Observed wind: a live wind reading from one of our weather stations feeding us realtime data.
Forecasted wind: a wind reading driven by the GFS global wind model.
Predicted wind: a corrected/updated wind forecast based on the history of observed wind readings and the GFS forecasted wind.
What is Live Wind?
Wind forecasts on Surfline (like the one screenshotted below) are driven by the GFS global wind model.
Global models take large-scale factors (such as the ocean and the dynamics of the atmosphere) into consideration. Small-scale phenomena such as thermal sea breezes, air interacting with topography, or localized temperature differences near the coast can have a significant impact on surf quality. Small-scale phenomena are potentially missed by the GFS global wind forecast. This is where Surfline’s Live Wind readings come in handy...
How to know if you're looking at Live or modelled wind?
Look for the red dot! A red dot & live wind button indicate the wind is live. Click the Live Wind > button to dive in.
The Live Wind > button
Live wind options: switch between the Bar Graph and Line Graph.
If you click the Live Wind > button, you'll be taken to a page with 2 different chart options to interpret the data: the Bar Graph and the Line Graph.
The Bar Graph view (screenshot below) helps you determine whether the wind recorded by our live station is onshore or offshore. Use this to identify when wind conditions will be detrimental or beneficial to the surf quality. Great for planning when you'll surf during any given day.
How to read: bars reaching downwards into the onshore half are bad for surf quality. Bars reaching upwards into the offshore half are good for surf quality. Look for windows with bars reaching into the offshore half (or for smaller bars in the onshore half).
The data below the graph. Arrows represent wind direction/strength. The black number below is average windspeed, and the grey number is the gusting windspeed. The colored line below represents the rating* we have assigned for the hour of the day, and the grey numbers at the bottom show 12 am, 3 am, 12 pm, etc..
*see this article for guidance: Surf Conditions Ratings and Colors
The Line Graph's main purpose is to help you see how the GFS wind model is performing against our live readings.
The below video shows an example of how the observed wind peaked earlier than the GFS model had forecasted. The colored/dotted line into the future shows our predicted wind forecast, based on a blend of recorded live observations and the GFS forecast. In the below case, we predict afternoon winds to be lighter than forecasted. The colored/dotted line sits below the grey line until around 6 pm.
What do the size of the bars in the onshore/offshore chart represent? Bar height is a measure of impact. For example, direct onshore 10 knot wind will appear as a taller bar than wind blowing at the same strength but at an angle to onshore. Cross shore wind appears as a point on the axis (neither onshore nor offshore).
Why is the red "Live" dot grey? Just like with our cams; wind stations can experience technical difficulties. If the dot is grey, it means the spot normally has Live Wind, but the station is down and we are showing forecasted (GFS) wind instead.
Where is the weather station providing the data mounted? From a spot with live wind; hit the Live Wind button to open the graph page. Just below the Live Wind title, we note the station's location and distance from the surf spot.
Why is the dotted line showing in the past? This means the station has probably dropped offline, and is no longer providing observations
How do I know if I'm reading Live Wind, GFS modelled wind, or our prediction based on the live data we're recording?
- Live wind is noted as "Observed".
- We call GFS wind (that drives spot/regional pages) "Forecasted".
- We call the GFS forecasted wind corrected by our live wind observations "Predicted".
As you slide your finger through any day, you'll see the GFS modelled wind remains "Forecasted". Our Live Wind will show "Observed" for any readings recorded in the past, and "Predicted" for any moment in the future.