Be Your Own Surf Forecaster
Ocean swell and wind reports and surf
forecasting resources for the weather savvy
surfer
Apologies to Hokusai
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This site is for ocean people, surfers
generally and me in particular. It's a
collection of gadgets that help us visualize
marine weather. I started building these tools
in 1998 when I wanted to graphically see buoy
data in ways that weren't available anywhere
else. I've been improving and adding to the
tool set ever since.
I've started a
parallel site for people who want to build
something like this for themselves. I'll be
slowly posting papers that explain the techniques
and code I use. If you're a programmer check
out The Open
BuoyTools Project here.
If you have any comments or suggestions
about this site let me know at surfcast@pwizardry.com
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PLEASE READ THE SAFETY AND
COPYRIGHT NOTICE AT THE BOTTOM OF THIS
PAGE.
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Tides at the Golden Gate in feet for yesterday, today,
and tomorrow
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Predicted Golden Gate tides. The time of tides
for all our breaks outside the Gate are
earlier then Golden Gate times by about
40 - 80 minutes. See the table below
for more details.
Data generated by WXTide32, image
created by my Buoy_tool tool kit.
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Swell heights and periods with wind and spectrum images
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Blue bars height in feet, red bars period in
seconds, horizontal lines 5 units apart, "wind
birds" red beak points into the wind and
the number in the circle is wind speed in
knots. Grayed bars indicate hours of missing
data that are filled in by the Buoy_tool
software. See below for a
discussion of the spectrum images.
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GIFF images created with Buoy_tool.pm,
written by me in 100% pure Perl
The predicted Golden Gate tides are given for
yesterday, today and tomorrow. Yesterday so if
you went out and it got better of worse at some
point, you can look back -- could have been a
tide thing but check the buoy too. Tomorrow so
we can plan.
Data generated by WXTide32, image created by
my Buoy_tool tool kit.
Time Differences for Nearby Tides
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Location
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High
Tide
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Low Tide
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Point Arena
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-0:42
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-0:21
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Fort Ross
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-0:51
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-0:30
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Point Reyes
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-0:50
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-0:26
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Ocean Beach
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-0:49
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-0:35
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Half Moon Bay
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-1:06
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-0:50
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Santa Cruz, Monterey
Bay
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-1:15
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-0:58
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Use this table to correct Golden Gate tide
times for nearby locations. The time of tides
for all breaks outside the Gate are
earlier then Golden Gate times (i.e. all
the correction factors in this table are
negative). As a rule of thumb, if you surf
Ocean Beach or north of the bay remember that
the tides are about 40 minutes earlier then the
Golden Gate and you'll be close. If you go
south of Half Moon Bay think an hour.
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The wind reports are extracted from the excellent wind
model "SAN FRANCISCO BAY WIND PATTERNS" at http://sfports.wr.usgs.gov/wind/wind.html.
Note that these are modeled winds based on
current observations at about 20 weather stations
scattered around the greater Bay Area. None of these
breaks (other than Fort Point) have networked wind
sensors. Also, at the time this page is updated these
wind observations can be 15 to 45 or more minutes old.
This is about the best that can be done on an automated
page like this. (Of course, we could put in our own
network of wind sensors like the windsurfing guys do --
Funding anyone?). Enjoy.
This is my winter buoy pattern.
The SE Papa Buoy 46006 is about 24 hours out for a 20
second North Pacific swell heading towards the
Northern California beaches. Shorter period swell
components will take longer with 13 second swells
taking about 40 hours. The California Buoy 46059 is
about 12 hours out and San Francisco 46026 is just an
hour or so out.
Drop me an e-mail and let me know what you think at
surfcast@pwizardry.com
About the Swell Spectrum Images
In the swell spectrum images, the bar height for each
hour is the sum of swell height in feet and dominant
period in seconds just like the the images above
them. The colors show the mix of wave lengths in the
swell with the size of each color proportional to the
energy in that band. A powerful, clean ground swell
will have most of its energy at the red, long period
end of the spectrum. The faster moving long waves
will be the first to arrive from a distant storm with
shorter waves coming later as the swell tapers off.
Local wind swell will add cooler colors to the mix.
This version of the software uses 33 colors to
display the 33 bands in the the raw buoy data. This
makes a pretty picture but as surfers we're more
interested in periods above about 12 seconds. When I
revisit this part of the project I want to try to re
map the data to favor the longer end of the spectrum
and use fewer colors so the changes in the bands will
be clearer. For now I'll be interested to see what
this display will do as different swells roll
through.
Buoy locations in the Eastern Pacific
 The map to the right is a
detail from the blue rectangle in the map
above. Red indicates buoys used in the above
graphs
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Development notes (mostly
geek speak and safe to ignore...):
PLEASE READ THIS SAFETY AND
COPYRIGHT NOTICE:
The information on this page is gathered
from sources beyond my control but the
representations of the data are generated by
programs created by me for my use and our
enjoyment. Everything on this site is
copyright protected © by Frank Cox and
Practical Wizardry. I'll be as careful as I
can be to publish accurate reports but I
can't guarantee them. Ocean sports contain
an element of risk and it's up to you to
surf safe.
In other words, you can't sue
me if you get hurt, no matter what you
see here.
(Not that I think you would, but
it's a weird world out there!)
And, you can't use my images
or other works without asking me. Enjoy
them here. (But do ask, I usually say yes.)
Thanks, -- Frank Cox
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Comments and questions: surfcast@pwizardry.com