Playbuoy Nowcast: Machine Learning Meets Real-Time Buoy Data

Wave models track storms across the ocean and estimate when wave energy will arrive at your coast. But the actual size often misses: a forecasted 6-foot day shows up as 4 feet, or a swell arrives hours early. Playbuoy's new Nowcast model closes that gap.

How It Works

The Nowcast is built around the full directional wave energy spectrum, the 2D picture of wave energy across frequency and direction, rather than scalar summaries like significant wave height. Working in this native space is what lets us keep the architecture simple and most importantly, the output is itself a full spectrum in the same format Playbuoy ingests from every other wave model. This means all of our advanced downstream analysis (swell partitioning, spectrum comparison, etc) continues to work with our custom model.

We rely on the Earthmover platform to reliably prepare and version our training data for this model with icechunk. Versioning our training data allows us to confidently update and scale out our training datasets to include more history and stations.

Under the hood, the model reads the past six hours of buoy observations alongside the matching GFS-Wave output, looks ahead at the next six hours of GFS forecast so it can see incoming swells before they reach the buoy, and emits an hourly correction to GFS-Wave across the whole spectrum in a single forward pass.

Performance

Across a 31-day backtest over six buoys on both coasts, the Nowcast cuts GFS-Wave's mean absolute error on significant wave height roughly in half. At the one-hour mark the model's MAE is 0.33 ft against GFS-Wave's 0.89 ft, a 63% reduction. By six hours out the margin narrows to 36% as forecast uncertainty grows with lead time, similar to how ensemble spread widens out, as discussed in Seeing the Spread: GEFS Ensemble Forecasts.

The biggest wins show up on stations where GFS-Wave carries a persistent bias. The Nowcast picks that bias up from the live buoy signal and corrects for it in real time, so the forecast tracks what the buoy is actually seeing.

Supported Stations

The Playbuoy's Nowcast is currently available for some of our most popular stations:

• 44097: Block Island, RI
• 44008: Nantucket Shoals
• 44011: Georges Bank
• 41002: South Hatteras
• 46013: Bodega Bay
• 46026: San Francisco
• 46218: Harvest, CA

Support for more stations is coming, and if your favorite buoy is not listed contact us at matt@playbuoy.app

In the app, the Nowcast is visible with a dashed line in the forecast chart. As you select a future time on the dashed line, the wave information for the Nowcast model will display in comparison with the main wave model.

Try it out on the web, iOS, or Android and let us know what you think.