couple of other situations that can override those factors.

When it comes down to it you need either:

1. A weather system that is over-riding the "typical" conditions and somehow forcing light or offshore winds to develop at the end of the day. Things like the Santa Ana's or a passing storm front are good examples of what I mean.

Or...

2. You need a "land breeze" to form. This usually occurs when we have a very stable air-mass over Socal. What happens is that you need to have a temperature difference between the air over the ocean and the air over land...in this case you need to have the air over the water be warmer than the air over land. The warm air over the water rises, creating a vacuum along the surface of the water, which then sucks in the colder denser air over the land. You generally see a set up like this in the winter and the fall when you have high-pressure ridging over SoCal. The water is pretty warm, but due to the change in seasons, and shorter days, the land can cool pretty fast as the sun starts to set, developing that land-breeze.

There are a lot of other factors to consider as well...there are a handful of spots that like winds from the more adverse directions...spots that work on N-NW winds, or eddy S winds. Depending on the wind for the day they can stay a lot cleaner by having some protection...and then as the winds shift slightly as we head into the end of the day they can clean up a lot compared to other more exposed spots. Breaks that have high-cliffs or other land features that knock down the wind are more likely to clean up as well.

I guess the good news is that we are heading into the right season for the afternoon/evening sessions, so hopefully we will see a lot more of them.

--------------

Shane – All of you guys have pretty much hit the “tide” nail on the head.

For the tide affecting the surf...it is driven by water depth and how the wave’s energy is hitting the seafloor. Waves have energy that extends well below the ocean’s surface...and the energy reaches deeper as the swell-period increases. Waves start to break as the energy below the surface is forced up by the seafloor and slowed down by the friction...eventually the bottom of the wave is going slower than the top and the lip tumbles over forming the breaking action.

The shape of the wave is determined by how fast that seafloor/wave interaction occurs...the faster it occurs the more hollow and punchy the wave will be. (How much energy/size of the wave plays an important role in this as well.) Where the tide comes in...is that by adding more or less water to a surf spot changes the ratio needed for the wave to break. With more water the wave passes over the area it would normally break at, and in some cases (if the surf is small) then it will keep going until it reaches the right water depth for breaking. If the surf is larger, then the wave can bleed off extra energy trying the break on the outside, sort of standing up but not quite hitting the right depth. If you have a beach where the water depth drops drastically as you move away from the shore the high tide can be particularly brutal, basically turning a rideable swell into shore break.

Hope this helps!

Adam

Anonymous said...

Your the man Adam thanks for answering the evening glass of question so thoroughly................I feel like I learned so much about them yet still am baffeled by them!



Cheers

Anonymous said...

Makes perfect sense now - thanks Adam!

- shane

Anonymous said...

One more question - where would I find a bathymetry map of my local break (I surf in Venice)?

- shane

Adam Wright said...

Shane,

This is a good site to find those maps.

http://www.charts.noaa.gov/OnLineViewer/18748.shtml

That should open to the sea-chart for the one that covers Vience... You can find almost the whole west coast on these things.