Frequently asked questions
Common questions about Lakebrief's data sources, scoring, and coverage. Read the about page for the project overview.
Where does Lakebrief's data come from?
Wind and weather come from Open-Meteo, which serves several operational NWP models — NOAA GFS (default), NOAA HRRR, ECMWF IFS, DWD ICON, UK Met Office, and Environment Canada GEM. Water-level readings come straight from USGS Water Services for any lake with a public reservoir gauge. Active alerts come from the National Weather Service plus a 30-minute check of state-park advisory pages where the operating agency publishes them. Every value comes from a public agency feed; nothing is fabricated.
Which wind model should I use?
The honest answer is: check several and learn which one verifies best at your home lake. Models behave differently depending on local terrain, fetch, and how far you are from the nearest observation station. GFS is the default and a solid starting point — it covers every lake in the catalog and runs out to 16 days. HRRR is worth comparing for short-range US forecasts (it resolves finer detail and uses live radar data), but it only covers 48 hours. The more sessions you spend comparing what each model predicted against what the wind actually did at your spot, the faster you'll develop a feel for which one to trust and by how much.
Why does HRRR only show two days of forecast?
HRRR — the High-Resolution Rapid Refresh — has a hard 48-hour horizon by design. It trades range for resolution and data freshness: it runs every hour, assimilates real-time radar and surface observations, and resolves weather features at 3 km, but those choices make extending it beyond 48 hours computationally impractical. For anything beyond two days, switch to GFS or pull up a second model to compare. Seeing multiple models agree on a day-three forecast is a good sign; seeing them disagree is a useful signal to wait before committing to a plan.
How often is the data updated?
Wind and water-level readings refresh every five minutes in the browser. NWS active alerts refresh every ten minutes. The agency-page check (e.g. NJDEP advisories) runs every thirty minutes and saves a fresh snapshot when the content changes.
What is a 'sailing score' and how is it calculated?
It's a 0–100 number combining wind speed (40%), gust risk (25%), water level (20%), and rain (15%), tuned for small-craft sailing — boats under roughly 25 ft. Wind peaks at 8–14 knots; gusts above 22 kt sharply penalize; water level scales from full pool to historical low. A documented park-rule wind prohibition zeroes the score. The rationale line under the score names the dominating factor.
Why doesn't every lake show a water-level chart?
Some lakes don't have a public USGS gauge with real-time elevation data. Lake Norman (Duke Energy keeps the canonical record), Lake Dillon (Denver Water), and Lake Washington (USACE Seattle) all fall in this category — the dashboard hides the water-level card on those pages rather than show fabricated readings. Adding new data sources (Denver Water, Duke Energy, USACE district feeds) is on the roadmap.
Why is the wind-speed limit different for different lakes?
Some operating agencies publish a documented sustained-wind boating prohibition. New Jersey state parks, for example, prohibit boating once sustained wind reaches 25 mph (21.7 kt). Other agencies — USACE districts, Duke Energy, the City of Oklahoma City — don't publish a hard rule, so we use a soft 30 kt small-craft threshold (roughly the gale-warning band). Each lake's value is documented with a citation.
Is the wind score tuned for big keelboats or for dinghies?
Dinghies and small keelboats. The sweet spot is 8–14 kt; 17 kt sustained pushes the score down because most dinghies need to reef, and 19 kt is the upper end of useful for trapeze classes. If you're sailing a 35-foot cruiser the score will read low at conditions you'd consider fine. A per-lake sailing-profile override is on the Phase 2 roadmap.
Why is Lake Tahoe shown as 'CA' when it's on the CA/NV border?
Most of the surface area is in California and the operational USGS gauge is on the California side, so we group it under CA in the picker. The east shore is in Nevada. We don't currently group lakes under more than one state; if it becomes important we'll revisit.
Can I request a new lake?
Coverage expands periodically. New lakes are evaluated based on whether public data sources (USGS gauge, NWS forecast zone, agency advisory page) exist for the water body. If you'd like a lake added, send the lake's name and any known USGS site ID through the contact channel and it'll be considered for the next batch.
How do I trust this for actual sailing decisions?
Verify before launching. Lakebrief is a decision aid that reduces the work of pulling these numbers from five different agency websites; it isn't a substitute for the operating agency's official channels. Always cross-check the park's posted advisories at the ramp, the NWS marine forecast, and your own observation of the water before making a go/no-go call.