Meta Surf Forecast

• Purposes
• Developer Setup
  • Prerequisites
  • Steps
  • Tips
• Adding Spots
• Data Sources
  • Surfline
    • New API (v2)
      • Responses
      • Requests
    • Old API (v1 - no longer supported)
  • Spitcast
  • MagicSeaweed (no longer supported)
• The Magic
  • Surf quality ratings
  • Timestamps
• TODO

Purposes

1. Display a chart of approximate wave height (swell height * period * 0.1) for the last 24 hours from NDBC Buoys
2. Query the Surfline & Spitcast APIs to display an aggregated surf forecast.

Developer Setup

Prerequisites

• ruby 3.3.x
• node 20.x
• yarn 1.x
• postgresql

Steps

1. Install dependencies using Homebrew: brew bundle
2. If on Linux: pg_ctl -D /home/linuxbrew/.linuxbrew/var/postgres start
3. gem install bundler -v=$(cat Gemfile.lock | tail -1 | tr -d " ")
4. bundle
5. yarn
6. cp config/database.yml.example config/database.yml
7. bin/rails db:create db:schema:load:with_data db:seed
8. Grab some data: bin/rails buoys:update forecasts:update
9. bin/foreman start -f Procfile.dev
10. Open http://localhost:5000
11. Any changes you make to view files will auto-reload the browser

Tips

• You will not get Surfline forecast data without a valid Surfline premium login. Add your credentials to .env.development:

  SURFLINE_EMAIL=xxx
  SURFLINE_PASSWORD=yyy
  

  Then run bin/rails forecasts:update again
• When running migrations, use bin/rails db:migrate:with_data to include Data Migrations

Adding Spots

Contributing new spots is easy! Make sure you're signed into your Github account and edit the seeds file:

1. Create a new Region/Subregion if necessary. For example, Los Angeles is created like so:

   CA = Region.find_or_create_by(name: 'California')
   LA = Subregion.find_or_create_by(name: 'Los Angeles', region: CA)
   LA.timezone = 'America/Los_Angeles'
   LA.save!

   You can get valid timezone names from this list.
2. Use this tool to draw a bounding box around the area you want to find spots for.
3. Choose CSV from the dropdown at the bottom & copy the coordinates string.
4. Run rails console, then run SpotFinder.new('{string}').formatted_spots.
5. Copy the output and paste it into the spots array in seeds.rb, then make sure to assign each spot to the right subregion & delete extraneous fields (msw_name, match_type, distance).
6. It's strongly encouraged to add all spots for a particular county or region rather than just a single one. Be a pal!
7. Submit a pull request and I'll get it on the site ASAP!

Use the following as a template. Delete the lines for surfline_v2_id, msw_id, etc, if that spot doesn't exist on that particular site.

  {
    name: 'County Line',
    lat: 34.051,
    lon: -118.964,
    surfline_v2_id: '590927576a2e4300134fbed8',
    msw_id: 277,
    subregion: LA,
  },

Data Sources

Surfline

New API (v2)

Responses

Surfline's new API is undocumented but easy to reverse engineer using their new website's code. Thankfully its structure is much more sane than the old API.

Requests

https://services.surfline.com/kbyg/spots/forecasts/{type}?{params}

For reference, I believe kbyg stands for "Know Before You Go," which is their tagline.

Type	Data
rating	array of human-readable and numeric (0-6) ratings
wave	array of min/max sizes & optimal scores
wind	array of wind directions/speeds & optimal scores
tides	array of types & heights
weather	array of sunrise/set times, array of temperatures/weather conditions

Param	Values	Effect
spotId	string	Surfline spot id that you want data for. A typical Surfline URL is https://www.surfline.com/surf-report/venice-breakwater/590927576a2e4300134fbed8 where 590927576a2e4300134fbed8 is the spotId
days	integer	Number of forecast days to get (Max 6 w/o access token, Max 17 w/ premium token)
intervalHours	integer	Minimum of 1 (hour)
maxHeights	boolean	true seems to remove min & optimal values from the wave data output
sds	boolean	If true, use the new LOTUS forecast engine
accesstoken	string	Auth token to get premium data access (optional)

Anywhere there is an optimalScore the value can be interpreted as follows:

Value	Meaning
0	Suboptimal
1	Good
2	Optimal

However, I have never seen a score of 1 in any of their API responses (only 0 or 2), which is unfortunate when it comes to granularity of ratings. Hopefully this changes in the future.

Old API (v1 - no longer supported)

Surfline's old API is undocumented and unauthenticated, but was used via javascript on their website, so it was fairly easy to reverse-engineer. However, they have updated their site & apps to use the new API, and it appears that they've stopped including some critical data in the responses for the old API, so it's disabled in this app for now (and probably forever).

It returned JSON, but with a very odd structure, with each item that is time-sensitive containing an array of daily arrays of values that correspond to timestamps provided in a separate set of arrays. For example (lots of data left out for brevity):

"Surf": {
  "dateStamp": [
      [
        "January 24, 2016 04:00:00",
        "January 24, 2016 10:00:00",
        "January 24, 2016 16:00:00",
        "January 24, 2016 22:00:00"
      ],
      [
        "January 25, 2016 04:00:00",
        "January 25, 2016 10:00:00",
        "January 25, 2016 16:00:00",
        "January 25, 2016 22:00:00"
      ]
    ],
  "surf_min": [
      [
        2.15,
        1.8,
        1.4,
        1
      ],
      [
        0.7,
        0.4,
        0.3,
        0.3
      ]
    ],
}

Requests are structured as follows:

https://api.surfline.com/v1/forecasts/{spot_id}?{params}

This is a breakdown of the params available:

Param	Values	Effect
spot_id	integer	Surfline spot id that you want data for. A typical legacy Surfline URL is https://www.surfline.com/surf-report/venice-beach-southern-california_4211/ where 4211 is the spot_id. You can also get this from a v2 API response's legacyId property.
resources	string	Any comma-separated list of "surf,analysis,wind,weather,tide,sort". There could be more available that I haven't discovered. "Sort" gives an array of swells, periods & heights that are used for the tables on spot forecast pages. To see the whole list, just set 'all'.
days	integer	Number of days of forecast to get. This seems to cap out at 16 for Wind and 25 for Surf.
getAllSpots	boolean	false returns an object containing the single spot you requested, true returns an array of data for all spots in the same region as your spot, in this case "South Los Angeles"
units	string	e returns American units (ft/mi), m uses metric
usenearshore	boolean	The best that I can gather, you want this set to true to use the more accurate nearshore models that take into account how each spot's unique bathymetry affects the incoming swells.
interpolate	boolean	Provide "forecasts" every 3 hours instead of ever 6. These interpolations seem to be simple averages of the values of the 6-hour forecasts.
showOptimal	boolean	Includes arrays of 0's & 1's indicating whether each wind & swell forecast is optimal for this spot or not. Unfortunately the optimal swell data is only provided if you include the "sort" resource - it is not included in the "surf" resource.
callback	string	jsonp callback function name

Spitcast

Spitcast has a documented API.

I've also asked Jack from Spitcast a few questions and added his responses below:

• Why does the site show a size range, but the API only returns one size value?

  I actually take the API number and create the max by adding 1/6 the height (in feet), and then create the min by subtracting 1/6 the height."

• All possible values for shape:
  • Poor
  • Poor-Fair
  • Fair
  • Fair-Good
  • Good

MagicSeaweed (no longer supported)

MagicSeaweed was acquired by Surfline an shut down in 2023. Prior to this, MagicSeaweed had a well-documented JSON API that required requesting an API key via email. This was a straightforward process and they got back to me quickly with my key.

I've asked MagicSeaweed a few questions and added their responses below:

• "Our API provides 5 days of forecast data, with segments of data provided for each 3 hour interval during that 5 day time span."
• "Our data is updated every 3 hours."

The Magic

Surf quality ratings

All of the forecasting services (including Surfline v1 vs v2) use different systems for rating waves. I've attempted to normalize them all to a 0-5 (6-point) scale as best as possible, which is perhaps easier to understand when mapped onto the commonly-used Poor-Good scale (some throw Epic in there at the top end, but I went with Very Good):

• 0 => Poor
• 1 => Poor - Fair
• 2 => Fair
• 3 => Fair - Good
• 4 => Good
• 5 => Very Good

Each forecasting service is massaged onto that scale as follows:

• Surfline v2: "Seven point" decimal ratings (0-6). These are massaged by multiplying by 5/6 to get a 0-5 scale.

• Spitcast: ratings in text form:

  • 0.0 => Poor
  • 0.5 => Poor-Fair
  • 1.0 => Fair
  • 1.5 => Good

  These are massaged by multiplying by 5/1.5 (essentially 3.3̅) to get a 0-5 scale.

For record-keeping, these are the formulae for formerly-supported services:

• MagicSeaweed: integer fadedRating (0-5) & solidRating (0-5). I simply subtract fadedRating (which is essentially the negative effect of wind) from solidRating.
• Surfline v1: decimal ratings (0-1) for up to 6 different swells at each spot, as well as an optimalWind boolean. I take the max swell rating at any given time for that spot, multiply it by 5, and then halve it if the wind is not optimal.

Timestamps

It took me a long time to land on a solution here, but I've finally settled on storing all timestamps in the database in the spot's local time. This defies Rails convention, but makes intuitive sense. If you pull up the forecasts table and look at the timestamp, that's the actual local time at that spot that it's forecast for (even though Rails & Postgres both think it's being stored in UTC). This is typically the format that the forecasting service gives it to us in, and what users want to see it in, so there's no point in doing all sorts of fancy conversion when it should be the same all the way through the pipeline. Now, you may ask, why am I still using the Rails default of TIMESTAMP WITHOUT TIMEZONE, and the answer is that shockingly enough, TIMESTAMP WITH TIMEZONE doesn't actually store timezone data!

TODO

• Use SoFar API to get data from additional buoys
• Figure out a way to convey forecast certainty in charts (ie: most forecasts are in agreement, or they disagree by a wide margin)
• Explore lazy-loading components
• Explore SSR for possibly faster browser paint
• Fetch & display tide/wind/water temperature data from NOAA (they actually have a decent API!)
• Update Surfline v2 API to use their new 7-point rating scale
• Improve charts:
  • Fix timestamp formatting.
  • Account for min/max size forecast. Currently charts just reflect the max.
  • Display forecast quality ratings. Perhaps color each bar different depending on how good the rating is. Surfline also has an optimal_wind boolean that is being crudely integrated into the display_swell_rating method - improvements welcome.
• Fetch & display recent buoy trends that are relevant to each spot to give an idea of when swell is actually arriving.
• Refresh data on a schedule based on when new data is available (refreshing all forecast sources hourly)
• Support multiple timezones as opposed to Pacific Time only
• New Surfline API
• Stop manually seeding the db and figure out a way to pull all spots from each data source and automatically associate them to a canonical spot record (probably using geocoding)
• Dark Theme
• Remove asset pipeline & process CSS w/ webpacker